SRF2017 - List of Keywords (vacuum)

Paper	Title	Other Keywords	Page
MOPB011	CEA Cryomodules Design for SARAF Phase 2	ion, cavity, cryomodule, simulation	70
	C. Madec CEA, Gif-sur-Yvette, France N. Bazin, D. Chirpaz-Cerbat, R. Cubizolles CEA/IRFU, Gif-sur-Yvette, France P. Brédy CEA/DSM/IRFU, France R. Bruce, P. Hardy, F. Leseigneur, Th. Plaisant, J. Plouin CEA/DRF/IRFU, Gif-sur-Yvette, France
	CEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5mA beam of either protons from 1.3 MeV to 35 MeV or deuterons from 2.6 MeV to 40.1 MeV. The SCL consists in 4 cryomodules separated by warm diagnostics housing beam diagnostics. The first two identical cryomodules host 6 half-wave resonator (HWR) low beta cavities (β = 0.091), 176 MHz. The last two identical cryomodules are equipped with 7 HWR high-beta cavities (β = 0.181), 176 MHz. The beam is focused through superconducting solenoids located between cavities housing steering coils. A Beam Position Monitor is placed upstream each solenoid. A diagnostic box containing a beam profiler and a vacuum pump will be placed at the end of each cryomodule. The cryomodules and the warm sections are being designed. These studies will be presented in this poster.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB011
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MOPB015	Accelerator Module Repair for the European XFEL Installation	ion, FEL, cavity, linac	82
	E. Vogel, S. Barbanotti, F. Hoffmann, K. Jensch, D. Kostin, L. Lilje, W.-D. Möller, M. Schmökel, H. Weise DESY, Hamburg, Germany S. Berry, O. Napoly CEA/DSM/IRFU, France M. Sienkiewicz, J. Świerbleski, M. Wiencek IFJ-PAN, Kraków, Poland
	Repair actions of different extent have been performed at 61 modules of the 100 accelerating series modules for the European XFEL to qualify them for the tunnel installation. Four modules could not be repaired in time. CEA Saclay managed to perform three major repairs in parallel to the series module integration, the residual repair actions took place at DESY Hamburg. In this paper we will give an overview on the various technical problems which required being fixed before the tunnel installation and on the repair actions performed.
	Poster MOPB015 [9.354 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB015
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MOPB016	Operation of Diamond Superconducting RF Cavities	cavity, ion, operation, GUI	87
	P. Gu, C. Christou, P.J. Marten, S.A. Pande, A.F. Rankin, D. Spink DLS, Oxfordshire, United Kingdom
	The Diamond Light Source storage ring has been in operation using superconducting RF cavities since 2007. Diamond has four superconducting cavity modules with two usually installed at any one time. The four cavities perform differently in many aspects such as reliable operating parameters and time in service, with the longest in continuous service for 7 years without failure and the shortest failing after only 8 months. All Diamond superconducting RF cavities suffered many fast vacuum trips in their early years, but after many years of efforts, the performance of the cavities have now been effectively managed by weekly conditioning, partial warm-up during shut down and cavity voltage level control. We will discuss our experience with superconducting RF cavities and our future plan.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB016
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MOPB020	An Optimal Procedure for Coupler Conditioning for ESS Superconducting Linac	ion, cavity, interface, controls	103
	H. Li Uppsala University, Uppsala, Sweden E. Asensi Conejero, C.G. Maiano, R. Zeng ESS, Lund, Sweden
	An optimal procedure for coupler and cavity conditioning is proposed for the ESS superconducting cavities, which is applicable for different test stands and following installation in the ESS tunnel. A preliminary procedure has been developed and successfully tested at FREIA facility, Uppsala. The preliminary procedure will now be improved by integrating it into LLRF and EPICS control. This will be a joint effort between FREIA and ESS and will be used at the test stands in Lund and on the couplers installed in the tunnel. Developing the conditioning procedures on a common platform offers ESS significant advantages by allowing the procedures to be reused at different sites and by recording data in a consistent format. The details of the procedure, its development and testing will be reported and the future activities will be described.
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MOPB046	LCLS-II Cryomodule Production at JLab	ion, cryomodule, cavity, SRF	163
	R.A. Legg, G. Cheng, E. Daly, G.K. Davis, M.A. Drury, J.F. Fischer, T. Hiatt, N.A. Huque, L.K. King, J.P. Preble, A.V. Reilly, M. Stirbet, K.M. Wilson JLab, Newport News, Virginia, USA
	Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515. The LCLS-II cryomodule construction program leverages the mature XFEL cryomodule design to produce technologically sophisticated cryomodules with a minimum of R&D according to an accelerated manufacturing schedule. Jlab, as one of the partner labs, is producing 18 cryomodules for LCLS-II. To meet the quality and schedule demands of LCLS-II, many upgrades to the JLAB cryomodule assembly infrastructure and techniques have been made. JLab has installed a new cleanroom for string assembly and instituted new protocols to minimize particulate transfer into the cavities during the cryomodule construction process. JLab has also instituted a set of magnetic hygiene protocols to be used during the assembly process to minimize magnetic field impingement on the finished cavity structure. The goal has been to have gradients, both maximum and field emission onset, that do not degrade between the cavity vertical test and final cryomodule qualification, while maximizing the Q0 of each finished cavity. Results from the prototype cryomodule assembly are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB046
