SRF Technology
Cavity design/fabrication/preparation/tuning
Paper Title Page
MOPMB006 SIMS Characterization of Nitrogen Doping of LCLS-II-HE Production Cavities 67
 
  • C.E. Reece, M.J. Kelley, E.M. Lechner
    JLab, Newport News, Virginia, USA
  • J.W. Angle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of High Energy Physics grant DE-SC-0014475.
The thermal diffusion of nitrogen into the surface of niobium has been shown to yield superior low-loss SRF performance. An effective solution was identified and promptly employed in the production of cryomodules for LCLS-II. With added experience and R&D, a modified process was chosen for use in the upgrade for LCLS-II-HE. Largely motivated by this circumstance, supporting research has significantly refined the technique for making calibrated secondary ion mass spectrometry (SIMS) measurements of the N concentration depth profiles produced by production processes. Standardized reference samples were included with four HE production cavities in their N-doping furnace runs. We report the calibrated dynamic SIMS depth profiles of N, C, and O for these samples, together with the cryogenic acceptance test performance of the associated cavities. Interpretation and comparison with similar samples acquired in other furnaces highlights the importance of intentional process quality control of furnace conditions. 		 
poster icon Poster MOPMB006 [1.380 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB006  
About • Received ※ 16 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023
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MOPMB009 Plasma Electrolytic Polishing Technology Progress Development for Nb and Cu Substrates Preparation 75
SUSPB005   use link to see paper's listing under its alternate paper code  
 
  • E. Chyhyrynets, O. Azzolini, R. Caforio, D. Fonnesu, D. Ford, G. Keppel, C. Pira, A. Salmaso, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
  • G. Marconato
    Università degli Studi di Padova, Padova, Italy
  
  Funding: Work supported by the INFN CSNV experiment SAMARA. Fundings from the EU’s Horizon 2020 Research and Innovation programme under Grant Agreement N 101004730. PNRR MUR project PE0000023-NQSTI.
Superconducting radio frequency (SRF) cavity performance is highly dependent on surface preparation. Conventionally, electropolishing (EP) is used to achieve a clean surface and low roughness for both Nb and Cu substrates, but it requires harsh and corrosive solutions like concentrated acids. Plasma Electrolytic Polishing (PEP) is a promising alternative that uses only diluted salt solutions and has several advantages over EP. PEP can replace intermediate steps like mechanical or chemical polishing, thanks to its superior removal rate of up to 2-8 um/min of Nb and 3-30 um/min of Cu. It achieves Ra roughness of 100 nm for both substrates and has a higher smoothing effect than EP. PEP is also suitable for normal conducting cavities and other accelerator components, including couplers. We demonstrate the effectiveness of PEP on SRF substrates and analyse substrate defect evaluation. We demonstrate the application of PEP onto SRF substrates and analyse the substrate’s defect evaluation. The ongoing work includes Nb bulk and Nb on Cu QPR treatments and RF tests in collaboration with HZB. 		 
poster icon Poster MOPMB009 [11.877 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB009  
About • Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 17 July 2023
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TUPTB016 Summary of the FRIB Electropolishing Facility Design and Commissioning, Cavity Processing, and Cavity Test Results 419
 
  • E.S. Metzgar, B.W. Barker, K. Elliott, J.D. Hulbert, C. Knowles, L. Nguyen, A.R. Nunham, L. Popielarski, A.T. Taylor, T. Xu
    FRIB, East Lansing, Michigan, USA
  
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics and used resources of the FRIB, which is a DOE Office of Science User Facility, under Award Number DE-SC0000661.
Recently, a new Electropolishing (EP) facility was con-structed and commissioned at the Facility for Rare Isotope Beam (FRIB) with the purpose of supporting advanced surface processing techniques for SRF R&D activities. The FRIB production cavities opted for a Buffered Chemical Polish (BCP) method due to its cost effectiveness and was supported by successful outcomes in other facilities with low beta cavities in a similar frequency range. All 324 cavities used in FRIB Linac were processed in-house at MSU using BCP and exhibited satisfactory performance during testing. As part of the FRIB energy upgrade R&D, 5-cell 644 MHz elliptical resonators will be employed, desiring the use of EP and advanced techniques such as nitrogen doping and medium-T baking. The EP facility is designed to accommodate all types of cavities used in FRIB and possesses the capability for performing EP at low temperatures. Here we report the details of design and commissioning of the EP facility, highlights of encountered issues and subsequent improvements, and preliminary results from vertical tests conducted on the cavities. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB016  
About • Received ※ 15 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 14 July 2023
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TUPTB035 Design, Fabrication, and Test of a 175 MHz, β = 0.18, Half Wave Resonator for the IFMIF-DONES SRF-Linac 477
 
  • J. Plouin, M. Baudrier, S. Chel, G. Devanz, A. Madur, L. Maurice, C. Servouin
    CEA-DRF-IRFU, France
  • N. Bazin, G. Jullien
    CEA-IRFU, Gif-sur-Yvette, France
  
  The IFMIF-DONES facility will serve as a fusion-like neutron source for the assessment of materials damage in future fusion reactors. The neutron flux will be generated by the interaction between the lithium curtain and the deuteron beam from an RF linear accelerator at 40 MeV and nominal CW current of 125 mA. The last accelerating stage is a superconducting (SRF) Linac hosting five cryomodules. This SRF-Linac is equipped of two types of 175 MHz half wave superconducting cavities (HWRs). The first type of cavities (cryomodules 1 and 2), characterized by beta equal to 0.11, have been studied and qualified in the frame of IFMIF/EVEDA project. The development of the second type of cavities (cryomodules 3, 4 and 5), with higher beta of 0.18 is presented in this paper. A prototype has been designed, fabricated and tested in a vertical cryostat at CEA. The measured quality factor at nominal accelerating field (4.5 MV/m) is 2.3 109 and keeps higher than 109 up to 10 MV/m, which gives confidence in the cavity design and preparation to reach the expected performances after integration in the SRF linac.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB035  
About • Received ※ 20 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 15 July 2023
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TUPTB036 Equidistant Optimization of Elliptical SRF Standing Wave Cavities 480
 
