SRF2021 - List of Keywords (controls)

Paper	Title	Other Keywords	Page
SUPFDV007	Magnetic Field Penetration of Niobium Thin Films Produced by the ARIES Collaboration	cavity, dipole, site, SRF	77
	D.A. Turner Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G. Burt, K.D. Dumbell, O.B. Malyshev, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom G. Burt Lancaster University, Lancaster, United Kingdom E. Chyhyrynets, C. Pira INFN/LNL, Legnaro (PD), Italy T. Junginger TRIUMF, Vancouver, Canada T. Junginger UVIC, Victoria, Canada S.B. Leith, M. Vogel University Siegen, Siegen, Germany O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A. Medvids, P. Onufrijevs Riga Technical University, Riga, Latvia R. Ries Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic E. Seiler IEE, Bratislava, Slovak Republic A. Sublet CERN, Meyrin, Switzerland J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Superconducting (SC) thin film coatings on Cu substrates are already widely used as an alternative to bulk Nb SRF structures. Using Cu allows improved thermal stability compared to Nb due to having a greater thermal conductivity. Niobium thin film coatings also reduce the amount of Nb required to produce a cavity. The performance of thin film Nb cavities is not as good as bulk Nb cavities. The H2020 ARIES WP15 collaboration studied the impact of substrate polishing and the effect produced on Nb thin film depositions. Multiple samples were produced from Cu and polished with various techniques. The polished Cu substrates were then coated with a Nb film at partner institutions. These samples were characterised with surface characterisation techniques for film morphology and structure. The SC properties were studied with 2 DC techniques, a vibrating sample magnetometer (VSM) and a magnetic field penetration (MFP) facility. The results conclude that both chemical polishing and electropolishing produce the best DC properties in the MFP facility. A comparison between the VSM and the MFP facility can be made for 10 micron thick samples, but not for 3 micron thick samples.
	Poster SUPFDV007 [1.064 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV007
About •	Received ※ 21 June 2021 — Accepted ※ 28 October 2021 — Issue date ※ 09 April 2022
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SUPFDV016	A Low Power Test Facility for SRF Thin Film Testing with High Sample Throughput Rate	cavity, SRF, niobium, pick-up	100
	D.J. Seal Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G. Burt, P. Goudket, O.B. Malyshev, B.S. Sian, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom G. Burt, B.S. Sian Lancaster University, Lancaster, United Kingdom J.A. Conlon, P. Goudket, O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	A low-power SRF test facility is being upgraded at Daresbury Laboratory as part of the superconducting thin film testing programme. The facility consists of a bulk niobium test cavity operating at 7.8 GHz, surrounded by RF chokes, and can be run with input RF powers up to 1 W. It is housed within a liquid helium free cryostat and is able to test thin film planar samples up to 100 mm in diameter with a thickness between 1 and 20 mm. The RF chokes allow the cavity to be physically and thermally isolated from the sample, thus reducing the need for complicated sample mounting, whilst minimising field leakage out of the cavity. This allows for a fast turnaround time of two to three days per sample. Initial tests using a newly designed sample holder have shown that an RF-DC compensation method can be used successfully to calculate the surface resistance of samples down to 4 K. Potential upgrades include a pick-up antenna for direct measurements of stored energy and the addition of a self-excited loop to mitigate the effects of microphonics. Details of this facility and preliminary results are described in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV016
About •	Received ※ 21 June 2021 — Accepted ※ 12 August 2021 — Issue date ※ 18 December 2021
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SUPTEV007	Development of a System for Coating SRF Cavities Using Remote Plasma CVD	cavity, plasma, SRF, vacuum	129
	G. Gaitan, P. Bishop, A.T. Holic, G. Kulina, M. Liepe, J. Sears, Z. Sun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was supported by the National Science Foundation under Grant No. PHY-1549132. Next-generation, thin-film surfaces employing Nb₃Sn, NbN, NbTiN, and other compound superconductors are destined to allow reaching superior RF performance levels in SRF cavities. Optimized, advanced deposition processes are required to enable high-quality films of such materials on large and complex-shaped cavities. For this purpose, Cornell University is developing a remote plasma-enhanced chemical vapor deposition (CVD) system that facilitates coating on complicated geometries with a high deposition rate. This system is based on a high-temperature tube furnace with a clean vacuum and furnace loading system. The use of plasma alongside reacting precursors will significantly reduce the required processing temperature and promote precursor decomposition. A vacuum quality monitor (VQM) is used to characterize the residual gases before coating. The CVD system has been designed and is currently under assembly and commissioning.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV007
About •	Received ※ 09 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 10 February 2022
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SUPTEV008	CW Operation of Conduction-Cooled Nb₃Sn SRF Cavity	cavity, SRF, operation, cryomodule	133
	N.A. Stilin, A.T. Holic, M. Liepe, R.D. Porter, J. Sears, Z. Sun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Significant progress in the performance of SRF cavities coated with Nb₃Sn films during the last few years has provided an energy efficient alternative to traditional Nb cavities, thereby initiating a fundamental shift in SRF technology. These Nb₃Sn cavities can operate at significantly higher temperatures than Nb cavities while simultaneously requiring less cooling power. This allows for the use of new cryogenic cooling schemes based on conduction cooling with robust, commercialized turn-key style cryocoolers. Cornell University has developed and tested a 2.6 GHz Nb₃Sn cavity assembly which utilizes such cooling methods. These tests have demonstrated stable RF operation at 10 MV/m with measured thermal dynamics which match numerical simulations. These results also serve as a foundation for designing a new standalone SRF cryomodule which will use a pair of cryocoolers to cool a 1.3 GHz Nb₃Sn cavity with an input coupler capable of supporting high beam current operation.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV008
About •	Received ※ 22 June 2021 — Accepted ※ 13 August 2021 — Issue date ※ 08 November 2021
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MOOFAV01	Successful Beam Commissioning of Heavy-Ion Superconducting Linac at RIKEN	linac, vacuum, cavity, acceleration	167
	K. Yamada, T. Dantsuka, M. Fujimaki, E. Ikezawa, H. Imao, O. Kamigaito, M. Komiyama, K. Kumagai, T. Nagatomo, T. Nishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe RIKEN Nishina Center, Wako, Japan H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa MHI-MS, Kobe, Japan E. Kako, H. Nakai, H. Sakai, K. Umemori KEK, Ibaraki, Japan
	A new superconducting booster linac, so-called SRILAC, has been constructed at the RIKEN Nishina Center to upgrade the acceleration voltage of the existing linac in order to enable further investigation of new super-heavy elements and the production of useful RIs. The SRILAC consists of 10 TEM quarter-wavelength resonators made from pure niobium sheets which operate at 4.5 K. We succeeded to develop high performance SC-cavities which satisfies the required Q₀ of 1E+9 with a wide margin. Installation of the cryomodule and He refrigerator system was completed by the end of FY2018, and the first cooling test was performed in September 2019. After various tests of the RF system, the beam acceleration was successfully commissioned in January 2020. In June 2020, the beam supply to the experiment was started. In this talk, I will report on the beam commissioning of SRILAC as well as the status of the frequency tuner and the differential pump system.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOOFAV01
About •	Received ※ 26 July 2021 — Revised ※ 30 August 2021 — Accepted ※ 05 March 2022 — Issue date ※ 16 May 2022
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MOOFAV06	Four Years of Successful Operation of the European XFEL	cavity, operation, linac, FEL	190
	J. Branlard, S. Choroba, M.K. Grecki, S. Köpke, D. Kostin, D. Nölle, V. Vogel, N. Walker, S. Wiesenberg DESY, Hamburg, Germany
	The European X-Ray Free-Electron Laser (EuXFEL) has been successfully operating for almost 4 years, and routinely delivering 6- to 14-KeV X-rays to users (30 KeV photon energy was demonstrated). At the heart of the machine is the 1.3 km long 1.3 GHz SCRF linac which can reach a maximum electron energy of 17.6 GeV, and is capable of accelerating up to 2700 bunches per RF pulse at a repetition rate of 10 Hz, delivering beam to 6 experiments via 3 SASE undulator sections. In this contribution, we relate on the linac operational experience and highlight some recent developments towards monitoring and improving operations and linac availability.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOOFAV06
About •	Received ※ 18 June 2021 — Accepted ※ 18 August 2021 — Issue date ※ 18 September 2021
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MOPTEV010	RF System Experience for FRIB Half Wave Resonators	cavity, MMI, linac, detector	226
