SRF2017 - List of Keywords (FEL)

Paper	Title	Other Keywords	Page
MOXA02	The Commissioning of the European XFEL Linac and its Performance	ion, MMI, linac, cavity	1
	D. Reschke, W. Decking, N. Walker, H. Weise DESY, Hamburg, Germany
	Funding: Presented on behalf of the XFEL Accelerator Consortium. Work supported by the respective funding agencies of the contributing institutes; for details see www.xfel.eu. The main linac of the superconducting accelerator of the European XFEL presently consists of 96 accelerator modules, each housing eight 1.3 GHz TESLA-type cavi-ties, with an average design gradient of 23.6 MV/m. The performance of each individual module has been tested after module assembly in the Accelerator Module Test Facility (AMTF) at DESY. The 2-year period of module installation to the accelerator tunnel was finished in August 2016. In order to recheck and re-establish the performance of the input power couplers, warm processing of nearly all installed modules was performed before the first cool-down during Dec 2016 / Jan 2017. Four consecutive modules are connected to one 10 MW klystron and form a so-called RF station, which is powered and controlled individually during operation. By June 2017 23 of 25 RF stations have been commissioned for beam acceleration including frequency tuning, various calibrations and LLRF adjustments. A preliminary beam energy of 14 GeV was achieved, which is sufficient for first lasing experiments. No significant performance degradation has been observed so far. The commissioning experience and the available RF performance data will be presented.
	Slides MOXA02 [6.896 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOXA02
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MOPB013	European XFEL Input Coupler Experiences and Challenges in a Test Field	ion, GUI, SRF, operation	78
	F. Hoffmann, D. Kostin, W.-D. Möller, D. Reschke, M. Wiencek DESY, Hamburg, Germany
	102 European XFEL accelerating modules with 816 superconducting cavities and main input RF power couplers were assembled and then tested at DESY prior to installation in the European XFEL tunnel. In the Accelerating Module Test Facility (AMTF) warm and cold RF tests were done. The test results went directly to the operational setup for the LINAC. Main input couplers did present several problems during the tests, resulting in some minor coupler design changes as well as in a few repair actions. The experience got from the said testing operation is worth to be shared and is presented here together with a discussion.
	Poster MOPB013 [0.648 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB013
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MOPB015	Accelerator Module Repair for the European XFEL Installation	ion, cavity, vacuum, 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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MOPB050	Cavity Processing and Testing Activities at Jefferson Lab for LCLS-II Production	cavity, ion, SRF, cryomodule	173
	L. Zhao, G.K. Davis, J. Follkie, D. Forehand, K. Macha, A.D. Palczewski, A.V. Reilly JLab, Newport News, Virginia, USA
	Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515 for the LCLS-II Project. Cryomodule production for LCLS-II is well underway at Jefferson Lab. This paper explains the process flow for production cavities, from being received at the Test Lab to being assembled onto cavity strings. Taking our facility and infrastructure into consideration, process optimization and process control are implemented to ensure high quality products.
	Poster MOPB050 [2.338 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB050
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MOPB063	Fundamental Studies for the STF-type Power Coupler for ILC	ion, vacuum, 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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MOPB076	Analysis of the Production, Installation and Commissioning of the European-XFEL Frequency Tuners	ion, cavity, cryomodule, controls	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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MOPB077	Operational Experience of the European-XFEL 3.9 GHz Coaxial Tuners	ion, cavity, operation, MMI	240
	R. Paparella, A. Bellandi, A. Bignami, A. Bosotti, D. Sertore INFN/LASA, Segrate (MI), Italy C.G. Maiano ESS, Lund, Sweden P. Pierini DESY, Hamburg, Germany
	The European-XFEL injector hosts a third-harmonic section composed by a module with eigth 3.9 GHz cavities equipped with a coaxial frequency tuner inspired by INFN-LASA Blade Tuner design. The 3.9 GHz tuning system met specifications during all the injector runs in 2016 up to the recent commissioning of the entire linac; it matched the required tuning range and frequency sensitivity although higher than expected cavity detuning was experienced during pressure transients in the cryogenic system. An analysis of all collected experimental data is reported in this paper together with the strategy developed to provide a sound and effective retuning routine to the control room operator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB077
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MOPB088	Experience on In-situ Module Repair and Set Up of Non XFEL Cavity Strings at DESY	ion, cavity, HOM, pick-up	269
	M. Schmökel, A. Daniel, N. Krupka, A. Matheisen, S. Saegebarth, M. Schalwat, P. Schilling DESY, Hamburg, Germany