  • V.D. Shemelin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  A record accelerating rate was achieved earlier in standing wave (SW) SRF cavities when their shape was optimized for lower peak surface magnetic field. In view of new materials with higher limiting magnetic fields, expected for SRF cavities, in the first line Nb₃Sn, the approach to optimization of cavity shape should be revised. A method of equidistant optimization, offered earlier for traveling wave cavities is applied to SW cavities. It is shown here that without limitation by magnetic field, the maximal accelerating rate is defined to a significant degree by the cavity shape. For example, for a cavity with the aperture radius Ra = 35 mm the minimal ratio of the peak surface electric field to the accelerating rate is about Epk/Eacc = 1.54. So, with the maximal surface field experimentally achieved Epk ¿ 125 MV/m, the maximal achievable accelerating rate is about 80 MeV/m even if there are no restrictions by the magnetic field. Another opportunity ¿ optimization for a low magnetic field, is opening for the same material, Nb₃Sn, with the purpose to have a high quality factor and increased accelerating rate that can be used for industrial linacs.  
poster icon Poster TUPTB036 [0.787 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB036  
About • Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 08 July 2023
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TUPTB037 Refurbishment and Reactivation of a Niobium Retort Furnace at DESY 485
 
  • L. Trelle, C. Bate, H. Remde, D. Reschke, J. Schaffran, L. Steder, H. Weise
    DESY, 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.
For research in the field of heat treatments of supercon-ducting cavities, a niobium ultra-high vacuum furnace built in 1992 - originally used for the titanization of 1.3 GHz nine-cell cavities - and later shut down was recently refurbished and reactivated. A significant upgrade is the ability to run the furnace in partial pressure mode with nitrogen. The furnace is connected directly to the ISO4 area of the clean room for cavity handling. At room temperature vacuum values of around 3×10-8 mbar are achieved. The revision included the replacement of the complete control system and a partial renewal of the pump technology. The internal mounting structures are optimized for single-cell operation including tandem operation (two single-cell cavities at once) and corresponding accessories such as witness-samples and caps for the cavities. The installation of additional thermocouples for a detailed monitoring of the temperature curves is also possible at the mounting structure. Due to the furnace design, its location and the strict routines in handling, very high purity levels are achieved in comparison to similar setups and hence provide a mighty tool for SRF cavity R&D at DESY. 		 
poster icon Poster TUPTB037 [0.404 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB037  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 01 July 2023
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TUPTB038 Novel Approaches in Characterization and Modelling of Fabrication Processes for SRF Components 490
 
  • J.S. Swieszek, A. Gallifa Terricabras, M. Garlasché, D. Smakulska
    CERN, Meyrin, Switzerland
  • J.S. Swieszek
    Kraftanlagen Nukleartechnik GmbH, Heidelberg, Germany
  
  In the past years, Finite Element Methods have been increasingly applied at CERN, with the aim of modelling fabrication processes for SRF components. Currently, many large deformation processes such as deep drawing, forging, hydroforming, and spinning, are being simulat-ed. Taking the initial trials out of the workshop via simu-lation has proven very efficient for steering fabrication strategy, avoiding unnecessary trials, and helping to re-duce time and costs. This contribution will present a novel approach for studying fabrication process feasibil-ity and failure prediction using numerical tools, based on the Forming Limit Diagram method, developed for OFE copper sheets. This contribution will show the applica-tion of the mentioned method on the study of tubular hydroforming, as an alternative way to produce seamless elliptical RF cavities. Analysis of past hydroforming trials is also discussed, together with the comparison of different fabrication strategies.  
poster icon Poster TUPTB038 [1.674 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB038  
About • Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 17 July 2023
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TUPTB039 Simulation of High Pressure Rinse in Superconducting Radio Frequency Cavities 496
 
  • B.E. Gower, K. Elliott, E.S. Metzgar, T. Xu
    FRIB, East Lansing, Michigan, USA
  
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics. Resources of the Facility for Rare Isotope Beams, a DOE Office of Science User Facility, under Award Number DE-SC0000661.
The finish of radio frequency (RF) surfaces inside superconducting RF (SRF) cavities is of utmost importance as it dictates ultimate cavity performance. After the cavity surfaces have undergone chemical etching, polishing, and hydrogen degassing, the final step in surface preparation involves cleaning using a high pressure rinse (HPR) with ultra-high purity water (UPW) to remove any residue from the previous chemical processes. The complex surface geometry of cavities poses difficulties in achieving effective and thorough HPR cleaning. This study introduces a versatile simulation tool created in MATLAB, which has the potential to be applied to various SRF cavities. The detail of the algorithm used and nozzle and motion setup will be described using an FRIB 0.53 half wave resonator (HWR) cavity as an example. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB039  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 07 July 2023
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TUPTB040 Mechanical Design and Analysis of SRF Gun Cavity Using ASME BPVC Section Viii, Division-2, Design by Analysis Requirement 501
 
  • M.S. Patil, C. Compton, S.H. Kim, S.J. Miller, T. Xu
    FRIB, East Lansing, Michigan, USA
  
  Funding: Work supported by the Department of Energy Contract DE-AC02- 76SF00515
A prototype SRF gun is currently being designed at FRIB, MSU for the Low Emittance Injector of the Linac Coherent Light Source high energy upgrade at SLAC. This employs a 185.7 MHz superconducting quarter-wave resonator (QWR). The mechanical design of this cavity has been optimized for performance and to comply with ASME Section VIII, Div 2, Design by analysis requirements. This paper presents the various design by analysis procedures and how they have been adopted for the SRF gun cavity design. 		 
poster icon Poster TUPTB040 [1.235 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB040  
About • Received ※ 15 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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TUPTB041 Visual, Optical and Replica Inspections: Surface Preparation of 650 MHz Nb Cavity for PIP-II Linac 507
 