	S. Zhao, W. Chang, E. Daykin, E. Gutierrez, S.H. Kim, S.R. Kunjir, T.L. Larter, D.G. Morris, J.T. Popielarski FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The installation and commissioning of the FRIB superconducting linac adopts a phased strategy. In SRF’19 we reported the progress on the commissioning of the linear segment 1 (LS1) which contains mainly the quarter wave resonators (QWRs). In this paper, we will report the recent progress on the commissioning of the remainder of the linac, including linear segment 2 (LS2), folding segment 2 (FS2) and linear segment 3 (LS3), focusing on the RF system experience for the half wave resonators (HWRs). Compared to the QWRs, the HWRs have a different type of tuner, run at higher power levels and have additional components (for example, high voltage bias tee for multipacting suppression and spark detector). Topics such as nonlinear tuner control for the pneumatic tuners; auto turn on/off implementation; and early issues and failures will be discussed in more detail.
	Poster MOPTEV010 [1.604 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV010
About •	Received ※ 22 June 2021 — Revised ※ 22 August 2021 — Accepted ※ 16 November 2021 — Issue date ※ 22 November 2021
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MOPTEV012	Extra-Cold EP Process at Fermilab	cavity, niobium, SRF, target	230
	F. Furuta, D.J. Bice, M. Martinello, T.J. Ring Fermilab, Batavia, Illinois, USA
	FNAL has established a cold Electro-Polishing (EP) method which maintains the outer surface temperature of cavity cell around 12~15°C during EP process. Cold EP has been applied on the various SRF cavities and contributed to achieve high RF performances with them. To investigate more feasibility and capability of EP at lower temperature, the FNAL EP temperature control tool was recently improved. Extra-cold EP process below 0°C at cavity cell region was successfully performed on 1.3 GHz 1-cell cavity. A compatible RF performance with cold EP method was also demonstrated during the cavity vertical testing. The details of extra-cold EP process and the cavity test results will be presented.
	Poster MOPTEV012 [2.038 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV012
About •	Received ※ 21 June 2021 — Accepted ※ 14 December 2021 — Issue date ※ 16 May 2022
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MOPTEV014	New Improved Horizontal Electropolishing System for SRF Cavities	cavity, cathode, operation, MMI	237
	C.E. Reece, S. Castagnola, P. Denny, A.L.A. Mitchell JLab, Newport News, Virginia, USA
	Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OThR23177. The best performance of niobium SRF accelerating cavities is obtained with surfaces smoothed with electropolishing chemical finishing. Jefferson Lab has recently specified, procured, installed, and commissioned a new versatile production electropolishing (EP) tool. Experience with EP research and operations at JLab as well as vendor interactions and experience guided development of the system specification. Detailed design and fabrication was awarded by contract to Semiconductor Process Equipment Corporation (SPEC). The delivered system was integrated into the JLab chemroom infrastructure and commissioned in 2020. The new EP tool provides much improved heat exchange from the circulating H₂SO₄/HF electrolyte and also the cavity via variable temperature external cooling water flow, resulting in quite uniform cavity wall temperature control and thus improved removal uniformity. With the JLab infrastructure, stabilized process temperature as low as 5 C is available. We describe the system and illustrate operational modes in this contribution.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV014
About •	Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 31 March 2022
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MOPTEV015	Spoke Tuner for the Minerva Project	cavity, operation, linac, experiment	241
	N. Gandolfo, S. Blivet, P. Duchesne, D. Le Dréan Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
	In the framework of the MINERVA construction (MYRRHA Isotopes productioN coupling the linEar acceleRator to the Versatile proton target fAcility), a fully equipped prototype cryomodule is being developed. In order to control the resonance frequency of the cavities during operation, a deformation tuner has been studied. The kinematic model is based on a double lever system coupled with a screw nut linear actuator. The motion is generated by a stepper motor and two piezoelectric actuators working at low temperatures within the thermal insulation vacuum of the cryomodule. Key parameter of this work is the high tuning speed which is required to fulfill the fault tolerance strategy. This paper reports the design study and first tests of the built tuners at room temperature and in vertical cryostat configuration.
	Poster MOPTEV015 [3.184 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV015
About •	Received ※ 28 June 2021 — Revised ※ 15 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 01 April 2022
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MOPCAV009	A New Process for Nitrogen Doping of Niobium Cavities	cavity, niobium, SRF, superconductivity	276
	M. Cavellier Omega Physics, St Gildas de Rhuys, France
	Nitrogen-doping of Niobium cavities is now well known and industrialization of this process is emerging. However, the current process, based on thermal treatment in Nitrogen atmosphere leads to various inaccuracies (what is the concentration of Nitrogen in the Nb material? Penetration depth, created phases, …) and some post-treatment like chemical-mechanical polishing of the inner surface. This work presents a new and more accurate patented process based on nitrogen ion beam implantation into the inner surface of Nb cavities. Ion implantation is a well-known, controlled, accurate and reproducible process that does not require post-treatment. For these reasons, the industrialization of Nitrogen-doping Nb cavities will be improved through ion implantation.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV009
About •	Received ※ 19 June 2021 — Revised ※ 10 July 2021 — Accepted ※ 19 November 2021 — Issue date ※ 06 April 2022
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MOPFDV003	Measuring Flux Trapping Using Flat Samples	cavity, simulation, experiment, HOM	326
	F. Kramer, S. Keckert, J. Knobloch, O. Kugeler HZB, Berlin, Germany J. Knobloch University of Siegen, Siegen, Germany
	With modern superconducting cavities flux trapping is a limiting factor for the achievable quality factor. Flux trapping is influenced by various parameters such as geometry, material, and cooldown dynamics. At SRF2019 we presented data showing the magnetic field surrounding a cavity. We now present supplemental simulations for this data focusing on geometric effects. As these simulations are inconclusive, we have designed a new setup to measure trapped flux in superconducting samples which is presented as well. The advantages compared to a cavity test are the simpler sample geometry, and quicker sample production, as well as shorter measurement times. With this setup we hope to identify fundamental mechanisms of flux trapping, including geometry effects, different materials, and different treatments. First results are presented along with the setup itself.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFDV003
About •	Received ※ 21 June 2021 — Accepted ※ 03 April 2022 — Issue date ※ 02 May 2022
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TUPFAV004	Surface Polishing Facility for Superconducting RF Cavities at CERN	cavity, interface, PLC, niobium	387
	L.M.A. Ferreira, N.S. Chritin, R. Ferreira, V. Gerbet CERN, Meyrin, Switzerland
	A new SRF cavity polishing facility which covers the needs for present projects like the HL-LHC and its CRAB cavities as well as ongoing and future activities in the frame of the FCC study was commissioned at CERN in 2019. This facility can handle chemical and electrochemical polishing baths, can process both niobium and copper-based cavities on a wide range of geometries, starting at 400 MHz up to 1.3 GHz for elliptical type of cavities and more complex shapes as defined by the DQW and RFD CRAB design. The main subassemblies of this facility are presented. Some important design details and materials choices of the facility will be briefly discussed together with the range of operational parameters. First results on different substrates and geometries are discussed in terms of surface finishing and polishing rate uniformity.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFAV004
About •	Received ※ 17 June 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 25 October 2021
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TUPFDV008	Instrumentation R&D for the Studies of SRF Thin-Film Structures at KEK and Kyoto University	cavity, SRF, experiment, superconductivity	421
	Y. Fuwa JAEA/J-PARC, Tokai-mura, Japan H. Hayano, H. Ito, R. Katayama, T. Kubo, T. Saeki KEK, Ibaraki, Japan Y. Iwashita, Y. Kuriyama Kyoto University, Research Reactor Institute, Osaka, Japan H. Tongu Kyoto ICR, Uji, Kyoto, Japan
	We have been developing SRF instrumentations by which the effective lower critical magnetic field H_c1,eff of superconducting-material sample is evaluated through the method of the third-order harmonic voltage measurement mainly for the studies of new SRF thin-film structures. Recently, the quad coil system, which enables us to measure four samples simultaneously in a single batch of an experiment, has been developed. In order to study the creation of thin-film structures inside the SRF cavity, we developed 3-GHz-shaped coupon cavities and an XT-map system for the performance tests of 3 GHz cavities. This article reports the details of these works.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFDV008
About •	Received ※ 01 July 2021 — Revised ※ 19 December 2021 — Accepted ※ 02 April 2022 — Issue date ※ 02 May 2022
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TUPCAV006	Nb₃Sn Films Depositions from Targets Synthesized via Liquid Tin Diffusion	target, niobium, cavity, site	452
	M. Zanierato, O. Azzolini, E. Chyhyrynets, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello INFN/LNL, Legnaro (PD), Italy