	All components installed to the European XFEL cavity string modules underwent an intensive inspection and quality control before acceptance for installation to cavities or modules. Even though some RF feed throughs for HOM coupler- and Pick Up antennas showed leaks at the ceramic insulation after module test at 2 K. Due to time restriction and continuity of production the exchange of these parts needed to be done without reentering the cleanroom. Successful repair of these modules took place by setting up a local cleanroom onto the cavity string. In collaboration with Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a cavity string for the ELBE project was assembled at DESY and transported to HZDR for installation to the vacuum vessel. A spare module with 3.9 GHz Resonators for the European XFEL was set up at DESY and will be tested and qualified for the European XFEL. Due to delay in delivery of the power couplers, four power couplers were installed after string assembly.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB088
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MOPB106	Test Results of the European XFEL Serial-production Accelerator Modules	ion, cavity, cryomodule, operation	312
	K. Kasprzak, M. Wiencek, A. Zwozniak IFJ-PAN, Kraków, Poland D. Kostin, D. Reschke, N. Walker DESY, Hamburg, Germany
	The serial-production tests of 100 cryomodules for the European XFEL have been finished. In this paper the statistics of the cold RF measurements in the AMTF (Accelerator Module Test Facility) are reported for all the modules. In addition comparison between the cavity vertical test results and module test results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB106
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MOPB111	European XFEL Linac RF System Conditioning and Operating Test	ion, cavity, vacuum, 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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THXA04	Fabrication, Treatment and Test of Large Grain Cavities	cavity, ion, SRF, superconducting-cavity	700
	J.K. Hao, J.E. Chen, L.W. Feng, L. Lin, K.X. Liu, S.W. Quan, F. Wang, H.M. Xie, F. Zhu PKU, Beijing, People's Republic of China
	Development of SRF technology has been included in the project of Soft X-ray FEL (SXFEL) for a hard X-ray FEL plan in China which would be operated in CW mode. Six 9-cell TESLA type cavities as well as several single-cell cavities made of Ningxia large grain niobium material have been fabricated by Peking University for achieving high gradient and high intrinsic quality factor Q0. The measurements of gradient and Q0 have been carried out with a new vertical test system at PKU. The process of fabrication, surface treatment and test results of these large grain cavities will be presented.
	Slides THXA04 [7.911 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THXA04
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THXA06	Advanced OST System for the Second-sound Test of Fully Dressed Cavities	ion, cavity, power-supply, detector	703
	Y. Tamashevich HZB, Berlin, Germany Y. Tamashevich University of Hamburg, Hamburg, Germany
	Cavities which exhibit a low field quench are normally discarded from usage in accelerator projects. However, they can be repaired if the exact location of the quench is known. Optical inspection alone cannot reliably locate the source of a quench. Methods that directly measure the quench, such as thermometry or second sound detection, could so far only be performed at undressed cavities. A new, specially designed, second-sound system for the first time allows the localization of the quench in multicell cavities equipped with a helium vessel. It can be easily installed in the helium pipe of the cavity. Information on the quench location can be acquired during a standard rf test. A new algorithm localizes the quench based on the real path of the second-sound wave around the cavity surface, rather than using simple triangulation. The implemented pathfinding method leads to a high precision and high accuracy of the quench location. This was verified by testing standard dressed 9-cell XFEL cavities. The system can be easily applied to other cavity shapes and sizes.
	Slides THXA06 [9.681 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THXA06
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FRXBA01	LLRF Commissioning at the European XFEL	ion, MMI, LLRF, cavity	941
	M. Omet, V. Ayvazyan, J. Branlard, L. Butkowski, M. Fenner, M.K. Grecki, M. Hierholzer, M. Hoffmann, M. Killenberg, D. Kühn, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Pryschelski, K.P. Przygoda, R. Rybaniec, H. Schlarb, Ch. Schmidt, B. Szczepanski, H.C. Weddig DESY, Hamburg, Germany W. Cichalewski, D.R. Makowski, F. Makowski, A. Mielczarek TUL-DMCS, Łódź, Poland K. Czuba, B. Gąsowski, S. Hanasz, P.K. Jatczak, D. Kolcz, T.P. Leśniak, D. Sikora Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	The European X-ray Free-Electron Laser (XFEL) at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany is a user facility under commissioning, providing ultrashort X-ray flashes with a high brilliance in the near future. All LLRF stations of the injector, covering the normal conducting RF gun, A1 (8 1.3 GHz superconducting cavities (SCs) and AH1 (8 3.9 GHz SCs), were successfully commissioned by the end of 2015. The injector was operated with beam transmission to the injector dump since then. After the conclusion of the construction work in the XFEL accelerator tunnel (XTL), the commissioning of 22 LLRF stations (A2 to A23) started with the beginning of 2017. Every station consists of a semi-distributed LLRF system controlling 32 1.3 GHz SCs. Stable operation with beam transport to the main dump (TLD) was achieved. The commissioning procedure applied, experience gained and performance reached are described.
	Slides FRXBA01 [2.159 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-FRXBA01
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Paper