  • V. Chouhan, D.J. Bice, D.A. Burk, M.K. Ng, G. Wu
    Fermilab, Batavia, Illinois, USA
  
  Surface preparation of niobium superconducting RF cavities is a critical step for achieving good RF performance under the superconducting state. Surface defect, roughness, and contamination affect the accelerating gradient and quality factor of the cavities. We report surface inspection methods used to control the surface processing of 650 MHz cavities that will be used in the pre-production cryomodule for PIP-II linac. The cavity surface was routinely inspected visually, with an optical camera, and by microscopic scanning of surface replicas. This article covers details on the surface inspection methods and surface polishing process used to repair the surface.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB041  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 12 July 2023
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TUPTB042 Latest Development of Electropolishing Optimization for 650 MHz Cavity 512
 
  • V. Chouhan, D.J. Bice, D.A. Burk, S.K. Chandrasekaran, A.T. Cravatta, P.F. Dubiel, G.V. Eremeev, F. Furuta, O.S. Melnychuk, A.V. Netepenko, M.K. Ng, J.P. Ozelis, H. Park, T.J. Ring, G. Wu
    Fermilab, Batavia, Illinois, USA
  • B.M. Guilfoyle, M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
  
  Electropolishing (EP) of 1.3 GHz niobium (Nb) superconducting RF cavities is conducted to achieve a desired smooth and contaminant-free surface that yields good RF performance. Achieving a smooth surface of a large-sized elliptical cavity with the standard EP conditions was found to be challenging. This work aimed to conduct a systematic parametric EP study to understand the effects of various EP parameters on the surface of 650 MHz cavities used in PIP-II linac. Parameters optimized in this study provided a smooth surface of the cavities. The electropolished cavities met the baseline requirement of field gradient and qualified for further surface treatment to improve the cavity quality factor.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB042  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 06 July 2023
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TUPTB043 Development of 3-Cell Traveling Wave SRF Cavity 517
 
  • F. Furuta, T.N. Khabiboulline, K.E. McGee, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • P.V. Avrakhov, R.A. Kostin
    Euclid TechLabs, Solon, Ohio, 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
Traveling wave SRF cavity is a new technology and requires a multi-stage process for development. Concep-tual designs have been proposed to adopt TW resonance in an SRF cavity The early stages of developments have been funded by several SBIR grants to Euclid Techlabs which were completed in collaboration with Fermilab. A 3-cell proof-of-principle TW cavity was fabricated as part of that and demonstrated the TW resonance excita-tion at room temperature. A TW resonance control tuner for the 3-cell was also fabricated and the preliminary tests were performed. Now, the 3-cell cavity is being processed and prepared for the first cryogenic testing. 		 
poster icon Poster TUPTB043 [1.743 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB043  
About • Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 02 July 2023
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TUPTB044 Compact Multicell Superconducting Crab Cavity for ILC 521
 
  • A. Lunin, S.A. Belomestnykh, I.V. Gonin, T.N. Khabiboulline, Y.M. Orlov, V. Poloubotko, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by the Fermi National Accelerator Laboratory; managed by Fermi Research Alliance, LLC under Contract No. DEAC02-07CH11359 with the U.S. Department of Energy
We propose a novel design of a deflecting cavity for the ILC project with low parasitic HOM losses and preserving the beam emittance, which is critical for operation with high beam current intensity. Multiple electrodes immersed in the hollow waveguide form a trapped-mode resonator. The transverse components of the electromagnetic field of the trapped dipole mode induce a transverse kick and efficiently deflect charged particles passing through the cavity. We present a scalable design of a superconducting Quasi-waveguide Multicell Resonator (QMiR) seamlessly connected with a beam vacuum chamber. The cavity is completely open at both ends, which significantly reduces the maximum loaded quality factor of the higher order modes (HOM), avoids complex HOM couplers and thus simplifies the mechanical design of the cavity. The same port is used to feed RF power to the operating mode and to extract the same order modes (SOM). Finally, we estimate the expected cryogenic losses, HOM impedance limits, RF input power required, and frequency tuning for a QMiR cavity designed to operate at 2.6 GHz. 		 
poster icon Poster TUPTB044 [6.975 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB044  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 16 July 2023
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TUPTB045 PIP-II SSR2 Cavities Fabrication and Processing Experience 526
 
  • M. Parise, P. Berrutti, D. Passarelli
    Fermilab, Batavia, Illinois, USA
  • P. Duchesne, D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  The Proton Improvement Plan-II (PIP-II) linac will include 35 Single Spoke Resonators type 2 (SSR2). A pre-production SSR2 cryomodule will contain 5 jacketed cavities. Several units are already manufactured and prepared for cold testing. In this work, data collected from the fabrication, processing and preparation of the cavities will be presented and the improvements implemented after the completion of the first unit will be highlighted.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB045  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 08 July 2023
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TUPTB046 Development and Performance of RFD Crab Cavity Prototypes for HL-LHC AUP 531
 
  • L. Ristori, P. Berrutti, M. Narduzzi
    Fermilab, Batavia, Illinois, USA
  • A. Castilla
    JLAB, Newport News, USA
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • N.A. Huque
    JLab, Newport News, Virginia, USA
  • Z. Li, A. Ratti
    SLAC, Menlo Park, California, USA
  
  Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
The US will be contributing to the HL-LHC upgrade at CERN with the fabrication and qualification of RFD crabbing cavities in the framework of the HL-LHC Accelerator Upgrade Project (AUP) managed by Fermilab. AUP received Critical Decision 3 (CD-3) approval by DOE in December 2020 launching the project into the production phase. The electro-magnetic design of the cavity was inherited from the LHC Accelerator Research Program (LARP) but needed to be revised to meet new project requirements and to prevent issues encountered during beam tests performed at CERN in the R&D phase. Two prototype cavities were manufactured in industry and cold tested. Challenges specific to the RFD cavity were the stringent interface tolerances, the pole symmetry and the higher-order-mode impedance spectrum. Chemical processing and heat treatments were performed initially at FNAL/ANL and are now being transferred to industry for the production phase. HOM dampers are manufactured and validated by JLAB. A summary of cold test results with and without HOM dampers is presented. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB046  
About • Received ※ 20 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 11 July 2023
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TUPTB047 The Evaluation of Mechanical Properties of LB650 Cavities 536
 
  • G. Wu, S.D. Adams, D.J. Bice, S.K. Chandrasekaran, I.V. Gonin, C.J. Grimm, J.P. Holzbauer, T.N. Khabiboulline, C.S. Narug, J.P. Ozelis, H. Park, G.V. Romanov, R. Thiede, R. Treece, A.D. Wixson
    Fermilab, Batavia, Illinois, USA
  • K.E. McGee
    FRIB, East Lansing, Michigan, 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 650 MHz cavities have a stronger requirement of niobium mechanical properties because of the geometric shape of the cavity due to reduced beta. The mechanical property of the niobium half-cell was measured following various heat treatments. The 5-cell cavities were tested in a controlled drop test fashion and the real-world road test. The result showed that the 900C heat treatment was compatible with cavity handling and transportation during production. The test provides the bases of the transportation specification and shipping container design guidelines. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB047  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 14 July 2023
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TUPTB049 Horizontal Test Results of 1.3 GHz Superconducting RF Gun #2 at KEK 540
 
  • T. Konomi, K. Hara, Y. Honda, K. Hosoyama, H. Inoue, E. Kako, Y. Kondo, M. Masuzawa, M. Omet, T. Takatomi, A. Terashima, K. Tsuchiya, R. Ueki, K. Umemori, X. Wang
    KEK, Ibaraki, Japan
  
  Superconducting radio-frequency (SRF) electron guns are attractive for delivery of beams at a high bunch repetition rate with a high accelerating field. KEK has been developing the SRF gun to demonstrate basic performance. The SRF gun consists of 1.3 GHz and 1.5 cell SRF gun cavity and K2CsSb photocathode coated on 2K cathode plug. In the vertical test, the surface peak electric field and the surface peak magnetic field reached to 75 MV/m and 170 mT respectively. The SRF gun was installed to horizontal multipurpose cryostat equipped with a superconducting solenoid, photocathode preparation chamber and beam diagnostic line. The results showed the peak surface electric field degraded to 42 MV/m. We suspect that cavity was contaminated during assembly. In this presentation, we will present the high gradient performance in vertical and horizontal test and individual test for each beam line components.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB049  
About • Received ※ 24 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 15 July 2023
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TUPTB052 A Novel Manufacture of Niobium SRF Cavities by Cold Spray 545
 
  • M. Yamanaka
    KEK, Ibaraki, Japan
  • K. Shimada
    Nihon University, College of Engineering, Koriyama, Japan
  
  Cold spray is a lower-temperature solid-state thermal spray process that deposits metal powder using a heated inert gas through a supersonic nozzle. When the material hits at supersonic speed and reaches the critical speed, the particles themselves are plastically deformed to form a film. The material of the superconducting cavity is niobium, a very expensive rare metal. To reduce the amount of niobium and the cost, we propose a novel manufacturing method of forming a thick niobium film on the surface of a mandrel by cold spray using niobium powder and removing the mandrel to finish a hollow shape. We confirmed the feasibility of the proposed method using a model similar to a 3.9 GHz one-cell cavity. Also, the RRR measurement of the niobium specimen made by cold spray was carried out and the measured value of 11 was obtained. We report on these results.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB052  
About • Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 10 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB059 INFN LASA Experimental Activities for the PIP-II Project 549
 
  • M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, E. Del Core, F. Fiorina, A.T. Grimaldi, L. Monaco, C. Pagani, R. Paparella, D. Sertore, G.M. Zaggia
    INFN/LASA, Segrate (MI), Italy
  
  INFN LASA is upgrading its vertical test facility to allow high-Q measurements of the PIP-II LB650 SRF cavities. Such facility is equipped with a wide set of diagnostics for quench, field emission and magnetic flux expulsion studies and will offer a better understanding of cavity performance. At the same time, R&D on LB650 cavity prototypes is ongoing, in order to optimize the overall processing as well as the cavity Jacketing in view of the forthcoming series production with industry. This paper reports on the overall status of these experimental activities.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB059  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB060 Reconstruction of Field Emission Pattern for PIP-II LB650 Cavity 554
 
  • E. Del Core, M. Bertucci, A. Bosotti, A.T. Grimaldi, L. Monaco, C. Pagani, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  
  Field emission (FE) is a key limiting phenomenon in SRF cavities. An algorithm exploiting a self-consistent model of cavity FE has been developed. This method exploits experimental observables (such as Q value , X-ray endpoint, and dose rate) to reconstruct emitter position and size as well as the field enhancement factor. To demonstrate the model effectiveness, the algorithm has been applied to a data set of the PIP-II LB650 prototype cavity.  
poster icon Poster TUPTB060 [0.956 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB060  
About • Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 28 June 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB061 Status of the ESS Medium Beta Cavities at INFN LASA 559
 
  • D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, E. Del Core, F. Fiorina, A.T. Grimaldi, L. Monaco, C. Pagani, R. Paparella, G.M. Zaggia
    INFN/LASA, Segrate (MI), Italy
  