	The deposition of Nb₃Sn on copper cavities is inter-esting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. Magnetron sputtering technology allows the deposi-tion of Nb₃Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require targets with non-planar shape, difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD tech-nique is a wire fabrication technology, already devel-oped in the past at LNL for SRF applications [2], that allows the deposition of very thick and uniform coat-ing on Nb substrates even with complex geometry [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb₃Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work.
	Poster TUPCAV006 [5.037 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV006
About •	Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 02 September 2021
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TUPTEV010	Camera Placement in a Short Working Distance Optical Inspection System for RF Cavities	cavity, laser, focusing, SRF	503
	A. Macpherson, L.R. Buonocore, M. Di Castro, H. Gamper, A. Luthi CERN, Meyrin, Switzerland
	Inspection of the RF surface of cavities for the purpose of detecting surface anomalies has been well established, and is typically based on long working distance optical systems using on-axis camera and mirror systems to scan the cavity surface. In order to improve the systematic inspection of the full RF surface of large area cavities, a novel short working distance inspection system is being developed at CERN. This new system is based on a mechatronic robotic system to position that camera at normal incidence close to the cavity surface. To accommodate working distance fluctuations, and to provide increased depth of field resolution, the short working distance camera is coupled with a liquid lens focusing system, providing a programmable focusing function. Details of inspection bench design and first results are reported, as well as details on camera positioning optimisation and the proximity detection surveillance for collision-free scanning of the full-cavity surface.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPTEV010
About •	Received ※ 21 June 2021 — Revised ※ 25 August 2021 — Accepted ※ 18 November 2021 — Issue date ※ 30 January 2022
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TUPTEV012	Progress and Preliminary Statistics for the ESS Series Spoke Cryomodule Test	cavity, cryomodule, LLRF, SRF	512
	H. Li, K. Fransson, K.J. Gajewski, L. Hermansson, A. Miyazaki, R.J.M.Y. Ruber, R. Santiago Kern, M. Zhovner Uppsala University, Uppsala, Sweden
	The European spallation source (ESS), as a world-class high power proton accelerator facility, will be the first one to adopt 26 double spoke resonators (DSR) at its low energy section. As a new superconducting accelerating structure, these DSRs are therefore considered key technology and a challenge for the whole project. They will be the first DSRs in the world to be commissioned for a high power proton accelerator. Since 2019, FREIA Laboratory, Uppsala university, has successfully tested the first DSR prototype cryomodule and is now in charge of the acceptance tests of the ESS series cryomodules prior to installation in the tunnel. The cryomodule test, including cryogenic and RF testing, verifies operation of the cavities, couplers and cold tuning systems. This poster will present the test results for the ESS series spoke cryomodules, including preliminary statistics, experience in general.
	Poster TUPTEV012 [0.898 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPTEV012
About •	Received ※ 21 June 2021 — Revised ※ 18 December 2021 — Accepted ※ 06 May 2022 — Issue date ※ 06 May 2022
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WEPCAV008	A Fast Mechanical Tuner for SRF Cavities	cavity, SRF, acceleration, simulation	600
	S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	There is a particular need for fast tuners and phase shifters for advanced superconducting accelerator RF systems. The tuners based on ferrite, ferroelectric and piezo materials are commonly used. However, those methods suffer from one or another issue of high power loss, slow response, and narrow tuning range. We propose a robust, fast (up to ~5 MHz/sec), high efficient mechanical tuner for SRF cavities operating at the frequency 50 MHz. We develop an external mechanical tuner that is strongly coupled to the cavity. The tuner design represents a trade-off of high efficiency (low RF losses and low heat flux) and frequency tunability range. Our approach solves this trade-off issue. We propose RF design which exploits two coupled resonators so that a main high-field cavity is controlled with a small tunable resonator with a flexible metallic wall operating in a relatively low RF field. Simulations, carried out for a 7.5 MV/m 50 MHz SRF Quarter Wave Resonator (QWR), show that frequency tunability at level 10^-3 is obtainable.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV008
About •	Received ※ 17 June 2021 — Revised ※ 06 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 04 February 2022
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WEPCAV010	Comparison of Electromagnetic Properties During Fabrication of Copper and Niobium Prototypes of 325 MHz Coaxial Half-Wave Resonator	cavity, niobium, experiment, electron	609
	D. Bychanok, V. Bayev, S. Huseu, S.A. Maksimenko, A.E. Sukhotski, E. Vasilevich INP BSU, Minsk, Belarus A.V. Butenko, E. Syresin JINR, Dubna, Moscow Region, Russia M. Gusarova, M.V. Lalayan, S.M. Polozov MEPhI, Moscow, Russia V.S. Petrakovsky, A.I. Pokrovsky, A. Shvedov, S.V. Yurevich Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus Y. Tamashevich HZB, Berlin, Germany
	The main fabrication stages of niobium and copper prototypes of coaxial half-wave resonators (HWR) operating at frequency 325 MHz for the Nuclotron-based Ion Collider fAcility (NICA) injector are presented and discussed. Results of intermediate measurements and electromagnetic properties control for niobium and copper cavities of equivalent geometrical characteristics are compared and analyzed. The comparison of electromagnetic properties of Cu- and Nb-prototypes allows estimating specific features and differences of intermediate "warm" measurements of niobium and copper cavities. The presented results will be used for further development and production of superconductive niobium cavities with a similar design for the NICA-project.
	Poster WEPCAV010 [3.185 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV010
About •	Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 27 December 2021 — Issue date ※ 05 May 2022
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WEPTEV013	New Frequency-Tuning System and Digital LLRF for Stable and Reliable Operation of SRILAC	cavity, cryomodule, linac, SRF	666
	K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, K. Yamada RIKEN Nishina Center, Wako, Japan H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa MHI-MS, Kobe, Japan E. Kako, H. Nakai, H. Sakai, K. Umemori KEK, Ibaraki, Japan
	The superconducting booster linac at RIKEN (SRILAC) has ten 73-MHz quarter-wavelength resonators (QWRs) that are contained in three cryomodules. The beam commissioning of SRILAC was successfully performed in January 2020. Frequency tuning during cold operation is performed by compressing the beam port of the cavity with stainless wires and decreasing the length of each beam gap, similar to the method adopted at ANL and FRIB. However, each tuner is driven by a motor connected to gears, instead of using gas pressure. Since the intervals of the QWRs are small due to the beam dynamics, a compact design for the tuner was adopted. Each cavity was tuned to the design frequency, which required frequency changes of 3 kHz to 7 kHz depending on the cavity. Although no piezoelectric actuator is mounted on the tuning system, phase noise caused by microphonics can be sufficiently reduced by a phase-locked loop using a newly developed digital LLRF. The details of the tuning system as well as the digital LLRF will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPTEV013
About •	Received ※ 13 August 2021 — Revised ※ 13 September 2021 — Accepted ※ 11 November 2021 — Issue date ※ 22 November 2021
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WEOCAV03	RF Dipole Crab Cavity Testing for HL-LHC	cavity, HOM, dipole, target	687
	N. Valverde Alonso, R. Calaga, S.J. Calvo, O. Capatina, O. Capatina, A. Castilla, M. Chiodini, C. Duval, L.M.A. Ferreira, M. Gourragne, P.J. Kohler, T. Mikkola, J.A. Mitchell, E. Montesinos, C. Pasquino, G. Pechaud, N. Stapley, M. Therasse, K. Turaj, J.D. Walker CERN, Meyrin, Switzerland A. Castilla Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A. Castilla Lancaster University, Lancaster, United Kingdom
	RF Crab Cavities are an essential element of the High Luminosity LHC (HL-LHC) upgrade at CERN. Two RF dipole crab cavity used for the compensation of the horizontal crossing angle were recently manufactured and integrated into Titanium Helium tank and RF ancillaries necessary for the beam operation. The two cavities will be integrated into a cryomodule in collaboration with UK-STFC and tested with proton beams in the SPS in 2023. This paper will highlight the RF measurements during the important manufacturing steps, surface preparation and cavity performance at 2K.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEOCAV03
About •	Received ※ 18 June 2021 — Revised ※ 07 September 2021 — Accepted ※ 16 September 2021 — Issue date ※ 22 November 2021
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WEOTEV03	Toward Stoichiometric and Low-Surface-Roughness Nb₃Sn Thin Films via Direct Electrochemical Deposition	cavity, SRF, superconductivity, electron	710
	Z. Sun, G. Gaitan, M. Ge, K. Howard, M. Liepe, T.E. Oseroff, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Arias, Z. Baraissov, M.M. Kelley, D.A. Muller, J.P. Sethna, N. Sitaraman Cornell University, Ithaca, New York, USA K.D. Dobson University of Delaware, Newark, Delaware, USA
