SRF2017 - List of Keywords (controls)

Paper	Title	Other Keywords	Page
MOPB020	An Optimal Procedure for Coupler Conditioning for ESS Superconducting Linac	ion, cavity, vacuum, interface	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB020
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MOPB044	Magnetic Hygiene Control on LCLS-II Cryomodules Fabricated at JLab	ion, cavity, cryomodule, shielding	153
	G. Cheng, E. Daly, G.K. Davis, J.F. Fischer, N.A. Huque, R.A. Legg, H. Park, K.M. Wilson, L. Zhao JLab, Newport News, Virginia, USA
	Funding: U.S. DOE Contract No. DE-AC05-06OR23177 and the LCLS-II project. Jefferson Lab (JLab) is in collaboration with Fermi Na-tional Accelerator Laboratory (Fermilab) to build 18 cryomodules to install at the SLAC National Accelerator Laboratory's tunnel as part of the Linac Coherent Light Source upgrade project (LCLS-II). Each LCLS-II cry-omodule hosts 8 superconducting niobium cavities that adopt the nitrogen doping technique, which aims to en-hance the cavity quality factor Qo to reduce the consumption of liquid helium used to cool down the cavities. It is known that the Qo of niobium cavities is affected by cavity surface magnetic field. Traditionally, magnetic shields made of high magnetic permeability mu-metals are employed as a passive shielding of the ambient magnetic fluxes. During the LCLS-II cryomodule development, magnetic hygiene control that includes magnetic shielding and demagnetization of parts and the whole-machine is implemented. JLab and Fermilab worked closely on developing magnetic hygiene control procedures, identifying relevant tools, investigating causes of magnetization, magnetic field monitoring, etc. This paper focuses on JLab's experiences with LCLS-II cryomodule magnetic hygiene control during its fabrication. Authored by Jefferson Science Associates, LLC. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for Government purposes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB044
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MOPB061	Quality Control of Copper Plating in STF-2 Input Power Couplers	ion, cavity, vacuum, cryomodule	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB061
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MOPB072	The Development of the LLRF Control System for the New High Power Test Stand of Couplers	ion, vacuum, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB072
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MOPB075	Quench Protection in Digital Power Supplies for Superconducting Magnets in ADS	ion, power-supply, superconducting-magnet, solenoid	233
	J. Zhao, S. Zhang, Z.Z. Zhou IMP/CAS, Lanzhou, People's Republic of China
	The front-end demo superconducting Linac for Chinese ADS (Accelerator Driven Sub-critical System) project is under construction at institute of modern physics(IMP) in Lanzhou. It will demonstrate the key technologies and the feasibility of a high power beam for the future national project " the Chinese Initiative Accelerator Driven Subcritical System(CIADS)". In this system, there are about 60 superconducting magnets, including solenoids, vertical correction and horizontal correction. They are utilized to focus and correct the proton beam. Quench protection of the superconducting magnets is key to reliability of the facility. A full digital power supply is developed and employed as excitation source for all of these superconducting magnets. In this paper, an FPGA-based quench protection plan implemented in the power supplies is mainly described. The commissioning results show that it is feasible.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB075
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MOPB076	Analysis of the Production, Installation and Commissioning of the European-XFEL Frequency Tuners	ion, cavity, FEL, cryomodule	235
	R. Paparella, A. Bosotti, D. Sertore INFN/LASA, Segrate (MI), Italy C. Albrecht, S. Barbanotti, A. Bellandi, J. Branlard, K. Jensch, L. Lilje DESY, Hamburg, Germany C. Cloué, T. Trublet CEA/IRFU, Gif-sur-Yvette, France C. Madec CEA, Gif-sur-Yvette, France
	In the European-XFEL superconducting linac, mechanical frequency tuners equipped with stepper motors and piezoelectric actuators provide cold tuning of each of the 768 1.3 GHz cavities. More than 820 complete tuning systems were fabricated and pre-assembled in industry, tested at several stages before and after assembly and successfully commissioned during cryo-module cold tests at AMTF (DESY). Quality control strategy adopted to preserve the well-assessed tuner reliability through such a large-scale industrial production is critically reviewed and the lessons learned are presented in this paper. The statistical analysis of the large set of data acquired up to the recent commissioning of the entire linac is then summarized.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB076
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MOPB086	First Results of the IFMIF/EVEDA-SaTHoRI Tests	ion, cavity, SRF, cryomodule	262