  The INFN LASA’s contribution to the ESS Medium Beta Superconducting Linac consists of 36 cavities that raise the proton beam energy from 216 MeV to 571 MeV. Out of the 36 cavities, 28 have been successfully qualified and delivered for assembly into a cryomodule at CEA Saclay. The remaining cavities have been reprocessed in order to bring them up to ESS specifications. To mitigate further delays in the delivery of the cavities, four new ones are currently under construction. We are reporting on the current status of both the recovery actions we have developed so far and the performance of the newly produced resonators.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB061  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 14 July 2023
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TUPTB062 RF Measurements of the 3rd Harmonic Superconducting Cavity for a Bunch Lengthening 565
 
  • J.Y. Yoon, J.H. Han, H.S. Park, Y.D. Yoon
    Kiswire Advanced Technology Ltd., Daejeon, Republic of Korea
  • E. Kako
    KEK, Ibaraki, Japan
  • E.-S. Kim
    Korea University Sejong Campus, Sejong, Republic of Korea
  
  The brightness can be increased by minimizing the emittance in the light source, but the reduced emittance also increases the number of collisions of electrons in the beam bunch. Therefore, the bunch lengthening by using the 3rd harmonic cavity reduces the collisions of electrons and increases the Touschek lifetime. Since the resonant frequency of the main RF cavity is 500 MHz, the resonant frequency of 3rd harmonic cavity is selected as 1500 MHz. The prototype cavity is a passive type in which a power coupler is not used, and power is supplied from the beam. The operating temperature is 4.5 K, which is a superconducting cavity. The elliptical double-cell geometry was selected to increase the accelerating voltage of the cavity and reduce power losses. Based on this design, three niobium cavities are fabricated and tested. In this paper, we present the RF measurement results of the 3rd harmonic cavity at room temperature.
*3rd harmonic cavity
*4th generation storage ring 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB062  
About • Received ※ 12 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 13 July 2023
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TUPTB063 Fabrication Efforts Toward a Superconducting Rf Photo-Infector Quarter-Wave Cavity for Use in Low Emittance Injector Applications 568
 
  • C. Compton
    NSCL, East Lansing, Michigan, USA
  • K. Elliott, W. Hartung, J.D. Hulbert, S.H. Kim, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, L. Popielarski, K. Saito, K. Witgen, T. Xu
    FRIB, East Lansing, Michigan, USA
  • M. Kedzie, M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
  • J.W. Lewellen, J. Smedley
    SLAC, Menlo Park, California, USA
  
  Funding: * Work supported by the Department of Energy Contract DE-AC02- 76SF00515
The Facility for Rare Isotope Beams (FRIB), in collaboration with Argonne National Laboratory (ANL) and Helmholtz-Zentrum Dresden-Rossendorf (HDZR), is working on the design and fabrication of a photo-injector cryomodule; suitable for operation as part of accelerator systems at SLAC National Accelerator Laboratory. Project scope requires the fabrication of two 185.7 MHz superconducting, quarter-wave resonators (QWR) based, injector cavities. Cavity fabrication will be completed at FRIB with contracted vendors supporting subcomponent fabrication and electron-beam welding. Fabrication will use poly-crystalline and large grain RRR niobium materials. The current status of cavity fabrication will be presented including material procurement, prototype forming, and electron-beam welding development. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB063  
About • Received ※ 17 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 21 August 2023 — Issue date ※ 21 August 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTB066 Fabrication and Testing of a Prototype RF-Dipole Crabbing Cavity 573
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • H. Park
    Fermilab, Batavia, Illinois, USA
  
  Crabbing cavities are essential in particle colliders to compensate the luminosity degradation due to beam collision at a crossing angle. The 952.6 MHz 2-cell rf-dipole crabbing cavity system was proposed for the Jef-ferson Lab Electron-Ion Collider to restore the head-on collisions of electron and proton bunches at the interac-tion point. A prototype cavity was designed and devel-oped to demonstrate the performance of multi-cell rf-dipole structures. This paper presents the fabrication pro-cess and cold test results of the first 2-cell rf-dipole proto-type cavity.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB066  
About • Received ※ 18 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 21 August 2023
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TUPTB067 Fabrication and Surface Treatment of Superconducting Rf Single Spoke Cavities for the Myrrha Project 578
 
  • M. Moretti, Y.N. Hoerstensmeyer, A. Navitski
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
  • F. Marhauser
    SCK•CEN, Mol, Belgium
  
  The MYRRHA project, based at SCK•CEN (Belgium), aims at coupling a 600 MeV proton accelerator to a subcritical fission core with a maximal output of 100 MWth. The first phase of the project, MINERVA, includes the design, construction, and commissioning of a 100 MeV superconducting RF linac in order to demonstrate the machine requirements in terms of reliability and fault tolerance. The MINERVA linac comprises several cryomodules, each containing two Single Spoke 352.2 MHz cavities made out of high RRR niobium and operating at 2K. The fabrication and surface treatment of the Single Spoke RF Cavities is currently ongoing and completely carried out by RI Research Instruments GmbH (Germany); the first pre-series cavities were completed and delivered for cold testing. Main highlights of the fabrication include the deep-drawing of complex shapes, such as central spokes and outer caps of the cavity, which was successfully accomplished. As for the surface treatment, RI has commissioned, tested, and effectively started utilizing a new rotational buffered chemical polishing facility; this is required to polish the cavity inner surface, while ensuring an almost uniform material removal.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB067  
About • Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 09 July 2023
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TUPTB068 EIC 197 MHz Crab Cavity RF Optimization 584
 
  • Z. Li
    SLAC, Menlo Park, California, USA
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • Q. Wu, B.P. Xiao, W. Xu
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under U.S. DOE K No. DE-SC0012704, by Jefferson Science Associates, LLC under U.S. DOE K No. DE-SC0002769, and by DOE K No. DE-AC02-76SF00515.
Crab cavities, operating at 197 MHz and 394 MHz respectively, will be used to compensate the loss of luminosity due to a 25 mrad crossing angle at the interaction point in the Electron Ion Collider (EIC). Both crab cavities are of the RF Dipole (RFD) shape. To meet the machine design requirements, there are a few important cavity design considerations that need to be addressed. First, to achieve stable cavity operation at the design voltages, cavity geometry details must be optimized to suppress potential multipacting. Incorporating strong HOM damping in the cavity design is required for the beam stability and quality. Furthermore, due to the finite pole width, the multipole fields, especially the sextupole and the decapole terms, need to be minimized to maintain an acceptable beam dynamic aperture. This paper will present the RF optimization details of the 197 MHz cavity. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB068  
About • Received ※ 16 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 08 July 2023
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TUPTB069 Design and Tests of a Cathode Stalk for the LCLS-II-HE Low Emittance Injector SRF Gun 589
 