	Reducing surface roughness and attaining stoichiometry of Nb₃Sn superconducting films are required to push their superheating field to the theoretical limit in SRF cavities. As such, we explore direct electrochemical processes that minimize involving foreign elements to deposit high-quality Sn, Nb, and NbxSn films on Nb and Cu surfaces. These films are then thermally annealed to Nb₃Sn. We find that smooth Sn pre-depositions via electroplating on Nb surfaces significantly reduce the average roughness of resultant Nb₃Sn to 65 nm, with a dramatic reduction in power intensity at medium special frequencies. Structural and superconducting properties demonstrate a Nb₃Sn A15 phase with a stoichiometry of 25 at% Sn. This process is being scaled-up to a 3.9 GHz cavity. Moreover, preliminary results on electroplating on Cu surface show that Nb plating undergoes a slow growth rate while subsequent Sn plating on the plated Nb surface can be controlled with varied thickness. The Nb plating process is currently being optimized.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEOTEV03
About •	Received ※ 09 July 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 16 January 2022
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THPFAV004	Solenoid Automatic Turn-On and Degaussing for FRIB Cryomodules	solenoid, cryomodule, MMI, status	737
	W. Chang, Y. Choi, J.T. Popielarski, K. Saito, T. Xu, C. Zhang FRIB, East Lansing, Michigan, USA
	The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) will accelerate heavy ions to 200 MeV per nucleon. The linac includes 46 SRF cryomodules, with a total of 69 solenoid packages for beam focusing and steering. For efficient beam commissioning and future operation, all of the solenoids must be turned on and reach a stable operating condition in a short time. Additionally, when a warm-up of the cryomodules is needed, degaussing of the solenoid packages is needed to minimize the residual magnetic field in the SRF cavities. An automatic turn-on and degaussing program had been implemented for FRIB cryomodules to meet these requirements. This paper will describe the design, development, and implementation of the automated solenoid control program.
	Poster THPFAV004 [1.863 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPFAV004
About •	Received ※ 21 June 2021 — Revised ※ 19 September 2021 — Accepted ※ 15 December 2021 — Issue date ※ 01 March 2022
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THPCAV002	Low Temperature Heat Treatment on the HWR Cavity	cavity, cryomodule, SRF, niobium	779
	Y. Jung, H. Jang, H. Kim, H. Kim, J.W. Kim, M.S. Kim, J. Lee, M. Lee IBS, Daejeon, Republic of Korea S. Jeon Kyungpook National University, Daegu, Republic of Korea
	Institute for Basic Science have been constructing Superconducting LINAC composed of quarter wave resonator (QWR) and half wave resonator (HWR). All QWR cavities have been completely fabricated and successfully tested to be assembled in QWR cryomodules. For now, we have been testing HWR cavities over 50%. For the testing period, the success rate experienced up and downs like we went through during the QWR tests. In many cases, we observed that some cavities did not reach requirement performance 2K although they showed high performance at 4K. We increased the temperature of heat treatment to cure the rapid Q drop at the high gradient and observed most cavities passed the test after heat treatment.
	Poster THPCAV002 [1.979 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPCAV002
About •	Received ※ 21 June 2021 — Revised ※ 25 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 23 February 2022
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THPCAV006	Recent Activities Regarding 9-Cell TESLA-Type Cavities at KEK	cavity, EPICS, niobium, SRF	792
	M. Omet, R. Katayama, K. Umemori KEK, Ibaraki, Japan
	In this contribution we report on two topics regarding recent activities on 9-cell TESLA-type cavities at the High Energy Accelerator Research Organization (KEK). First, we give an overview of the inner surface treatments and vertical test (VT) results of four fine grain 9-cell TESLA-type cavities over the last one and a half years. Secondly, we report on the upgrade of the VT DAQ system at the Superconducting RF Test Facility (STF) at KEK. In this upgrade, most components of the VT system were integrated in an EPICS control system. Based on Control System Studio (CSS) and Python a new user interface was created, improving the workflow during and after VTs at STF.
	Poster THPCAV006 [1.752 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPCAV006
About •	Received ※ 18 June 2021 — Revised ※ 26 August 2021 — Accepted ※ 23 November 2021 — Issue date ※ 04 March 2022
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THPCAV011	Operational Experience with the Mechanical Tuner Systems in the Superconducting Linac at IUAC	cavity, linac, operation, resonance	809
	A. Pandey, R. Ahuja, G.K. Chaudhari, B.B. Chaudhary, R.N. Dutt, S. Ghosh, B. Karmakar, J. Karmakar, R. Kumar, D.S. Mathuria, P. Patra, P.N. Potukuchi, A. Rai, B.K. Sahu, S.K. Saini, A. Sharma, S.K. Sonti, S.K. Suman IUAC, New Delhi, India
	The phase locking of the QWRs by dynamic phase control method in the superconducting linac at IUAC is done in a faster time scale. The slow frequency drifts (few hundreds of ms) are corrected using a niobium bellows tuner attached at the open end of the cavity. Initially, the tuners in the cavities were operated using helium gas. This system had the limitation of non-linearity, hysteresis and slow response due to which the cavities could not be phase locked at higher fields. To address this, piezo based tuning system was implemented in the cavities of the 2nd and 3rd linac modules. But due to space constraints, the same could not be used in the 1st linac module and the buncher modules. For them, the helium gas based system was continued, albeit with suitable modifications. The old flow control valves which operated with DC voltages were replaced with valves operating in pulsed mode and controlled by varying the duty cycle of the input pulses. The above mentioned limitations were overcome by using this PWM based technique and this enabled phase locking at higher gradients. This paper presents our operational experience with all the different tuning systems and their comparison.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPCAV011
About •	Received ※ 21 June 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 October 2021
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THPTEV002	Enhanced Pneumatic Tuner Control for FRIB Half-Wave Resonators	cavity, solenoid, cryomodule, feedback	829
	W. Chang, W. Hartung, S.H. Kim, J.T. Popielarski, T. Xu, C. Zhang, S. Zhao FRIB, East Lansing, Michigan, USA
	The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) includes a total of 46 cryomodules; 31 cryomodules contain half-wave resonators (HWRs) with pneumatic tuners. Pneumatic tuner control is via solenoid valves connecting the tuner to a helium gas supply manifold and a gas return line. For precise compensation of cavity detuning over a small range, the control voltage for the solenoid valves must be calibrated. Some valves have hysteresis in the gas flow rate as a function of control voltage, such that their response may be nonlinear and not repeatable–this makes the control algorithm challenging. To improve the system performance, a new pneumatic tuner control system was developed which regulates the position of one stepper motor instead of the two solenoid valves.
	Poster THPTEV002 [1.325 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV002
About •	Received ※ 24 June 2021 — Revised ※ 15 December 2021 — Accepted ※ 17 February 2022 — Issue date ※ 16 May 2022
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THPTEV003	LCLS-II Cryomodules Production Experience and Lessons Learned Towards LCLS-II-HE Project	cavity, cryomodule, vacuum, SRF	832
	T.T. Arkan, D.J. Bice, J.N. Blowers, C.J. Grimm, B.D. Hartsell, J.A. Kaluzny, M. Martinello, T.H. Nicol, Y.M. Orlov, S. Posen, K.S. Premo, R.P. Stanek Fermilab, Batavia, Illinois, USA
	Funding: DOE LCLS-II is an upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLS-II linac consists of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF (SRF) continuous wave (CW) cryomodules with high quality factor cavities. Cryomodules were produced at Fermilab and at Jefferson Lab in collaboration with SLAC. Fermilab successfully completed the assembly, testing and delivery of seventeen 1.3 GHz and three 3.9 GHz cryomodules. LCLS-II-HE is a planned upgrade project to LCLS-II. The LCLS-II-HE linac will consist of twenty-three 1.3 GHz cryomodules with high gradient and high quality factor cavities. This paper presents LCLS-II-HE cryomodule production plans, emphasizing the improvements done based on the challenges, mitigations, and lessons learned from LCLS-II.
	Poster THPTEV003 [0.620 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV003
About •	Received ※ 21 June 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 October 2021
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THPTEV008	Development of a Digital LLRF System for SRF Cavities in RAON Accelerator	cavity, LLRF, SRF, cryomodule	845
	H. Jang, D.H. Gil, Y. Jung, H. Kim, Y. Kim, M. Lee IBS, Daejeon, Republic of Korea
	An ion accelerator, RAON is planned and under construction in Daejeon, Korea by Rare Isotope Science Project (RISP) team in Institute of Basic Science (IBS). The purpose of this accelerator is the generation of rare isotope by ISOL (Isotope Separation On-Line) and IF (In-flight Fragmentation) method. To achieve this goal RAON adopted the superconducting cavities at three different frequency (81.25 MHz, 162.5 MHz and 325 MHz) and their RF field will be controlled independently for the acceleration of ions with various A/q. A solid state power amplifier and a low level RF (LLRF) controller pairs are under development to generate and to control the RF for the cavities. Recently the development and evaluation of the digital-based LLRF have been performed. For the operation and test of SRF cavities, self-excited loop (SEL) and generator-driven-resonator (GDR) algorithm is digitally implemented and its test was performed. In this paper the status and test result of RAON LLRF controller will be described.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV008
About •	Received ※ 21 June 2021 — Revised ※ 30 August 2021 — Accepted ※ 26 September 2021 — Issue date ※ 23 November 2021
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Paper