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MOPB061	Quality Control of Copper Plating in STF-2 Input Power Couplers	ion, cavity, cryomodule, controls	186
	E. Kako, R. Ueki KEK, Ibaraki, Japan K. Hiroaki, J. Taguchi Nomura Plating Co, Ltd., Osaka, Japan K. Okihira, K. Sennyu MHI, Hiroshima, Japan F. Saito, H. Umezawa Tokyo Denkai Co., Ltd., Tokyo, Japan O. Yushiro Toshiba Electron Tubes & Devices Co., Ltd, Tokyo, Japan
	Purity of thin copper plating using in input power couplers for superconducting cavities is one of important characteristics for considering thermal losses at low temperature. Various samples of thin copper plating on stainless sheets was fabricated by three companies with their own plating techniques. The RRR values of the samples with different thickness of copper plating were compared in the condition before and after heat treatment at 800oC in a brazing furnace. Deterioration of the RRR was observed in all of samples after heat treatment. The results of the RRR measurements and sample analysis of impurities will be reported in this paper.
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MOPB063	Fundamental Studies for the STF-type Power Coupler for ILC	ion, FEL, cavity, SRF	194
	Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto KEK, Ibaraki, Japan M. Irikura, M. Ishibashi, H. Yasutake Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan
	From the view point of mass-production for the power coupler in ILC, the fundamental studies for the STF-type power coupler are under progress by the collaboration between KEK and TETD. At present, there are various rinsing procedures for power coupler in the world-wide laboratories. In this R&D, the main topic is to investigate the various rinsing effects in the copper plating and the ceramic through the high power test. In this paper, the first results will be presented.
	Poster MOPB063 [2.237 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB063
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MOPB064	High Power Test for Plug-compatible STF-type Power Coupler for ILC	ion, electron, simulation, GUI	199
	Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto KEK, Ibaraki, Japan C. Julie, E. Montesinos CERN, Geneva, Switzerland
	From the view point of plug-compatibility for the power coupler in the ILC, recommended by Linear Collider Collaboration in 2013, new STF-type power couplers with 40mm of input port diameter were re-designed, fabricated and successfully high-power-tested. Moreover, from the view point of the cost reduction for the ILC, another type of power couplers with TiN coating-free ceramic were also fabricated and high-power-tested by the collaboration between CERN and KEK. In this paper, the detailed results for the both power couplers will be presented.
	Poster MOPB064 [6.671 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB064
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MOPB069	Design of the High Power Input Coupler for CEPC Main Ring Cavity *	ion, cavity, coupling, cryogenics	216
	T.M. Huang, Q. Ma, J.Y. Zhai IHEP, Beijing, People's Republic of China K.X. Gu Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	The main ring cavities of CEPC project are two-cell el-liptical superconducting cavities operating at 650 MHz in CW mode. Each cavity equips with one high power input coupler and each coupler has to deliver at least 300 kW of CW RF power to the beam. A variable coupling from 10⁵ to 2·10⁶ is required to meet different operation modes. Considering the cavities working with high quali-ty factor up to 2·10¹⁰, the coupler assembled with cavity in class 10 clean room is strongly recommended to protect the cavity from contamination. Also, low cryogenic heat loss is one of the important issues for a large scale CW operation machine. Some of the above requirements should be compromise. Therefore, it's a big challenge to design a high power input coupler fulfilling the above requirements simultaneously. A new coupler that employs 75 Ω coaxial line sections, a planar ceramic disk win-dow, a coaxial to waveguide transition and a coupling adjusting actuator has been designed. In this paper, the RF design, thermal stress analysis and preliminary me-chanical design of the coupler are presented.
	Poster MOPB069 [0.735 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB069
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MOPB072	The Development of the LLRF Control System for the New High Power Test Stand of Couplers	ion, controls, LLRF, FPGA	227
	L. Chen, W. Chang, T.C. Jiang, C.L. Li, Y.M. Li, R.X. Wang, S.H. Zhang IMP/CAS, Lanzhou, People's Republic of China
	RF power conditioning is an effective way to suppress multipacting in fundamental mode power couplers. Room temperature test-stand conditioning is an essential step that can be hardly circumvented before couplers are installed on SC cavities. Based on our original one, a new test-stand has been designed and being assembled at IMP. It can work as a multi-task platform conditioning different couplers, including couplers for HWR010 cavities and HWR015 cavities. It is also featured with the capacity to flexibly change β according to different specifications. A variety of conditioning modes have been incorporated into the LLRF system, including frequency sweeping mode, amplitude sweeping mode, arbitrary-duty-cycle mode and triangle-wave mode. In addition, smartly-conditioning has been achieved because of the accomplishment of smart interlocks and automatic reset in the system.
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MOPB109	LCLS-II Cryomodule Transport System Testing	ion, cavity, cryomodule, ISOL	317
	N.A. Huque, E. Daly JLab, Newport News, Virginia, USA M.W. McGee Fermilab, Batavia, Illinois, USA