  • T.K. Konomi, W. Hartung, S.H. Kim, S.J. Miller, D.G. Morris, K. Saito, A.T. Taylor, T. Xu, Z.Y. Yin
    FRIB, East Lansing, Michigan, USA
  • C. Adolphsen, J. Smedley, L. Xiao
    SLAC, Menlo Park, California, USA
  • S. Gatzmaga, P. Murcek, R. Xiang
    HZDR, Dresden, Germany
  • M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
  • J.W. Lewellen
    LANL, Los Alamos, New Mexico, USA
  
  A SRF gun can operate CW with a high gradient and ultra-low vacuum for high-quantum efficiency, low MTE photocathodes, useful features for delivery of high-brightness, high-repetition-rate beams. For these reasons, an SRF gun based photoinjector was chosen for a proposed Low Emittance Injector addition to the LCLS-II-HE facility, which will operate CW with bunch rates up to 1 MHz. For this injector, a prototype 185.7 MHz QWR gun is being developed in a collaborative effort among FRIB, HZDR, ANL and SLAC, with the goal of achieving a photocathode gradient of at least 30 MV/m. The photocathode is held by a coaxial fixture (cathode stalk) for thermal isolation from the cavity body. The system must allow for precise alignment of the photocathode, particle-free photocathode exchange, cryogenic (55-70 K) or warm (273-300 K) photocathode operating temperatures, and DC biasing to inhibit multipacting. A prototype cathode stalk has been built and bench tests are underway to validate the design. Measurements include RF power dissipation, DC bias hold-off, multipacting suppression and heat transfer effectiveness. This paper describes the cathode stalk design and the test results.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB069  
About • Received ※ 03 July 2023 — Revised ※ 27 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 20 August 2023
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WEIXA03 Optimizing the Manufacture of High-Purity Niobium SRF Cavities Using the Forming Limit Diagram: A Case Study of the HL-LHC Crab Cavities RFD Pole 627
 
  • A. Gallifa Terricabras, I. Aviles Santillana, S. Barrière, M. Garlasché, L. Prever-Loiri, J.S. Swieszek
    CERN, Meyrin, Switzerland
  • E. Cano-Pleite
    UC3M, Leganes, Spain
  • M. Narduzzi
    Fermilab, Batavia, Illinois, USA
  • S. Pfeiffer
    European Organization for Nuclear Research (CERN), Geneva, Switzerland
  
  Funding: CERN HL-LHC
The Crab Cavities are key components of the High Luminosity Large Hadron Collider (HL-LHC) project at CERN, which aims to increase the integrated luminosity of the LHC, the world’s largest particle accelerator, by a factor of ten. This paper explores the application of the Forming Limit Diagram (FLD) to enhance the manufacturing process of complex-shape Nb-based cavities, with a focus on the formability challenges experienced with the pole of the Radio Frequency Dipole (RFD) Crab Cavities. The study includes the material characterization of ultra-high-purity niobium (Nb RRR300) sheets, namely mechanical tests and microstructural analysis; it also contains large-deformation Finite Element simulations of the pole deep drawing process, and the translation of the resulting strains in a FLD diagram, together with several suggestions on how to improve the manufacturing process of such deep drawn parts. The results of this study can provide valuable insights into improving the design and fabrication of complex-shaped superconducting radio-frequency cavities made by large-deformation metal-sheet forming processes. 		 
slides icon Slides WEIXA03 [15.991 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA03  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 27 June 2023
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WEIXA05 Electropolishing Study on Nitrogen-Doped Niobium Surface 641
 
  • V. Chouhan, T.J. Ring, G. Wu
    Fermilab, Batavia, Illinois, USA
  • E.A.S. Viklund
    NU, Evanston, Illinois, USA
  
  The nitrogen doping (N-doping) process is applied to niobium (Nb) superconducting cavities to enhance their quality factors. The N-doping is followed by an electropolishing process that provides the final surface of the cavities. A controlled EP process is necessary to get the benefit of N-doping and achieve a high accelerating gradient. We have performed electropolishing of N-doped Nb surface under various conditions to understand their impact on the surface. A modified EP process was developed to obtain a smooth pit-free surface.  
slides icon Slides WEIXA05 [17.622 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA05  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 03 July 2023
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WEIXA07
 Review of Thermal Treatments: Effects, Reliability, and Open Questions  
 
  • S. Posen
    Fermilab, Batavia, Illinois, USA
  
  Over years of research and development, a variety of thermal treatments have been developed for bulk niobium cavities, providing different high performance capabilities for SRF resonators depending on the application. Key considerations include maximum field, quality factor at a desired field, sensitivity to trapped flux, and reproducibility of performance. In this talk, we overview the last decade of development of heat treatments, as well as what is reliability achieved at different laboratories, and open questions.  
slides icon Slides WEIXA07 [6.423 MB]  
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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 (Eacc) 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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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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
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 icon 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
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 icon 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
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 icon 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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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 icon 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
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 (Qext 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 icon 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THIAA01 Development of 3.9 GHz 9-Cell Cavities at SHINE 921
 