Title

Other Keywords

Page

SUPFDV007

Magnetic Field Penetration of Niobium Thin Films Produced by the ARIES Collaboration

cavity, dipole, site, SRF

77

D.A. Turner
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
G. Burt, K.D. Dumbell, O.B. Malyshev, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G. Burt
Lancaster University, Lancaster, United Kingdom
E. Chyhyrynets, C. Pira
INFN/LNL, Legnaro (PD), Italy
T. Junginger
TRIUMF, Vancouver, Canada
T. Junginger
UVIC, Victoria, Canada
S.B. Leith, M. Vogel
University Siegen, Siegen, Germany
O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Medvids, P. Onufrijevs
Riga Technical University, Riga, Latvia
R. Ries
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
E. Seiler
IEE, Bratislava, Slovak Republic
A. Sublet
CERN, Meyrin, Switzerland
J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Superconducting (SC) thin film coatings on Cu substrates are already widely used as an alternative to bulk Nb SRF structures. Using Cu allows improved thermal stability compared to Nb due to having a greater thermal conductivity. Niobium thin film coatings also reduce the amount of Nb required to produce a cavity. The performance of thin film Nb cavities is not as good as bulk Nb cavities. The H2020 ARIES WP15 collaboration studied the impact of substrate polishing and the effect produced on Nb thin film depositions. Multiple samples were produced from Cu and polished with various techniques. The polished Cu substrates were then coated with a Nb film at partner institutions. These samples were characterised with surface characterisation techniques for film morphology and structure. The SC properties were studied with 2 DC techniques, a vibrating sample magnetometer (VSM) and a magnetic field penetration (MFP) facility. The results conclude that both chemical polishing and electropolishing produce the best DC properties in the MFP facility. A comparison between the VSM and the MFP facility can be made for 10 micron thick samples, but not for 3 micron thick samples.

Poster SUPFDV007 [1.064 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV007

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Received ※ 21 June 2021 — Accepted ※ 28 October 2021 — Issue date ※ 09 April 2022

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SUPFDV016

A Low Power Test Facility for SRF Thin Film Testing with High Sample Throughput Rate

cavity, SRF, niobium, pick-up

100

D.J. Seal
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
G. Burt, P. Goudket, O.B. Malyshev, B.S. Sian, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G. Burt, B.S. Sian
Lancaster University, Lancaster, United Kingdom
J.A. Conlon, P. Goudket, O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

A low-power SRF test facility is being upgraded at Daresbury Laboratory as part of the superconducting thin film testing programme. The facility consists of a bulk niobium test cavity operating at 7.8 GHz, surrounded by RF chokes, and can be run with input RF powers up to 1 W. It is housed within a liquid helium free cryostat and is able to test thin film planar samples up to 100 mm in diameter with a thickness between 1 and 20 mm. The RF chokes allow the cavity to be physically and thermally isolated from the sample, thus reducing the need for complicated sample mounting, whilst minimising field leakage out of the cavity. This allows for a fast turnaround time of two to three days per sample. Initial tests using a newly designed sample holder have shown that an RF-DC compensation method can be used successfully to calculate the surface resistance of samples down to 4 K. Potential upgrades include a pick-up antenna for direct measurements of stored energy and the addition of a self-excited loop to mitigate the effects of microphonics. Details of this facility and preliminary results are described in this paper.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPFDV016

About •

Received ※ 21 June 2021 — Accepted ※ 12 August 2021 — Issue date ※ 18 December 2021

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SUPTEV007

Development of a System for Coating SRF Cavities Using Remote Plasma CVD

cavity, plasma, SRF, vacuum

129

G. Gaitan, P. Bishop, A.T. Holic, G. Kulina, M. Liepe, J. Sears, Z. Sun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the National Science Foundation under Grant No. PHY-1549132.
Next-generation, thin-film surfaces employing Nb₃Sn, NbN, NbTiN, and other compound superconductors are destined to allow reaching superior RF performance levels in SRF cavities. Optimized, advanced deposition processes are required to enable high-quality films of such materials on large and complex-shaped cavities. For this purpose, Cornell University is developing a remote plasma-enhanced chemical vapor deposition (CVD) system that facilitates coating on complicated geometries with a high deposition rate. This system is based on a high-temperature tube furnace with a clean vacuum and furnace loading system. The use of plasma alongside reacting precursors will significantly reduce the required processing temperature and promote precursor decomposition. A vacuum quality monitor (VQM) is used to characterize the residual gases before coating. The CVD system has been designed and is currently under assembly and commissioning.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV007

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Received ※ 09 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 10 February 2022

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SUPTEV008

CW Operation of Conduction-Cooled Nb₃Sn SRF Cavity

cavity, SRF, operation, cryomodule

133

N.A. Stilin, A.T. Holic, M. Liepe, R.D. Porter, J. Sears, Z. Sun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Significant progress in the performance of SRF cavities coated with Nb₃Sn films during the last few years has provided an energy efficient alternative to traditional Nb cavities, thereby initiating a fundamental shift in SRF technology. These Nb₃Sn cavities can operate at significantly higher temperatures than Nb cavities while simultaneously requiring less cooling power. This allows for the use of new cryogenic cooling schemes based on conduction cooling with robust, commercialized turn-key style cryocoolers. Cornell University has developed and tested a 2.6 GHz Nb₃Sn cavity assembly which utilizes such cooling methods. These tests have demonstrated stable RF operation at 10 MV/m with measured thermal dynamics which match numerical simulations. These results also serve as a foundation for designing a new standalone SRF cryomodule which will use a pair of cryocoolers to cool a 1.3 GHz Nb₃Sn cavity with an input coupler capable of supporting high beam current operation.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV008

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Received ※ 22 June 2021 — Accepted ※ 13 August 2021 — Issue date ※ 08 November 2021

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MOOFAV01

Successful Beam Commissioning of Heavy-Ion Superconducting Linac at RIKEN

linac, vacuum, cavity, acceleration

167

K. Yamada, T. Dantsuka, M. Fujimaki, E. Ikezawa, H. Imao, O. Kamigaito, M. Komiyama, K. Kumagai, T. Nagatomo, T. Nishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe
RIKEN Nishina Center, Wako, Japan
H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
MHI-MS, Kobe, Japan
E. Kako, H. Nakai, H. Sakai, K. Umemori
KEK, Ibaraki, Japan

A new superconducting booster linac, so-called SRILAC, has been constructed at the RIKEN Nishina Center to upgrade the acceleration voltage of the existing linac in order to enable further investigation of new super-heavy elements and the production of useful RIs. The SRILAC consists of 10 TEM quarter-wavelength resonators made from pure niobium sheets which operate at 4.5 K. We succeeded to develop high performance SC-cavities which satisfies the required Q₀ of 1E+9 with a wide margin. Installation of the cryomodule and He refrigerator system was completed by the end of FY2018, and the first cooling test was performed in September 2019. After various tests of the RF system, the beam acceleration was successfully commissioned in January 2020. In June 2020, the beam supply to the experiment was started. In this talk, I will report on the beam commissioning of SRILAC as well as the status of the frequency tuner and the differential pump system.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOOFAV01

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Received ※ 26 July 2021 — Revised ※ 30 August 2021 — Accepted ※ 05 March 2022 — Issue date ※ 16 May 2022

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MOOFAV06

Four Years of Successful Operation of the European XFEL

cavity, operation, linac, FEL

190

J. Branlard, S. Choroba, M.K. Grecki, S. Köpke, D. Kostin, D. Nölle, V. Vogel, N. Walker, S. Wiesenberg
DESY, Hamburg, Germany

The European X-Ray Free-Electron Laser (EuXFEL) has been successfully operating for almost 4 years, and routinely delivering 6- to 14-KeV X-rays to users (30 KeV photon energy was demonstrated). At the heart of the machine is the 1.3 km long 1.3 GHz SCRF linac which can reach a maximum electron energy of 17.6 GeV, and is capable of accelerating up to 2700 bunches per RF pulse at a repetition rate of 10 Hz, delivering beam to 6 experiments via 3 SASE undulator sections. In this contribution, we relate on the linac operational experience and highlight some recent developments towards monitoring and improving operations and linac availability.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOOFAV06

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Received ※ 18 June 2021 — Accepted ※ 18 August 2021 — Issue date ※ 18 September 2021

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MOPTEV010

RF System Experience for FRIB Half Wave Resonators

cavity, MMI, linac, detector

226

S. Zhao, W. Chang, E. Daykin, E. Gutierrez, S.H. Kim, S.R. Kunjir, T.L. Larter, D.G. Morris, J.T. Popielarski
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The installation and commissioning of the FRIB superconducting linac adopts a phased strategy. In SRF’19 we reported the progress on the commissioning of the linear segment 1 (LS1) which contains mainly the quarter wave resonators (QWRs). In this paper, we will report the recent progress on the commissioning of the remainder of the linac, including linear segment 2 (LS2), folding segment 2 (FS2) and linear segment 3 (LS3), focusing on the RF system experience for the half wave resonators (HWRs). Compared to the QWRs, the HWRs have a different type of tuner, run at higher power levels and have additional components (for example, high voltage bias tee for multipacting suppression and spark detector). Topics such as nonlinear tuner control for the pneumatic tuners; auto turn on/off implementation; and early issues and failures will be discussed in more detail.