	The Cryomodules (CM) for the Linear Coherent Light Source II (LCLS-II) will be shipped to SLAC (Menlo Park, California) from JLab (Newport News, Virginia) and FNAL (Batavia, Illinois). A transportation system has been designed and built to safely transport the CMs over the road. It uses an array of helical isolator springs to attenuate shocks on the CM to below 1.5g in all directions. The system rides on trailers equipped with Air-Ride suspension, which attenuates vibration loads. The prototype LCLS-II CM (pCM) was driven 750 miles to test the transport system; shock loggers recorded the shock attenuation on the pCM and vacuum gauges were used to detect any compromises in beamline vacuum. Alignment measurements were taken before and after the trip to check whether cavity positions had shifted beyond the ± 0.2mm spec. Passband frequencies and cavity gradients were measured at 2K at the Cryomodule Test Facility (CMTF) at JLab to identify any degradation of CM performance after transportation. The transport system was found to have safely carried the CM and is cleared to begin shipments from JLab and FNAL to SLAC.
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MOPB111	European XFEL Linac RF System Conditioning and Operating Test	ion, cavity, FEL, MMI	328
	D. Kostin, J. Branlard, A. Gössel, O. Hensler, M. Omet, D. Reschke, A.A. Sulimov, N. Walker, M. Wiencek DESY, Hamburg, Germany
	96 accelerating modules with 768 TESLA/European-XFEL type superconducting cavities were installed in the European XFEL LINAC tunnel (XTL) in the fall 2016. Warm conditioning of the RF system - High/Low Level RF System and main input couplers - begun even before finishing the accelerator installation works. All modules were conditioned and tested prior to the installation in the tunnel in the AMTF test stand at DESY. Nevertheless, due to some repair activities on warm input coupler parts, warm conditioning was needed on a few modules/couplers. Cooling down to 2K begun in December 2016 and was finished in January 2017. Since then cold conditioning and tests are running. Several cavities in a few modules did show the multipacting (MP) effects, mostly because a cavity vacuum was filled with a dry nitrogen for before mentioned repairs on couplers in some modules. Said MP effects were seen in AMTF as well. All MP effects were successfully conditioned until now. The warm/cold RF system conditioning and its results/experiences/limits are described and discussed.
	Poster MOPB111 [1.267 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB111
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TUXBA01	Low Temperature Doping of Niobium Cavities: What is Really Going on?	ion, cavity, niobium, background	353
	P.N. Koufalis, M. Liepe, J.T. Maniscalco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Initial work, first at Fermilab and subsequently at Cornell, has shown that low temperature heat treatments (120 - 160 C) in a low pressure atmosphere can lead to a 'Q-rise' and high quality factors similar to that of cavities nitrogen-doped at high temperatures (~800 C). It was suggested that the low-temperature baking effect is a result of nitrogen doping or 'infusion'. We conducted a systematic study of this effect, using both RF measurements of cavities treated at different doping temperatures as well as detailed SIMS analysis of the surface layer. We match RF performance and extracted material parameters (especially electron mean free path) to the measured doping concentration profiles. We conclusively show that the low-temperature baking is drastically lowering the mean free path in the penetration layer, and that this is not the result of nitrogen doping or infusion. Instead, other interstitial impurities (specifically oxygen and carbon) are diffused into the surface in the low temperature heat treatment and are the source of lowering of the mean free path and, thus, of the observed Q-rise.
	Slides TUXBA01 [4.153 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUXBA01
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TUPB048	INFN- LASA Medium Beta Cavity Prototypes for ESS Linac	cavity, ion, controls, niobium	494
	D. Sertore, M. Bertucci, A. Bignami, A. Bosotti, J.F. Chen, P. Michelato, L. Monaco, R. Paparella INFN/LASA, Segrate (MI), Italy C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy S. Pirani ESS, Lund, Sweden
	INFN-LASA, in the framework of INFN contribution to the European Spallation Source, has developed, produced and tested 704.4 MHz Medium Beta (β = 0.67) cavities. Mode separation and avoidance of HOM excitation by machine line frequencies have driven the cavity design. The production at the industry, also in view of the INFN in-kind contribution of series cavities, has been done "build-to-print" and we have implemented our own quality control process, based on our XFEL experience, from raw material to cavity ready for test. The cavities have been then cold tested in our upgraded Vertical Test Facility. In this paper, we report on our experience on the different phases of the cavity production and test processes.
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THYA05	Developments and Progress with ESS Elliptical Cryomodules at CEA-Saclay and IPN-orsay	ion, cavity, cryomodule, cryogenics	729
	F. Peauger, C. Arcambal, F. Ardellier, S. Berry, P. Bosland, A. Bouygues, E. Cenni, J.-P. Charrier, G. Devanz, F. Éozénou, A. Gaget, D. Gevaert, A. Gomes, T. Hamelin, X. Hanus, P. Hardy, V.M. Hennion, T.J. Joannem, C. Marchand, O. Piquet, J.P. Poupeau, B. Renard, P. Sahuquet, T. Trublet CEA/DRF/IRFU, Gif-sur-Yvette, France C. Darve ESS, Lund, Sweden G. Olivier IPN, Orsay, France
	CEA Saclay in collaboration with IPN Orsay is in charge of the ESS elliptical cavities cryomodule design, prototyping and series production. Two cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. The main cryomodule design features are first reminded. We present the cavities and couplers test results and the achieved assembly sequences of the first medium beta cavities cryomodule demonstrator M-ECCTD. The progress on the preparation of the CEA cryomodule test station is given. The procurement status and development plan of the second high beta demonstrator H-ECCTD are also reported. Finally we give the components procurement progress and the assembly strategy of the 30 series cry-omodules to be integrated at CEA before delivery to ESS at Lund.