	O. Piquet, N. Bazin, P. Carbonnier, J.K. Chambrillon, M. Desmons, G. Devanz, H. Jenhani, C. Servouin CEA/DRF/IRFU, Gif-sur-Yvette, France P. Cara Fusion for Energy, Garching, Germany J.F. Denis, L. Maurice, J. Relland CEA/IRFU, Gif-sur-Yvette, France F. Éozénou, P. Hardy, E. Jacques, Y. Lussignol, P. Sahuquet CEA/DSM/IRFU, France D. Gex, A. Jokinen, G. Phillips F4E, Germany I. Moya, P. Méndez CIEMAT, Madrid, Spain
	The SaTHoRI test stand (Satellite de Tests Horizontal des Résonateurs IFMIF) aims to characterize a jacketed and fully dressed cavity with its coupler and tuner. A dedicated test cryostat has been manufactured and is connected to an existing horizontal test cryostat which provides the cryogenic coolant. A RF source ' provided by the IFMIF collaboration, one of the four RF sources which will be used for the cryomodule at Rokkasho ' has been installed and commissioned at CEA. This paper describes the test stand and presents the first results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB086
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TUPB028	Improvement of Magnetic Condition for KEK-STF Vertical Test Facility Toward High-Q Study	ion, cavity, solenoid, SRF	444
	K. Umemori, T. Dohmae, E. Kako, T. Konomi, T. Kubo, M. Masuzawa, G.-T. Park, A. Terashima, K. Tsuchiya, R. Ueki KEK, Ibaraki, Japan T. Okada Sokendai, Ibaraki, Japan
	Improvement of unloaded Q-values of SRF cavities are important to reduce surface loss of cavity and heat loads of He refrigerators. R&D activities have been developed worldwide. We also started work toward high-Q, but soon realized that magnetic condition of KEK-STF vertical test facility was not good enough to carry out high-Q measurements. First, magnetized components were searched. Shafts to move variable coupler were found to be most magnetized one and exceed more than 1 Gauss. Magnetized components were exchanged to non-magnetized one. In order to further reduce remnant magnetic field, a solenoid coil was prepared and used to cancel it. To suppress flux trapping, a heater was located around an upper beampipe of cavity and made thermal gradient. Owing to these efforts, Q-value of more than 1x10¹¹ can be measured with a condition of residual resistance of ~3 nΩ. Clear flux expulsion signal can be also observed. In this presentation, we report about efforts to reduce ambient magnetic field and to realize high-Q measurements. Results of vertical tests, including flux expulsion measurements, are also presented.
	Poster TUPB028 [1.961 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB028
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TUPB048	INFN- LASA Medium Beta Cavity Prototypes for ESS Linac	cavity, ion, niobium, vacuum	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB048
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TUPB084	EP System Development at IHEP	cavity, ion, cathode, SRF	586
	S. Jin, J. Dai, J. Gao, D.J. Gong, F.S. He, Z.Q. Li, Z.C. Liu, P. Sha, J.Y. Zhai, P. Zhang, T.X. Zhao IHEP, Beijing, People's Republic of China
	Electropolishing (EP) System is a critical facility for SRF cavity treatment, especially for high performance cavities which are necessary for several great projects like LCLS-II, CEPC, Shanghai XFEL, and so on. So, an EP system was under development at IHEP. At this stage, we would like a horizontal EP facility. Main purpose is for elliptical SRF Nb cavities like 500MHz single cell cavities. Besides, it should be compatible for other frequency cavities, such as 650MHz and 1.3GHz cavities. In this paper, we will mainly report the preliminary design for the EP system. Several key points in the design will be also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB084
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TUPB099	Vertical Test System for Superconducting RF Cavities at Peking University	ion, cavity, shielding, radiation	631
	D. Zhou, J.E. Chen, W. Cheng, L.W. Feng, J.K. Hao, L. Lin, K.X. Liu, S.W. Quan, F. Wang, H.M. Xie, F. Zhu, D.H. Zhuang PKU, Beijing, People's Republic of China
	A new vertical test system (VTS) for superconducting RF cavities has been designed and constructed at Peking University. This facility is designed to operate at a temperature of 2K and with pumping speed of 10g/s for helium gas at 30 mbar. In this paper, we present the structure design, modification of 2K system, ambient magnetic field and radiation shielding, LLRF and the test run of this VTS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB099
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TUPB112	First Test of Electropolishing System at IMPCAS	ion, cavity, cathode, SRF	660
	L. Li, Q.W. Chu, H. Guo, Y. He, P.R. Xiong, Z.Q. Yang, Z.M. You, B. Zhang, S.H. Zhang, X. Zhu IMP/CAS, Lanzhou, People's Republic of China
	The first SRF cavity electropolishing system of China has been built by IMPCAS. We used two type of cathodes in different process parameters to test the typical Voltage-Current Density curves of 1.3GHz one-cell SRF cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB112
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THPB021	Trial of Nitrogen Infusion and Nitrogen Doping by Using J-PARC Furnace	ion, cavity, niobium, SRF	775