Poster MOPTEV010 [1.604 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV010

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Received ※ 22 June 2021 — Revised ※ 22 August 2021 — Accepted ※ 16 November 2021 — Issue date ※ 22 November 2021

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MOPTEV012

Extra-Cold EP Process at Fermilab

cavity, niobium, SRF, target

230

F. Furuta, D.J. Bice, M. Martinello, T.J. Ring
Fermilab, Batavia, Illinois, USA

FNAL has established a cold Electro-Polishing (EP) method which maintains the outer surface temperature of cavity cell around 12~15°C during EP process. Cold EP has been applied on the various SRF cavities and contributed to achieve high RF performances with them. To investigate more feasibility and capability of EP at lower temperature, the FNAL EP temperature control tool was recently improved. Extra-cold EP process below 0°C at cavity cell region was successfully performed on 1.3 GHz 1-cell cavity. A compatible RF performance with cold EP method was also demonstrated during the cavity vertical testing. The details of extra-cold EP process and the cavity test results will be presented.

Poster MOPTEV012 [2.038 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV012

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Received ※ 21 June 2021 — Accepted ※ 14 December 2021 — Issue date ※ 16 May 2022

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MOPTEV014

New Improved Horizontal Electropolishing System for SRF Cavities

cavity, cathode, operation, MMI

237

C.E. Reece, S. Castagnola, P. Denny, A.L.A. Mitchell
JLab, Newport News, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OThR23177.
The best performance of niobium SRF accelerating cavities is obtained with surfaces smoothed with electropolishing chemical finishing. Jefferson Lab has recently specified, procured, installed, and commissioned a new versatile production electropolishing (EP) tool. Experience with EP research and operations at JLab as well as vendor interactions and experience guided development of the system specification. Detailed design and fabrication was awarded by contract to Semiconductor Process Equipment Corporation (SPEC). The delivered system was integrated into the JLab chemroom infrastructure and commissioned in 2020. The new EP tool provides much improved heat exchange from the circulating H₂SO₄/HF electrolyte and also the cavity via variable temperature external cooling water flow, resulting in quite uniform cavity wall temperature control and thus improved removal uniformity. With the JLab infrastructure, stabilized process temperature as low as 5 C is available. We describe the system and illustrate operational modes in this contribution.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV014

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Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 31 March 2022

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MOPTEV015

Spoke Tuner for the Minerva Project

cavity, operation, linac, experiment

241

N. Gandolfo, S. Blivet, P. Duchesne, D. Le Dréan
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

In the framework of the MINERVA construction (MYRRHA Isotopes productioN coupling the linEar acceleRator to the Versatile proton target fAcility), a fully equipped prototype cryomodule is being developed. In order to control the resonance frequency of the cavities during operation, a deformation tuner has been studied. The kinematic model is based on a double lever system coupled with a screw nut linear actuator. The motion is generated by a stepper motor and two piezoelectric actuators working at low temperatures within the thermal insulation vacuum of the cryomodule. Key parameter of this work is the high tuning speed which is required to fulfill the fault tolerance strategy. This paper reports the design study and first tests of the built tuners at room temperature and in vertical cryostat configuration.

Poster MOPTEV015 [3.184 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPTEV015

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Received ※ 28 June 2021 — Revised ※ 15 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 01 April 2022

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MOPCAV009

A New Process for Nitrogen Doping of Niobium Cavities

cavity, niobium, SRF, superconductivity

276

M. Cavellier
Omega Physics, St Gildas de Rhuys, France

Nitrogen-doping of Niobium cavities is now well known and industrialization of this process is emerging. However, the current process, based on thermal treatment in Nitrogen atmosphere leads to various inaccuracies (what is the concentration of Nitrogen in the Nb material? Penetration depth, created phases, …) and some post-treatment like chemical-mechanical polishing of the inner surface. This work presents a new and more accurate patented process based on nitrogen ion beam implantation into the inner surface of Nb cavities. Ion implantation is a well-known, controlled, accurate and reproducible process that does not require post-treatment. For these reasons, the industrialization of Nitrogen-doping Nb cavities will be improved through ion implantation.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV009

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Received ※ 19 June 2021 — Revised ※ 10 July 2021 — Accepted ※ 19 November 2021 — Issue date ※ 06 April 2022

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MOPFDV003

Measuring Flux Trapping Using Flat Samples

cavity, simulation, experiment, HOM

326

F. Kramer, S. Keckert, J. Knobloch, O. Kugeler
HZB, Berlin, Germany
J. Knobloch
University of Siegen, Siegen, Germany

With modern superconducting cavities flux trapping is a limiting factor for the achievable quality factor. Flux trapping is influenced by various parameters such as geometry, material, and cooldown dynamics. At SRF2019 we presented data showing the magnetic field surrounding a cavity. We now present supplemental simulations for this data focusing on geometric effects. As these simulations are inconclusive, we have designed a new setup to measure trapped flux in superconducting samples which is presented as well. The advantages compared to a cavity test are the simpler sample geometry, and quicker sample production, as well as shorter measurement times. With this setup we hope to identify fundamental mechanisms of flux trapping, including geometry effects, different materials, and different treatments. First results are presented along with the setup itself.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPFDV003

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Received ※ 21 June 2021 — Accepted ※ 03 April 2022 — Issue date ※ 02 May 2022

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TUPFAV004

Surface Polishing Facility for Superconducting RF Cavities at CERN

cavity, interface, PLC, niobium

387

L.M.A. Ferreira, N.S. Chritin, R. Ferreira, V. Gerbet
CERN, Meyrin, Switzerland

A new SRF cavity polishing facility which covers the needs for present projects like the HL-LHC and its CRAB cavities as well as ongoing and future activities in the frame of the FCC study was commissioned at CERN in 2019. This facility can handle chemical and electrochemical polishing baths, can process both niobium and copper-based cavities on a wide range of geometries, starting at 400 MHz up to 1.3 GHz for elliptical type of cavities and more complex shapes as defined by the DQW and RFD CRAB design. The main subassemblies of this facility are presented. Some important design details and materials choices of the facility will be briefly discussed together with the range of operational parameters. First results on different substrates and geometries are discussed in terms of surface finishing and polishing rate uniformity.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFAV004

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Received ※ 17 June 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 25 October 2021

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TUPFDV008

Instrumentation R&D for the Studies of SRF Thin-Film Structures at KEK and Kyoto University

cavity, SRF, experiment, superconductivity

421

Y. Fuwa
JAEA/J-PARC, Tokai-mura, Japan
H. Hayano, H. Ito, R. Katayama, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
Y. Iwashita, Y. Kuriyama
Kyoto University, Research Reactor Institute, Osaka, Japan
H. Tongu
Kyoto ICR, Uji, Kyoto, Japan

We have been developing SRF instrumentations by which the effective lower critical magnetic field H_c1,eff of superconducting-material sample is evaluated through the method of the third-order harmonic voltage measurement mainly for the studies of new SRF thin-film structures. Recently, the quad coil system, which enables us to measure four samples simultaneously in a single batch of an experiment, has been developed. In order to study the creation of thin-film structures inside the SRF cavity, we developed 3-GHz-shaped coupon cavities and an XT-map system for the performance tests of 3 GHz cavities. This article reports the details of these works.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFDV008

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Received ※ 01 July 2021 — Revised ※ 19 December 2021 — Accepted ※ 02 April 2022 — Issue date ※ 02 May 2022

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TUPCAV006

Nb₃Sn Films Depositions from Targets Synthesized via Liquid Tin Diffusion

target, niobium, cavity, site

452

M. Zanierato, O. Azzolini, E. Chyhyrynets, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello
INFN/LNL, Legnaro (PD), Italy

The deposition of Nb₃Sn on copper cavities is inter-esting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. Magnetron sputtering technology allows the deposi-tion of Nb₃Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require targets with non-planar shape, difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD tech-nique is a wire fabrication technology, already devel-oped in the past at LNL for SRF applications [2], that allows the deposition of very thick and uniform coat-ing on Nb substrates even with complex geometry [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb₃Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work.