	Slides THYA05 [11.226 MB]
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THPB004	Impact of the Duration of Low Temperature Doping on Superconducting Cavity Performance	cavity, ion, niobium, superconducting-cavity	750
	P.N. Koufalis, F. Furuta, J.J. Kaufman, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Low temperature treatments of superconducting cavities in a low pressure ambient atmosphere have been shown to introduce a 'Q-rise' up to moderate surface fields and an overall increase in quality factor. However, the effect of varying the doping time at a fixed temperature on cavity performance has not been systematically examined. We present results of such an investigation for cavities prepared at 120 and 160 C in a continuously flowing low pressure atmosphere for various amounts of time. We show that the introduction of impurities to the RF penetration layer can improve cavity performance and investigate the relationship between electron mean free path and the temperature-dependent component of the surface resistance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB004
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THPB038	Local Magnetometer: First Critical Field Measurement of Multilayer Superconductors	ion, experiment, cavity, ion-effects	830
	M. Aburas, C.Z. Antoine CEA/IRFU, Gif-sur-Yvette, France A. Four CEA/DRF/IRFU, Gif-sur-Yvette, France
	S-I-S (Superconductor-Insulator-Superconductor) nanometric superconducting multilayers have been proposed by Gurevich* to increase the maximum accelerating field of Nb RF cavities. This enhancement of HC1 may be done by coating Nb with thin layers of thickness less than the penetration depth. Therefore, it is necessary to find a particular tool, which allows us measuring HC1 directly. In fact, DC magnetometers (e.g. magnetometer SQUID) are largely used for magnetic measurements but these last are strongly influenced by orientation, edge and shape effects, especially in the case of superconductor thin films. For that reason, we developed at Saclay facilities a specific local magnetic measurement of first critical field HC1. The principle of our local magnetometer is based on the third-harmonic voltage method purposed by Claassen, which is very useful to estimate the first critical field HC1 of superconducting multilayer samples with nondestructive and contactless, but more importantly, without demagnetization effects. This paper will present the evolution of the magnetometer to overcome all types of difficulties. A. Gurevich, Appl. Phys. Lett. 88, 012511 (2006) J. H. Claassen et al., Review of Scientific Instruments 62, 996 (1991) * M. Aurino et al., Journal of Applied Physics 98, 123901 (2005)
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THPB066	Introducing the Vertical High-temperature UHV Furnace of the S-DALINAC for Future Cavity Material Studies	ion, niobium, cavity, linac	891
	R. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla TU Darmstadt, Darmstadt, Germany F. Hug IKP, Mainz, Germany
	Funding: Work supported by the Federal Ministry of Education and Research through grant No. 05H15RDRBA. Since 2005 the Institute for Nuclear Physics in Darmstadt operates a high temperature UHV furnace for temperatures of up to 1750°C. It has been used several times for hydrogen bake-out of the SRF cavities of the S-DALINAC with proven success. In 2013, studies at FNAL have shown that cavities treated with nitrogen reached an up to four times higher q-factor. The cavities are exposed to N2 at 850°C at the end of the H2 bake-out. A thin layer of normalconducting hexagonal niobium nitride (NbN) forms at the surface which is removed by electropolishing while the higher quality factors are attributed to the N2 diffusion into the bulk Nb. At temperatures from 1300°C to 1700°C a thin layer of the superconducting cubic phase of NbN can be observed, e.g. delta-phase NbN, which has a higher critical field and higher critical temperature and thus is very intereresting for applications for SRF cavities*. The UHV furnace has been prepared for future treatments of Nb samples and cavities in a N2 atmosphere at high temperatures for research on cubic NbN. The material properties of the samples will be analyzed at the ATFT group at the Department for Material Sciences of TU Darmstadt. Grasselino et al., Superconducting Science and Technology, 2013 Hennessey et al., Oxidation of Metals, 1992 *Martienssen et al., Springer Handbook of Condensed Matter and Materials Data, 2005
	Poster THPB066 [3.024 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB066
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FRXAA01	Production Status of Superconducting Cryomodules for the Facility for Rare Isotope Beams	cryomodule, ion, cavity, linac	928
	C. Compton, H. Ao, J. Asciutto, B. Bird, W. Hartung, S.J. Miller, J.T. Popielarski, L. Popielarski, M.A. Reaume, K. Saito, M. Shuptar, S. Stark, B.P. Tousignant, T. Xu FRIB, East Lansing, USA
	The Facility for Rare Isotope Beams (FRIB) is an SRF accelerator project in full production at Michigan State University (MSU). With the civil construction nearly complete, the installation of accelerator equipment into the tunnel has taken center stage. A total of 46 superconducting cryomodules are needed for the FRIB linac to reach 200 MeV per nucleon. The linac consist of four cavity types (β = 0.041, 0.085, 0.29, and 0.53) and 6 different cryomodule designs. Cryomodule assembly is done in 5 parallel bays, each one compatible with every cryomodule type. Completed cryomodules undergo full system testing in bunkers before being accepted and delivered to the tunnel. The current status of the cryomodule assembly effort will be presented, including lessons learned and overall experience to date.
	Slides FRXAA01 [9.990 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-FRXAA01
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Paper