	T. Konomi, T. Dohmae, Y. Hori, E. Kako, T. Kubo, G.-T. Park, H. Sakai, K. Umemori KEK, Ibaraki, Japan J. Kamiya, K. Takeishi JAEA/J-PARC, Tokai-mura, Japan T. Nagata ULVAC, Inc., Tsukuba, Japan
	KEK has been carrying out SRF cavity developments toward higher Q-values and higher accelerating gradients. In the past nitrogen-doping was tested using the KEK furnaces, but it did not succeed. This time nitrogen infusion and nitrogen doping are tested using the J-PARC's furnace, which has an oil-free pumping system and is mainly pumped by a 10000 L/s cryopump and three 3000 L/s turbo pumps. Nitrogen pressure is controlled by a variable leak valve and an additional turbo pump. To avoid performance degradation during heat treatment, flanges of cavities are covered by Nb caps and foils. Nitrogen infusion at 120 degrees was applied to a single cell cavity and cavity performance was measured by vertical tests after HPR and assembly. Nitrogen doping at 800 degrees is also applied to another single cell cavity. After applying EP and HPR, vertical tests were carried out. Nb samples were also installed into the furnace during heat treatment. Surfaces are analyzed by SIMS and XPS. In this presentation, we report procedure of nitrogen infusion and doping, vertical test results and results of surface analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB021
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THPB035	High Power Testing of the First ESS SPOKE Cavity Package	ion, cavity, accelerating-gradient, linac	817
	H. Li, A.K. Bhattacharyya, L. Hermansson, M. Jobs, R.J.M.Y. Ruber, R. Santiago Kern Uppsala University, Uppsala, Sweden
	The first double spoke cavity for the ESS project was tested with high power in the HNOSS cryostat at the FREIA Laboratory. This cavity is designed for 325.21MHz, pulsed mode with 14 Hz repetition rate, up to a peak power of 360 kW. The qualification of the cavity package in a horizontal test, involving a superconducting spoke cavity, a fundamental power coupler (FPC), LLRF system and RF station, represents an important verification before the module assembly. This paper presents the test configuration, RF conditioning history and first high power performance of this cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB035
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THPB058	R&D of Thin Film Coating on Superconductors	ion, cryogenics, embedded, FPGA	877
	Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan M. Hino Kyoto University, Research Reactor Institute, Osaka, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	Funding: This research is partially supported by Grant-in-Aid for Exploratory Research JSPS KAKENHI Grant Number 26600142, and Photon and Quantum Basic Research Coordinated Development Program from the MEXT. Multilayer thin film coating is a promising technology to enhance performance of superconducting cavities. Until recently, principal parameters to achieve the sufficient performance had not been known, such as the thickness of each layer. We proposed a method to deduce a set of the parameters to exhibit a good performances. In order to verify the scheme, we are trying to make some experiments on the subject at Kyoto. The sample preparation and the test setup for the measurement apparatus will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB058
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FRXBA02	High Precision RF Control for SRF Cavities in LCLS-II	ion, cavity, LLRF, feedback	944
	L.R. Doolittle, K.S. Campbell, Q. Du, G. Huang, J.A. Jones, C. Serrano, V.K. Vytla LBNL, Berkeley, California, USA S. Babel, A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, J.H. De Long, J.A. Diaz Cruz, D.B. Greg, B. Hong, R.S. Kelly, A. McCollough, A. Ratti, C.H. Rivetta SLAC, Menlo Park, California, USA R. Bachimanchi, C. Hovater, D.J. Seidman JLab, Newport News, Virginia, USA B.E. Chase, E. Cullerton, J. Einstein, D.W. Klepec Fermilab, Batavia, Illinois, USA
	Funding: This work supported under DOE Contract DE-AC02-76SF00515 The unique properties of SRF cavities enable a new generation of X-ray light sources in XFEL and LCLS-II. The LCLS-II design calls for 280 L-band cavities to be operated in CW mode with a Q_L of 4x10⁷, using Single-Source Single-Cavity control. The target RF field stability is 0.01% and 0.01 degree for the band above 1 Hz. Hardware and software implementing a digital LLRF system has been constructed by a four-lab collaboration to minimize known contributors to cavity RF field fluctuation. Efforts include careful attachment to the phase reference line, and minimizing the effects of RF crosstalk by placing forward and reverse signals in chassis separate from the cavity measurement. A low-noise receiver/digitizer section will allow feedback to operate with high proportional gain without excessive noise being sent to the drive amplifier. Test results will show behavior on prototype cryomodules at FNAL and JLab, ahead of the 2018 final accelerator installation.
	Slides FRXBA02 [3.425 MB]
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Paper