Poster TUPCAV006 [5.037 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV006

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Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 02 September 2021

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TUPTEV010

Camera Placement in a Short Working Distance Optical Inspection System for RF Cavities

cavity, laser, focusing, SRF

503

A. Macpherson, L.R. Buonocore, M. Di Castro, H. Gamper, A. Luthi
CERN, Meyrin, Switzerland

Inspection of the RF surface of cavities for the purpose of detecting surface anomalies has been well established, and is typically based on long working distance optical systems using on-axis camera and mirror systems to scan the cavity surface. In order to improve the systematic inspection of the full RF surface of large area cavities, a novel short working distance inspection system is being developed at CERN. This new system is based on a mechatronic robotic system to position that camera at normal incidence close to the cavity surface. To accommodate working distance fluctuations, and to provide increased depth of field resolution, the short working distance camera is coupled with a liquid lens focusing system, providing a programmable focusing function. Details of inspection bench design and first results are reported, as well as details on camera positioning optimisation and the proximity detection surveillance for collision-free scanning of the full-cavity surface.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPTEV010

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Received ※ 21 June 2021 — Revised ※ 25 August 2021 — Accepted ※ 18 November 2021 — Issue date ※ 30 January 2022

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TUPTEV012

Progress and Preliminary Statistics for the ESS Series Spoke Cryomodule Test

cavity, cryomodule, LLRF, SRF

512

H. Li, K. Fransson, K.J. Gajewski, L. Hermansson, A. Miyazaki, R.J.M.Y. Ruber, R. Santiago Kern, M. Zhovner
Uppsala University, Uppsala, Sweden

The European spallation source (ESS), as a world-class high power proton accelerator facility, will be the first one to adopt 26 double spoke resonators (DSR) at its low energy section. As a new superconducting accelerating structure, these DSRs are therefore considered key technology and a challenge for the whole project. They will be the first DSRs in the world to be commissioned for a high power proton accelerator. Since 2019, FREIA Laboratory, Uppsala university, has successfully tested the first DSR prototype cryomodule and is now in charge of the acceptance tests of the ESS series cryomodules prior to installation in the tunnel. The cryomodule test, including cryogenic and RF testing, verifies operation of the cavities, couplers and cold tuning systems. This poster will present the test results for the ESS series spoke cryomodules, including preliminary statistics, experience in general.

Poster TUPTEV012 [0.898 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPTEV012

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Received ※ 21 June 2021 — Revised ※ 18 December 2021 — Accepted ※ 06 May 2022 — Issue date ※ 06 May 2022

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WEPCAV008

A Fast Mechanical Tuner for SRF Cavities

cavity, SRF, acceleration, simulation

600

S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

There is a particular need for fast tuners and phase shifters for advanced superconducting accelerator RF systems. The tuners based on ferrite, ferroelectric and piezo materials are commonly used. However, those methods suffer from one or another issue of high power loss, slow response, and narrow tuning range. We propose a robust, fast (up to ~5 MHz/sec), high efficient mechanical tuner for SRF cavities operating at the frequency 50 MHz. We develop an external mechanical tuner that is strongly coupled to the cavity. The tuner design represents a trade-off of high efficiency (low RF losses and low heat flux) and frequency tunability range. Our approach solves this trade-off issue. We propose RF design which exploits two coupled resonators so that a main high-field cavity is controlled with a small tunable resonator with a flexible metallic wall operating in a relatively low RF field. Simulations, carried out for a 7.5 MV/m 50 MHz SRF Quarter Wave Resonator (QWR), show that frequency tunability at level 10^-3 is obtainable.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV008

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Received ※ 17 June 2021 — Revised ※ 06 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 04 February 2022

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WEPCAV010

Comparison of Electromagnetic Properties During Fabrication of Copper and Niobium Prototypes of 325 MHz Coaxial Half-Wave Resonator

cavity, niobium, experiment, electron

609

D. Bychanok, V. Bayev, S. Huseu, S.A. Maksimenko, A.E. Sukhotski, E. Vasilevich
INP BSU, Minsk, Belarus
A.V. Butenko, E. Syresin
JINR, Dubna, Moscow Region, Russia
M. Gusarova, M.V. Lalayan, S.M. Polozov
MEPhI, Moscow, Russia
V.S. Petrakovsky, A.I. Pokrovsky, A. Shvedov, S.V. Yurevich
Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus
Y. Tamashevich
HZB, Berlin, Germany

The main fabrication stages of niobium and copper prototypes of coaxial half-wave resonators (HWR) operating at frequency 325 MHz for the Nuclotron-based Ion Collider fAcility (NICA) injector are presented and discussed. Results of intermediate measurements and electromagnetic properties control for niobium and copper cavities of equivalent geometrical characteristics are compared and analyzed. The comparison of electromagnetic properties of Cu- and Nb-prototypes allows estimating specific features and differences of intermediate "warm" measurements of niobium and copper cavities. The presented results will be used for further development and production of superconductive niobium cavities with a similar design for the NICA-project.

Poster WEPCAV010 [3.185 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPCAV010

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Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 27 December 2021 — Issue date ※ 05 May 2022

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WEPTEV013

New Frequency-Tuning System and Digital LLRF for Stable and Reliable Operation of SRILAC

cavity, cryomodule, linac, SRF

666

K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, K. Yamada
RIKEN Nishina Center, Wako, Japan
H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
MHI-MS, Kobe, Japan
E. Kako, H. Nakai, H. Sakai, K. Umemori
KEK, Ibaraki, Japan

The superconducting booster linac at RIKEN (SRILAC) has ten 73-MHz quarter-wavelength resonators (QWRs) that are contained in three cryomodules. The beam commissioning of SRILAC was successfully performed in January 2020. Frequency tuning during cold operation is performed by compressing the beam port of the cavity with stainless wires and decreasing the length of each beam gap, similar to the method adopted at ANL and FRIB. However, each tuner is driven by a motor connected to gears, instead of using gas pressure. Since the intervals of the QWRs are small due to the beam dynamics, a compact design for the tuner was adopted. Each cavity was tuned to the design frequency, which required frequency changes of 3 kHz to 7 kHz depending on the cavity. Although no piezoelectric actuator is mounted on the tuning system, phase noise caused by microphonics can be sufficiently reduced by a phase-locked loop using a newly developed digital LLRF. The details of the tuning system as well as the digital LLRF will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEPTEV013

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Received ※ 13 August 2021 — Revised ※ 13 September 2021 — Accepted ※ 11 November 2021 — Issue date ※ 22 November 2021

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WEOCAV03

RF Dipole Crab Cavity Testing for HL-LHC

cavity, HOM, dipole, target

687

N. Valverde Alonso, R. Calaga, S.J. Calvo, O. Capatina, O. Capatina, A. Castilla, M. Chiodini, C. Duval, L.M.A. Ferreira, M. Gourragne, P.J. Kohler, T. Mikkola, J.A. Mitchell, E. Montesinos, C. Pasquino, G. Pechaud, N. Stapley, M. Therasse, K. Turaj, J.D. Walker
CERN, Meyrin, Switzerland
A. Castilla
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A. Castilla
Lancaster University, Lancaster, United Kingdom

RF Crab Cavities are an essential element of the High Luminosity LHC (HL-LHC) upgrade at CERN. Two RF dipole crab cavity used for the compensation of the horizontal crossing angle were recently manufactured and integrated into Titanium Helium tank and RF ancillaries necessary for the beam operation. The two cavities will be integrated into a cryomodule in collaboration with UK-STFC and tested with proton beams in the SPS in 2023. This paper will highlight the RF measurements during the important manufacturing steps, surface preparation and cavity performance at 2K.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEOCAV03

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Received ※ 18 June 2021 — Revised ※ 07 September 2021 — Accepted ※ 16 September 2021 — Issue date ※ 22 November 2021

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WEOTEV03

Toward Stoichiometric and Low-Surface-Roughness Nb₃Sn Thin Films via Direct Electrochemical Deposition

cavity, SRF, superconductivity, electron

710

Z. Sun, G. Gaitan, M. Ge, K. Howard, M. Liepe, T.E. Oseroff, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Arias, Z. Baraissov, M.M. Kelley, D.A. Muller, J.P. Sethna, N. Sitaraman
Cornell University, Ithaca, New York, USA
K.D. Dobson
University of Delaware, Newark, Delaware, USA

Reducing surface roughness and attaining stoichiometry of Nb₃Sn superconducting films are required to push their superheating field to the theoretical limit in SRF cavities. As such, we explore direct electrochemical processes that minimize involving foreign elements to deposit high-quality Sn, Nb, and NbxSn films on Nb and Cu surfaces. These films are then thermally annealed to Nb₃Sn. We find that smooth Sn pre-depositions via electroplating on Nb surfaces significantly reduce the average roughness of resultant Nb₃Sn to 65 nm, with a dramatic reduction in power intensity at medium special frequencies. Structural and superconducting properties demonstrate a Nb₃Sn A15 phase with a stoichiometry of 25 at% Sn. This process is being scaled-up to a 3.9 GHz cavity. Moreover, preliminary results on electroplating on Cu surface show that Nb plating undergoes a slow growth rate while subsequent Sn plating on the plated Nb surface can be controlled with varied thickness. The Nb plating process is currently being optimized.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEOTEV03

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Received ※ 09 July 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 16 January 2022

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THPFAV004

Solenoid Automatic Turn-On and Degaussing for FRIB Cryomodules

solenoid, cryomodule, MMI, status

737

W. Chang, Y. Choi, J.T. Popielarski, K. Saito, T. Xu, C. Zhang
FRIB, East Lansing, Michigan, USA

The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) will accelerate heavy ions to 200 MeV per nucleon. The linac includes 46 SRF cryomodules, with a total of 69 solenoid packages for beam focusing and steering. For efficient beam commissioning and future operation, all of the solenoids must be turned on and reach a stable operating condition in a short time. Additionally, when a warm-up of the cryomodules is needed, degaussing of the solenoid packages is needed to minimize the residual magnetic field in the SRF cavities. An automatic turn-on and degaussing program had been implemented for FRIB cryomodules to meet these requirements. This paper will describe the design, development, and implementation of the automated solenoid control program.

