SRF2023 - Table of Session: WEPWB (Wednesday Poster Session)

Paper	Title	Page
WEPWB001	Preparation and Characterization of Nb Films Deposited in SRF Cavity via HiPIMS	651
	P. He, J. Dai, H.C. Duan, J.W. Kan, Y. Ma, T. Xin, Y.C. Yang, P. Zhang IHEP, Beijing, People’s Republic of China
	The RF performance of the niobium superconducting cavity has been continuously improved in recent 50 years. Since the maximum acceleration field (E_acc) has approached its theoretical limit, developing a more efficient and low-cost SRF cavity is one of the key challenges of the next generation particle accelerators. Niobium coated copper cavities are promising solutions because the SRF phenomenon occurrs within several hundred nanometers under the cavity surface. In literatures, the Nb coated Cu cavity prepared by direct current magnetron sputtering (DCMS) has serious Q-slope problem, which may be related to the low energy deposition. High power impulse magnetron sputtering (HiPIMS) can produce a high peak power and high ionization rate which may improve the thin film quality. Therefore, we prepared Nb coated Cu samples via HiPIMS on the 1.3 GHz dummy cavity at IHEP.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB001
About •	Received ※ 15 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 20 August 2023
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WEPWB043	Nb₃Sn Vapor Diffusion Coating System at SARI: Design, Construction, and Commissioning	655
SUSPB038	use link to see paper's listing under its alternate paper code
	Q.X. Chen, Y. Zongpresenter SINAP, Shanghai, People’s Republic of China J.F. Chen, S. Xing SARI-CAS, Pudong, Shanghai, People’s Republic of China J. Rong SSRF, Shanghai, People’s Republic of China
	This paper describes the design of a coating system for the preparation of a superconducting radio-frequency cavity with Nb₃Sn thin films. The device consists of a coating chamber made of pure niobium, a vacuum furnace for heating the coating chamber, a superconducting cavity bracket and two crucible heaters. The chamber is vacuum isolated from the furnace body to protect the superconducting cavity from contamination during the coating process. The device has been built and commissioned, which could be used for Nb₃Sn coating of a 1.3 GHz single-cell superconducting cavity in future.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB043
About •	Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 08 July 2023
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WEPWB044	Realization of Accelerating Gradient Larger than 25 MV/m on High-Q 1.3 GHz 9-Cell Cavities for SHINE	658
SUSPB039	use link to see paper's listing under its alternate paper code
	Y. Zong, Q.X. Chen, X. Huang, Z. Wang SINAP, Shanghai, People’s Republic of China J.F. Chen, P.C. Dong, H.T. Hou, X.Y. Pu, J. Shi, S. Sun, D. Wang, J.N. Wu, S. Xing, S.J. Zhao, Y.L. Zhao SARI-CAS, Pudong, Shanghai, People’s Republic of China Y.W. Huang ShanghaiTech University, Shanghai, People’s Republic of China X.W. Wu Zhangjiang Lab, Shanghai, People’s Republic of China
	Funding: This work was supported by Shanghai Municipal Science and Technology Major Project (No. 2017SHZDZX02). We present our studies on the optimized nitrogen-doping and medium-temperature baking recipes applied on 1.3GHz SRF cavities, aiming at meeting the requirements of the SHINE project. The optimized nitrogen-doping process resulted in achieving a Q₀ of over 4.0×10¹⁰ at medium field and a maximum accelerating gradient exceeding 35 MV/m on single cell cavities, and a Q₀ of over 2.8×10¹⁰ at medium field and a maximum accelerating gradient exceeding 26 MV/m in 9-cell cavities. For 1.3 GHz 9-cell cavities subjected to medium-temperature baking, Q₀ values exceeding 3.5×10¹⁰ at 16 MV/m and maximum accelerating gradients surpassing 25 MV/m were achieved. These studies provide two options of high-Q recipes for SHINE cavities. The treatment processes of cavities and their vertical test results are described in this paper. *chenjinfang@sari.ac.cn
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB044
About •	Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 26 June 2023
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WEPWB045	The Oxidizing Responses of Baked Niobium Exposed to Various Gases via In-situ NAXPS	662
SUSPB040	use link to see paper's listing under its alternate paper code
	Z.T. Yang, J.K. Hao, K.X. Liu, S.W. Quan PKU, Beijing, People’s Republic of China
	We carried out in-situ NAXPS (Near-atmospheric X-ray Photoelectron Spectroscopy) on SRF-cavity class niobium to observe its oxidizing responses when exposed to various gases. The niobium samples were baked at 800°C until the peaks of niobium oxides disappeared in the spectrum. Then the revealed pure niobium samples were exposed to the air-proportion mixture of nitrogen and oxygen, pure oxygen, and pure water vapor respectively. And for the pure oxygen and water vapor group, we also carried out TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectroscopy) measurements before and after the baking and oxidation experiments. We found that pure oxygen and water vapor could oxidize niobium at similar rate which was faster than the N2/O2 mixture. After re-oxidized by pure oxygen and water vapor, the niobium sample presented a significant increase of interstitial carbon and a moderate increase of interstitial oxygen in the magnetic penetration depth, while it showed a mild decrease of interstitial hydrogen.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB045
About •	Received ※ 15 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 25 June 2023 — Issue date ※ 31 July 2023
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WEPWB047	Higher Order Mode Analysis of a 915 MHz 2-Cell Cavity for a Prototype Industrial Accelerator	667
	A. Castilla JLAB, Newport News, USA G. Ciovati, J. Guo, G.-T. Park, R.A. Rimmer, H. Vennekate JLab, Newport News, Virginia, USA
	A possible solution to reduce the complexity posed by the cryogenic systems in a superconducting RF accelerator for industrial applications, is to capitalize on the advances achieved by the Nb₃Sn superconducting RF technology, as well as the feasibility of a reliable 4 K cooling system, based on commercial cryocoolers. Following this philosophy, the conceptual design for a prototype, conduction-cooled, 4 MeV, 20 kW SRF electron linac, is being developed at Jefferson Lab. Such design is based on a 915 MHz two-cell Nb₃Sn cavity. In this contribution, we present the proposed cavity design, including the fundamental power coupler, and the preliminary analysis of the Higher Order Modes, using numerical simulations to estimate the potentially dangerous modes as a starting point to evaluate the requirements for damping for reliable operations with a cryocooler. Finally, different methods to calculate the Higher Order Modes’ Impedances are briefly discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB047
About •	Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 16 July 2023
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WEPWB048	Geometry Optimization for a Quadrupole Resonator at Jefferson Lab	670
	S. Bira, M. Ge, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA L. Vega Cid, W. Venturini Delsolaro CERN, Meyrin, Switzerland
	Funding: This manuscript is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-6OR23177 with Jefferson Science Associates The quadrupole resonator (QPR) is a sample characterization tool to measure the RF properties of superconducting materials using the calorimetry method at different temperatures, magnetic fields, and frequencies. Such resonators are currently operating at CERN and HZB but suffer from Lorentz force detuning and modes overlapping, resulting in higher uncertainties in surface resistance measurement. Using the two CERN’s QPR model iterations, the geometry was optimized via electromagnetic and mechanical simulations to eliminate these issues. The new QPR version was modeled for an increasing range of magnetic fields. The magnetic field is concentrated at the center of the sample to reduce the uncertainty in surface resistance measurements significantly. This paper will discuss the QPR geometry optimization for the new version of QPR, which is now progressing towards fabrication.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB048
About •	Received ※ 19 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 21 August 2023
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WEPWB049	Multipacting in C75 Cavities	674
	G. Ciovati, P. Dhakal, R.A. Rimmer, H. Wang, S. Wang JLab, Newport News, Virginia, USA
	Funding: This work was supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Cavities for the C75 cryomodule refurbishment program are currently being built, processed, tested and installed in the CEBAF accelerator at Jefferson Lab. They consist of 5-cell, 1497 MHz cavities with waveguide-type power coupler and for higher-order modes. Most of the cavities rf tests in a vertical cryostat at 2.07 K were limited by strong multipacting at accelerating gradients in the range 18 - 23 MV/m. A softer multipacting barrier was sometimes found at 13 - 15 MV/m. An unusual feature of the multipacting was that the barrier often shifted to a lower gradient ~17 MV/m, after multiple quenches at ~20 MV/m. This phenomenon was reproduced in a single-cell cavity of the same shape. The cavity was tested after different amounts of mechanical tuning and residual magnetic field, with no significant impact to the multipacting behavior. This contribution summarizes the experimental results from cavity rf tests, some of which were complemented by additional diagnostic instrumentation. Results from 2D and 3D simulations are also presented, indicating favorable conditions for multipacting at the equator in the range 20 - 29 MV/m.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB049
About •	Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 01 July 2023
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WEPWB050	Exploring Innovative Pathway for SRF Cavity Fabrication	680
	O. Hryhorenko JLab, Newport News, Virginia, USA C.Z. Antoine Université Paris-Saclay, CEA, Gif-sur-Yvette, France T. Dohmae KEK, Ibaraki, Japan D. Longuevergne Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: ENSAR-2 under grant agreement N° 654002. The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. This article shows a study on an alternative pathway for the fabrication of a complete 1.3 GHz SRF cavity, aiming at improving production reliability, reducing the use of chemical polishing (EP or BCP) which is a costly and safety-critical step, and preserving surface quality after forming. Unlike the conventional pathway, the fabrication process is performed after polishing. This point is crucial as the used polishing technology could be applied only to flat geometries. The performed investigation demonstrates that damages during the fabrication process are considered minor, localized, and limited to the near-surface. Moreover, these studies confirm that the damaged layer (100-200 µm) is mainly caused by the rolling process, and not by the subsequent fabrication steps. A laser confocal microscope and SEM-EBSD technique were used to compare samples before and after forming. The preliminary results are discussed and presented in this paper.
	Poster WEPWB050 [2.263 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB050
About •	Received ※ 20 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023
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WEPWB051	Development of a Prototype 197 MHz Crab Cavity for the Electron-Ion Collider at JLab	685
	N.A. Huque, E.F. Daly, E. Drachuk, J. Henry, M. Marchlik JLab, Newport News, Virginia, USA A. Castilla JLAB, Newport News, USA S.U. De Silva ODU, Norfolk, Virginia, USA B.P. Xiao BNL, Upton, New York, USA
	Thomas Jefferson National Accelerator Facility (JLab) is currently developing a prototype 197 MHz Radio-Frequency Dipole (RFD) crab cavity as part of the Electron-Ion Collider (EIC) to be built at Brookhaven National Laboratory (BNL). Cryomodules containing these cavities will be part of Hadron Storage Ring (HSR) of the EIC. The prototype cavity is constructed primarily of formed niobium sheets of thickness 4.17 mm, with machined niobium parts used as interfaces where tight tolerancing is required. The cavity¿s large size and complex features present a number of challenges in fabrication, tuning, and RF testing. Structural and forming analyses have been carried out to optimize the design and fabricated processes. An overview of the design phase and the current state of fabrication are presented in this paper. Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB051
About •	Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 16 July 2023
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WEPWB052	Temperature, RF Field, and Frequency Dependence Performance Evaluation of Superconducting Niobium Half-Wave Coaxial Cavity	691
	N.K. Raut, G. Ciovati, P. Dhakal JLab, Newport News, Virginia, USA S.U. De Silva, J.R. Delayen, B.D. Khanal, J.K. Tiskumara ODU, Norfolk, Virginia, USA
	Funding: This is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177 Recent advancement in superconducting radio frequency cavity processing techniques, with diffusion of impurities within the RF penetration depth, resulted in high quality factor with increase in quality factor with increasing accelerating gradient. The increase in quality factor is the result of a decrease in the surface resistance as a result of nonmagnetic impurities doping and change in electronic density of states. The fundamental understanding of the dependence of surface resistance on frequency and surface preparation is still an active area of research. Here, we present the result of RF measurements of the TEM modes in a coaxial half-wave niobium cavity resonating at frequencies between 0.3 - 1.3 GHz. The temperature dependence of the surface resistance was measured between 4.2 K and 1.6 K. The field dependence of the surface resistance was measured at 2.0 K. The baseline measurements were made after standard surface preparation by buffered chemical polishing.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB052
About •	Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 20 July 2023
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WEPWB053	Simulation of the Dynamics of Gas Mixtures during Plasma Processing in the C75 Cavity	696
	N.K. Raut, P. Dhakal, T.D. Ganey, T. Powers JLab, Newport News, Virginia, USA
	Funding: The work is supported by SC Nuclear Physics Program through DOE SC Lab funding announcement DE-FOA-0002670 & is authored by JSA, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177 Plasma processing using a mixture of noble gas and oxygen is a technique that is currently being used to reduce field emission and multipacting in accelerating cavities. Plasma is created inside the cavity when the gas mixture is exposed to an electromagnetic field that is generated by applying RF power through the fundamental power or higher-order mode couplers. Oxygen ions and atomic oxygen are created in the plasma which breaks down the hydrocarbons on the surface of the cavity and the residuals from this process are removed as part of the process gas flow. Removal of hydrocarbons from the surface increases the work function and reduces the secondary emission coefficient. This work describes the initial results of plasma simulation, which provides insight into the ignition process, distribution of different species, and interactions of free oxygen and oxygen ions with the cavity surfaces. The simulations have been done with an Ar/¿2 plasma using COMSOL® multiphysics. These simulations help in understanding the dynamics and control of plasma inside the cavity and the exploration of different gas mixtures.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB053
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 29 June 2023
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WEPWB054	In Situ Plasma Processing of Superconducting Cavities at JLab, 2023 Update	701
	T. Powers, N.C. Brock, T.D. Ganey JLab, Newport News, Virginia, USA
	Jefferson Lab has an ongoing R&D program in plasma processing which just completed a round of production processing in the CEBAF accelerator. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the secondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The initial focus of the effort was processing C100 cavities by injecting RF power into the HOM coupler ports. Results from processing cryomodules in the CEBAF accelerator as well as vertical test results will be presented. The goal will be to improve the operational gradients and the energy margin of the linacs. This work will describe the systems and methods used at JLAB for processing cavities using an argon-oxygen gas mixture as well as a helium-oxygen gas mixture. Before and after plasma processing results will also be presented. Funding provided by SC Nuclear Physics Program through DOE SC Lab funding announcement DE-FOA-0002670.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB054
About •	Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023
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WEPWB055	First Experience with Liquid Nitrogen Cleaning	706
	R.J.M.Y. Ruber, A.B. Eslinger, R.L. Geng JLab, Newport News, Virginia, USA
	Field emission caused by microscopic particulate contamination is a limiting factor for the performance of superconducting RF (SRF) cavities. In an SRF accelerator, particulates may be transported over the surface of an operational SRF cavity, becoming field emitters and consequentially degrading the performance of the SRF cavity. The most commonly used method for removing particulates from cavity surfaces is high-pressure ultra-pure water rinsing. We are developing a novel high-pressure liquid nitrogen cleaning technique that may possibly enable superior cleaning power and particulate removal from cavities in a cryomodule without taking apart the cryomodule components. This technique provides cleaning mechanisms beyond what are accessible by its high-pressure water counterpart and leaves no residues on the cleaned surface. We present the test setup and first experience.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB055
About •	Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 27 June 2023
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WEPWB057	Refurbishment of an Elbe-Type Cryomodule for Coated HOM-Antenna Tests for MESA	709
SUSPB042	use link to see paper's listing under its alternate paper code
	P.S. Plattner, F. Hug, T. Stengler KPH, Mainz, Germany
	Funding: The work received funding by BMBF through 05H21UMRB1. The Mainz Energy-Recovering Superconducting Accelerator (MESA), an energy-recovering (ER) LINAC, is currently under construction at the university Mainz. In the ER mode a continues wave (CW) beam is accelerated from 5 MeV up to 10⁵ MeV with a beam current of up to 1 mA. This current is accelerated and decelerated twice within a cavity. For future experiments, the beam current limit has to be pushed up to 10 mA. An analysis of the MESA cavities has shown that the HOM antennas quench at such high beam currents due to the extensive power deposition and the resulting heating of the HOM coupler. To avoid quenching it is necessary to use superconducting materials with higher critical temperature. For this purpose, the HOM antennas will be coated with NbTiN and Nb3SN and their properties will be investigated. For use in the accelerator, the HOM antennas will be installed in the cavities of a former ALICE cryomodule, kindly provided by STFC Daresburry. This paper will show both the status of the refurbishment of the ALICE module to suit MESA, and the coating of the HOM antennas. The authors would like to express their sincere gratitude to STFC Daresbury for the donation of the ALICE module, which strongly supports SRF research in Mainz.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB057
About •	Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 09 July 2023
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WEPWB058	Contribution of IN2P3 to PIP-II Project: Plans and Progress	714
	D. Longuevergne, N. Bippus, P. Duchesne, N. Gandolfo, D. Le Dréan, G. Mavilla, T. Pépin-Donat, S. Roset, L.M. Vogt, S. Wallon Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France P. Berrutti, J. Helsper, S. Kazakov, M. Parise, D. Passarelli, N. Solyak, A.I. Sukhanov Fermilab, Batavia, Illinois, USA
	Funding: Work supported by IN2P3. Work supported, in part, by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under U.S. DOE Contract No. DE-AC02-07CH11359. IJCLab is one of the labs of IN2P3 (National institute of nuclear and particle physics), one of the ten research institutes composing the French National Center for Scientific Research (CNRS). Since 2018, IJCLab has been involved in the PIP-II project, assisting with the design, development, and qualification of accelerator components for the SSR2 (Single Spoke Resonator type 2) section of the superconducting linac. The first pre-production components (cavity, coupler, and tuner) have been fabricated, and some of the first qualification tests have been performed at IJCLab. This paper will summarize the complete scope of IJCLab¿s contributions to PIP-II and give updates on the performances of the first pre-production components.