Title

Other Keywords

Page

MOXA02

The Commissioning of the European XFEL Linac and its Performance

ion, MMI, linac, cavity

1

D. Reschke, W. Decking, N. Walker, H. Weise
DESY, Hamburg, Germany

Funding: Presented on behalf of the XFEL Accelerator Consortium. Work supported by the respective funding agencies of the contributing institutes; for details see www.xfel.eu.
The main linac of the superconducting accelerator of the European XFEL presently consists of 96 accelerator modules, each housing eight 1.3 GHz TESLA-type cavi-ties, with an average design gradient of 23.6 MV/m. The performance of each individual module has been tested after module assembly in the Accelerator Module Test Facility (AMTF) at DESY. The 2-year period of module installation to the accelerator tunnel was finished in August 2016. In order to recheck and re-establish the performance of the input power couplers, warm processing of nearly all installed modules was performed before the first cool-down during Dec 2016 / Jan 2017. Four consecutive modules are connected to one 10 MW klystron and form a so-called RF station, which is powered and controlled individually during operation. By June 2017 23 of 25 RF stations have been commissioned for beam acceleration including frequency tuning, various calibrations and LLRF adjustments. A preliminary beam energy of 14 GeV was achieved, which is sufficient for first lasing experiments. No significant performance degradation has been observed so far. The commissioning experience and the available RF performance data will be presented.

Slides MOXA02 [6.896 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOXA02

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MOPB013

European XFEL Input Coupler Experiences and Challenges in a Test Field

ion, GUI, SRF, operation

78

F. Hoffmann, D. Kostin, W.-D. Möller, D. Reschke, M. Wiencek
DESY, Hamburg, Germany

102 European XFEL accelerating modules with 816 superconducting cavities and main input RF power couplers were assembled and then tested at DESY prior to installation in the European XFEL tunnel. In the Accelerating Module Test Facility (AMTF) warm and cold RF tests were done. The test results went directly to the operational setup for the LINAC. Main input couplers did present several problems during the tests, resulting in some minor coupler design changes as well as in a few repair actions. The experience got from the said testing operation is worth to be shared and is presented here together with a discussion.

Poster MOPB013 [0.648 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB013

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MOPB015

Accelerator Module Repair for the European XFEL Installation

ion, cavity, vacuum, 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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MOPB050

Cavity Processing and Testing Activities at Jefferson Lab for LCLS-II Production

cavity, ion, SRF, cryomodule

173

L. Zhao, G.K. Davis, J. Follkie, D. Forehand, K. Macha, A.D. Palczewski, A.V. Reilly
JLab, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515 for the LCLS-II Project.
Cryomodule production for LCLS-II is well underway at Jefferson Lab. This paper explains the process flow for production cavities, from being received at the Test Lab to being assembled onto cavity strings. Taking our facility and infrastructure into consideration, process optimization and process control are implemented to ensure high quality products.

Poster MOPB050 [2.338 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB050

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MOPB063

Fundamental Studies for the STF-type Power Coupler for ILC

ion, vacuum, 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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MOPB076

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

ion, cavity, cryomodule, controls

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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MOPB077

Operational Experience of the European-XFEL 3.9 GHz Coaxial Tuners

ion, cavity, operation, MMI

240

R. Paparella, A. Bellandi, A. Bignami, A. Bosotti, D. Sertore
INFN/LASA, Segrate (MI), Italy
C.G. Maiano
ESS, Lund, Sweden
P. Pierini
DESY, Hamburg, Germany

The European-XFEL injector hosts a third-harmonic section composed by a module with eigth 3.9 GHz cavities equipped with a coaxial frequency tuner inspired by INFN-LASA Blade Tuner design. The 3.9 GHz tuning system met specifications during all the injector runs in 2016 up to the recent commissioning of the entire linac; it matched the required tuning range and frequency sensitivity although higher than expected cavity detuning was experienced during pressure transients in the cryogenic system. An analysis of all collected experimental data is reported in this paper together with the strategy developed to provide a sound and effective retuning routine to the control room operator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB077