Title

Other Keywords

Page

MOPB011

CEA Cryomodules Design for SARAF Phase 2

ion, cavity, cryomodule, simulation

70

C. Madec
CEA, Gif-sur-Yvette, France
N. Bazin, D. Chirpaz-Cerbat, R. Cubizolles
CEA/IRFU, Gif-sur-Yvette, France
P. Brédy
CEA/DSM/IRFU, France
R. Bruce, P. Hardy, F. Leseigneur, Th. Plaisant, J. Plouin
CEA/DRF/IRFU, Gif-sur-Yvette, France

CEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5mA beam of either protons from 1.3 MeV to 35 MeV or deuterons from 2.6 MeV to 40.1 MeV. The SCL consists in 4 cryomodules separated by warm diagnostics housing beam diagnostics. The first two identical cryomodules host 6 half-wave resonator (HWR) low beta cavities (β = 0.091), 176 MHz. The last two identical cryomodules are equipped with 7 HWR high-beta cavities (β = 0.181), 176 MHz. The beam is focused through superconducting solenoids located between cavities housing steering coils. A Beam Position Monitor is placed upstream each solenoid. A diagnostic box containing a beam profiler and a vacuum pump will be placed at the end of each cryomodule. The cryomodules and the warm sections are being designed. These studies will be presented in this poster.

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MOPB015

Accelerator Module Repair for the European XFEL Installation

ion, FEL, cavity, linac

82

E. Vogel, S. Barbanotti, F. Hoffmann, K. Jensch, D. Kostin, L. Lilje, W.-D. Möller, M. Schmökel, H. Weise
DESY, Hamburg, Germany
S. Berry, O. Napoly
CEA/DSM/IRFU, France
M. Sienkiewicz, J. Świerbleski, M. Wiencek
IFJ-PAN, Kraków, Poland

Repair actions of different extent have been performed at 61 modules of the 100 accelerating series modules for the European XFEL to qualify them for the tunnel installation. Four modules could not be repaired in time. CEA Saclay managed to perform three major repairs in parallel to the series module integration, the residual repair actions took place at DESY Hamburg. In this paper we will give an overview on the various technical problems which required being fixed before the tunnel installation and on the repair actions performed.

Poster MOPB015 [9.354 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB015

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MOPB016

Operation of Diamond Superconducting RF Cavities

cavity, ion, operation, GUI

87

P. Gu, C. Christou, P.J. Marten, S.A. Pande, A.F. Rankin, D. Spink
DLS, Oxfordshire, United Kingdom

The Diamond Light Source storage ring has been in operation using superconducting RF cavities since 2007. Diamond has four superconducting cavity modules with two usually installed at any one time. The four cavities perform differently in many aspects such as reliable operating parameters and time in service, with the longest in continuous service for 7 years without failure and the shortest failing after only 8 months. All Diamond superconducting RF cavities suffered many fast vacuum trips in their early years, but after many years of efforts, the performance of the cavities have now been effectively managed by weekly conditioning, partial warm-up during shut down and cavity voltage level control. We will discuss our experience with superconducting RF cavities and our future plan.

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MOPB020

An Optimal Procedure for Coupler Conditioning for ESS Superconducting Linac

ion, cavity, interface, controls

103

H. Li
Uppsala University, Uppsala, Sweden
E. Asensi Conejero, C.G. Maiano, R. Zeng
ESS, Lund, Sweden

An optimal procedure for coupler and cavity conditioning is proposed for the ESS superconducting cavities, which is applicable for different test stands and following installation in the ESS tunnel. A preliminary procedure has been developed and successfully tested at FREIA facility, Uppsala. The preliminary procedure will now be improved by integrating it into LLRF and EPICS control. This will be a joint effort between FREIA and ESS and will be used at the test stands in Lund and on the couplers installed in the tunnel. Developing the conditioning procedures on a common platform offers ESS significant advantages by allowing the procedures to be reused at different sites and by recording data in a consistent format. The details of the procedure, its development and testing will be reported and the future activities will be described.

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MOPB046

LCLS-II Cryomodule Production at JLab

ion, cryomodule, cavity, SRF

163

R.A. Legg, G. Cheng, E. Daly, G.K. Davis, M.A. Drury, J.F. Fischer, T. Hiatt, N.A. Huque, L.K. King, J.P. Preble, A.V. Reilly, M. Stirbet, K.M. Wilson
JLab, Newport News, Virginia, USA

Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515.
The LCLS-II cryomodule construction program leverages the mature XFEL cryomodule design to produce technologically sophisticated cryomodules with a minimum of R&D according to an accelerated manufacturing schedule. Jlab, as one of the partner labs, is producing 18 cryomodules for LCLS-II. To meet the quality and schedule demands of LCLS-II, many upgrades to the JLAB cryomodule assembly infrastructure and techniques have been made. JLab has installed a new cleanroom for string assembly and instituted new protocols to minimize particulate transfer into the cavities during the cryomodule construction process. JLab has also instituted a set of magnetic hygiene protocols to be used during the assembly process to minimize magnetic field impingement on the finished cavity structure. The goal has been to have gradients, both maximum and field emission onset, that do not degrade between the cavity vertical test and final cryomodule qualification, while maximizing the Q0 of each finished cavity. Results from the prototype cryomodule assembly are presented.