	Poster WEPWB058 [1.727 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB058
About •	Received ※ 24 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 05 July 2023 — Issue date ※ 10 July 2023
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WEPWB061	Pre-Installation Performance of the RHIC 56 MHz Superconducting System	718
	Z.A. Conway, R. Anderson, J.C. Brutus, K. Hernandez, D. Holmes, K. Mernick, G. Narayan, S. Polizzo, S.K. Seberg, F. Severino, M. Sowinski, R. Than, Q. Wu, B.P. Xiao, W. Xu, A. Zaltsman BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under contract No. DE-SC0012704 with the U.S. Department of Energy. Pre-installation test results for the RHIC 56 MHz superconducting RF system are presented here. The 56 MHz quarter-wave resonator achieved a stable accelerating potential of 1.1 MV with 13 W of RF loss at 4.5 K demonstrating its viability for increasing the luminosity of sPHENIX collisions. The new 120 kW travelling wave fundamental mode damper and dual 6 kW combined-function fundamental power couplers perform as expected at 3 kW but remain to be operated with the expected ~40 times greater power achievable with the RHIC sPHENIX beams.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB061
About •	Received ※ 15 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 02 July 2023 — Issue date ※ 17 July 2023
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WEPWB063	Final Design of the LB650 Cryomodule for the PIP-II Linear Accelerator	721
	R. Cubizolles, S. Ladegaillerie, A. Moreau CEA-IRFU, Gif-sur-Yvette, France N. Bazinpresenter, S. Berry, J. Drant, P. Garin, A. Raut, C. Simon CEA-DRF-IRFU, France S.K. Chandrasekaran, O. Napoly, V. Roger Fermilab, Batavia, Illinois, USA
	The Proton Improvement Plan II (PIP-II) that will be installed at Fermilab is the first U.S. accelerator project that will have significant contributions from international partners. CEA joined the international collaboration in 2018, and its scope covers the supply of the 650 MHz low-beta cryomodule section, with the design of the cryostat (i.e the cryomodule without the cavities, the power couplers and the frequency tuning systems) and the manufacturing of its components, the assembly and tests of the pre-production cryomodule and 9 production modules. An important milestone was reached in April 2023 with the Final Design Review. This paper presents the detailed design of the 650 MHz low-beta cryomodules.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB063
About •	Received ※ 21 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 20 July 2023
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WEPWB064	Performance Analysis from ESS Cryomodule Testing at CEA	727
	O. Piquet, C. Arcambal, Q. Bertrand, P. Bosland, E. Cenni, G. Devanz, T. Hamelin CEA-IRFU, Gif-sur-Yvette, France P. Sahuquet CEA-DRF-IRFU, France
	CEA Saclay is in charge of the production of 30 elliptical cavities cryomodule as part of the in Kind contribution to the ESS superconducting. The two medium and high beta prototypes and the three first of each type of the series cryomodules have been tested at CEA in slightly different conditions than at ESS (both in terms of cryogenic operation as well as RF conditions). The goal of these tests was to validate the assembly procedure before the delivery of the series to ESS where the final acceptance tests are performed. This paper summarizes the main results obtained during the tests at CEA with a particular attention to the field emission behaviour.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB064
About •	Received ※ 20 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 07 July 2023
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WEPWB065	Impact of Medium Temperature Heat Treatments on the Magnetic Flux Expulsion Behavior of SRF Cavities	731
SUSPB043	use link to see paper's listing under its alternate paper code
	J.C. Wolff, J. Eschke, A. Gössel, K. Kasprzak, D. Reschke, L. Steder, L. Trelle, M. Wiencek DESY, Hamburg, Germany W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program. Medium temperature (mid-T) heat treatments at 300 °C are used to enhance the intrinsic quality factor of superconducting radio frequency (SRF) cavities. Unfortunately, such treatments potentially increase the sensitivity to trapped magnetic flux and consequently the surface resistance of the cavity. For this reason, it is crucial to maximize the expulsion of magnetic flux during the cool down. The flux expulsion behavior is next to the heat treatment mainly determined by the geometry, the niobium grain size and the grain orientation. However, it is also affected by parameters of the cavity performance tests like the cool down velocity, the spatial temperature gradient along the cavity surface and the magnetic flux density during the transition of the critical temperature. To improve the flux expulsion behavior and hence the efficiency of future accelerator facilities, the impact of these adjustable parameters as well as the mid-T heat treatment on 1.3 GHz TESLA-Type single-cell cavities is investigated by a new approach of a magnetometric mapping system. In this contribution first performance test results of cavities before- and after mid-T heat treatment are presented.
	Poster WEPWB065 [3.077 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB065
About •	Received ※ 21 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 13 July 2023
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WEPWB066	Final Design of the Production SSR1 Cryomodule for PIP-II Project at Fermilab	736
	J. Bernardini, M. Chen, J. Helsper, M. Kramp, F.L. Lewis, T.H. Nicol, M. Parise, D. Passarelli, V. Roger, G.V. Romanov, B. Squires Fermilab, Batavia, Illinois, USA P. Neri University of Pisa, Pisa, Italy
	Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy, Office of Science, Office of High Energy Physics. This contribution reports the design of the production Single Spoke Resonator Type 1 Cryomodule (SSR1 CM) for the PIP-II project at Fermilab. The innovative design is based on a structure, the strongback, which supports the coldmass from the bottom, stays at room temperature during operations, and can slide longitudinally with respect to the vacuum vessel. The Fermilab style cryomodule developed for the prototype Single Spoke Resonator Type 1 (pSSR1), the prototype High Beta 650 MHz (pHB650), and preproduction Single Spoke Resonator Type 2 (ppSSR2) cryomodules is the baseline of the present design. The focus of this contribution is on the results of calculations and finite element analyses performed to optimize the critical components of the cryomodule: vacuum vessel, strongback, thermal shield, and magnetic shield.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB066
About •	Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 15 July 2023
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WEPWB067	HB650 Cryomodule Design: From Prototype to Production	741
	V. Roger, S.K. Chandrasekaran, C.J. Grimm, J.P. Holzbauer, O. Napoly, J.P. Ozelispresenter, D. Passarelli Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. In early 2023 the assembly of the prototype HB650 cryomodule (pHB650 CM) was completed and cold tests started to evaluate its performance. The lessons learned from the design, assembly and preliminary cold tests of this cryomodule, and from the design of the SSR2 pre-production cryomodule played a fundamental role during the design optimization process of the production HB650 cryomodule (HB650 CM). Several workshops have been organized to share experiences and solve problems. This paper presents the main design changes from pHB650 to the HB650 production cryomodules and their impact on the heat loads.
	Poster WEPWB067 [2.178 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB067
About •	Received ※ 18 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023
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WEPWB068	Characterization of Additive Manufacturing Materials for String Assembly in Cleanroom	746
	J. Bernardini, M. Parise, D. Passarelli Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy, Office of Science, Office of High Energy Physics. Beamline components, such as superconducting radio frequency cavities and focusing lenses, need to be assembled together in a string while in a cleanroom environment. The present contribution identifies and characterizes materials for additive manufacturing that can be used in a cleanroom. The well known advantages of additive manufacturing processes would highly benefit the design and development of tooling needed for the mechanical support and alignment of string components. Cleanliness, mechanical properties, and leak tightness of the chosen materials are the main focus of this contribution, which also paves the way for the integration of such materials in cryomodule assemblies. Results reported here were obtained in the framework of the PIP-II project at Fermilab.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB068
About •	Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 July 2023
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WEPWB070	Test Shipment of the PIP-II 650 MHz Transport Frame Between FNAL to STFC-UKRI	750
	J.P. Holzbauer, S.K. Chandrasekaran, C.J. Grimm, J.P. Ozelis, R. Thiede, A.D. Wixson Fermilab, Batavia, Illinois, USA M.T.W. Kane STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy The PIP-II Project will receive fully assembled cryomodules from CEA and STFC-UKRI as in-kind contributions. Damage to these cryomodules during transport is understood to be a significant risk to the project, so an extensive testing and validation program is in process to mitigate this risk. The centerpiece of this effort is the eventual shipment from FNAL to STFC-UKRI and back of a prototype HB650 cryomodule with cold testing before and after shipment to verify no functionality changes from shipment. Most recently, a test shipment to the UK and back using a cryomodule analog was completed using realistic logistics, handling, instrumentation, and planning. The process of executing this test shipment, lessons learned, and plan moving forward will be presented here.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB070
About •	Received ※ 18 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 17 July 2023
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WEPWB073	Prototype HB650 Cryomodule Heat Loads Simulations	755
	G. Coladonato University of Illinois at Chicago, Chicago, USA D. Passarellipresenter, V. Roger Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. During the design stages of the PIP-II cryomodules, many analytical calculations and FEA have been performed on simpler geometry in order to estimate the heat loads and also to optimize the design. To better analyze the cryomodule cold tests, simulations have been performed with MATLAB to determine the temperature of the main components during cool down and to determine the heat loads of the cryomodule. These simulations have been applied to the High Beta 650 MHz prototype cryomodule design and compared to the cold tests performed on it.
	Poster WEPWB073 [1.981 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB073
About •	Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 28 June 2023
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WEPWB074	Commissioning of the UHH Quadrupole Resonator at DESY
SUSPB045	use link to access more material from this paper's primary paper code
THCAA02	use link to access more material from this paper's primary paper code
	R. Monroy-Villa, W. Hillert, M. Wenskat University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany A. Gössel, D. Reschke, M. Röhling, M. Schmökel, J.H. Thie, M. Wiencek DESY, Hamburg, Germany C. Martens University of Hamburg, Hamburg, Germany
	Funding: This work was supported by the BMBF under the research grants 05H18GURB1, 05K19GUB and 05H2021. Pushing the limits of the accelerating field or quality factor of SRF cavities beyond pure Nb requires the implementation of specific inner surface treatments, which are yet to be studied and optimized. One of the fundamental challenges in exploring alternative materials is that only samples or cavity cuts can be fully characterized from a material point of view. On the other hand, complete cavities allow for the SRF characterization of the inner surface, while samples can usually only be analyzed using DC methods. To address this problem, a test resonator for samples, called "Quadrupole Resonator", was designed and operated at CERN and later at HZB. It allows for a full RF characterization of samples at frequencies of 0.42 GHz, 0.86 GHz, and 1.3 GHz, within a temperature range of 2-20 K and at magnetic fields up to 120 mT. This work presents the design process, which incorporated improvements motivated by mechanical and RF studies and experience, and the results from both warm and cold commissioning are discussed. More important, the results for the RF tests of a Nb sample after undergoing a series of heat treatments and an outlook of the further usage of the QPR is presented.
	Slides THCAA02 [6.677 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-THCAA02
About •	Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 19 August 2023
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WEPWB075	Impact of Solenoid Induced Residual Magnetic Fields on the Prototype SSR1 CM Performance	760
	D. Passarelli, J. Bernardini, C. Boffo, S.K. Chandrasekaran, A.H. Hogberg, T.N. Khabiboulline, J.P. Ozelis, M. Parise, V. Roger, G.V. Romanov, A.I. Sukhanov, G. Wu, Y. Xie, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. A prototype cryomodule containing eight Single Spoke Resonators type-1 (SSR1) operating at 325 MHz and four superconducting focusing lenses was successfully assembled, cold tested, and accelerated beam in the framework of the PIP-II project at Fermilab. The impact of induced residual magnetic fields from the solenoids on performance of cavities is presented in this contribution. In addition, design optimizations for the production cryomodules as a result of this impact are highlighted.
	Poster WEPWB075 [2.429 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB075
About •	Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 11 July 2023
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WEPWB076	Low Particulates Nitrogen Purge and Backfill during Prototype HB650 Cryomodule String Assembly	765
	T.J. Ring, M.B. Quinlan, G. Wupresenter Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. A low particulate vacuum and purging system was developed to support PIP-II cryomodule string assembly. The overpressure can be controlled at a precision of 1 mbar above the atmospheric pressure regardless of the cavity or string assembly air volume. The system minimized the risk of uncontrolled nitrogen flow during the string assembly. Design features will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB076
About •	Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 09 July 2023
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WEPWB082	Operational Experience with Turn-Key SRF Systems for Small Accelerators Like MESA	768
	T. Stengler, K. Aulenbacher, F. Hug, P.S. Plattner KPH, Mainz, Germany
	Funding: The work is funded by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019 and the Federal Ministry of Education and Research (BMBF) through project 05H21UMRB1 New SRF-based accelerator development at sites without long-term experience in SRF development is a major challenge. Especially in-house development of cryomodules is an almost impossible obstacle to overcome for small projects. To minimize such obstacles, turn-key SRF systems provided by industry can be of great importance. For the multiturn ERL MESA, which is currently under construction at Johannes Gutenberg-Universität Mainz, two turnkey cryomodules have been purchased from industry and successfully tested. The specifications of a design gradient of 12.5 MV/m in CW operation with an unloaded Q of 1.25*10¹⁰ at 1.8 K had to be met. Since the design of the modules had to be modified for high current CW operation, a close cooperation with the manufacturer was of great importance. By purchasing such a turn-key SRF system, the MESA project successfully established the SRF accelerator technology at the site within six years. This was achieved through close monitoring of the manufacturing process and close cooperation with the manufacturer. An overview of the experience with the successful technology transfer of a complete turn-key SRF system for small accelerators will be given.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB082
About •	Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 03 August 2023
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WEPWB083	Basic Design and Consideration of Li-Vapor Contamination for A-FNS SRF	773
	T. Ebisawa, K. Hasegawa, A. Kasugai, M. Oyaidzu, S. Sato QST Rokkasho, Aomori, Japan E. Kako, H. Sakai, K. Umemori KEK, Ibaraki, Japan
	The Advanced Fusion Neutron Source (A-FNS) project is in progressing in Japan, QST Rokkasho institute. A-FNS will demonstrate a performance of the DEMO DT fusion reactor material. In order to perform the test, a high intensity deuteron beam accelerator will be used to produce a high flux neutron field which is similar to the 14 MeV DT neutron. The Superconducting Radio-Frequency linear accelerator (SRF) is one component of the A-FNS accelerator system. Although the A-FNS accelerator system design is based on the IFMIF design, the improvement of some subsystem has been considering by taking into account the lessons learnt from the LIPAc project. In order to keep a high stability and availability of the SRF performance, we plan to increase the number of SRF cavities and cryomodules considering the trouble or degradation of the cavity performance and modify the engineering design of some components. In addition, changing of the beam transport line design and Li vapor contamination study of SRF cavity are conducting. In this presentation, the progress of the SRF design and related activities for A-FNS in QST will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB083
About •	Received ※ 28 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 17 August 2023
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WEPWB084	The Interaction among Interstitial C/N/O/H and Vacancy in Niobium via First-Principles Calculation	778
	H. Liu, J.K. Hao, Z.T. Yangpresenter PKU, Beijing, People’s Republic of China
	We calculate the interaction among zero dimensional defects in niobium lattice through first-principles calculation. And we compare the trapping effect of hydrogen among carbon, nitrogen, and oxygen as well as the trapping effect of interstitial atoms by vacancy. We find that the interstitial C/N/O have similar effect of trapping interstitial hydrogen in niobium lattice, and the vacancy can trap interstitial C/N/O/H in adjacent protocells and strengthen their chemical bond with Nb. These calculations give some explanation for improving superconducting performance of niobium cavities through medium temperature baking.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB084
About •	Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 03 July 2023
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WEPWB085	Degradation and Recovery of Cavity Performance in SRILAC Cryomodules at RIBF	784
	N. Sakamoto, O. Kamigaito, K. Ozeki, K. Suda, K. Yamada RIKEN Nishina Center, Wako, Japan
	The RIKEN superconducting (SC) heavy-ion linear accelerator (SRILAC) has been providing beam supply for super-heavy elements synthesis experiments since its commissioning in January 2020. However, the long-term operation of SC radio-frequency (RF) cavities leads an increase in the X-ray levels caused by field emissions resulting from changes in the inner surface conditions. More than half of the ten SC 1/4 wavelength resonators (SC-QWRs) of SRILAC, operating at a frequency of 73 MHz, have experienced an increase in X-ray levels, thus, requiring adjustments to the acceleration voltage for continuous operation. While several conditioning methods have been employed for SC cavities, a fully established technique is yet to be determined. To address this situation, a relatively simple conditioning method was implemented at RIKEN. The proposed method uses high-voltage pulsed power and imposes a low load on the cavities.
	Poster WEPWB085 [12.789 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB085
About •	Received ※ 13 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 01 July 2023
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WEPWB087	Copper Plating Qualification Process for the Fundamental Power Coupler Waveguides for CEBAF Cryomodules	790
	L. Zhao, G. Cheng, G. Ciovati, K.M. Wilson JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC, supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. To provide sufficient energy for CEBAF operation, cryomodules and components are being refurbished yearly as necessary. Copper plated fundamental power coupler waveguides are important components of the cryomodules. The integrity and quality of copper plating is critical to reduce the heat load from the waveguides into the He bath at 2.07 K. A search of copper plating resources is underway for plating or re-plating CEBAF-style waveguides. This effort ensures a continuous capability of copper plating on cryomodule components, especially on waveguides. To qualify plating vendors, the waveguide copper plating specifications were revisited, and a thorough plating evaluation process is being developed. The evaluation process ranges from coupon testing to sample waveguide qualification. Recent results are summarized and future work is planned.