Poster THPFAV004 [1.863 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPFAV004

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Received ※ 21 June 2021 — Revised ※ 19 September 2021 — Accepted ※ 15 December 2021 — Issue date ※ 01 March 2022

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THPCAV002

Low Temperature Heat Treatment on the HWR Cavity

cavity, cryomodule, SRF, niobium

779

Y. Jung, H. Jang, H. Kim, H. Kim, J.W. Kim, M.S. Kim, J. Lee, M. Lee
IBS, Daejeon, Republic of Korea
S. Jeon
Kyungpook National University, Daegu, Republic of Korea

Institute for Basic Science have been constructing Superconducting LINAC composed of quarter wave resonator (QWR) and half wave resonator (HWR). All QWR cavities have been completely fabricated and successfully tested to be assembled in QWR cryomodules. For now, we have been testing HWR cavities over 50%. For the testing period, the success rate experienced up and downs like we went through during the QWR tests. In many cases, we observed that some cavities did not reach requirement performance 2K although they showed high performance at 4K. We increased the temperature of heat treatment to cure the rapid Q drop at the high gradient and observed most cavities passed the test after heat treatment.

Poster THPCAV002 [1.979 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPCAV002

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Received ※ 21 June 2021 — Revised ※ 25 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 23 February 2022

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THPCAV006

Recent Activities Regarding 9-Cell TESLA-Type Cavities at KEK

cavity, EPICS, niobium, SRF

792

M. Omet, R. Katayama, K. Umemori
KEK, Ibaraki, Japan

In this contribution we report on two topics regarding recent activities on 9-cell TESLA-type cavities at the High Energy Accelerator Research Organization (KEK). First, we give an overview of the inner surface treatments and vertical test (VT) results of four fine grain 9-cell TESLA-type cavities over the last one and a half years. Secondly, we report on the upgrade of the VT DAQ system at the Superconducting RF Test Facility (STF) at KEK. In this upgrade, most components of the VT system were integrated in an EPICS control system. Based on Control System Studio (CSS) and Python a new user interface was created, improving the workflow during and after VTs at STF.

Poster THPCAV006 [1.752 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPCAV006

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Received ※ 18 June 2021 — Revised ※ 26 August 2021 — Accepted ※ 23 November 2021 — Issue date ※ 04 March 2022

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THPCAV011

Operational Experience with the Mechanical Tuner Systems in the Superconducting Linac at IUAC

cavity, linac, operation, resonance

809

A. Pandey, R. Ahuja, G.K. Chaudhari, B.B. Chaudhary, R.N. Dutt, S. Ghosh, B. Karmakar, J. Karmakar, R. Kumar, D.S. Mathuria, P. Patra, P.N. Potukuchi, A. Rai, B.K. Sahu, S.K. Saini, A. Sharma, S.K. Sonti, S.K. Suman
IUAC, New Delhi, India

The phase locking of the QWRs by dynamic phase control method in the superconducting linac at IUAC is done in a faster time scale. The slow frequency drifts (few hundreds of ms) are corrected using a niobium bellows tuner attached at the open end of the cavity. Initially, the tuners in the cavities were operated using helium gas. This system had the limitation of non-linearity, hysteresis and slow response due to which the cavities could not be phase locked at higher fields. To address this, piezo based tuning system was implemented in the cavities of the 2nd and 3rd linac modules. But due to space constraints, the same could not be used in the 1st linac module and the buncher modules. For them, the helium gas based system was continued, albeit with suitable modifications. The old flow control valves which operated with DC voltages were replaced with valves operating in pulsed mode and controlled by varying the duty cycle of the input pulses. The above mentioned limitations were overcome by using this PWM based technique and this enabled phase locking at higher gradients. This paper presents our operational experience with all the different tuning systems and their comparison.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPCAV011

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Received ※ 21 June 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 October 2021

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THPTEV002

Enhanced Pneumatic Tuner Control for FRIB Half-Wave Resonators

cavity, solenoid, cryomodule, feedback

829

W. Chang, W. Hartung, S.H. Kim, J.T. Popielarski, T. Xu, C. Zhang, S. Zhao
FRIB, East Lansing, Michigan, USA

The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) includes a total of 46 cryomodules; 31 cryomodules contain half-wave resonators (HWRs) with pneumatic tuners. Pneumatic tuner control is via solenoid valves connecting the tuner to a helium gas supply manifold and a gas return line. For precise compensation of cavity detuning over a small range, the control voltage for the solenoid valves must be calibrated. Some valves have hysteresis in the gas flow rate as a function of control voltage, such that their response may be nonlinear and not repeatable–this makes the control algorithm challenging. To improve the system performance, a new pneumatic tuner control system was developed which regulates the position of one stepper motor instead of the two solenoid valves.

Poster THPTEV002 [1.325 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV002

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Received ※ 24 June 2021 — Revised ※ 15 December 2021 — Accepted ※ 17 February 2022 — Issue date ※ 16 May 2022

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THPTEV003

LCLS-II Cryomodules Production Experience and Lessons Learned Towards LCLS-II-HE Project

cavity, cryomodule, vacuum, SRF

832

T.T. Arkan, D.J. Bice, J.N. Blowers, C.J. Grimm, B.D. Hartsell, J.A. Kaluzny, M. Martinello, T.H. Nicol, Y.M. Orlov, S. Posen, K.S. Premo, R.P. Stanek
Fermilab, Batavia, Illinois, USA

Funding: DOE
LCLS-II is an upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLS-II linac consists of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF (SRF) continuous wave (CW) cryomodules with high quality factor cavities. Cryomodules were produced at Fermilab and at Jefferson Lab in collaboration with SLAC. Fermilab successfully completed the assembly, testing and delivery of seventeen 1.3 GHz and three 3.9 GHz cryomodules. LCLS-II-HE is a planned upgrade project to LCLS-II. The LCLS-II-HE linac will consist of twenty-three 1.3 GHz cryomodules with high gradient and high quality factor cavities. This paper presents LCLS-II-HE cryomodule production plans, emphasizing the improvements done based on the challenges, mitigations, and lessons learned from LCLS-II.

Poster THPTEV003 [0.620 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV003

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Received ※ 21 June 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 October 2021

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

THPTEV008

Development of a Digital LLRF System for SRF Cavities in RAON Accelerator

cavity, LLRF, SRF, cryomodule

845

H. Jang, D.H. Gil, Y. Jung, H. Kim, Y. Kim, M. Lee
IBS, Daejeon, Republic of Korea

An ion accelerator, RAON is planned and under construction in Daejeon, Korea by Rare Isotope Science Project (RISP) team in Institute of Basic Science (IBS). The purpose of this accelerator is the generation of rare isotope by ISOL (Isotope Separation On-Line) and IF (In-flight Fragmentation) method. To achieve this goal RAON adopted the superconducting cavities at three different frequency (81.25 MHz, 162.5 MHz and 325 MHz) and their RF field will be controlled independently for the acceleration of ions with various A/q. A solid state power amplifier and a low level RF (LLRF) controller pairs are under development to generate and to control the RF for the cavities. Recently the development and evaluation of the digital-based LLRF have been performed. For the operation and test of SRF cavities, self-excited loop (SEL) and generator-driven-resonator (GDR) algorithm is digitally implemented and its test was performed. In this paper the status and test result of RAON LLRF controller will be described.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV008

About •

Received ※ 21 June 2021 — Revised ※ 30 August 2021 — Accepted ※ 26 September 2021 — Issue date ※ 23 November 2021

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