Title

Other Keywords

Page

MOPB020

An Optimal Procedure for Coupler Conditioning for ESS Superconducting Linac

ion, cavity, vacuum, interface

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB020

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MOPB044

Magnetic Hygiene Control on LCLS-II Cryomodules Fabricated at JLab

ion, cavity, cryomodule, shielding

153

G. Cheng, E. Daly, G.K. Davis, J.F. Fischer, N.A. Huque, R.A. Legg, H. Park, K.M. Wilson, L. Zhao
JLab, Newport News, Virginia, USA

Funding: U.S. DOE Contract No. DE-AC05-06OR23177 and the LCLS-II project.
Jefferson Lab (JLab) is in collaboration with Fermi Na-tional Accelerator Laboratory (Fermilab) to build 18 cryomodules to install at the SLAC National Accelerator Laboratory's tunnel as part of the Linac Coherent Light Source upgrade project (LCLS-II). Each LCLS-II cry-omodule hosts 8 superconducting niobium cavities that adopt the nitrogen doping technique, which aims to en-hance the cavity quality factor Qo to reduce the consumption of liquid helium used to cool down the cavities. It is known that the Qo of niobium cavities is affected by cavity surface magnetic field. Traditionally, magnetic shields made of high magnetic permeability mu-metals are employed as a passive shielding of the ambient magnetic fluxes. During the LCLS-II cryomodule development, magnetic hygiene control that includes magnetic shielding and demagnetization of parts and the whole-machine is implemented. JLab and Fermilab worked closely on developing magnetic hygiene control procedures, identifying relevant tools, investigating causes of magnetization, magnetic field monitoring, etc. This paper focuses on JLab's experiences with LCLS-II cryomodule magnetic hygiene control during its fabrication.
Authored by Jefferson Science Associates, LLC. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for Government purposes.