	Poster WEPWB087 [1.582 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB087
About •	Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 11 July 2023
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WEPWB089	Theoretical Model of External Q Tuning for an SRF Cavity with Waveguide Tuner	794
	W. Xu, Z.A. Conway, K.S. Smith, A. Zaltsman BNL, Upton, New York, USA E.F. Daly, J. Guo, R.A. Rimmer JLab, Newport News, Virginia, USA
	Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. A wide range of electron beam energies (5 ¿ 18 GeV) and beam currents (0.2 ¿ 2.5 A) in EIC Electron Storage Ring (ESR) operating scenarios requires a capability of adjusting coupling factor up to a factor of 20 for the 591 MHz Superconducting Radio Frequency (SRF) cavities, which contains two fundamental power couplers (FPC) delivering continuous wave (CW) 800 kW RF power to the beam. Currently, adjusting external Q of a SRF cavity is done by varying protrusion of FPC¿s inner conductor in beam pipe or using three stub tuner to adjust external Q value, which either has limit on tuning range or limit on operating power. This paper presents a method of tuning the FPC external Q by a multiple-waveguide tuner, which allows for high power, wide tuning range operations. The theoretical model of matching beam impedance with waveguide tuner and detailed matching conditions and limits will be presented. Follow the theoretical model, a preliminary design of a 3D waveguide tuner will be presented. The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
	Poster WEPWB089 [1.269 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB089
About •	Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023
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WEPWB092	Test-Stand for Conditioning of Fundamental Power Couplers at DESY	797
	K. Kasprzak, Th. Buettner, A. Gössel, D. Klinke, D. Kostin, C. Müller, E. Vogel, M. Wiencek DESY, Hamburg, Germany
	During the construction of the European-XFEL, activities related to Fundamental Power Couplers (FPCs) were outsourced to external partners and the former FPC test-stand area at DESY was given up due to infrastructure rearrangements. For the study of various XFEL upgrade scenarios a new test-stand for conditioning of FPCs at DESY is required. It will be used for evaluation of new coupler preparation methods with particular emphasis on Continuous Wave (CW) and long RF pulse operation. The new test-stand has been recently commissioned. Four FPCs have been prepared and tested. RF pulses were applied to the couplers, starting with the shortest possible pulse and increasing it’s power until maximum power was reached. The process was repeated with several pulse lengths until the maximum RF pulse length was reached. A review of the commissioning and first operation experience of the RF system are presented here.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB092
About •	Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 16 July 2023
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WEPWB093	Transportation Fatigue Testing of the pHB650 Power Coupler Antenna for the PIP-II Project at Fermilab	801
	J. Helsper, S.K. Chandrasekaran, J.P. Holzbauer, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The PIP-II Project will see international shipment of cryomodules from Europe to the United States, and as such, the shocks which can occur during shipment pose a risk to the internal components. Of particular concern is the coupler ceramic window and surrounding brazes, which can see relatively high stress during an excitation event. Since the antenna design is new, and because of the setback failure would create, a cyclic stress test was devised for the antenna. This paper presents the experimental methods, setup, and results of the test.
	Poster WEPWB093 [2.913 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB093
About •	Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 03 July 2023
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WEPWB094	Design, Manufacturing, Assembly, and Lessons Learned of the Pre-Production 325 MHz Couplers for the PIP-II Project at Fermilab	806
	J. Helsper, S. Kazakov, D. Passarelli, N. Solyak Fermilab, Batavia, Illinois, USA D. Longuevergne, S. Wallon Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Five 325 MHz high-power couplers will be integrated into the pre-production Single Spoke Resonator Type-II (ppSSR2) cryomodule for the PIP-II project at Fermilab. Couplers were procured by both Fermilab and IJCLAB for this effort. The design of the coupler is described, including design optimizations from the previous generation. This paper then describes the coupler life cycle, including design, manufacturing, and assembly, along with the lessons learned at each stage.
	Poster WEPWB094 [3.561 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB094
About •	Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 29 June 2023
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WEPWB096	Testing of PIP-II Pre-production 650 MHz Couplers in Warm Test Stand and Cryomodule	812
	N. Solyak, S.K. Chandrasekaran, B.M. Hanna, J. Helsper, J.P. Holzbauer, S. Kazakov, A.I. Sukhanov Fermilab, Batavia, Illinois, USA
	650 MHz fundamental power couplers were developed for PIP-II project to deliver RF power for low-beta and high-beta elliptical cavities. Few prototypes were built and tested and after some modification we built 8 pre-production couplers (with three spares for vacuum side) for ppHB650 cryomodule. All couplers were successfully tested in pulse mode (up to 100kW) and in CW mode (up to 50kW) in test stand at full reflection at 8 phases. In baseline configuration with DC bias we do not see any multipactoring activity after short processing. We also tested power processing without bias for uncoated and TiN coated ceramic window. Results of these studies presented in this paper. One of the coupler was assembled on LB650 cavity and tested at cryogenic environment in STC cryostat at ~30kW power with full reflection at different reflection phase. We also demonstrated good result from power processing without bias for warm and cold cavity. Six couplers were assembled on HB650 cavities in pre-production cryomodule. Test results from cryomodule qualification is discussing in this paper.
	Poster WEPWB096 [2.748 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB096
About •	Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023
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WEPWB097	Testing and Processing of Pre-production 325 MHz Single Spoke Resonator Power Couplers for PIP-II Project	816
	N. Solyak, B.M. Hanna, J. Helsper, S. Kazakov, D. Passarelli Fermilab, Batavia, Illinois, USA S. Wallon Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
	Fundamental 325 MHz power couplers are designed, built and tested for SSR cavities in PIP-II project [1]. Couplers should work in CW mode at power level 7.5kW w/o beam and ~15 kW with the 2 mA beam. At pre-production stage we built and tested 6 couplers, produced by CPI (FNAL) and PMB (IJCLab) and 4 more couplers will be tested soon. Two of tested cou-plers had TiN coated ceramic window. In warm test stand two couplers were mounted on the coupling chamber and tested in SW regime at full reflection with phase controlled by position of short and reflection insert. Couplers were tested at pulse mode (up to 25kW) and cw mode (12kW) with HV bias or without bias. Test results demonstrated that 3.5 kV DC bias completely suppresses multipactor in coupler. Vacuum activity in coupler was controlled by e-pickups and build-in vacuum gauges, located near the vacuum side of window. Power processing without DC bias was done for several couplers with and without TiN coating on ceramic window. Test results are presented and discussing in paper.
	Poster WEPWB097 [2.439 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB097
About •	Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 29 June 2023
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WEPWB098	Development and Evaluation of STF-Type Power Coupler for Cost Reduction at the High Energy Accelerator Research Organization	820
	Y. Yamamoto, T. Matsumoto, S. Michizono KEK, Ibaraki, Japan
	At KEK, cost reduction study for STF-type input power coupler used in the STF-2 accelerator has been attempted since FY2015. In FY2019, one coupler was fabricated by some cost-effective and non-conventional methods including different alumina-ceramic material, copper plating and TiN coating. In high power RF test at room temperature, this coupler achieved 1 MW at 900 µsec/5Hz, and 935 kW @1.65 msec/5Hz. After that, this coupler experienced 10 thermal cycle tests from room temperature to liquid nitrogen temperature without vacuum leakage. In this report, the detailed results will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB098
About •	Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023
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WEPWB101	Present Status of RIKEN Power Couplers for SRILAC	823
	K. Ozeki, O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada RIKEN Nishina Center, Wako, Japan
	The heavy ion linac of the RIKEN, utilizing superconducting technology, began operations in September 2019. Over the following 13 months, two of the ten superconducting accelerating cavities experienced vacuum leaks from the vacuum windows of the fundamental power couplers (FPCs). Currently, additional vacuum windows are installed on all ten FPCs and the beam supply continues without encountering any major issues with the FPCs. Additionally, the fabrication of ten replacement FPCs has been completed, addressing the underlying issues that led to the deterioration of the vacuum window strength. Currently, we are conducting radio frequency (RF) process of the new FPCs. In addition, we are designing a bias applying component to suppress multipacting in the FPCs. This paper reports the status of these issues related to the FPCs at the RIKEN.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB101
About •	Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 14 July 2023
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WEPWB102	Recent Progress of Fundamental Power Couplers for the SHINE Project	827
	Z.Y. Ma, J.F. Chen, H.T. Hou, B. Liu, Y. Liu, S. Sun, D. Wang, L. Yin, M. Zhang, S.J. Zhao, Y.B. Zhao, Z.T. Zhao, X. Zheng SARI-CAS, Pudong, Shanghai, People’s Republic of China
	Funding: Project supported by Shanghai Municipal Science and Technology Major Project (Grant No.2017SHZDZX02). The superconducting radio-frequency electron linear accelerator of the Shanghai HIgh repetition rate XFEL aNd Extreme light facility (SHINE) contains 610 1.3 GHz fundamental power couplers which are assembled in 77 superconducting cryomodules used for beam acceleration, and 16 3.9 GHz fundamental power couplers, which are assembled in two third harmonic superconducting cryomodules used for linearizing the longitudinal phase space. The first batch of 26 1.3 GHz coupler prototypes and two 3.9 GHz coupler prototypes have been fabricated from three domestic manufacturers for basic research. Several key manufacturing processes have been developed and qualified, including high residual resistivity ratio (RRR) copper plating, vacuum brazing of ceramic windows, electron beam welding and titanium nitride coating. All the 1.3 GHz coupler prototypes have been power conditioned with 14 kW travelling wave (TW) and 7 kW standing wave (SW) RF in continuous-wave (CW) mode. Even higher power levels have been demonstrated with 20 kW TW and 10 kW SW RF, which indicates their robustness. Both 3.9 GHz coupler prototypes have been power conditioned with 2.2 kW TW and 2 kW SW RF in CW mode.
	Poster WEPWB102 [2.361 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB102
About •	Received ※ 16 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 05 July 2023
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WEPWB103	Simulations and First RF Measurements of Coaxial HOM Coupler Prototypes for PERLE SRF Cavities	831
	C. Barbagallo, P. Duchesne, W. Kaabi, G. Olivier, G. Olry, S. Roset, Z.F. Zomer Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France B.S. Barriere, C.S. Clement, R.L.A. Gerard, F. Gerigk, P.M. Maurin CERN, Meyrin, Switzerland J. Henry, S.A. Overstreet, G.-T. Park, R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	Superconducting Radio-Frequency (SRF) linac cryomodules are foreseen for the high-current multi-turn energy recovery linac PERLE (Powerful Energy Recovery Linac for Experiments). Coaxial higher order mode (HOM) couplers are the primary design choice to absorb beam-induced power and avoid beam instabilities. We have used 3D-printed and copper-coated HOM couplers for the prototyping and bench RF measurements on the copper PERLE cavities. We have started a collaboration with JLab and CERN on this effort. This paper presents electromagnetic simulations of the cavity HOM-damping performance on those couplers. Bench RF measurements of the HOMs on an 801.58 MHz 2-cell copper cavity performed at JLab are detailed. The results are compared to eigenmode simulations in CST to confirm the design. RF-thermal simulations are conducted to investigate if the studied HOM couplers undergo quenching.
	Poster WEPWB103 [1.533 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB103
About •	Received ※ 18 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 02 July 2023
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WEPWB104	RF Conditioning of MYRRHA Couplers at IJCLab	835
	N. ElKamchi, S. Berthelot, P. Duchesne, C. Joly, W. Kaabi, C. Magueur Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France Y. Gómez Martínez LPSC, Grenoble Cedex, France C. Lhomme IJCLab, ORSAY, France
	Multi-purpose hYbrid Research Reactor for High-tech Applications (MYRRHA) is an experimental accelerator-driven system in development at SCK•CEN. It will allow fuel developments, material developments for GEN IV systems, material developments for fusion reactors and radioisotope production for medical and industrial applications1. The IJCLab has in charge the industrial monitoring, the quality control and the RF conditioning of the power couplers up to 80KW at 352Mhz. This paper presents the conditioning bench adapted from the successful experience of IJCLab in the conditioning of the XFEL couplers2. The results of the conditioning of prototype couplers are described and discussed. 1. Abderrahim, P. MYRRHA a multi-purpose hybrid research reactor for high-tech applications. United States: N. p., 2012. Web 2. H. Guler, Proceedings of IPAC2016, Busan, Korea
	Poster WEPWB104 [0.875 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB104
About •	Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 08 August 2023
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WEPWB105	Improved Study of the Multipactor Phenomenon for the MYRRHA 80 kW CW RF Couplers	838
	Y. Gómez Martínez, P.-O. Dumont LPSC, Grenoble Cedex, France P. Duchesne, N. ElKamchipresenter, C. Joly, W. Kaabi Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France C. Lhomme IJCLab, ORSAY, France C. Lhomme ACS, Orsay, France
	MYRRHA (Multi Purpose Hybrid Reactor for High Tech Applications) is an Accelerator Driven System (ADS) project. Its superconducting linac will provide a 600 MeV - 4 mA proton beam. The first project phase based on a 100 MeV linac is launched. The Radio-Frequency (RF) couplers have been designed to handle 80 kW CW (Continuous Wave) at 352.2 MHz. This paper describes the multipactor studies on the coupler when it does not work in the nominal configuration without reflected power.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB105
About •	Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 12 July 2023
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WEPWB108	Update on Cornell High Pulsed Power Sample Host Cavity	841
SUSPB029	use link to see paper's listing under its alternate paper code
	N.M. Verboncoeur, A.T. Holic, M. Liepe, T.E. Oseroff, R.D. Porter, J. Sears, L. Shpani Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA R.D. Porter SLAC, Menlo Park, California, USA
	The Cornell High Pulsed Power Sample Host Cavity (CHPPSHC) is designed to measure the temperature-dependent superheating fields of future SRF materials and thereby gain insights into the ultimate limits of their performance. Theoretical estimation of the superheating fields of SRF materials is challenging and mostly has been done for temperatures near the critical temperature or in the infinite kappa limit. Experimental data currently available is incomplete, and often impacted by material defects and their resulting thermal heating, preventing finding the fundamental limits of theses materials. The CHPPSHC system allows reaching RF fields in excess of half a Tesla within microseconds on material samples by utilizing high pulsed power, thereby outrunning thermal effects. We are principally interested in the superheating field of Nb₃Sn, a material of interest for the SRF community, and present here the current fabrication and assembly status of the CHPPSHC as well as early results.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB108
About •	Received ※ 27 June 2023 — Revised ※ 20 July 2023 — Accepted ※ 20 August 2023 — Issue date ※ 22 August 2023
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WEPWB109	PI Loop Resonance Control for the Dark Photon Experiment at 2 K using a 2.6 GHz SRF cavity	847
	C. Contreras-Martinez, B. Giaccone, O.S. Melnychuk, A.V. Netepenko, Y.M. Pischalnikov, S. Posen, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Two 2.6 GHz cavities are being used for dark photon search at VTS in FNAL. During testing at 2 K the cavities experience frequency detuning caused by microphonics and slow frequency drifts. The experiment requires that the two cavities have the same frequency within 5 Hz. These two cavities are equipped with frequency tuners consisting of three piezo actuators. The piezo actuators are used for fine-fast frequency tuning. A PI loop utilizing the piezos was used to maintain both cavities at the same frequency, and the results are presented.
	Poster WEPWB109 [1.151 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB109
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023
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WEPWB110	Prevention of Dual-Mode Excitation in 9-Cell Cavities for LCLSII-HE	852
	P.D. Owen JLab, Newport News, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. Dual-Mode Excitation, also referred to as mode-mixing, is a superposition of two pi modes in an SRF cavity. In 9-cell TESLA cavities used for the LCLSII-HE project, the two modes that are commonly excited are the pi mode (1300.2 MHz), and the 7/9 pi mode (1297.8 MHz). During vertical cavity qualification testing, it is regularly observed that emitted power at the frequency of the 7/9 pi mode grows, despite the RF system only driving the pi mode. When this happens, the RF power measurement system is unable to differentiate between the superimposed modes which invalidates any data taken. A new RF control solution prevents the 7/9 pi mode from being excited. A second RF control system is connected to drive the 7/9 pi mode. The loop phase for driving this mode is determined, then shifted by 180 degrees, thus providing a negative feedback to the undesired mode. Because this off-resonance power can be very small, it does not interfere with the high-power measurements of the fundamental pi mode. At Jefferson Lab, we are now able to test a cavity for the LCLSII-HE project with no complications from mode-mixing, which allows for CW processing of high-gradient multipacting.
	Poster WEPWB110 [1.818 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB110
About •	Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 13 July 2023
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WEPWB111	A New Ultra-High Vacuum Furnace for SRF R&D	855
	M. Wenskat, C. Bate DESY, Hamburg, Germany C. Bate, C. Martens University of Hamburg, Hamburg, Germany R. Ghanbari, W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Funding: This work was supported by the BMBF under the research grants 05K19GUB and 05H2021. A new vacuum furnace has been designed and purchased by the University of Hamburg and is operating in an ISO5 cleanroom. This furnace can anneal single-cell TESLA cavities at temperatures up to 1000°C and with a pressure of less than 10-7mbar or in a nitrogen atmosphere of up to 10-2mbar. We will lay out the underlying design ideas, based on the gained experience from our previous annealing research, and present the commissioning of the furnace itself. Additionally, we will show for the first time the results of sample and cavity tests after annealing in the furnace. This will be accompanied by an overview of the intended R&D process and scientific questions to be addressed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB111
About •	Received ※ 21 June 2023 — Revised ※ 15 July 2023 — Accepted ※ 20 August 2023 — Issue date ※ 21 August 2023
