SRF2023 - Classification: SRF Technology / Input couplers; higher-order mode couplers and dampers

Paper	Title	Page
MOPMB094	Design of a 1.3 GHz High-Power RF Coupler for Conduction-Cooled Systems	342
SUSPB027	use link to see paper's listing under its alternate paper code
	N.A. Stilin, A.T. Holic, M. Liepe, T.I. O’Connell, P. Quigley, J. Sears, V.D. Shemelin, J. Turco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Cornell is designing a new standalone, compact SRF cryomodule which uses cryocoolers in place of liquid helium for cooling. One of the biggest challenges in implementing such a system is designing a high-power input coupler which is able to be cooled by the cryocoolers without any additional liquid cryogenics. Due to the limited heat load capacity of the cryocoolers at 4.2 K, this requires very careful thermal isolation of the 4.2 K portion of the coupler and thorough optimization of the RF behavior to minimize losses. This paper will present the various design considerations which enabled the creating of a conduction-cooled 1.3 GHz input coupler capable of delivering up to 100 kW CW RF power.
	Poster MOPMB094 [0.964 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB094
About •	Received ※ 16 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 23 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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. ElKamchi, 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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THCAA03	Recent Advances in Fundamental RF Power Couplers
	W. Xu BNL, Upton, New York, USA
	Funding: Work supported by LDRD program of Brookhaven Science Associ-ates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. This presentation will overview the recent development on high power FPC around world and will report the status of high power FPC development for EIC RF/SRF systems. Work supported by LDRD program of Brookhaven Science Associ-ates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
	Slides THCAA03 [3.804 MB]
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Paper

Title

Page

MOPMB094

Design of a 1.3 GHz High-Power RF Coupler for Conduction-Cooled Systems

342

SUSPB027

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

N.A. Stilin, A.T. Holic, M. Liepe, T.I. O’Connell, P. Quigley, J. Sears, V.D. Shemelin, J. Turco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell is designing a new standalone, compact SRF cryomodule which uses cryocoolers in place of liquid helium for cooling. One of the biggest challenges in implementing such a system is designing a high-power input coupler which is able to be cooled by the cryocoolers without any additional liquid cryogenics. Due to the limited heat load capacity of the cryocoolers at 4.2 K, this requires very careful thermal isolation of the 4.2 K portion of the coupler and thorough optimization of the RF behavior to minimize losses. This paper will present the various design considerations which enabled the creating of a conduction-cooled 1.3 GHz input coupler capable of delivering up to 100 kW CW RF power.

Poster MOPMB094 [0.964 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB094

About •

Received ※ 16 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 23 July 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Cite •

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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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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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]

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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. ElKamchi, 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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THCAA03

Recent Advances in Fundamental RF Power Couplers

W. Xu
BNL, Upton, New York, USA

Funding: Work supported by LDRD program of Brookhaven Science Associ-ates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
This presentation will overview the recent development on high power FPC around world and will report the status of high power FPC development for EIC RF/SRF systems.
Work supported by LDRD program of Brookhaven Science Associ-ates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.

Slides THCAA03 [3.804 MB]

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