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MOPB061

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

ion, cavity, vacuum, cryomodule

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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MOPB072

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

ion, vacuum, 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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MOPB075

Quench Protection in Digital Power Supplies for Superconducting Magnets in ADS

ion, power-supply, superconducting-magnet, solenoid

233

J. Zhao, S. Zhang, Z.Z. Zhou
IMP/CAS, Lanzhou, People's Republic of China

The front-end demo superconducting Linac for Chinese ADS (Accelerator Driven Sub-critical System) project is under construction at institute of modern physics(IMP) in Lanzhou. It will demonstrate the key technologies and the feasibility of a high power beam for the future national project " the Chinese Initiative Accelerator Driven Subcritical System(CIADS)". In this system, there are about 60 superconducting magnets, including solenoids, vertical correction and horizontal correction. They are utilized to focus and correct the proton beam. Quench protection of the superconducting magnets is key to reliability of the facility. A full digital power supply is developed and employed as excitation source for all of these superconducting magnets. In this paper, an FPGA-based quench protection plan implemented in the power supplies is mainly described. The commissioning results show that it is feasible.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB075

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MOPB076

Analysis of the Production, Installation and Commissioning of the European-XFEL Frequency Tuners

ion, cavity, FEL, cryomodule

235

R. Paparella, A. Bosotti, D. Sertore
INFN/LASA, Segrate (MI), Italy
C. Albrecht, S. Barbanotti, A. Bellandi, J. Branlard, K. Jensch, L. Lilje
DESY, Hamburg, Germany
C. Cloué, T. Trublet
CEA/IRFU, Gif-sur-Yvette, France
C. Madec
CEA, Gif-sur-Yvette, France

In the European-XFEL superconducting linac, mechanical frequency tuners equipped with stepper motors and piezoelectric actuators provide cold tuning of each of the 768 1.3 GHz cavities. More than 820 complete tuning systems were fabricated and pre-assembled in industry, tested at several stages before and after assembly and successfully commissioned during cryo-module cold tests at AMTF (DESY). Quality control strategy adopted to preserve the well-assessed tuner reliability through such a large-scale industrial production is critically reviewed and the lessons learned are presented in this paper. The statistical analysis of the large set of data acquired up to the recent commissioning of the entire linac is then summarized.

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MOPB086

First Results of the IFMIF/EVEDA-SaTHoRI Tests

ion, cavity, SRF, cryomodule

262

O. Piquet, N. Bazin, P. Carbonnier, J.K. Chambrillon, M. Desmons, G. Devanz, H. Jenhani, C. Servouin
CEA/DRF/IRFU, Gif-sur-Yvette, France
P. Cara
Fusion for Energy, Garching, Germany
J.F. Denis, L. Maurice, J. Relland
CEA/IRFU, Gif-sur-Yvette, France
F. Éozénou, P. Hardy, E. Jacques, Y. Lussignol, P. Sahuquet
CEA/DSM/IRFU, France
D. Gex, A. Jokinen, G. Phillips
F4E, Germany
I. Moya, P. Méndez
CIEMAT, Madrid, Spain

The SaTHoRI test stand (Satellite de Tests Horizontal des Résonateurs IFMIF) aims to characterize a jacketed and fully dressed cavity with its coupler and tuner. A dedicated test cryostat has been manufactured and is connected to an existing horizontal test cryostat which provides the cryogenic coolant. A RF source ' provided by the IFMIF collaboration, one of the four RF sources which will be used for the cryomodule at Rokkasho ' has been installed and commissioned at CEA. This paper describes the test stand and presents the first results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB086

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TUPB028

Improvement of Magnetic Condition for KEK-STF Vertical Test Facility Toward High-Q Study

ion, cavity, solenoid, SRF

444

K. Umemori, T. Dohmae, E. Kako, T. Konomi, T. Kubo, M. Masuzawa, G.-T. Park, A. Terashima, K. Tsuchiya, R. Ueki
KEK, Ibaraki, Japan
T. Okada
Sokendai, Ibaraki, Japan