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WEPWB113	Evaluation of Photo-Cathode Port Multipacting in the SRF Photo-Injector Cryomodule for the LCLS-II High-Energy Upgrade	859
SUSPB032	use link to see paper's listing under its alternate paper code
	Z.Y. Yin, W. Hartung, S.H. Kim, T. Konomi, T. Xu FRIB, East Lansing, Michigan, USA
	The high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE) will increase the photon energy and brightness. A low-emittance injector (LEI) was proposed to increase the photon flux for high X-ray energies. FRIB, HZDR, Argonne, and SLAC are developing a 185.7 MHz superconducting radio-frequency photo-injector (SRF-PI) cryomodule for the LEI. The photo-cathode system requirements are challenging, as cathodes must be maintained at the desired temperature, precisely aligned, and operated without multipacting (MP); to avoid field emission, cathode exchange must be particulate-free. A support stalk has been designed to hold the cathode in position under these requirements. A DC bias is used to inhibit MP. We simulated MP for various surface conditions and bias levels. An RF/DC test was developed to evaluate the cathode stalk performance as a subsystem and to identify and correct issues before assembly into the full cryomodule. The RF/DC test makes use of a resonant coaxial line to generate an RF magnetic field similar to that of the cathode-in-SRF-PI-cavity case. High-power test results will be presented and compared to the MP simulations. * Work supported by the Department of Energy Contract DE-AC02-76SF00515
	Poster WEPWB113 [1.410 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB113
About •	Received ※ 20 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 26 July 2023
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WEPWB116	The Influence of Sample Preparation, Soak Time, and Heating Rate on Measured Recrystallization of Deformed Polycrystalline Niobium	863
	Z.L. Thune MSU, East Lansing, USA T.R. Bielerpresenter Michigan State University, East Lansing, Michigan, USA
	Funding: DOE/OHEP (Grant Number: DE-SC0009960) Improving accelerator performance relies on consistent production of high-purity niobium superconducting radiofrequency (SRF) cavities. Current production uses an 800 °C 3 hr heat treatment, but 900-1000 °C can improve cavity performance via recrystallization (Rx) and grain growth. As Rx is thermally activated, increasing the temperature and/or the heating rate could facilitate a reduction in geometrically necessary dislocation (GND) density that is associated with the degradation of cavity performance via trapped magnetic flux. Recent work shows that increasing the annealing temperature increased the Rx fraction in cold-rolled polycrystalline niobium. However, the influence of heating rate on the extent of Rx was minimal with a 3 hr soak time. To further assess the influence of heating rate on measured Rx, as well as the effects of sample preparation, electron backscatter diffraction (EBSD) was used to quantify the extent of Rx on samples annealed at a single temperature with different soak times. Comparing samples with different surface preparation shows that pinned grain boundaries on the free surface reveal a much smaller grain size than below the surface. * Z.L. Thune et al., "The Influence of Strain Path and Heat Treatment Variations on Recrystallization in Cold-Rolled High-Purity Niobium Polycrystals," doi: 10.1109/TASC.2023.3248533.
	Poster WEPWB116 [1.312 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB116
About •	Received ※ 23 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 20 August 2023 — Issue date ※ 21 August 2023
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WEPWB118	Study and Improvements of Liquid Tin Diffusion Process to Synthesize Nb₃Sn Cylindrical Targets	868
SUSPB033	use link to see paper's listing under its alternate paper code
	D. Ford, E. Chyhyrynets, D. Fonnesu, G. Keppel, G. Marconato, C. Pira, A. Salmaso INFN/LNL, Legnaro (PD), Italy
	Funding: This project has received funding from the European Union¿s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730. Work supported by the INFN CSNV experiment SAMARA. Nb₃Sn thin films on bulk Nb cavities exhibit comparable performance to bulk Nb at lower temperatures, and using Cu as a substrate material can further improve performance and reduce costs. However, coating substrates with curved geometries like elliptical cavities can be challenging due to the brittleness of Nb₃Sn targets produced by a classical sintering technique. This work explores the use of the Liquid Tin Diffusion (LTD) technique to produce sputtering targets for 6 GHz elliptical cavities, which allows for the deposition of thick and uniform coatings on Nb substrate, even for complex geometries. The study includes improvements in the LTD process and the production of a single-use LTD target, as well as the characterization of Nb₃Sn films coated by DC magnetron sputtering using these innovative targets.
	Poster WEPWB118 [5.462 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB118
About •	Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 01 August 2023
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WEPWB119	Additive Manufacturing of Pure Niobium and Copper Using Laser Powder Bed Fusion for Particle Accelerator Applications	872
SUSPB034	use link to see paper's listing under its alternate paper code
	D. Ford, R. Caforio, E. Chyhyrynets, G. Keppel, C. Pira INFN/LNL, Legnaro (PD), Italy M. Bonesso, S. Candela, V. Candela, R. Dima, G. Favero, A. Pepato, P. Rebesan, M. Romanato INFN- Sez. di Padova, Padova, Italy M. Pozzi Rösler Italiana s.r.l., Concorezzo, Italy
	Funding: This project has received funding from the European Union¿s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730. Work supported by the INFN CSNV experiment SAMARA. In this study, Metal Additive Manufacturing (MAM) was evaluated as a viable method for producing seamless 6 GHz pure copper and niobium prototypes without the use of internal supports. Preliminary tests were performed to evaluate printability, leading to further investigations into surface treatments to reduce surface roughness from 35 µm to less than 1 µm. Additional prototypes were printed using different powders and machines, exploring various printing parameters and innovative contactless supporting structures to improve the quality of downward-facing surfaces with small inclination angles. These structures enabled the fabrication of seamless SRF cavities with a relative density greater than 99.8%. Quality testing was conducted using techniques such as tomography, leak testing, resonant frequency assessment, and internal inspection. The results of this study are presented herein.
	Poster WEPWB119 [9.235 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB119
About •	Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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WEPWB120	Flux Expulsion Testing for LCLS-II-HE Cavity Production	876
	J.T. Maniscalco, S. Aderhold, M. Checchin, D. Gonnella, R.D. Porter SLAC, Menlo Park, California, USA T.T. Arkan, D. Bafia, J.A. Kaluzny, S. Posen Fermilab, Batavia, Illinois, USA M.E. Bevins, A.J. Grabowski, J. Hogan, C.E. Reece, D. Savransky, H. Vennekate JLab, Newport News, Virginia, USA
	Nitrogen-doped niobium SRF cavities are sensitive to trapped magnetic flux, which decreases the cavity intrinsic Q₀. Prior experimental results have shown that heat treatments to 900°C and higher can result in stronger flux expulsion during cooldown; the precise temperature required tends to vary by vendor lot/ingot of the niobium material used in the cavity cells. For LCLS-II-HE, to ensure sufficient flux expulsion in all cavities, we built and tested single-cell cavities to determine this required temperature for each vendor lot of niobium material to be used in cavity cells. In this report, we present the results of the single-cell flux expulsion testing and the Q₀ of the nine-cell cavities built using the characterized vendor lots. We discuss mixing material from different vendor lots, examine the lessons learned, and finally present an outlook on possible refinements to the single-cell technique.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB120
About •	Received ※ 15 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 13 July 2023
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WEPWB121	Niobium Chronicles: Surface Quality Investigation and Recovery During Material Procurement for the PIP-II High Beta 650 MHz Cavities	880
	A.D. Shabalina STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The surface quality of high-purity niobium for superconducting radiofrequency cavities experienced a sudden and significant decline in 2021. The recovery process and root cause analysis were challenging due to a variety of factors such as COVID-19 travel restrictions, cultural differences, and bureaucratic processes. Effective open communication was crucial to resolving the issue, especially with direct vendor oversight being impossible.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB121
About •	Received ※ 28 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 20 August 2023 — Issue date ※ 20 August 2023
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WEPWB125	Thermodynamic Properties of Srf Niobium	884
	P. Dhakal JLab, Newport News, Virginia, USA
	Funding: This is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177. Bulk and thin films of niobium are the materials of choice in fabricating superconducting radio frequency (SRF) cavities for modern particle accelerators and quantum computing applications. The thermodynamic properties of Nb are of particular interest in heat management in cryogenic environments. Here, we report the results of measurements of the thermodynamic properties of niobium used in the fabrication of superconducting radio frequency (SRF) cavities. The temperature and magnetic field dependence of thermal conductivity, Seebeck coefficient, and specific heat capacity was measured on bulk niobium samples.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB125
About •	Received ※ 11 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 04 July 2023
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WEPWB126	First Results from Nanoindentation of Vapor Diffused Nb₃Sn Films on Nb	888
	U. Pudasaini JLab, Newport News, Virginia, USA S. Cheban, G.V. Eremeev Fermilab, Batavia, Illinois, USA
	Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics & Office of High Energy Physics. The mechanical vulnerability of the Nb₃Sn-coated cavities is identified as one of the significant technical hurdles toward deploying them in practical accelerator applications in the not-so-distant future. It is crucial to characterize the material’s mechanical properties in ways to address such vulnerability. Nanoindentation is a widely used technique for measuring the mechanical properties of thin films that involves indenting the film with a small diamond tip and measuring the force-displacement response to calculate the film’s elastic modulus, hardness, and other mechanical properties. The nanoindentation analysis was performed on multiple vapor-diffused Nb₃Sn samples coated at Jefferson Lab and Fermilab coating facilities for the first time. This contribution will discuss the first results obtained from the nanoindentation of Nb₃Sn-coated Nb samples prepared via the Sn vapor diffusion technique.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB126
About •	Received ※ 19 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 16 July 2023
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WEPWB127	Investigation of Coupler Breakdown Thresholds for Plasma Processing of FRIB Quarter-Wave Resonators with Fundamental and Higher-Order Modes	893
SUSPB035	use link to see paper's listing under its alternate paper code
	P.R. Tutt, W. Hartung, S.H. Kim, T. Xu FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and used resources of the Facility for Rare Isotope Beams (FRIB) under Award Number DE-SC0000661. FRIB is developing plasma processing techniques for in-situ recovery of cavity performance in linac cryomodules during long-term user operation. While plasma processing has been shown to be effective for high-frequency (0.8 - 1.5 GHz) elliptical cavities, one of the challenges for FRIB is to avoid plasma breakdown in the fundamental input coupler (FPC), which has relatively weak coupling strength (Q_ext ranging from 2E6 to 1E7). FRIB cavities are not equipped with higher-order-mode (HOM) couplers; however, in preliminary tests, we found that HOMs are suitable for plasma processing of FRIB Quarter-Wave Resonators (QWRs) driven via the FPC. In this study, we investigated plasma breakdown thresholds in the fundamental and the first 2 HOMs for the FRIB β = 0.085 QWRs. Electric field distributions in the FPC region and cavity region were calculated for the room-temperature case using CST Microwave Studio’s frequency domain solver (FDS). Simulation results will be presented, with comparison of breakdown thresholds inferred from the RF modeling to the experimental results.
	Poster WEPWB127 [5.068 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB127
About •	Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 11 August 2023
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WEPWB128	Experimental Study of Mechanical Dampers for the FRIB β=0.041 Quarter-Wave Resonators	898
SUSPB036	use link to see paper's listing under its alternate paper code
	J. Brown, W. Chang, W. Hartung, S.H. Kim, T. Xu FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award numbers DE-SC0018362 and DE-SC0000661 and Michigan State University. The ’pendulum’ mechanical mode of quarter-wave resonators (QWR) often causes an issue with microphonics and/or ponderomotive instability unless otherwise the inner conductors are properly stiffened and/or damped. FRIB QWRs are equipped with a Legnaro-style frictional damper installed inside of the inner conductor such that it counteracts the oscillations of the inner conductor. In cryomodule tests and linac operation, we observed that the damping efficiency is different for a few β=0.041 QWRs. This study aimed to experimentally characterize the damping efficacy as a function of damper mass and surface roughness. We present damping measurements at room temperature and at two different masses and surface roughness as well as discuss future studies for damper re-optimization based on this follow-on study.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB128
About •	Received ※ 20 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 04 August 2023
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WEPWB131	Demonstration of Magnetron as an Alternative RF Source for SRF Accelerators	902
	H. Wang, K. Jordan, R.A. Rimmer JLab, Newport News, Virginia, USA J.P. Anderson, C.P. Moeller, K.A. Thackston GA, San Diego, California, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and DOE OS/ARDAP Accelerator Stewardship award 2019-2023. Magnetron has been considered as alternate high-efficiency, low-cost RF sources for linacs and storage rings [1] for national labs and industrial applications. After the demonstration of magnetrons power to drive and combine for a radio frequency cavity at 2450 MHz in CW mode, we have used trim coils adding to a water-cooled magnetron and amplitude modulation feedback to further suppress the side-band noise to -46.7 dBc level. We also demonstrated the phase-locking to an industrial grade cooking magnetron transmitter at 915 MHz with a 75 kW CW power delivered to a water load by using a -26.6 dBc injection signal [2]. The sideband noise from the 3-Phase SCRs DC power supply can be reduced to -16.2 dBc level. Further noise reduction and their power combining scheme using magic-tee and cavity type combiners for higher power application (2x75kW) are to be presented. We intent to use one power station to drive the normal conducting and superconducting RF cavities for the inductrial linac. We also going to demonstarte a vertical SRF cavity test with a high input coupling Q using a 2.45GHz magnetron and comparing with a baseline test result using a solid state amplifier. [1]. doi:10.18429/JACoW-IPAC2015-WEPWI028. [2]. doi:10.18429/JACoW-NAPAC2022-WEZD3.
	Poster WEPWB131 [2.445 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB131
About •	Received ※ 16 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 19 August 2023
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WEPWB133	Testing of the 2.6 GHz SRF Cavity Tuner for the Dark Photon Experiment at 2 K	907
	C. Contreras-Martinez, B. Giaccone, I.V. Gonin, T.N. Khabiboulline, O.S. Melnychuk, Y.M. Pischalnikov, S. Posen, O.V. Pronitchev, J.C. Yun Fermilab, Batavia, Illinois, USA
	At FNAL two 2.6 GHz SRF cavities are being used to search for dark photons, the experiment can be conducted at 2 K or in a dilution refrigerator. Precise frequency tuning is required for these two cavities so they can be matched in frequency. A cooling capacity constraint on the dilution refrigerator only allows piezo actuators to be part of the design of the 2.6 GHz cavity tuner. The tuner is equipped with three encapsulated piezo that deliver the long- and short-range frequency tuning. Modifications were implemented on the first tuner design due to the low forces on the piezos due to the cavity. Three brass rods with Belleville washers were added to the design to increase the overall force on the piezos. The results at 2 K of testing this tuner with and without the modification will be presented.
	Poster WEPWB133 [0.829 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB133
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 July 2023
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WEPWB134	Study of Different Piezoelectric Material Stroke Displacement at Different Temperatures Using an SRF Cavity	911
	C. Contreras-Martinez, Y.M. Pischalnikov, J.C. Yun Fermilab, Batavia, Illinois, USA
	Piezoelectric actuators are used for resonance control in superconducting linacs. The level of frequency compensation depends on the piezoelectric stroke displacement. In this study, the stroke displacement will be measured with a 1.3 GHz SRF cavity by measuring the frequency shift with respect to the voltage applied. The entire system was submerged in liquid helium. This study characterizes the PZT piezoelectric actuator (P-844K093) and a lithium niobate (P-844B0005) piezoelectric actuator. All these actuators were developed at Physik Instrumente (PI). The piezo-electric displacement was measured at different temperatures.
	Poster WEPWB134 [0.776 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB134
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 13 July 2023
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WEPWB135	A Novel Twin Drive Tuner Mechanism for 1.3 GHz ILC Cavity	914
	M. Yamanaka KEK, Ibaraki, Japan
	A tuner is a device that adjusts the resonant frequency of a cavity. Here we propose a new tuner mechanism for the 1.3 GHz ILC cavity. A bellow is provided in the central portion of the helium tank in the longitudinal direction, and flanges are provided on both sides of the bellows. A linear motion actuator is fixed to the flange on one side, and the frequency is changed by pushing and pulling the flange on the opposite side. Significantly, two linear motion actuators are placed in circumference and working simultaneously. It is named a twin-drive tuner. According to the ILC specification, the cavity has a spring constant of 3 KN/mm, requiring a stroke of 2 mm to adjust the 600 kHz range. A loading force of 6 kN is required. This is shared by two linear motion actuators. We developed a prototype actuator with a loading force of 4 kN per unit. It consists of a stepping motor and a sliding screw with a plastic nut. An experimental device was constructed using this actuator and a 1.3 GHz cavity with a helium tank, and the frequency tuning was evaluated. The displacement between the flanges and the frequency are proportional, both have good linearity, and the slope is 296 kHz/mm.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB135
About •	Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023
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WEPWB137	Prototype SSR2 Tuner Procurement and Testing at IJCLab for PIP-II Project	917
	N. Gandolfo, P. Duchesne, D. Le Dréan, D. Longuevergne, G. Mavilla, T. Pépin-Donat Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France M. Parise, D. Passarelli, Y.M. Pischalnikov Fermilab, Batavia, Illinois, USA
	Funding: Work supported by IN2P3. Work supported, in part, by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under U.S. DOE Contract No. DE-AC02-07CH11359. IJCLab is involved in the PIP-II project on the design and development of accelerator components for the SSR2 (Single Spoke Resonator type 2) section of the superconducting linac. Five prototype tuners have been built and are being tested at IJCLab. After a short description of the tuner, this paper reports on the procurement strategy and the performance observed at both room and low temperatures in vertical cryostat test with SSR2 prototype cavities. This paper will also share results on accelerated lifetime tests performed in a dedicated nitrogen-cooled cryostat.
	Poster WEPWB137 [1.395 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB137
About •	Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 16 July 2023
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Paper