  • X.W. Wu
    Zhangjiang Lab, Shanghai, People’s Republic of China
  • J.F. Chen, P.C. Dong, Y.F. Liu, X.H. Ouyang, S. Sun, J.N. Wu, S. Xing, Y.X. Zhang, S.J. Zhao, Y.L. Zhao
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • X. Huang, Z. Wang, Y. Zong
    SINAP, Shanghai, People’s Republic of China
  • Y.W. Huang, R.Z. Xia
    ShanghaiTech University, Shanghai, People’s Republic of China
  
  The Shanghai high-repetition-rate XFEL and extreme light facility (SHINE) Linac requires two 3.9~GHz crymodules to linearize energy distribution before the bunch compressor. As a key component to the project, studies of 3.9~GHz cavities were conducted in the past few years. The first 3.9~GHz 9-cell prototype cavity has been fabricated, tested, and qualified. It reached Q0=3.5×109 at 13.1~MV/m and a maximum accelerating gradient of 25.0~MV/m during the vertical test of the bare cavity. The prototype has been helium tank integrated and reached Q0=2.9×109 at 13.1~MV/m in the vertical test, with a large margin with respect to the SHINE specification. The second prototype has been fabricated and is planned to be tested in 2023. This paper will cover the fabrication, surface treatment, and RF test of the 3.9~GHz cavities.  
slides icon Slides THIAA01 [7.573 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIAA01  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 18 July 2023
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THIAA04 Performance Analysis of Spoke Resonators, Statistics from Cavity Fabrication to Cryomodule Testing 940
 
  • A. Miyazaki, P. Duchesne, D. Le Dréan, D. Longuevergne, G. Olry
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  Irène Joliot-Curie Laboratory (IJCLab) has been leading the development of spoke resonators in multiple interna- tional SRF projects, from fundamental R&D, prototyping, to series production. The European Spallation Source (ESS) superconducting linac is the first of its kind to put into op- eration the spoke resonators. After three prototype cavities, 29 ESS production cavities have been processed, tested, as- sembled into cryomodules at IJCLab, and then shipped to Uppsala for the site acceptance test. Seven prototypes for two other major projects, Multi-purpose hYbrid Research Reactor for High-tech Application (MYRRHA) and Proton Improvement Plan II (PIP-II), designed in collaboration with external institutions, have as well been processed and tested at IJCLab. A new challenge is to fully process series cavi- ties in industry, following the successful implementation of 1.3 GHz elliptical cavities in the other projects. This paper summarises main results obtained from fabrication to final testing, including frequency tuning strategy, performance, limitation in vertical cryostat, and identifies future direction of projects and R&D in the field of spoke cavities.  
slides icon Slides THIAA04 [4.623 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIAA04  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 19 July 2023
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THCAA01 Development of Single-spoke Cavities for ADS at JAEA 947
 
  • Y. Kondo
    JAEA, Ibaraki-ken, Japan
  • T. Dohmae, E. Kako, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  • F. Maekawa, S.I. Meigo, J. Tamura, B. Yee-Rendón
    JAEA/J-PARC, Tokai-mura, Japan
  
  Japan Atomic Energy Agency (JAEA) has been proposing an accelerator-driven system (ADS) as a future nuclear system to efficiently reduce the high-level radioactive waste generated at nuclear power plants. As the first step toward the full-scale CW proton linac for the JAEA-ADS, we are now prototyping a low-beta (around 0.2) single-spoke cavity. Because there is no experience in manufacturing superconducting spoke cavities in Japan, prototyping and performance testing of the cavity are essential to ensure the feasibility of the JAEA-ADS. The dimensional parameters of the prototype spoke cavity were optimized to obtain higher cavity performance. The actual cavity fabrication started in 2020. Most of the cavity parts were fabricated in fiscal year 2020 by press-forming and machining. In 2021, we started welding the cavity parts together. After investigating the optimum welding conditions using mock-up test pieces, each cavity part was joined with smooth welding beads. Currently, the cavity’s body section and the beam port sections have been assembled. This paper presents the current status of the JAEA-ADS and it’s cavity prototyping.  
slides icon Slides THCAA01 [8.433 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THCAA01  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 10 July 2023
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THIXA01 Investigation of Plasma Processing for Coaxial Resonators 960
 
  • W. Hartung, W. Chang, K. Elliott, S.H. Kim, T. Konomi, K. Saito, P.R. Tutt, T. Xu
    FRIB, East Lansing, Michigan, USA
  
  Plasma processing has been investigated by several facilities as a method to mitigate degradation of SRF cavity performance. It provides an alternative to removal and disassembly of cryomodules for refurbishment of each cavity via repeat etching and rinsing. Promising results have been obtained by several groups. Studies of plasma processing for quarter-wave resonators (QWRs) and half-wave resonators (HWRs) were undertaken at FRIB, where a total of 324 such resonators are presently in operation. Plasma ignition and optimization measurements were done with room-temperature-matched input couplers. Plasma cleaning tests were done on several QWRs using the fundamental power coupler (FPC) to drive the plasma. We investigated the usefulness of higher-order modes (HOMs) to drive the plasma. HOMs allow for less mismatch at the FPC and hence lower field in the coupler relative to the cavity. Before-and-after cold tests showed a significant reduction in field emission X-rays with judicious application of plasma processing.  
slides icon Slides THIXA01 [2.060 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THIXA01  
About • Received ※ 01 September 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023  
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THIXA02
 Plasma Cleaning at FNAL: LCLS-II HE vCM Results and Ongoing Studies on Spoke Resonators  
 
  • P. Berrutti
    Fermilab, Batavia, Illinois, USA
  
  Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Plasma cleaning has been proven effective in eliminating multipacting and in preserving the field emission free performance of the LCLS-II HE vCM. Using high order modes (HOMs) for plasma ignition allows overcoming limitations imposed by weakly coupled fundamental modes. HOMs ignition can be applied to different SRF cavities making plasma processing potentially possible for any cavity geometry, including spoke resonators like the SSR1 for PIP-II. The results of plasma processing of LCLS-II HE cavities in vCM are presented, along with the summary of the plasma cleaning operations in the CM test cave. The preliminary results of plasma cleaning tests of SSR1 cavities and future plans are discussed. 		 
slides icon Slides THIXA02 [7.045 MB]  
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THIXA04
 Development of a Prototype Superconducting Radio-Frequency Cavity for Conduction-Cooled Accelerators  
 