Improvement of unloaded Q-values of SRF cavities are important to reduce surface loss of cavity and heat loads of He refrigerators. R&D activities have been developed worldwide. We also started work toward high-Q, but soon realized that magnetic condition of KEK-STF vertical test facility was not good enough to carry out high-Q measurements. First, magnetized components were searched. Shafts to move variable coupler were found to be most magnetized one and exceed more than 1 Gauss. Magnetized components were exchanged to non-magnetized one. In order to further reduce remnant magnetic field, a solenoid coil was prepared and used to cancel it. To suppress flux trapping, a heater was located around an upper beampipe of cavity and made thermal gradient. Owing to these efforts, Q-value of more than 1x10¹¹ can be measured with a condition of residual resistance of ~3 nΩ. Clear flux expulsion signal can be also observed. In this presentation, we report about efforts to reduce ambient magnetic field and to realize high-Q measurements. Results of vertical tests, including flux expulsion measurements, are also presented.

Poster TUPB028 [1.961 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB028

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TUPB048

INFN- LASA Medium Beta Cavity Prototypes for ESS Linac

cavity, ion, niobium, vacuum

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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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB048

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TUPB084

EP System Development at IHEP

cavity, ion, cathode, SRF

586

S. Jin, J. Dai, J. Gao, D.J. Gong, F.S. He, Z.Q. Li, Z.C. Liu, P. Sha, J.Y. Zhai, P. Zhang, T.X. Zhao
IHEP, Beijing, People's Republic of China

Electropolishing (EP) System is a critical facility for SRF cavity treatment, especially for high performance cavities which are necessary for several great projects like LCLS-II, CEPC, Shanghai XFEL, and so on. So, an EP system was under development at IHEP. At this stage, we would like a horizontal EP facility. Main purpose is for elliptical SRF Nb cavities like 500MHz single cell cavities. Besides, it should be compatible for other frequency cavities, such as 650MHz and 1.3GHz cavities. In this paper, we will mainly report the preliminary design for the EP system. Several key points in the design will be also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB084

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TUPB099

Vertical Test System for Superconducting RF Cavities at Peking University

ion, cavity, shielding, radiation

631

D. Zhou, J.E. Chen, W. Cheng, L.W. Feng, J.K. Hao, L. Lin, K.X. Liu, S.W. Quan, F. Wang, H.M. Xie, F. Zhu, D.H. Zhuang
PKU, Beijing, People's Republic of China

A new vertical test system (VTS) for superconducting RF cavities has been designed and constructed at Peking University. This facility is designed to operate at a temperature of 2K and with pumping speed of 10g/s for helium gas at 30 mbar. In this paper, we present the structure design, modification of 2K system, ambient magnetic field and radiation shielding, LLRF and the test run of this VTS.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB099

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TUPB112

First Test of Electropolishing System at IMPCAS

ion, cavity, cathode, SRF

660

L. Li, Q.W. Chu, H. Guo, Y. He, P.R. Xiong, Z.Q. Yang, Z.M. You, B. Zhang, S.H. Zhang, X. Zhu
IMP/CAS, Lanzhou, People's Republic of China

The first SRF cavity electropolishing system of China has been built by IMPCAS. We used two type of cathodes in different process parameters to test the typical Voltage-Current Density curves of 1.3GHz one-cell SRF cavity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB112

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THPB021

Trial of Nitrogen Infusion and Nitrogen Doping by Using J-PARC Furnace

ion, cavity, niobium, SRF

775

T. Konomi, T. Dohmae, Y. Hori, E. Kako, T. Kubo, G.-T. Park, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
J. Kamiya, K. Takeishi
JAEA/J-PARC, Tokai-mura, Japan
T. Nagata
ULVAC, Inc., Tsukuba, Japan