Title

Page

Preparation and Characterization of Nb Films Deposited in SRF Cavity via HiPIMS

651

P. He, J. Dai, H.C. Duan, J.W. Kan, Y. Ma, T. Xin, Y.C. Yang, P. Zhang
IHEP, Beijing, People’s Republic of China

The RF performance of the niobium superconducting cavity has been continuously improved in recent 50 years. Since the maximum acceleration field (E_acc) has approached its theoretical limit, developing a more efficient and low-cost SRF cavity is one of the key challenges of the next generation particle accelerators. Niobium coated copper cavities are promising solutions because the SRF phenomenon occurrs within several hundred nanometers under the cavity surface. In literatures, the Nb coated Cu cavity prepared by direct current magnetron sputtering (DCMS) has serious Q-slope problem, which may be related to the low energy deposition. High power impulse magnetron sputtering (HiPIMS) can produce a high peak power and high ionization rate which may improve the thin film quality. Therefore, we prepared Nb coated Cu samples via HiPIMS on the 1.3 GHz dummy cavity at IHEP.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB001

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Received ※ 15 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 20 August 2023

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WEPWB043

Nb₃Sn Vapor Diffusion Coating System at SARI: Design, Construction, and Commissioning

655

SUSPB038

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Q.X. Chen, Y. Zongpresenter
SINAP, Shanghai, People’s Republic of China
J.F. Chen, S. Xing
SARI-CAS, Pudong, Shanghai, People’s Republic of China
J. Rong
SSRF, Shanghai, People’s Republic of China

This paper describes the design of a coating system for the preparation of a superconducting radio-frequency cavity with Nb₃Sn thin films. The device consists of a coating chamber made of pure niobium, a vacuum furnace for heating the coating chamber, a superconducting cavity bracket and two crucible heaters. The chamber is vacuum isolated from the furnace body to protect the superconducting cavity from contamination during the coating process. The device has been built and commissioned, which could be used for Nb₃Sn coating of a 1.3 GHz single-cell superconducting cavity in future.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB043

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Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 08 July 2023

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WEPWB044

Realization of Accelerating Gradient Larger than 25 MV/m on High-Q 1.3 GHz 9-Cell Cavities for SHINE

658

SUSPB039

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Y. Zong, Q.X. Chen, X. Huang, Z. Wang
SINAP, Shanghai, People’s Republic of China
J.F. Chen, P.C. Dong, H.T. Hou, X.Y. Pu, J. Shi, S. Sun, D. Wang, J.N. Wu, S. Xing, S.J. Zhao, Y.L. Zhao
SARI-CAS, Pudong, Shanghai, People’s Republic of China
Y.W. Huang
ShanghaiTech University, Shanghai, People’s Republic of China
X.W. Wu
Zhangjiang Lab, Shanghai, People’s Republic of China

Funding: This work was supported by Shanghai Municipal Science and Technology Major Project (No. 2017SHZDZX02).
We present our studies on the optimized nitrogen-doping and medium-temperature baking recipes applied on 1.3GHz SRF cavities, aiming at meeting the requirements of the SHINE project. The optimized nitrogen-doping process resulted in achieving a Q₀ of over 4.0×10¹⁰ at medium field and a maximum accelerating gradient exceeding 35 MV/m on single cell cavities, and a Q₀ of over 2.8×10¹⁰ at medium field and a maximum accelerating gradient exceeding 26 MV/m in 9-cell cavities. For 1.3 GHz 9-cell cavities subjected to medium-temperature baking, Q₀ values exceeding 3.5×10¹⁰ at 16 MV/m and maximum accelerating gradients surpassing 25 MV/m were achieved. These studies provide two options of high-Q recipes for SHINE cavities. The treatment processes of cavities and their vertical test results are described in this paper.
*chenjinfang@sari.ac.cn

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB044

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Received ※ 19 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 26 June 2023

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WEPWB045

The Oxidizing Responses of Baked Niobium Exposed to Various Gases via In-situ NAXPS

662

SUSPB040

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Z.T. Yang, J.K. Hao, K.X. Liu, S.W. Quan
PKU, Beijing, People’s Republic of China

We carried out in-situ NAXPS (Near-atmospheric X-ray Photoelectron Spectroscopy) on SRF-cavity class niobium to observe its oxidizing responses when exposed to various gases. The niobium samples were baked at 800°C until the peaks of niobium oxides disappeared in the spectrum. Then the revealed pure niobium samples were exposed to the air-proportion mixture of nitrogen and oxygen, pure oxygen, and pure water vapor respectively. And for the pure oxygen and water vapor group, we also carried out TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectroscopy) measurements before and after the baking and oxidation experiments. We found that pure oxygen and water vapor could oxidize niobium at similar rate which was faster than the N2/O2 mixture. After re-oxidized by pure oxygen and water vapor, the niobium sample presented a significant increase of interstitial carbon and a moderate increase of interstitial oxygen in the magnetic penetration depth, while it showed a mild decrease of interstitial hydrogen.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB045

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Received ※ 15 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 25 June 2023 — Issue date ※ 31 July 2023

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WEPWB047

Higher Order Mode Analysis of a 915 MHz 2-Cell Cavity for a Prototype Industrial Accelerator

667

A. Castilla
JLAB, Newport News, USA
G. Ciovati, J. Guo, G.-T. Park, R.A. Rimmer, H. Vennekate
JLab, Newport News, Virginia, USA

A possible solution to reduce the complexity posed by the cryogenic systems in a superconducting RF accelerator for industrial applications, is to capitalize on the advances achieved by the Nb₃Sn superconducting RF technology, as well as the feasibility of a reliable 4 K cooling system, based on commercial cryocoolers. Following this philosophy, the conceptual design for a prototype, conduction-cooled, 4 MeV, 20 kW SRF electron linac, is being developed at Jefferson Lab. Such design is based on a 915 MHz two-cell Nb₃Sn cavity. In this contribution, we present the proposed cavity design, including the fundamental power coupler, and the preliminary analysis of the Higher Order Modes, using numerical simulations to estimate the potentially dangerous modes as a starting point to evaluate the requirements for damping for reliable operations with a cryocooler. Finally, different methods to calculate the Higher Order Modes’ Impedances are briefly discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB047

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Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 16 July 2023

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WEPWB048

Geometry Optimization for a Quadrupole Resonator at Jefferson Lab

670

S. Bira, M. Ge, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA
L. Vega Cid, W. Venturini Delsolaro
CERN, Meyrin, Switzerland

Funding: This manuscript is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-6OR23177 with Jefferson Science Associates
The quadrupole resonator (QPR) is a sample characterization tool to measure the RF properties of superconducting materials using the calorimetry method at different temperatures, magnetic fields, and frequencies. Such resonators are currently operating at CERN and HZB but suffer from Lorentz force detuning and modes overlapping, resulting in higher uncertainties in surface resistance measurement. Using the two CERN’s QPR model iterations, the geometry was optimized via electromagnetic and mechanical simulations to eliminate these issues. The new QPR version was modeled for an increasing range of magnetic fields. The magnetic field is concentrated at the center of the sample to reduce the uncertainty in surface resistance measurements significantly. This paper will discuss the QPR geometry optimization for the new version of QPR, which is now progressing towards fabrication.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB048

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Received ※ 19 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 21 August 2023

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WEPWB049

Multipacting in C75 Cavities

674

G. Ciovati, P. Dhakal, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: This work was supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Cavities for the C75 cryomodule refurbishment program are currently being built, processed, tested and installed in the CEBAF accelerator at Jefferson Lab. They consist of 5-cell, 1497 MHz cavities with waveguide-type power coupler and for higher-order modes. Most of the cavities rf tests in a vertical cryostat at 2.07 K were limited by strong multipacting at accelerating gradients in the range 18 - 23 MV/m. A softer multipacting barrier was sometimes found at 13 - 15 MV/m. An unusual feature of the multipacting was that the barrier often shifted to a lower gradient ~17 MV/m, after multiple quenches at ~20 MV/m. This phenomenon was reproduced in a single-cell cavity of the same shape. The cavity was tested after different amounts of mechanical tuning and residual magnetic field, with no significant impact to the multipacting behavior. This contribution summarizes the experimental results from cavity rf tests, some of which were complemented by additional diagnostic instrumentation. Results from 2D and 3D simulations are also presented, indicating favorable conditions for multipacting at the equator in the range 20 - 29 MV/m.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB049

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Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 01 July 2023

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WEPWB050

Exploring Innovative Pathway for SRF Cavity Fabrication

680

O. Hryhorenko
JLab, Newport News, Virginia, USA
C.Z. Antoine
Université Paris-Saclay, CEA, Gif-sur-Yvette, France
T. Dohmae
KEK, Ibaraki, Japan
D. Longuevergne
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: ENSAR-2 under grant agreement N° 654002. The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
This article shows a study on an alternative pathway for the fabrication of a complete 1.3 GHz SRF cavity, aiming at improving production reliability, reducing the use of chemical polishing (EP or BCP) which is a costly and safety-critical step, and preserving surface quality after forming. Unlike the conventional pathway, the fabrication process is performed after polishing. This point is crucial as the used polishing technology could be applied only to flat geometries. The performed investigation demonstrates that damages during the fabrication process are considered minor, localized, and limited to the near-surface. Moreover, these studies confirm that the damaged layer (100-200 µm) is mainly caused by the rolling process, and not by the subsequent fabrication steps. A laser confocal microscope and SEM-EBSD technique were used to compare samples before and after forming. The preliminary results are discussed and presented in this paper.

Poster WEPWB050 [2.263 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB050

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Received ※ 20 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023

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WEPWB051

Development of a Prototype 197 MHz Crab Cavity for the Electron-Ion Collider at JLab

685

N.A. Huque, E.F. Daly, E. Drachuk, J. Henry, M. Marchlik
JLab, Newport News, Virginia, USA
A. Castilla
JLAB, Newport News, USA
S.U. De Silva
ODU, Norfolk, Virginia, USA
B.P. Xiao
BNL, Upton, New York, USA

Thomas Jefferson National Accelerator Facility (JLab) is currently developing a prototype 197 MHz Radio-Frequency Dipole (RFD) crab cavity as part of the Electron-Ion Collider (EIC) to be built at Brookhaven National Laboratory (BNL). Cryomodules containing these cavities will be part of Hadron Storage Ring (HSR) of the EIC. The prototype cavity is constructed primarily of formed niobium sheets of thickness 4.17 mm, with machined niobium parts used as interfaces where tight tolerancing is required. The cavity¿s large size and complex features present a number of challenges in fabrication, tuning, and RF testing. Structural and forming analyses have been carried out to optimize the design and fabricated processes. An overview of the design phase and the current state of fabrication are presented in this paper.
Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB051

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Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 16 July 2023

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WEPWB052

Temperature, RF Field, and Frequency Dependence Performance Evaluation of Superconducting Niobium Half-Wave Coaxial Cavity

691

N.K. Raut, G. Ciovati, P. Dhakal
JLab, Newport News, Virginia, USA
S.U. De Silva, J.R. Delayen, B.D. Khanal, J.K. Tiskumara
ODU, Norfolk, Virginia, USA

Funding: This is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177
Recent advancement in superconducting radio frequency cavity processing techniques, with diffusion of impurities within the RF penetration depth, resulted in high quality factor with increase in quality factor with increasing accelerating gradient. The increase in quality factor is the result of a decrease in the surface resistance as a result of nonmagnetic impurities doping and change in electronic density of states. The fundamental understanding of the dependence of surface resistance on frequency and surface preparation is still an active area of research. Here, we present the result of RF measurements of the TEM modes in a coaxial half-wave niobium cavity resonating at frequencies between 0.3 - 1.3 GHz. The temperature dependence of the surface resistance was measured between 4.2 K and 1.6 K. The field dependence of the surface resistance was measured at 2.0 K. The baseline measurements were made after standard surface preparation by buffered chemical polishing.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB052

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Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 20 July 2023

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WEPWB053

Simulation of the Dynamics of Gas Mixtures during Plasma Processing in the C75 Cavity

696

N.K. Raut, P. Dhakal, T.D. Ganey, T. Powers
JLab, Newport News, Virginia, USA

Funding: The work is supported by SC Nuclear Physics Program through DOE SC Lab funding announcement DE-FOA-0002670 & is authored by JSA, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177
Plasma processing using a mixture of noble gas and oxygen is a technique that is currently being used to reduce field emission and multipacting in accelerating cavities. Plasma is created inside the cavity when the gas mixture is exposed to an electromagnetic field that is generated by applying RF power through the fundamental power or higher-order mode couplers. Oxygen ions and atomic oxygen are created in the plasma which breaks down the hydrocarbons on the surface of the cavity and the residuals from this process are removed as part of the process gas flow. Removal of hydrocarbons from the surface increases the work function and reduces the secondary emission coefficient. This work describes the initial results of plasma simulation, which provides insight into the ignition process, distribution of different species, and interactions of free oxygen and oxygen ions with the cavity surfaces. The simulations have been done with an Ar/¿2 plasma using COMSOL® multiphysics. These simulations help in understanding the dynamics and control of plasma inside the cavity and the exploration of different gas mixtures.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB053

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Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 29 June 2023

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WEPWB054

In Situ Plasma Processing of Superconducting Cavities at JLab, 2023 Update

701

T. Powers, N.C. Brock, T.D. Ganey
JLab, Newport News, Virginia, USA

Jefferson Lab has an ongoing R&D program in plasma processing which just completed a round of production processing in the CEBAF accelerator. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the secondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The initial focus of the effort was processing C100 cavities by injecting RF power into the HOM coupler ports. Results from processing cryomodules in the CEBAF accelerator as well as vertical test results will be presented. The goal will be to improve the operational gradients and the energy margin of the linacs. This work will describe the systems and methods used at JLAB for processing cavities using an argon-oxygen gas mixture as well as a helium-oxygen gas mixture. Before and after plasma processing results will also be presented.
Funding provided by SC Nuclear Physics Program through DOE SC Lab funding announcement DE-FOA-0002670.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB054

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Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023

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WEPWB055

First Experience with Liquid Nitrogen Cleaning

706

R.J.M.Y. Ruber, A.B. Eslinger, R.L. Geng
JLab, Newport News, Virginia, USA

Field emission caused by microscopic particulate contamination is a limiting factor for the performance of superconducting RF (SRF) cavities. In an SRF accelerator, particulates may be transported over the surface of an operational SRF cavity, becoming field emitters and consequentially degrading the performance of the SRF cavity. The most commonly used method for removing particulates from cavity surfaces is high-pressure ultra-pure water rinsing. We are developing a novel high-pressure liquid nitrogen cleaning technique that may possibly enable superior cleaning power and particulate removal from cavities in a cryomodule without taking apart the cryomodule components. This technique provides cleaning mechanisms beyond what are accessible by its high-pressure water counterpart and leaves no residues on the cleaned surface. We present the test setup and first experience.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB055

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Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 27 June 2023

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WEPWB057

Refurbishment of an Elbe-Type Cryomodule for Coated HOM-Antenna Tests for MESA

709

SUSPB042

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P.S. Plattner, F. Hug, T. Stengler
KPH, Mainz, Germany

Funding: The work received funding by BMBF through 05H21UMRB1.
The Mainz Energy-Recovering Superconducting Accelerator (MESA), an energy-recovering (ER) LINAC, is currently under construction at the university Mainz. In the ER mode a continues wave (CW) beam is accelerated from 5 MeV up to 10⁵ MeV with a beam current of up to 1 mA. This current is accelerated and decelerated twice within a cavity. For future experiments, the beam current limit has to be pushed up to 10 mA. An analysis of the MESA cavities has shown that the HOM antennas quench at such high beam currents due to the extensive power deposition and the resulting heating of the HOM coupler. To avoid quenching it is necessary to use superconducting materials with higher critical temperature. For this purpose, the HOM antennas will be coated with NbTiN and Nb3SN and their properties will be investigated. For use in the accelerator, the HOM antennas will be installed in the cavities of a former ALICE cryomodule, kindly provided by STFC Daresburry. This paper will show both the status of the refurbishment of the ALICE module to suit MESA, and the coating of the HOM antennas.
The authors would like to express their sincere gratitude to STFC Daresbury for the donation of the ALICE module, which strongly supports SRF research in Mainz.

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB057

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Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 09 July 2023

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WEPWB058

Contribution of IN2P3 to PIP-II Project: Plans and Progress

714

D. Longuevergne, N. Bippus, P. Duchesne, N. Gandolfo, D. Le Dréan, G. Mavilla, T. Pépin-Donat, S. Roset, L.M. Vogt, S. Wallon
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
P. Berrutti, J. Helsper, S. Kazakov, M. Parise, D. Passarelli, N. Solyak, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

Funding: Work supported by IN2P3. Work supported, in part, by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under U.S. DOE Contract No. DE-AC02-07CH11359.
IJCLab is one of the labs of IN2P3 (National institute of nuclear and particle physics), one of the ten research institutes composing the French National Center for Scientific Research (CNRS). Since 2018, IJCLab has been involved in the PIP-II project, assisting with the design, development, and qualification of accelerator components for the SSR2 (Single Spoke Resonator type 2) section of the superconducting linac. The first pre-production components (cavity, coupler, and tuner) have been fabricated, and some of the first qualification tests have been performed at IJCLab. This paper will summarize the complete scope of IJCLab¿s contributions to PIP-II and give updates on the performances of the first pre-production components.