  • G. Ciovati, S. Balachandran, G. Cheng, E.F. Daly, P. Dhakal, K.A. Harding, F. Marhauser, T. Powers, U. Pudasaini, R.A. Rimmer, H. Vennekate
    JLab, Newport News, Virginia, USA
  • J.P. Anderson, B.R.L. Coriton, L.D. Holland, K.R. McLaughlin, D.A. Packard, D.M. Vollmer
    GA, San Diego, California, USA
  • A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • J. Rathke
    TechSource, Los Alamos, New Mexico, USA
  • T. Schultheiss
    TJS Technologies, Commack, New York, USA
  
  Funding: Work supported by the U.S. DOE, ARDAP Office, under contract No. DE-AC05-06OR23177. SB¿s microscopy work at the NHMFL was partly supported by the U.S. DOE, HEP Office under Award No. DE-SC0009960.
Recent progress in the development of high-quality Nb₃Sn film coatings along with the availability of cryocoolers with high cooling capacity at 4 K makes it feasible to operate SRF cavities cooled by thermal conduction at relevant accelerating gradients for use in accelerators. We have developed a prototype single-cell cavity to prove the feasibility of operation up to the accelerating gradient required for 1 MeV energy gain, cooled by conduction with cryocoolers. The cavity has a ~3 ¿m thick Nb₃Sn film on the inner surface, deposited on a ~4 mm thick bulk Nb substrate and a bulk ~7 mm thick Cu outer shell with three Cu attachment tabs. The cavity was tested up to a peak surface magnetic field of 53 mT in liquid He at 4.3 K. A horizontal test cryostat was designed and built to test the cavity cooled with three cryocoolers. The rf tests of the conduction-cooled cavity achieved a peak surface magnetic field of 50 mT and stable operation was possible with up to 18.5 W of rf heat load. The peak frequency shift due to microphonics was 23 Hz. These results represent the highest peak surface magnetic field achieved in a conduction-cooled SRF cavity to date 		 
slides icon Slides THIXA04 [3.906 MB]  
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FRIBA03 Heavily Damped Crab Cavities for High Luminosity Collisions 986
 
  • B.P. Xiao
    BNL, Upton, New York, USA
  • S.U. De Silva
    ODU, Norfolk, Virginia, USA
  
  Funding: Work supported by BSA under U.S. DOE contract No. DE-SC0012704, by JSA under U.S. DOE Contract No. DE-SC0002769, and by DOE Contract No. DE-AC02-76SF00515.
Next generation colliders require crab cavities to mitigate parasitic collisions caused by finite crossing angle for luminosity leveling and detector data pile up reduction. The Electron Ion Collider (EIC) crab cavity designs will be introduced as an example to fulfill the geometrical constraints, crabbing voltages, multipole components, Higher Order Mode (HOM) power and impedance budgets. Operational challenges such as tuning, high gain low delay control loop, amplitude and phase noises control will be discussed. 		 
slides icon Slides FRIBA03 [3.666 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA03  
About • Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 06 July 2023
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FRIBA04 Crab Cavities for ILC 990
 
  • P.A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S.A. Belomestnykh, I.V. Gonin, T.N. Khabiboulline, A. Lunin, Y.M. Orlov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • R. Calaga
    CERN, Meyrin, Switzerland
  • S.U. De Silva
    JLab, Newport News, Virginia, USA
  • J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • T. Okugi, A. Yamamoto
    KEK, Ibaraki, Japan
  • S. Verdú-Andrés, B.P. Xiao
    BNL, Upton, New York, USA
  
  For the 14 mrad crossing angle proposed, crab cavity systems are fundamentally anticipated for the viable operation of the International Linear Collider (ILC), in order to maximise its luminosity performance. Since 2021, a specialist development team have been defining optimum crab cavity technologies which can fulfil the operational requirements for ILC, both for its baseline centre-of-mass energy of 250 GeV, but also extending those requirements out to higher beam collision intensities. Five design teams have established crab cavity technology solutions, which have the capability to also operate up to 1 TeV centre-of-mass. This presentation showcases the key performance capabilities of these designs and their associated benefits for both manufacture and integration into the ILC Interaction Region. The recommended outcome of the recently conducted crab cavity technology down-selection, will also be highlighted.  
slides icon Slides FRIBA04 [2.526 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-FRIBA04  
About • Received ※ 19 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 20 July 2023
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FRIYA03
 Industrial SRF Activities at RadiaBeam Technologies  
 
  • S.V. Kutsaev, R.B. Agustsson, A.C. Araujo Martinez, R.D. Berry, P.R. Carriere, P. Frigola, A.Y. Murokh
    RadiaBeam, Santa Monica, California, USA
  
  Funding: This work was funded by the U.S. DOE SBIR awards DE-SC0018753, DE-SC0019973, DE-SC0020034, DE-SC0020930, and NP award DE-SC0021618.
RadiaBeam Technologies is active in a number of SRF-related topics including cavity fabrication, cryomodule design, and beamline HOM load absorbers. This work builds upon our world-class NCRF design, fabrication, and high-power RF testing capabilities and is performed in collaboration with various lab, industry, and university partners. This presentation will focus on our progress in cavity fabrication, including niobium plasticity modeling and instrumented niobium forming, in-house machining and chemistry capabilities, and 3rd party electron beam welding. Results from our machined 6 GHz quarter wave resonators for quantum computing will also be discussed. Finally, we will discuss our cross-cutting work on additive manufacturing of C-103 niobium alloy for aerospace applications and pure Nb for SRF components. 		 
slides icon Slides FRIYA03 [3.780 MB]  
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