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MOPB061

Quality Control of Copper Plating in STF-2 Input Power Couplers

ion, cavity, cryomodule, controls

186

E. Kako, R. Ueki
KEK, Ibaraki, Japan
K. Hiroaki, J. Taguchi
Nomura Plating Co, Ltd., Osaka, Japan
K. Okihira, K. Sennyu
MHI, Hiroshima, Japan
F. Saito, H. Umezawa
Tokyo Denkai Co., Ltd., Tokyo, Japan
O. Yushiro
Toshiba Electron Tubes & Devices Co., Ltd, Tokyo, Japan

Purity of thin copper plating using in input power couplers for superconducting cavities is one of important characteristics for considering thermal losses at low temperature. Various samples of thin copper plating on stainless sheets was fabricated by three companies with their own plating techniques. The RRR values of the samples with different thickness of copper plating were compared in the condition before and after heat treatment at 800oC in a brazing furnace. Deterioration of the RRR was observed in all of samples after heat treatment. The results of the RRR measurements and sample analysis of impurities will be reported in this paper.

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MOPB063

Fundamental Studies for the STF-type Power Coupler for ILC

ion, FEL, cavity, SRF

194

Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto
KEK, Ibaraki, Japan
M. Irikura, M. Ishibashi, H. Yasutake
Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan

From the view point of mass-production for the power coupler in ILC, the fundamental studies for the STF-type power coupler are under progress by the collaboration between KEK and TETD. At present, there are various rinsing procedures for power coupler in the world-wide laboratories. In this R&D, the main topic is to investigate the various rinsing effects in the copper plating and the ceramic through the high power test. In this paper, the first results will be presented.

Poster MOPB063 [2.237 MB]

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MOPB064

High Power Test for Plug-compatible STF-type Power Coupler for ILC

ion, electron, simulation, GUI

199

Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto
KEK, Ibaraki, Japan
C. Julie, E. Montesinos
CERN, Geneva, Switzerland

From the view point of plug-compatibility for the power coupler in the ILC, recommended by Linear Collider Collaboration in 2013, new STF-type power couplers with 40mm of input port diameter were re-designed, fabricated and successfully high-power-tested. Moreover, from the view point of the cost reduction for the ILC, another type of power couplers with TiN coating-free ceramic were also fabricated and high-power-tested by the collaboration between CERN and KEK. In this paper, the detailed results for the both power couplers will be presented.

Poster MOPB064 [6.671 MB]

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MOPB069

Design of the High Power Input Coupler for CEPC Main Ring Cavity *

ion, cavity, coupling, cryogenics

216

T.M. Huang, Q. Ma, J.Y. Zhai
IHEP, Beijing, People's Republic of China
K.X. Gu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

The main ring cavities of CEPC project are two-cell el-liptical superconducting cavities operating at 650 MHz in CW mode. Each cavity equips with one high power input coupler and each coupler has to deliver at least 300 kW of CW RF power to the beam. A variable coupling from 10⁵ to 2·10⁶ is required to meet different operation modes. Considering the cavities working with high quali-ty factor up to 2·10¹⁰, the coupler assembled with cavity in class 10 clean room is strongly recommended to protect the cavity from contamination. Also, low cryogenic heat loss is one of the important issues for a large scale CW operation machine. Some of the above requirements should be compromise. Therefore, it's a big challenge to design a high power input coupler fulfilling the above requirements simultaneously. A new coupler that employs 75 Ω coaxial line sections, a planar ceramic disk win-dow, a coaxial to waveguide transition and a coupling adjusting actuator has been designed. In this paper, the RF design, thermal stress analysis and preliminary me-chanical design of the coupler are presented.

Poster MOPB069 [0.735 MB]

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MOPB072

The Development of the LLRF Control System for the New High Power Test Stand of Couplers

ion, controls, LLRF, FPGA

227

L. Chen, W. Chang, T.C. Jiang, C.L. Li, Y.M. Li, R.X. Wang, S.H. Zhang
IMP/CAS, Lanzhou, People's Republic of China

RF power conditioning is an effective way to suppress multipacting in fundamental mode power couplers. Room temperature test-stand conditioning is an essential step that can be hardly circumvented before couplers are installed on SC cavities. Based on our original one, a new test-stand has been designed and being assembled at IMP. It can work as a multi-task platform conditioning different couplers, including couplers for HWR010 cavities and HWR015 cavities. It is also featured with the capacity to flexibly change β according to different specifications. A variety of conditioning modes have been incorporated into the LLRF system, including frequency sweeping mode, amplitude sweeping mode, arbitrary-duty-cycle mode and triangle-wave mode. In addition, smartly-conditioning has been achieved because of the accomplishment of smart interlocks and automatic reset in the system.