Poster WEPWB058 [1.727 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB058

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Received ※ 24 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 05 July 2023 — Issue date ※ 10 July 2023

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WEPWB061

Pre-Installation Performance of the RHIC 56 MHz Superconducting System

718

Z.A. Conway, R. Anderson, J.C. Brutus, K. Hernandez, D. Holmes, K. Mernick, G. Narayan, S. Polizzo, S.K. Seberg, F. Severino, M. Sowinski, R. Than, Q. Wu, B.P. Xiao, W. Xu, A. Zaltsman
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under contract No. DE-SC0012704 with the U.S. Department of Energy.
Pre-installation test results for the RHIC 56 MHz superconducting RF system are presented here. The 56 MHz quarter-wave resonator achieved a stable accelerating potential of 1.1 MV with 13 W of RF loss at 4.5 K demonstrating its viability for increasing the luminosity of sPHENIX collisions. The new 120 kW travelling wave fundamental mode damper and dual 6 kW combined-function fundamental power couplers perform as expected at 3 kW but remain to be operated with the expected ~40 times greater power achievable with the RHIC sPHENIX beams.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB061

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Received ※ 15 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 02 July 2023 — Issue date ※ 17 July 2023

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WEPWB063

Final Design of the LB650 Cryomodule for the PIP-II Linear Accelerator

721

R. Cubizolles, S. Ladegaillerie, A. Moreau
CEA-IRFU, Gif-sur-Yvette, France
N. Bazinpresenter, S. Berry, J. Drant, P. Garin, A. Raut, C. Simon
CEA-DRF-IRFU, France
S.K. Chandrasekaran, O. Napoly, V. Roger
Fermilab, Batavia, Illinois, USA

The Proton Improvement Plan II (PIP-II) that will be installed at Fermilab is the first U.S. accelerator project that will have significant contributions from international partners. CEA joined the international collaboration in 2018, and its scope covers the supply of the 650 MHz low-beta cryomodule section, with the design of the cryostat (i.e the cryomodule without the cavities, the power couplers and the frequency tuning systems) and the manufacturing of its components, the assembly and tests of the pre-production cryomodule and 9 production modules. An important milestone was reached in April 2023 with the Final Design Review. This paper presents the detailed design of the 650 MHz low-beta cryomodules.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB063

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Received ※ 21 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 20 July 2023

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WEPWB064

Performance Analysis from ESS Cryomodule Testing at CEA

727

O. Piquet, C. Arcambal, Q. Bertrand, P. Bosland, E. Cenni, G. Devanz, T. Hamelin
CEA-IRFU, Gif-sur-Yvette, France
P. Sahuquet
CEA-DRF-IRFU, France

CEA Saclay is in charge of the production of 30 elliptical cavities cryomodule as part of the in Kind contribution to the ESS superconducting. The two medium and high beta prototypes and the three first of each type of the series cryomodules have been tested at CEA in slightly different conditions than at ESS (both in terms of cryogenic operation as well as RF conditions). The goal of these tests was to validate the assembly procedure before the delivery of the series to ESS where the final acceptance tests are performed. This paper summarizes the main results obtained during the tests at CEA with a particular attention to the field emission behaviour.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB064

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Received ※ 20 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 07 July 2023

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WEPWB065

Impact of Medium Temperature Heat Treatments on the Magnetic Flux Expulsion Behavior of SRF Cavities

731

SUSPB043

use link to see paper's listing under its alternate paper code

J.C. Wolff, J. Eschke, A. Gössel, K. Kasprzak, D. Reschke, L. Steder, L. Trelle, M. Wiencek
DESY, Hamburg, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program.
Medium temperature (mid-T) heat treatments at 300 °C are used to enhance the intrinsic quality factor of superconducting radio frequency (SRF) cavities. Unfortunately, such treatments potentially increase the sensitivity to trapped magnetic flux and consequently the surface resistance of the cavity. For this reason, it is crucial to maximize the expulsion of magnetic flux during the cool down. The flux expulsion behavior is next to the heat treatment mainly determined by the geometry, the niobium grain size and the grain orientation. However, it is also affected by parameters of the cavity performance tests like the cool down velocity, the spatial temperature gradient along the cavity surface and the magnetic flux density during the transition of the critical temperature. To improve the flux expulsion behavior and hence the efficiency of future accelerator facilities, the impact of these adjustable parameters as well as the mid-T heat treatment on 1.3 GHz TESLA-Type single-cell cavities is investigated by a new approach of a magnetometric mapping system. In this contribution first performance test results of cavities before- and after mid-T heat treatment are presented.

Poster WEPWB065 [3.077 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB065

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Received ※ 21 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 13 July 2023

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WEPWB066

Final Design of the Production SSR1 Cryomodule for PIP-II Project at Fermilab

736

J. Bernardini, M. Chen, J. Helsper, M. Kramp, F.L. Lewis, T.H. Nicol, M. Parise, D. Passarelli, V. Roger, G.V. Romanov, B. Squires
Fermilab, Batavia, Illinois, USA
P. Neri
University of Pisa, Pisa, Italy

Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy, Office of Science, Office of High Energy Physics.
This contribution reports the design of the production Single Spoke Resonator Type 1 Cryomodule (SSR1 CM) for the PIP-II project at Fermilab. The innovative design is based on a structure, the strongback, which supports the coldmass from the bottom, stays at room temperature during operations, and can slide longitudinally with respect to the vacuum vessel. The Fermilab style cryomodule developed for the prototype Single Spoke Resonator Type 1 (pSSR1), the prototype High Beta 650 MHz (pHB650), and preproduction Single Spoke Resonator Type 2 (ppSSR2) cryomodules is the baseline of the present design. The focus of this contribution is on the results of calculations and finite element analyses performed to optimize the critical components of the cryomodule: vacuum vessel, strongback, thermal shield, and magnetic shield.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB066

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Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 15 July 2023

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WEPWB067

HB650 Cryomodule Design: From Prototype to Production

741

V. Roger, S.K. Chandrasekaran, C.J. Grimm, J.P. Holzbauer, O. Napoly, J.P. Ozelispresenter, D. Passarelli
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
In early 2023 the assembly of the prototype HB650 cryomodule (pHB650 CM) was completed and cold tests started to evaluate its performance. The lessons learned from the design, assembly and preliminary cold tests of this cryomodule, and from the design of the SSR2 pre-production cryomodule played a fundamental role during the design optimization process of the production HB650 cryomodule (HB650 CM). Several workshops have been organized to share experiences and solve problems. This paper presents the main design changes from pHB650 to the HB650 production cryomodules and their impact on the heat loads.

Poster WEPWB067 [2.178 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB067

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Received ※ 18 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023

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WEPWB068

Characterization of Additive Manufacturing Materials for String Assembly in Cleanroom

746

J. Bernardini, M. Parise, D. Passarelli
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy, Office of Science, Office of High Energy Physics.
Beamline components, such as superconducting radio frequency cavities and focusing lenses, need to be assembled together in a string while in a cleanroom environment. The present contribution identifies and characterizes materials for additive manufacturing that can be used in a cleanroom. The well known advantages of additive manufacturing processes would highly benefit the design and development of tooling needed for the mechanical support and alignment of string components. Cleanliness, mechanical properties, and leak tightness of the chosen materials are the main focus of this contribution, which also paves the way for the integration of such materials in cryomodule assemblies. Results reported here were obtained in the framework of the PIP-II project at Fermilab.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB068

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Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 July 2023

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WEPWB070

Test Shipment of the PIP-II 650 MHz Transport Frame Between FNAL to STFC-UKRI

750

J.P. Holzbauer, S.K. Chandrasekaran, C.J. Grimm, J.P. Ozelis, R. Thiede, A.D. Wixson
Fermilab, Batavia, Illinois, USA
M.T.W. Kane
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy
The PIP-II Project will receive fully assembled cryomodules from CEA and STFC-UKRI as in-kind contributions. Damage to these cryomodules during transport is understood to be a significant risk to the project, so an extensive testing and validation program is in process to mitigate this risk. The centerpiece of this effort is the eventual shipment from FNAL to STFC-UKRI and back of a prototype HB650 cryomodule with cold testing before and after shipment to verify no functionality changes from shipment. Most recently, a test shipment to the UK and back using a cryomodule analog was completed using realistic logistics, handling, instrumentation, and planning. The process of executing this test shipment, lessons learned, and plan moving forward will be presented here.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB070

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Received ※ 18 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 17 July 2023

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WEPWB073

Prototype HB650 Cryomodule Heat Loads Simulations

755

G. Coladonato
University of Illinois at Chicago, Chicago, USA
D. Passarellipresenter, V. Roger
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
During the design stages of the PIP-II cryomodules, many analytical calculations and FEA have been performed on simpler geometry in order to estimate the heat loads and also to optimize the design. To better analyze the cryomodule cold tests, simulations have been performed with MATLAB to determine the temperature of the main components during cool down and to determine the heat loads of the cryomodule. These simulations have been applied to the High Beta 650 MHz prototype cryomodule design and compared to the cold tests performed on it.

Poster WEPWB073 [1.981 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB073

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Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 28 June 2023

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WEPWB074

Commissioning of the UHH Quadrupole Resonator at DESY

SUSPB045

use link to access more material from this paper's primary paper code

THCAA02

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R. Monroy-Villa, W. Hillert, M. Wenskat
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
A. Gössel, D. Reschke, M. Röhling, M. Schmökel, J.H. Thie, M. Wiencek
DESY, Hamburg, Germany
C. Martens
University of Hamburg, Hamburg, Germany

Funding: This work was supported by the BMBF under the research grants 05H18GURB1, 05K19GUB and 05H2021.
Pushing the limits of the accelerating field or quality factor of SRF cavities beyond pure Nb requires the implementation of specific inner surface treatments, which are yet to be studied and optimized. One of the fundamental challenges in exploring alternative materials is that only samples or cavity cuts can be fully characterized from a material point of view. On the other hand, complete cavities allow for the SRF characterization of the inner surface, while samples can usually only be analyzed using DC methods. To address this problem, a test resonator for samples, called "Quadrupole Resonator", was designed and operated at CERN and later at HZB. It allows for a full RF characterization of samples at frequencies of 0.42 GHz, 0.86 GHz, and 1.3 GHz, within a temperature range of 2-20 K and at magnetic fields up to 120 mT. This work presents the design process, which incorporated improvements motivated by mechanical and RF studies and experience, and the results from both warm and cold commissioning are discussed. More important, the results for the RF tests of a Nb sample after undergoing a series of heat treatments and an outlook of the further usage of the QPR is presented.

Slides THCAA02 [6.677 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-THCAA02

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Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 19 August 2023

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WEPWB075

Impact of Solenoid Induced Residual Magnetic Fields on the Prototype SSR1 CM Performance

760

D. Passarelli, J. Bernardini, C. Boffo, S.K. Chandrasekaran, A.H. Hogberg, T.N. Khabiboulline, J.P. Ozelis, M. Parise, V. Roger, G.V. Romanov, A.I. Sukhanov, G. Wu, Y. Xie, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
A prototype cryomodule containing eight Single Spoke Resonators type-1 (SSR1) operating at 325 MHz and four superconducting focusing lenses was successfully assembled, cold tested, and accelerated beam in the framework of the PIP-II project at Fermilab. The impact of induced residual magnetic fields from the solenoids on performance of cavities is presented in this contribution. In addition, design optimizations for the production cryomodules as a result of this impact are highlighted.

Poster WEPWB075 [2.429 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB075

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Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 11 July 2023

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WEPWB076

Low Particulates Nitrogen Purge and Backfill during Prototype HB650 Cryomodule String Assembly

765

T.J. Ring, M.B. Quinlan, G. Wupresenter
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
A low particulate vacuum and purging system was developed to support PIP-II cryomodule string assembly. The overpressure can be controlled at a precision of 1 mbar above the atmospheric pressure regardless of the cavity or string assembly air volume. The system minimized the risk of uncontrolled nitrogen flow during the string assembly. Design features will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB076

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Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 09 July 2023

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WEPWB082

Operational Experience with Turn-Key SRF Systems for Small Accelerators Like MESA

768

T. Stengler, K. Aulenbacher, F. Hug, P.S. Plattner
KPH, Mainz, Germany

Funding: The work is funded by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019 and the Federal Ministry of Education and Research (BMBF) through project 05H21UMRB1
New SRF-based accelerator development at sites without long-term experience in SRF development is a major challenge. Especially in-house development of cryomodules is an almost impossible obstacle to overcome for small projects. To minimize such obstacles, turn-key SRF systems provided by industry can be of great importance. For the multiturn ERL MESA, which is currently under construction at Johannes Gutenberg-Universität Mainz, two turnkey cryomodules have been purchased from industry and successfully tested. The specifications of a design gradient of 12.5 MV/m in CW operation with an unloaded Q of 1.25*10¹⁰ at 1.8 K had to be met. Since the design of the modules had to be modified for high current CW operation, a close cooperation with the manufacturer was of great importance. By purchasing such a turn-key SRF system, the MESA project successfully established the SRF accelerator technology at the site within six years. This was achieved through close monitoring of the manufacturing process and close cooperation with the manufacturer. An overview of the experience with the successful technology transfer of a complete turn-key SRF system for small accelerators will be given.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB082

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Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 03 August 2023

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WEPWB083

Basic Design and Consideration of Li-Vapor Contamination for A-FNS SRF

773

T. Ebisawa, K. Hasegawa, A. Kasugai, M. Oyaidzu, S. Sato
QST Rokkasho, Aomori, Japan
E. Kako, H. Sakai, K. Umemori
KEK, Ibaraki, Japan

The Advanced Fusion Neutron Source (A-FNS) project is in progressing in Japan, QST Rokkasho institute. A-FNS will demonstrate a performance of the DEMO DT fusion reactor material. In order to perform the test, a high intensity deuteron beam accelerator will be used to produce a high flux neutron field which is similar to the 14 MeV DT neutron. The Superconducting Radio-Frequency linear accelerator (SRF) is one component of the A-FNS accelerator system. Although the A-FNS accelerator system design is based on the IFMIF design, the improvement of some subsystem has been considering by taking into account the lessons learnt from the LIPAc project. In order to keep a high stability and availability of the SRF performance, we plan to increase the number of SRF cavities and cryomodules considering the trouble or degradation of the cavity performance and modify the engineering design of some components. In addition, changing of the beam transport line design and Li vapor contamination study of SRF cavity are conducting. In this presentation, the progress of the SRF design and related activities for A-FNS in QST will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB083

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Received ※ 28 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 17 August 2023

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WEPWB084

The Interaction among Interstitial C/N/O/H and Vacancy in Niobium via First-Principles Calculation

778

H. Liu, J.K. Hao, Z.T. Yangpresenter
PKU, Beijing, People’s Republic of China

We calculate the interaction among zero dimensional defects in niobium lattice through first-principles calculation. And we compare the trapping effect of hydrogen among carbon, nitrogen, and oxygen as well as the trapping effect of interstitial atoms by vacancy. We find that the interstitial C/N/O have similar effect of trapping interstitial hydrogen in niobium lattice, and the vacancy can trap interstitial C/N/O/H in adjacent protocells and strengthen their chemical bond with Nb. These calculations give some explanation for improving superconducting performance of niobium cavities through medium temperature baking.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB084

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Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 03 July 2023

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WEPWB085

Degradation and Recovery of Cavity Performance in SRILAC Cryomodules at RIBF

784

N. Sakamoto, O. Kamigaito, K. Ozeki, K. Suda, K. Yamada
RIKEN Nishina Center, Wako, Japan

The RIKEN superconducting (SC) heavy-ion linear accelerator (SRILAC) has been providing beam supply for super-heavy elements synthesis experiments since its commissioning in January 2020. However, the long-term operation of SC radio-frequency (RF) cavities leads an increase in the X-ray levels caused by field emissions resulting from changes in the inner surface conditions. More than half of the ten SC 1/4 wavelength resonators (SC-QWRs) of SRILAC, operating at a frequency of 73 MHz, have experienced an increase in X-ray levels, thus, requiring adjustments to the acceleration voltage for continuous operation. While several conditioning methods have been employed for SC cavities, a fully established technique is yet to be determined. To address this situation, a relatively simple conditioning method was implemented at RIKEN. The proposed method uses high-voltage pulsed power and imposes a low load on the cavities.

Poster WEPWB085 [12.789 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB085

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Received ※ 13 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 01 July 2023

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WEPWB087

Copper Plating Qualification Process for the Fundamental Power Coupler Waveguides for CEBAF Cryomodules

790

L. Zhao, G. Cheng, G. Ciovati, K.M. Wilson
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC, supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
To provide sufficient energy for CEBAF operation, cryomodules and components are being refurbished yearly as necessary. Copper plated fundamental power coupler waveguides are important components of the cryomodules. The integrity and quality of copper plating is critical to reduce the heat load from the waveguides into the He bath at 2.07 K. A search of copper plating resources is underway for plating or re-plating CEBAF-style waveguides. This effort ensures a continuous capability of copper plating on cryomodule components, especially on waveguides. To qualify plating vendors, the waveguide copper plating specifications were revisited, and a thorough plating evaluation process is being developed. The evaluation process ranges from coupon testing to sample waveguide qualification. Recent results are summarized and future work is planned.