KEK has been carrying out SRF cavity developments toward higher Q-values and higher accelerating gradients. In the past nitrogen-doping was tested using the KEK furnaces, but it did not succeed. This time nitrogen infusion and nitrogen doping are tested using the J-PARC's furnace, which has an oil-free pumping system and is mainly pumped by a 10000 L/s cryopump and three 3000 L/s turbo pumps. Nitrogen pressure is controlled by a variable leak valve and an additional turbo pump. To avoid performance degradation during heat treatment, flanges of cavities are covered by Nb caps and foils. Nitrogen infusion at 120 degrees was applied to a single cell cavity and cavity performance was measured by vertical tests after HPR and assembly. Nitrogen doping at 800 degrees is also applied to another single cell cavity. After applying EP and HPR, vertical tests were carried out. Nb samples were also installed into the furnace during heat treatment. Surfaces are analyzed by SIMS and XPS. In this presentation, we report procedure of nitrogen infusion and doping, vertical test results and results of surface analysis.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB021

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THPB035

High Power Testing of the First ESS SPOKE Cavity Package

ion, cavity, accelerating-gradient, linac

817

H. Li, A.K. Bhattacharyya, L. Hermansson, M. Jobs, R.J.M.Y. Ruber, R. Santiago Kern
Uppsala University, Uppsala, Sweden

The first double spoke cavity for the ESS project was tested with high power in the HNOSS cryostat at the FREIA Laboratory. This cavity is designed for 325.21MHz, pulsed mode with 14 Hz repetition rate, up to a peak power of 360 kW. The qualification of the cavity package in a horizontal test, involving a superconducting spoke cavity, a fundamental power coupler (FPC), LLRF system and RF station, represents an important verification before the module assembly. This paper presents the test configuration, RF conditioning history and first high power performance of this cavity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB035

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THPB058

R&D of Thin Film Coating on Superconductors

ion, cryogenics, embedded, FPGA

877

Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
M. Hino
Kyoto University, Research Reactor Institute, Osaka, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Funding: This research is partially supported by Grant-in-Aid for Exploratory Research JSPS KAKENHI Grant Number 26600142, and Photon and Quantum Basic Research Coordinated Development Program from the MEXT.
Multilayer thin film coating is a promising technology to enhance performance of superconducting cavities. Until recently, principal parameters to achieve the sufficient performance had not been known, such as the thickness of each layer. We proposed a method to deduce a set of the parameters to exhibit a good performances. In order to verify the scheme, we are trying to make some experiments on the subject at Kyoto. The sample preparation and the test setup for the measurement apparatus will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB058

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FRXBA02

High Precision RF Control for SRF Cavities in LCLS-II

ion, cavity, LLRF, feedback

944

L.R. Doolittle, K.S. Campbell, Q. Du, G. Huang, J.A. Jones, C. Serrano, V.K. Vytla
LBNL, Berkeley, California, USA
S. Babel, A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, J.H. De Long, J.A. Diaz Cruz, D.B. Greg, B. Hong, R.S. Kelly, A. McCollough, A. Ratti, C.H. Rivetta
SLAC, Menlo Park, California, USA
R. Bachimanchi, C. Hovater, D.J. Seidman
JLab, Newport News, Virginia, USA
B.E. Chase, E. Cullerton, J. Einstein, D.W. Klepec
Fermilab, Batavia, Illinois, USA

Funding: This work supported under DOE Contract DE-AC02-76SF00515
The unique properties of SRF cavities enable a new generation of X-ray light sources in XFEL and LCLS-II. The LCLS-II design calls for 280 L-band cavities to be operated in CW mode with a Q_L of 4x10⁷, using Single-Source Single-Cavity control. The target RF field stability is 0.01% and 0.01 degree for the band above 1 Hz. Hardware and software implementing a digital LLRF system has been constructed by a four-lab collaboration to minimize known contributors to cavity RF field fluctuation. Efforts include careful attachment to the phase reference line, and minimizing the effects of RF crosstalk by placing forward and reverse signals in chassis separate from the cavity measurement. A low-noise receiver/digitizer section will allow feedback to operate with high proportional gain without excessive noise being sent to the drive amplifier. Test results will show behavior on prototype cryomodules at FNAL and JLab, ahead of the 2018 final accelerator installation.

Slides FRXBA02 [3.425 MB]

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