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MOPB109

LCLS-II Cryomodule Transport System Testing

ion, cavity, cryomodule, ISOL

317

N.A. Huque, E. Daly
JLab, Newport News, Virginia, USA
M.W. McGee
Fermilab, Batavia, Illinois, USA

The Cryomodules (CM) for the Linear Coherent Light Source II (LCLS-II) will be shipped to SLAC (Menlo Park, California) from JLab (Newport News, Virginia) and FNAL (Batavia, Illinois). A transportation system has been designed and built to safely transport the CMs over the road. It uses an array of helical isolator springs to attenuate shocks on the CM to below 1.5g in all directions. The system rides on trailers equipped with Air-Ride suspension, which attenuates vibration loads. The prototype LCLS-II CM (pCM) was driven 750 miles to test the transport system; shock loggers recorded the shock attenuation on the pCM and vacuum gauges were used to detect any compromises in beamline vacuum. Alignment measurements were taken before and after the trip to check whether cavity positions had shifted beyond the ± 0.2mm spec. Passband frequencies and cavity gradients were measured at 2K at the Cryomodule Test Facility (CMTF) at JLab to identify any degradation of CM performance after transportation. The transport system was found to have safely carried the CM and is cleared to begin shipments from JLab and FNAL to SLAC.

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MOPB111

European XFEL Linac RF System Conditioning and Operating Test

ion, cavity, FEL, MMI

328

D. Kostin, J. Branlard, A. Gössel, O. Hensler, M. Omet, D. Reschke, A.A. Sulimov, N. Walker, M. Wiencek
DESY, Hamburg, Germany

96 accelerating modules with 768 TESLA/European-XFEL type superconducting cavities were installed in the European XFEL LINAC tunnel (XTL) in the fall 2016. Warm conditioning of the RF system - High/Low Level RF System and main input couplers - begun even before finishing the accelerator installation works. All modules were conditioned and tested prior to the installation in the tunnel in the AMTF test stand at DESY. Nevertheless, due to some repair activities on warm input coupler parts, warm conditioning was needed on a few modules/couplers. Cooling down to 2K begun in December 2016 and was finished in January 2017. Since then cold conditioning and tests are running. Several cavities in a few modules did show the multipacting (MP) effects, mostly because a cavity vacuum was filled with a dry nitrogen for before mentioned repairs on couplers in some modules. Said MP effects were seen in AMTF as well. All MP effects were successfully conditioned until now. The warm/cold RF system conditioning and its results/experiences/limits are described and discussed.

Poster MOPB111 [1.267 MB]

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TUXBA01

Low Temperature Doping of Niobium Cavities: What is Really Going on?

ion, cavity, niobium, background

353

P.N. Koufalis, M. Liepe, J.T. Maniscalco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Initial work, first at Fermilab and subsequently at Cornell, has shown that low temperature heat treatments (120 - 160 C) in a low pressure atmosphere can lead to a 'Q-rise' and high quality factors similar to that of cavities nitrogen-doped at high temperatures (~800 C). It was suggested that the low-temperature baking effect is a result of nitrogen doping or 'infusion'. We conducted a systematic study of this effect, using both RF measurements of cavities treated at different doping temperatures as well as detailed SIMS analysis of the surface layer. We match RF performance and extracted material parameters (especially electron mean free path) to the measured doping concentration profiles. We conclusively show that the low-temperature baking is drastically lowering the mean free path in the penetration layer, and that this is not the result of nitrogen doping or infusion. Instead, other interstitial impurities (specifically oxygen and carbon) are diffused into the surface in the low temperature heat treatment and are the source of lowering of the mean free path and, thus, of the observed Q-rise.

Slides TUXBA01 [4.153 MB]

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TUPB048

INFN- LASA Medium Beta Cavity Prototypes for ESS Linac

cavity, ion, controls, niobium

494

D. Sertore, M. Bertucci, A. Bignami, A. Bosotti, J.F. Chen, P. Michelato, L. Monaco, R. Paparella
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
S. Pirani
ESS, Lund, Sweden

INFN-LASA, in the framework of INFN contribution to the European Spallation Source, has developed, produced and tested 704.4 MHz Medium Beta (β = 0.67) cavities. Mode separation and avoidance of HOM excitation by machine line frequencies have driven the cavity design. The production at the industry, also in view of the INFN in-kind contribution of series cavities, has been done "build-to-print" and we have implemented our own quality control process, based on our XFEL experience, from raw material to cavity ready for test. The cavities have been then cold tested in our upgraded Vertical Test Facility. In this paper, we report on our experience on the different phases of the cavity production and test processes.

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THYA05

Developments and Progress with ESS Elliptical Cryomodules at CEA-Saclay and IPN-orsay

ion, cavity, cryomodule, cryogenics

729

F. Peauger, C. Arcambal, F. Ardellier, S. Berry, P. Bosland, A. Bouygues, E. Cenni, J.-P. Charrier, G. Devanz, F. Éozénou, A. Gaget, D. Gevaert, A. Gomes, T. Hamelin, X. Hanus, P. Hardy, V.M. Hennion, T.J. Joannem, C. Marchand, O. Piquet, J.P. Poupeau, B. Renard, P. Sahuquet, T. Trublet
CEA/DRF/IRFU, Gif-sur-Yvette, France
C. Darve
ESS, Lund, Sweden
G. Olivier
IPN, Orsay, France

CEA Saclay in collaboration with IPN Orsay is in charge of the ESS elliptical cavities cryomodule design, prototyping and series production. Two cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. The main cryomodule design features are first reminded. We present the cavities and couplers test results and the achieved assembly sequences of the first medium beta cavities cryomodule demonstrator M-ECCTD. The progress on the preparation of the CEA cryomodule test station is given. The procurement status and development plan of the second high beta demonstrator H-ECCTD are also reported. Finally we give the components procurement progress and the assembly strategy of the 30 series cry-omodules to be integrated at CEA before delivery to ESS at Lund.