Poster WEPWB087 [1.582 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB087

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Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 11 July 2023

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WEPWB089

Theoretical Model of External Q Tuning for an SRF Cavity with Waveguide Tuner

794

W. Xu, Z.A. Conway, K.S. Smith, A. Zaltsman
BNL, Upton, New York, USA
E.F. Daly, J. Guo, R.A. Rimmer
JLab, Newport News, Virginia, USA

Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
A wide range of electron beam energies (5 ¿ 18 GeV) and beam currents (0.2 ¿ 2.5 A) in EIC Electron Storage Ring (ESR) operating scenarios requires a capability of adjusting coupling factor up to a factor of 20 for the 591 MHz Superconducting Radio Frequency (SRF) cavities, which contains two fundamental power couplers (FPC) delivering continuous wave (CW) 800 kW RF power to the beam. Currently, adjusting external Q of a SRF cavity is done by varying protrusion of FPC¿s inner conductor in beam pipe or using three stub tuner to adjust external Q value, which either has limit on tuning range or limit on operating power. This paper presents a method of tuning the FPC external Q by a multiple-waveguide tuner, which allows for high power, wide tuning range operations. The theoretical model of matching beam impedance with waveguide tuner and detailed matching conditions and limits will be presented. Follow the theoretical model, a preliminary design of a 3D waveguide tuner will be presented.
The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.

Poster WEPWB089 [1.269 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB089

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Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023

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WEPWB092

Test-Stand for Conditioning of Fundamental Power Couplers at DESY

797

K. Kasprzak, Th. Buettner, A. Gössel, D. Klinke, D. Kostin, C. Müller, E. Vogel, M. Wiencek
DESY, Hamburg, Germany

During the construction of the European-XFEL, activities related to Fundamental Power Couplers (FPCs) were outsourced to external partners and the former FPC test-stand area at DESY was given up due to infrastructure rearrangements. For the study of various XFEL upgrade scenarios a new test-stand for conditioning of FPCs at DESY is required. It will be used for evaluation of new coupler preparation methods with particular emphasis on Continuous Wave (CW) and long RF pulse operation. The new test-stand has been recently commissioned. Four FPCs have been prepared and tested. RF pulses were applied to the couplers, starting with the shortest possible pulse and increasing it’s power until maximum power was reached. The process was repeated with several pulse lengths until the maximum RF pulse length was reached. A review of the commissioning and first operation experience of the RF system are presented here.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB092

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Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 16 July 2023

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WEPWB093

Transportation Fatigue Testing of the pHB650 Power Coupler Antenna for the PIP-II Project at Fermilab

801

J. Helsper, S.K. Chandrasekaran, J.P. Holzbauer, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The PIP-II Project will see international shipment of cryomodules from Europe to the United States, and as such, the shocks which can occur during shipment pose a risk to the internal components. Of particular concern is the coupler ceramic window and surrounding brazes, which can see relatively high stress during an excitation event. Since the antenna design is new, and because of the setback failure would create, a cyclic stress test was devised for the antenna. This paper presents the experimental methods, setup, and results of the test.

Poster WEPWB093 [2.913 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB093

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Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 03 July 2023

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WEPWB094

Design, Manufacturing, Assembly, and Lessons Learned of the Pre-Production 325 MHz Couplers for the PIP-II Project at Fermilab

806

J. Helsper, S. Kazakov, D. Passarelli, N. Solyak
Fermilab, Batavia, Illinois, USA
D. Longuevergne, S. Wallon
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

Funding: This manuscript has been authored by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Five 325 MHz high-power couplers will be integrated into the pre-production Single Spoke Resonator Type-II (ppSSR2) cryomodule for the PIP-II project at Fermilab. Couplers were procured by both Fermilab and IJCLAB for this effort. The design of the coupler is described, including design optimizations from the previous generation. This paper then describes the coupler life cycle, including design, manufacturing, and assembly, along with the lessons learned at each stage.

Poster WEPWB094 [3.561 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB094

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Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 29 June 2023

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WEPWB096

Testing of PIP-II Pre-production 650 MHz Couplers in Warm Test Stand and Cryomodule

812

N. Solyak, S.K. Chandrasekaran, B.M. Hanna, J. Helsper, J.P. Holzbauer, S. Kazakov, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

650 MHz fundamental power couplers were developed for PIP-II project to deliver RF power for low-beta and high-beta elliptical cavities. Few prototypes were built and tested and after some modification we built 8 pre-production couplers (with three spares for vacuum side) for ppHB650 cryomodule. All couplers were successfully tested in pulse mode (up to 100kW) and in CW mode (up to 50kW) in test stand at full reflection at 8 phases. In baseline configuration with DC bias we do not see any multipactoring activity after short processing. We also tested power processing without bias for uncoated and TiN coated ceramic window. Results of these studies presented in this paper. One of the coupler was assembled on LB650 cavity and tested at cryogenic environment in STC cryostat at ~30kW power with full reflection at different reflection phase. We also demonstrated good result from power processing without bias for warm and cold cavity. Six couplers were assembled on HB650 cavities in pre-production cryomodule. Test results from cryomodule qualification is discussing in this paper.

Poster WEPWB096 [2.748 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB096

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Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023

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WEPWB097

Testing and Processing of Pre-production 325 MHz Single Spoke Resonator Power Couplers for PIP-II Project

816

N. Solyak, B.M. Hanna, J. Helsper, S. Kazakov, D. Passarelli
Fermilab, Batavia, Illinois, USA
S. Wallon
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

Fundamental 325 MHz power couplers are designed, built and tested for SSR cavities in PIP-II project [1]. Couplers should work in CW mode at power level 7.5kW w/o beam and ~15 kW with the 2 mA beam. At pre-production stage we built and tested 6 couplers, produced by CPI (FNAL) and PMB (IJCLab) and 4 more couplers will be tested soon. Two of tested cou-plers had TiN coated ceramic window. In warm test stand two couplers were mounted on the coupling chamber and tested in SW regime at full reflection with phase controlled by position of short and reflection insert. Couplers were tested at pulse mode (up to 25kW) and cw mode (12kW) with HV bias or without bias. Test results demonstrated that 3.5 kV DC bias completely suppresses multipactor in coupler. Vacuum activity in coupler was controlled by e-pickups and build-in vacuum gauges, located near the vacuum side of window. Power processing without DC bias was done for several couplers with and without TiN coating on ceramic window. Test results are presented and discussing in paper.

Poster WEPWB097 [2.439 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB097

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Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 29 June 2023

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WEPWB098

Development and Evaluation of STF-Type Power Coupler for Cost Reduction at the High Energy Accelerator Research Organization

820

Y. Yamamoto, T. Matsumoto, S. Michizono
KEK, Ibaraki, Japan

At KEK, cost reduction study for STF-type input power coupler used in the STF-2 accelerator has been attempted since FY2015. In FY2019, one coupler was fabricated by some cost-effective and non-conventional methods including different alumina-ceramic material, copper plating and TiN coating. In high power RF test at room temperature, this coupler achieved 1 MW at 900 µsec/5Hz, and 935 kW @1.65 msec/5Hz. After that, this coupler experienced 10 thermal cycle tests from room temperature to liquid nitrogen temperature without vacuum leakage. In this report, the detailed results will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB098

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Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023

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WEPWB101

Present Status of RIKEN Power Couplers for SRILAC

823

K. Ozeki, O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada
RIKEN Nishina Center, Wako, Japan

The heavy ion linac of the RIKEN, utilizing superconducting technology, began operations in September 2019. Over the following 13 months, two of the ten superconducting accelerating cavities experienced vacuum leaks from the vacuum windows of the fundamental power couplers (FPCs). Currently, additional vacuum windows are installed on all ten FPCs and the beam supply continues without encountering any major issues with the FPCs. Additionally, the fabrication of ten replacement FPCs has been completed, addressing the underlying issues that led to the deterioration of the vacuum window strength. Currently, we are conducting radio frequency (RF) process of the new FPCs. In addition, we are designing a bias applying component to suppress multipacting in the FPCs. This paper reports the status of these issues related to the FPCs at the RIKEN.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB101

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Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 14 July 2023

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WEPWB102

Recent Progress of Fundamental Power Couplers for the SHINE Project

827

Z.Y. Ma, J.F. Chen, H.T. Hou, B. Liu, Y. Liu, S. Sun, D. Wang, L. Yin, M. Zhang, S.J. Zhao, Y.B. Zhao, Z.T. Zhao, X. Zheng
SARI-CAS, Pudong, Shanghai, People’s Republic of China

Funding: Project supported by Shanghai Municipal Science and Technology Major Project (Grant No.2017SHZDZX02).
The superconducting radio-frequency electron linear accelerator of the Shanghai HIgh repetition rate XFEL aNd Extreme light facility (SHINE) contains 610 1.3 GHz fundamental power couplers which are assembled in 77 superconducting cryomodules used for beam acceleration, and 16 3.9 GHz fundamental power couplers, which are assembled in two third harmonic superconducting cryomodules used for linearizing the longitudinal phase space. The first batch of 26 1.3 GHz coupler prototypes and two 3.9 GHz coupler prototypes have been fabricated from three domestic manufacturers for basic research. Several key manufacturing processes have been developed and qualified, including high residual resistivity ratio (RRR) copper plating, vacuum brazing of ceramic windows, electron beam welding and titanium nitride coating. All the 1.3 GHz coupler prototypes have been power conditioned with 14 kW travelling wave (TW) and 7 kW standing wave (SW) RF in continuous-wave (CW) mode. Even higher power levels have been demonstrated with 20 kW TW and 10 kW SW RF, which indicates their robustness. Both 3.9 GHz coupler prototypes have been power conditioned with 2.2 kW TW and 2 kW SW RF in CW mode.

Poster WEPWB102 [2.361 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB102

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Received ※ 16 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 05 July 2023

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WEPWB103

Simulations and First RF Measurements of Coaxial HOM Coupler Prototypes for PERLE SRF Cavities

831

C. Barbagallo, P. Duchesne, W. Kaabi, G. Olivier, G. Olry, S. Roset, Z.F. Zomer
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
B.S. Barriere, C.S. Clement, R.L.A. Gerard, F. Gerigk, P.M. Maurin
CERN, Meyrin, Switzerland
J. Henry, S.A. Overstreet, G.-T. Park, R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

Superconducting Radio-Frequency (SRF) linac cryomodules are foreseen for the high-current multi-turn energy recovery linac PERLE (Powerful Energy Recovery Linac for Experiments). Coaxial higher order mode (HOM) couplers are the primary design choice to absorb beam-induced power and avoid beam instabilities. We have used 3D-printed and copper-coated HOM couplers for the prototyping and bench RF measurements on the copper PERLE cavities. We have started a collaboration with JLab and CERN on this effort. This paper presents electromagnetic simulations of the cavity HOM-damping performance on those couplers. Bench RF measurements of the HOMs on an 801.58 MHz 2-cell copper cavity performed at JLab are detailed. The results are compared to eigenmode simulations in CST to confirm the design. RF-thermal simulations are conducted to investigate if the studied HOM couplers undergo quenching.

Poster WEPWB103 [1.533 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB103

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Received ※ 18 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 02 July 2023

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WEPWB104

RF Conditioning of MYRRHA Couplers at IJCLab

835

N. ElKamchi, S. Berthelot, P. Duchesne, C. Joly, W. Kaabi, C. Magueur
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
Y. Gómez Martínez
LPSC, Grenoble Cedex, France
C. Lhomme
IJCLab, ORSAY, France

Multi-purpose hYbrid Research Reactor for High-tech Applications (MYRRHA) is an experimental accelerator-driven system in development at SCK•CEN. It will allow fuel developments, material developments for GEN IV systems, material developments for fusion reactors and radioisotope production for medical and industrial applications1. The IJCLab has in charge the industrial monitoring, the quality control and the RF conditioning of the power couplers up to 80KW at 352Mhz. This paper presents the conditioning bench adapted from the successful experience of IJCLab in the conditioning of the XFEL couplers2. The results of the conditioning of prototype couplers are described and discussed.
1. Abderrahim, P. MYRRHA a multi-purpose hybrid research reactor for high-tech applications. United States: N. p., 2012. Web
2. H. Guler, Proceedings of IPAC2016, Busan, Korea

Poster WEPWB104 [0.875 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB104

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Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 08 August 2023

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WEPWB105

Improved Study of the Multipactor Phenomenon for the MYRRHA 80 kW CW RF Couplers

838

Y. Gómez Martínez, P.-O. Dumont
LPSC, Grenoble Cedex, France
P. Duchesne, N. ElKamchipresenter, C. Joly, W. Kaabi
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
C. Lhomme
IJCLab, ORSAY, France
C. Lhomme
ACS, Orsay, France

MYRRHA (Multi Purpose Hybrid Reactor for High Tech Applications) is an Accelerator Driven System (ADS) project. Its superconducting linac will provide a 600 MeV - 4 mA proton beam. The first project phase based on a 100 MeV linac is launched. The Radio-Frequency (RF) couplers have been designed to handle 80 kW CW (Continuous Wave) at 352.2 MHz. This paper describes the multipactor studies on the coupler when it does not work in the nominal configuration without reflected power.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB105

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Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 12 July 2023

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WEPWB108

Update on Cornell High Pulsed Power Sample Host Cavity

841

SUSPB029

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N.M. Verboncoeur, A.T. Holic, M. Liepe, T.E. Oseroff, R.D. Porter, J. Sears, L. Shpani
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
R.D. Porter
SLAC, Menlo Park, California, USA

The Cornell High Pulsed Power Sample Host Cavity (CHPPSHC) is designed to measure the temperature-dependent superheating fields of future SRF materials and thereby gain insights into the ultimate limits of their performance. Theoretical estimation of the superheating fields of SRF materials is challenging and mostly has been done for temperatures near the critical temperature or in the infinite kappa limit. Experimental data currently available is incomplete, and often impacted by material defects and their resulting thermal heating, preventing finding the fundamental limits of theses materials. The CHPPSHC system allows reaching RF fields in excess of half a Tesla within microseconds on material samples by utilizing high pulsed power, thereby outrunning thermal effects. We are principally interested in the superheating field of Nb₃Sn, a material of interest for the SRF community, and present here the current fabrication and assembly status of the CHPPSHC as well as early results.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB108

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Received ※ 27 June 2023 — Revised ※ 20 July 2023 — Accepted ※ 20 August 2023 — Issue date ※ 22 August 2023

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WEPWB109

PI Loop Resonance Control for the Dark Photon Experiment at 2 K using a 2.6 GHz SRF cavity

847

C. Contreras-Martinez, B. Giaccone, O.S. Melnychuk, A.V. Netepenko, Y.M. Pischalnikov, S. Posen, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Two 2.6 GHz cavities are being used for dark photon search at VTS in FNAL. During testing at 2 K the cavities experience frequency detuning caused by microphonics and slow frequency drifts. The experiment requires that the two cavities have the same frequency within 5 Hz. These two cavities are equipped with frequency tuners consisting of three piezo actuators. The piezo actuators are used for fine-fast frequency tuning. A PI loop utilizing the piezos was used to maintain both cavities at the same frequency, and the results are presented.

Poster WEPWB109 [1.151 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB109

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Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023

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WEPWB110

Prevention of Dual-Mode Excitation in 9-Cell Cavities for LCLSII-HE

852

P.D. Owen
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Dual-Mode Excitation, also referred to as mode-mixing, is a superposition of two pi modes in an SRF cavity. In 9-cell TESLA cavities used for the LCLSII-HE project, the two modes that are commonly excited are the pi mode (1300.2 MHz), and the 7/9 pi mode (1297.8 MHz). During vertical cavity qualification testing, it is regularly observed that emitted power at the frequency of the 7/9 pi mode grows, despite the RF system only driving the pi mode. When this happens, the RF power measurement system is unable to differentiate between the superimposed modes which invalidates any data taken. A new RF control solution prevents the 7/9 pi mode from being excited. A second RF control system is connected to drive the 7/9 pi mode. The loop phase for driving this mode is determined, then shifted by 180 degrees, thus providing a negative feedback to the undesired mode. Because this off-resonance power can be very small, it does not interfere with the high-power measurements of the fundamental pi mode. At Jefferson Lab, we are now able to test a cavity for the LCLSII-HE project with no complications from mode-mixing, which allows for CW processing of high-gradient multipacting.