Slides THYA05 [11.226 MB]

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THPB004

Impact of the Duration of Low Temperature Doping on Superconducting Cavity Performance

cavity, ion, niobium, superconducting-cavity

750

P.N. Koufalis, F. Furuta, J.J. Kaufman, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Low temperature treatments of superconducting cavities in a low pressure ambient atmosphere have been shown to introduce a 'Q-rise' up to moderate surface fields and an overall increase in quality factor. However, the effect of varying the doping time at a fixed temperature on cavity performance has not been systematically examined. We present results of such an investigation for cavities prepared at 120 and 160 C in a continuously flowing low pressure atmosphere for various amounts of time. We show that the introduction of impurities to the RF penetration layer can improve cavity performance and investigate the relationship between electron mean free path and the temperature-dependent component of the surface resistance.

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THPB038

Local Magnetometer: First Critical Field Measurement of Multilayer Superconductors

ion, experiment, cavity, ion-effects

830

M. Aburas, C.Z. Antoine
CEA/IRFU, Gif-sur-Yvette, France
A. Four
CEA/DRF/IRFU, Gif-sur-Yvette, France

S-I-S (Superconductor-Insulator-Superconductor) nanometric superconducting multilayers have been proposed by Gurevich* to increase the maximum accelerating field of Nb RF cavities. This enhancement of HC1 may be done by coating Nb with thin layers of thickness less than the penetration depth. Therefore, it is necessary to find a particular tool, which allows us measuring HC1 directly. In fact, DC magnetometers (e.g. magnetometer SQUID) are largely used for magnetic measurements but these last are strongly influenced by orientation, edge and shape effects, especially in the case of superconductor thin films. For that reason, we developed at Saclay facilities a specific local magnetic measurement of first critical field HC1. The principle of our local magnetometer is based on the third-harmonic voltage method purposed by Claassen**, which is very useful to estimate the first critical field HC1 of superconducting multilayer samples with nondestructive and contactless, but more importantly, without demagnetization effects***. This paper will present the evolution of the magnetometer to overcome all types of difficulties.
* A. Gurevich, Appl. Phys. Lett. 88, 012511 (2006)
** J. H. Claassen et al., Review of Scientific Instruments 62, 996 (1991)
*** M. Aurino et al., Journal of Applied Physics 98, 123901 (2005)

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THPB066

Introducing the Vertical High-temperature UHV Furnace of the S-DALINAC for Future Cavity Material Studies

ion, niobium, cavity, linac

891

R. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: Work supported by the Federal Ministry of Education and Research through grant No. 05H15RDRBA.
Since 2005 the Institute for Nuclear Physics in Darmstadt operates a high temperature UHV furnace for temperatures of up to 1750°C. It has been used several times for hydrogen bake-out of the SRF cavities of the S-DALINAC with proven success. In 2013, studies at FNAL have shown that cavities treated with nitrogen reached an up to four times higher q-factor*. The cavities are exposed to N2 at 850°C at the end of the H2 bake-out. A thin layer of normalconducting hexagonal niobium nitride (NbN) forms at the surface which is removed by electropolishing while the higher quality factors are attributed to the N2 diffusion into the bulk Nb. At temperatures from 1300°C to 1700°C a thin layer of the superconducting cubic phase of NbN can be observed, e.g. delta-phase NbN**, which has a higher critical field and higher critical temperature and thus is very intereresting for applications for SRF cavities***. The UHV furnace has been prepared for future treatments of Nb samples and cavities in a N2 atmosphere at high temperatures for research on cubic NbN. The material properties of the samples will be analyzed at the ATFT group at the Department for Material Sciences of TU Darmstadt.
*Grasselino et al., Superconducting Science and Technology, 2013
**Hennessey et al., Oxidation of Metals, 1992
***Martienssen et al., Springer Handbook of Condensed Matter and Materials Data, 2005

Poster THPB066 [3.024 MB]

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FRXAA01

Production Status of Superconducting Cryomodules for the Facility for Rare Isotope Beams

cryomodule, ion, cavity, linac

928

C. Compton, H. Ao, J. Asciutto, B. Bird, W. Hartung, S.J. Miller, J.T. Popielarski, L. Popielarski, M.A. Reaume, K. Saito, M. Shuptar, S. Stark, B.P. Tousignant, T. Xu
FRIB, East Lansing, USA

The Facility for Rare Isotope Beams (FRIB) is an SRF accelerator project in full production at Michigan State University (MSU). With the civil construction nearly complete, the installation of accelerator equipment into the tunnel has taken center stage. A total of 46 superconducting cryomodules are needed for the FRIB linac to reach 200 MeV per nucleon. The linac consist of four cavity types (β = 0.041, 0.085, 0.29, and 0.53) and 6 different cryomodule designs. Cryomodule assembly is done in 5 parallel bays, each one compatible with every cryomodule type. Completed cryomodules undergo full system testing in bunkers before being accepted and delivered to the tunnel. The current status of the cryomodule assembly effort will be presented, including lessons learned and overall experience to date.

Slides FRXAA01 [9.990 MB]

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