Poster WEPWB110 [1.818 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB110

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Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 13 July 2023

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WEPWB111

A New Ultra-High Vacuum Furnace for SRF R&D

855

M. Wenskat, C. Bate
DESY, Hamburg, Germany
C. Bate, C. Martens
University of Hamburg, Hamburg, Germany
R. Ghanbari, W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Funding: This work was supported by the BMBF under the research grants 05K19GUB and 05H2021.
A new vacuum furnace has been designed and purchased by the University of Hamburg and is operating in an ISO5 cleanroom. This furnace can anneal single-cell TESLA cavities at temperatures up to 1000°C and with a pressure of less than 10-7mbar or in a nitrogen atmosphere of up to 10-2mbar. We will lay out the underlying design ideas, based on the gained experience from our previous annealing research, and present the commissioning of the furnace itself. Additionally, we will show for the first time the results of sample and cavity tests after annealing in the furnace. This will be accompanied by an overview of the intended R&D process and scientific questions to be addressed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB111

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Received ※ 21 June 2023 — Revised ※ 15 July 2023 — Accepted ※ 20 August 2023 — Issue date ※ 21 August 2023

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WEPWB113

Evaluation of Photo-Cathode Port Multipacting in the SRF Photo-Injector Cryomodule for the LCLS-II High-Energy Upgrade

859

SUSPB032

use link to see paper's listing under its alternate paper code

Z.Y. Yin, W. Hartung, S.H. Kim, T. Konomi, T. Xu
FRIB, East Lansing, Michigan, USA

The high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE) will increase the photon energy and brightness. A low-emittance injector (LEI) was proposed to increase the photon flux for high X-ray energies. FRIB, HZDR, Argonne, and SLAC are developing a 185.7 MHz superconducting radio-frequency photo-injector (SRF-PI) cryomodule for the LEI. The photo-cathode system requirements are challenging, as cathodes must be maintained at the desired temperature, precisely aligned, and operated without multipacting (MP); to avoid field emission, cathode exchange must be particulate-free. A support stalk has been designed to hold the cathode in position under these requirements. A DC bias is used to inhibit MP. We simulated MP for various surface conditions and bias levels. An RF/DC test was developed to evaluate the cathode stalk performance as a subsystem and to identify and correct issues before assembly into the full cryomodule. The RF/DC test makes use of a resonant coaxial line to generate an RF magnetic field similar to that of the cathode-in-SRF-PI-cavity case. High-power test results will be presented and compared to the MP simulations.
* Work supported by the Department of Energy Contract DE-AC02-76SF00515

Poster WEPWB113 [1.410 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB113

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Received ※ 20 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 26 July 2023

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WEPWB116

The Influence of Sample Preparation, Soak Time, and Heating Rate on Measured Recrystallization of Deformed Polycrystalline Niobium

863

Z.L. Thune
MSU, East Lansing, USA
T.R. Bielerpresenter
Michigan State University, East Lansing, Michigan, USA

Funding: DOE/OHEP (Grant Number: DE-SC0009960)
Improving accelerator performance relies on consistent production of high-purity niobium superconducting radiofrequency (SRF) cavities. Current production uses an 800 °C 3 hr heat treatment, but 900-1000 °C can improve cavity performance via recrystallization (Rx) and grain growth. As Rx is thermally activated, increasing the temperature and/or the heating rate could facilitate a reduction in geometrically necessary dislocation (GND) density that is associated with the degradation of cavity performance via trapped magnetic flux. Recent work shows that increasing the annealing temperature increased the Rx fraction in cold-rolled polycrystalline niobium. However, the influence of heating rate on the extent of Rx was minimal with a 3 hr soak time. To further assess the influence of heating rate on measured Rx, as well as the effects of sample preparation, electron backscatter diffraction (EBSD) was used to quantify the extent of Rx on samples annealed at a single temperature with different soak times. Comparing samples with different surface preparation shows that pinned grain boundaries on the free surface reveal a much smaller grain size than below the surface.
* Z.L. Thune et al., "The Influence of Strain Path and Heat Treatment Variations on Recrystallization in Cold-Rolled High-Purity Niobium Polycrystals," doi: 10.1109/TASC.2023.3248533.

Poster WEPWB116 [1.312 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB116

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Received ※ 23 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 20 August 2023 — Issue date ※ 21 August 2023

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WEPWB118

Study and Improvements of Liquid Tin Diffusion Process to Synthesize Nb₃Sn Cylindrical Targets

868

SUSPB033

use link to see paper's listing under its alternate paper code

D. Ford, E. Chyhyrynets, D. Fonnesu, G. Keppel, G. Marconato, C. Pira, A. Salmaso
INFN/LNL, Legnaro (PD), Italy

Funding: This project has received funding from the European Union¿s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730. Work supported by the INFN CSNV experiment SAMARA.
Nb₃Sn thin films on bulk Nb cavities exhibit comparable performance to bulk Nb at lower temperatures, and using Cu as a substrate material can further improve performance and reduce costs. However, coating substrates with curved geometries like elliptical cavities can be challenging due to the brittleness of Nb₃Sn targets produced by a classical sintering technique. This work explores the use of the Liquid Tin Diffusion (LTD) technique to produce sputtering targets for 6 GHz elliptical cavities, which allows for the deposition of thick and uniform coatings on Nb substrate, even for complex geometries. The study includes improvements in the LTD process and the production of a single-use LTD target, as well as the characterization of Nb₃Sn films coated by DC magnetron sputtering using these innovative targets.

Poster WEPWB118 [5.462 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB118

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Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 01 August 2023

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WEPWB119

Additive Manufacturing of Pure Niobium and Copper Using Laser Powder Bed Fusion for Particle Accelerator Applications

872

SUSPB034

use link to see paper's listing under its alternate paper code

D. Ford, R. Caforio, E. Chyhyrynets, G. Keppel, C. Pira
INFN/LNL, Legnaro (PD), Italy
M. Bonesso, S. Candela, V. Candela, R. Dima, G. Favero, A. Pepato, P. Rebesan, M. Romanato
INFN- Sez. di Padova, Padova, Italy
M. Pozzi
Rösler Italiana s.r.l., Concorezzo, Italy

Funding: This project has received funding from the European Union¿s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730. Work supported by the INFN CSNV experiment SAMARA.
In this study, Metal Additive Manufacturing (MAM) was evaluated as a viable method for producing seamless 6 GHz pure copper and niobium prototypes without the use of internal supports. Preliminary tests were performed to evaluate printability, leading to further investigations into surface treatments to reduce surface roughness from 35 µm to less than 1 µm. Additional prototypes were printed using different powders and machines, exploring various printing parameters and innovative contactless supporting structures to improve the quality of downward-facing surfaces with small inclination angles. These structures enabled the fabrication of seamless SRF cavities with a relative density greater than 99.8%. Quality testing was conducted using techniques such as tomography, leak testing, resonant frequency assessment, and internal inspection. The results of this study are presented herein.

Poster WEPWB119 [9.235 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB119

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Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023

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WEPWB120

Flux Expulsion Testing for LCLS-II-HE Cavity Production

876

J.T. Maniscalco, S. Aderhold, M. Checchin, D. Gonnella, R.D. Porter
SLAC, Menlo Park, California, USA
T.T. Arkan, D. Bafia, J.A. Kaluzny, S. Posen
Fermilab, Batavia, Illinois, USA
M.E. Bevins, A.J. Grabowski, J. Hogan, C.E. Reece, D. Savransky, H. Vennekate
JLab, Newport News, Virginia, USA

Nitrogen-doped niobium SRF cavities are sensitive to trapped magnetic flux, which decreases the cavity intrinsic Q₀. Prior experimental results have shown that heat treatments to 900°C and higher can result in stronger flux expulsion during cooldown; the precise temperature required tends to vary by vendor lot/ingot of the niobium material used in the cavity cells. For LCLS-II-HE, to ensure sufficient flux expulsion in all cavities, we built and tested single-cell cavities to determine this required temperature for each vendor lot of niobium material to be used in cavity cells. In this report, we present the results of the single-cell flux expulsion testing and the Q₀ of the nine-cell cavities built using the characterized vendor lots. We discuss mixing material from different vendor lots, examine the lessons learned, and finally present an outlook on possible refinements to the single-cell technique.

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB120

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Received ※ 15 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 13 July 2023

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WEPWB121

Niobium Chronicles: Surface Quality Investigation and Recovery During Material Procurement for the PIP-II High Beta 650 MHz Cavities

880

A.D. Shabalina
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The surface quality of high-purity niobium for superconducting radiofrequency cavities experienced a sudden and significant decline in 2021. The recovery process and root cause analysis were challenging due to a variety of factors such as COVID-19 travel restrictions, cultural differences, and bureaucratic processes. Effective open communication was crucial to resolving the issue, especially with direct vendor oversight being impossible.

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB121

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Received ※ 28 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 20 August 2023 — Issue date ※ 20 August 2023

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WEPWB125

Thermodynamic Properties of Srf Niobium

884

P. Dhakal
JLab, Newport News, Virginia, USA

Funding: This is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177.
Bulk and thin films of niobium are the materials of choice in fabricating superconducting radio frequency (SRF) cavities for modern particle accelerators and quantum computing applications. The thermodynamic properties of Nb are of particular interest in heat management in cryogenic environments. Here, we report the results of measurements of the thermodynamic properties of niobium used in the fabrication of superconducting radio frequency (SRF) cavities. The temperature and magnetic field dependence of thermal conductivity, Seebeck coefficient, and specific heat capacity was measured on bulk niobium samples.

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB125

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Received ※ 11 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 04 July 2023

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WEPWB126

First Results from Nanoindentation of Vapor Diffused Nb₃Sn Films on Nb

888

U. Pudasaini
JLab, Newport News, Virginia, USA
S. Cheban, G.V. Eremeev
Fermilab, Batavia, Illinois, USA

Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics & Office of High Energy Physics.
The mechanical vulnerability of the Nb₃Sn-coated cavities is identified as one of the significant technical hurdles toward deploying them in practical accelerator applications in the not-so-distant future. It is crucial to characterize the material’s mechanical properties in ways to address such vulnerability. Nanoindentation is a widely used technique for measuring the mechanical properties of thin films that involves indenting the film with a small diamond tip and measuring the force-displacement response to calculate the film’s elastic modulus, hardness, and other mechanical properties. The nanoindentation analysis was performed on multiple vapor-diffused Nb₃Sn samples coated at Jefferson Lab and Fermilab coating facilities for the first time. This contribution will discuss the first results obtained from the nanoindentation of Nb₃Sn-coated Nb samples prepared via the Sn vapor diffusion technique.

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB126

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Received ※ 19 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 16 July 2023

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WEPWB127

Investigation of Coupler Breakdown Thresholds for Plasma Processing of FRIB Quarter-Wave Resonators with Fundamental and Higher-Order Modes

893

SUSPB035

use link to see paper's listing under its alternate paper code

P.R. Tutt, W. Hartung, S.H. Kim, T. Xu
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and used resources of the Facility for Rare Isotope Beams (FRIB) under Award Number DE-SC0000661.
FRIB is developing plasma processing techniques for in-situ recovery of cavity performance in linac cryomodules during long-term user operation. While plasma processing has been shown to be effective for high-frequency (0.8 - 1.5 GHz) elliptical cavities, one of the challenges for FRIB is to avoid plasma breakdown in the fundamental input coupler (FPC), which has relatively weak coupling strength (Q_ext ranging from 2E6 to 1E7). FRIB cavities are not equipped with higher-order-mode (HOM) couplers; however, in preliminary tests, we found that HOMs are suitable for plasma processing of FRIB Quarter-Wave Resonators (QWRs) driven via the FPC. In this study, we investigated plasma breakdown thresholds in the fundamental and the first 2 HOMs for the FRIB β = 0.085 QWRs. Electric field distributions in the FPC region and cavity region were calculated for the room-temperature case using CST Microwave Studio’s frequency domain solver (FDS). Simulation results will be presented, with comparison of breakdown thresholds inferred from the RF modeling to the experimental results.

Poster WEPWB127 [5.068 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB127

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Received ※ 19 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 11 August 2023

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WEPWB128

Experimental Study of Mechanical Dampers for the FRIB β=0.041 Quarter-Wave Resonators

898

SUSPB036

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J. Brown, W. Chang, W. Hartung, S.H. Kim, T. Xu
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award numbers DE-SC0018362 and DE-SC0000661 and Michigan State University.
The ’pendulum’ mechanical mode of quarter-wave resonators (QWR) often causes an issue with microphonics and/or ponderomotive instability unless otherwise the inner conductors are properly stiffened and/or damped. FRIB QWRs are equipped with a Legnaro-style frictional damper installed inside of the inner conductor such that it counteracts the oscillations of the inner conductor. In cryomodule tests and linac operation, we observed that the damping efficiency is different for a few β=0.041 QWRs. This study aimed to experimentally characterize the damping efficacy as a function of damper mass and surface roughness. We present damping measurements at room temperature and at two different masses and surface roughness as well as discuss future studies for damper re-optimization based on this follow-on study.

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB128

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Received ※ 20 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 04 August 2023

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WEPWB131

Demonstration of Magnetron as an Alternative RF Source for SRF Accelerators

902

H. Wang, K. Jordan, R.A. Rimmer
JLab, Newport News, Virginia, USA
J.P. Anderson, C.P. Moeller, K.A. Thackston
GA, San Diego, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and DOE OS/ARDAP Accelerator Stewardship award 2019-2023.
Magnetron has been considered as alternate high-efficiency, low-cost RF sources for linacs and storage rings [1] for national labs and industrial applications. After the demonstration of magnetrons power to drive and combine for a radio frequency cavity at 2450 MHz in CW mode, we have used trim coils adding to a water-cooled magnetron and amplitude modulation feedback to further suppress the side-band noise to -46.7 dBc level. We also demonstrated the phase-locking to an industrial grade cooking magnetron transmitter at 915 MHz with a 75 kW CW power delivered to a water load by using a -26.6 dBc injection signal [2]. The sideband noise from the 3-Phase SCRs DC power supply can be reduced to -16.2 dBc level. Further noise reduction and their power combining scheme using magic-tee and cavity type combiners for higher power application (2x75kW) are to be presented. We intent to use one power station to drive the normal conducting and superconducting RF cavities for the inductrial linac. We also going to demonstarte a vertical SRF cavity test with a high input coupling Q using a 2.45GHz magnetron and comparing with a baseline test result using a solid state amplifier.
[1]. doi:10.18429/JACoW-IPAC2015-WEPWI028.
[2]. doi:10.18429/JACoW-NAPAC2022-WEZD3.

Poster WEPWB131 [2.445 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB131

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Received ※ 16 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 19 August 2023

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WEPWB133

Testing of the 2.6 GHz SRF Cavity Tuner for the Dark Photon Experiment at 2 K

907

C. Contreras-Martinez, B. Giaccone, I.V. Gonin, T.N. Khabiboulline, O.S. Melnychuk, Y.M. Pischalnikov, S. Posen, O.V. Pronitchev, J.C. Yun
Fermilab, Batavia, Illinois, USA

At FNAL two 2.6 GHz SRF cavities are being used to search for dark photons, the experiment can be conducted at 2 K or in a dilution refrigerator. Precise frequency tuning is required for these two cavities so they can be matched in frequency. A cooling capacity constraint on the dilution refrigerator only allows piezo actuators to be part of the design of the 2.6 GHz cavity tuner. The tuner is equipped with three encapsulated piezo that deliver the long- and short-range frequency tuning. Modifications were implemented on the first tuner design due to the low forces on the piezos due to the cavity. Three brass rods with Belleville washers were added to the design to increase the overall force on the piezos. The results at 2 K of testing this tuner with and without the modification will be presented.

Poster WEPWB133 [0.829 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB133

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Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 July 2023

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WEPWB134

Study of Different Piezoelectric Material Stroke Displacement at Different Temperatures Using an SRF Cavity

911

C. Contreras-Martinez, Y.M. Pischalnikov, J.C. Yun
Fermilab, Batavia, Illinois, USA

Piezoelectric actuators are used for resonance control in superconducting linacs. The level of frequency compensation depends on the piezoelectric stroke displacement. In this study, the stroke displacement will be measured with a 1.3 GHz SRF cavity by measuring the frequency shift with respect to the voltage applied. The entire system was submerged in liquid helium. This study characterizes the PZT piezoelectric actuator (P-844K093) and a lithium niobate (P-844B0005) piezoelectric actuator. All these actuators were developed at Physik Instrumente (PI). The piezo-electric displacement was measured at different temperatures.

Poster WEPWB134 [0.776 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB134

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Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 13 July 2023

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WEPWB135

A Novel Twin Drive Tuner Mechanism for 1.3 GHz ILC Cavity

914

M. Yamanaka
KEK, Ibaraki, Japan

A tuner is a device that adjusts the resonant frequency of a cavity. Here we propose a new tuner mechanism for the 1.3 GHz ILC cavity. A bellow is provided in the central portion of the helium tank in the longitudinal direction, and flanges are provided on both sides of the bellows. A linear motion actuator is fixed to the flange on one side, and the frequency is changed by pushing and pulling the flange on the opposite side. Significantly, two linear motion actuators are placed in circumference and working simultaneously. It is named a twin-drive tuner. According to the ILC specification, the cavity has a spring constant of 3 KN/mm, requiring a stroke of 2 mm to adjust the 600 kHz range. A loading force of 6 kN is required. This is shared by two linear motion actuators. We developed a prototype actuator with a loading force of 4 kN per unit. It consists of a stepping motor and a sliding screw with a plastic nut. An experimental device was constructed using this actuator and a 1.3 GHz cavity with a helium tank, and the frequency tuning was evaluated. The displacement between the flanges and the frequency are proportional, both have good linearity, and the slope is 296 kHz/mm.

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB135

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Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023

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WEPWB137

Prototype SSR2 Tuner Procurement and Testing at IJCLab for PIP-II Project

917

N. Gandolfo, P. Duchesne, D. Le Dréan, D. Longuevergne, G. Mavilla, T. Pépin-Donat
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
M. Parise, D. Passarelli, Y.M. Pischalnikov
Fermilab, Batavia, Illinois, USA

Funding: Work supported by IN2P3. Work supported, in part, by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under U.S. DOE Contract No. DE-AC02-07CH11359.
IJCLab is involved in the PIP-II project on the design and development of accelerator components for the SSR2 (Single Spoke Resonator type 2) section of the superconducting linac. Five prototype tuners have been built and are being tested at IJCLab. After a short description of the tuner, this paper reports on the procurement strategy and the performance observed at both room and low temperatures in vertical cryostat test with SSR2 prototype cavities. This paper will also share results on accelerated lifetime tests performed in a dedicated nitrogen-cooled cryostat.

Poster WEPWB137 [1.395 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB137

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Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 16 July 2023

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