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MOPB088

Experience on In-situ Module Repair and Set Up of Non XFEL Cavity Strings at DESY

ion, cavity, HOM, pick-up

269

M. Schmökel, A. Daniel, N. Krupka, A. Matheisen, S. Saegebarth, M. Schalwat, P. Schilling
DESY, Hamburg, Germany

All components installed to the European XFEL cavity string modules underwent an intensive inspection and quality control before acceptance for installation to cavities or modules. Even though some RF feed throughs for HOM coupler- and Pick Up antennas showed leaks at the ceramic insulation after module test at 2 K. Due to time restriction and continuity of production the exchange of these parts needed to be done without reentering the cleanroom. Successful repair of these modules took place by setting up a local cleanroom onto the cavity string. In collaboration with Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a cavity string for the ELBE project was assembled at DESY and transported to HZDR for installation to the vacuum vessel. A spare module with 3.9 GHz Resonators for the European XFEL was set up at DESY and will be tested and qualified for the European XFEL. Due to delay in delivery of the power couplers, four power couplers were installed after string assembly.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB088

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MOPB106

Test Results of the European XFEL Serial-production Accelerator Modules

ion, cavity, cryomodule, operation

312

K. Kasprzak, M. Wiencek, A. Zwozniak
IFJ-PAN, Kraków, Poland
D. Kostin, D. Reschke, N. Walker
DESY, Hamburg, Germany

The serial-production tests of 100 cryomodules for the European XFEL have been finished. In this paper the statistics of the cold RF measurements in the AMTF (Accelerator Module Test Facility) are reported for all the modules. In addition comparison between the cavity vertical test results and module test results are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB106

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MOPB111

European XFEL Linac RF System Conditioning and Operating Test

ion, cavity, vacuum, 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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THXA04

Fabrication, Treatment and Test of Large Grain Cavities

cavity, ion, SRF, superconducting-cavity

700

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

Development of SRF technology has been included in the project of Soft X-ray FEL (SXFEL) for a hard X-ray FEL plan in China which would be operated in CW mode. Six 9-cell TESLA type cavities as well as several single-cell cavities made of Ningxia large grain niobium material have been fabricated by Peking University for achieving high gradient and high intrinsic quality factor Q0. The measurements of gradient and Q0 have been carried out with a new vertical test system at PKU. The process of fabrication, surface treatment and test results of these large grain cavities will be presented.

Slides THXA04 [7.911 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THXA04

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THXA06

Advanced OST System for the Second-sound Test of Fully Dressed Cavities

ion, cavity, power-supply, detector

703

Y. Tamashevich
HZB, Berlin, Germany
Y. Tamashevich
University of Hamburg, Hamburg, Germany

Cavities which exhibit a low field quench are normally discarded from usage in accelerator projects. However, they can be repaired if the exact location of the quench is known. Optical inspection alone cannot reliably locate the source of a quench. Methods that directly measure the quench, such as thermometry or second sound detection, could so far only be performed at undressed cavities. A new, specially designed, second-sound system for the first time allows the localization of the quench in multicell cavities equipped with a helium vessel. It can be easily installed in the helium pipe of the cavity. Information on the quench location can be acquired during a standard rf test. A new algorithm localizes the quench based on the real path of the second-sound wave around the cavity surface, rather than using simple triangulation. The implemented pathfinding method leads to a high precision and high accuracy of the quench location. This was verified by testing standard dressed 9-cell XFEL cavities. The system can be easily applied to other cavity shapes and sizes.

Slides THXA06 [9.681 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THXA06

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FRXBA01

LLRF Commissioning at the European XFEL

ion, MMI, LLRF, cavity

941

M. Omet, V. Ayvazyan, J. Branlard, L. Butkowski, M. Fenner, M.K. Grecki, M. Hierholzer, M. Hoffmann, M. Killenberg, D. Kühn, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Pryschelski, K.P. Przygoda, R. Rybaniec, H. Schlarb, Ch. Schmidt, B. Szczepanski, H.C. Weddig
DESY, Hamburg, Germany
W. Cichalewski, D.R. Makowski, F. Makowski, A. Mielczarek
TUL-DMCS, Łódź, Poland
K. Czuba, B. Gąsowski, S. Hanasz, P.K. Jatczak, D. Kolcz, T.P. Leśniak, D. Sikora
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

The European X-ray Free-Electron Laser (XFEL) at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany is a user facility under commissioning, providing ultrashort X-ray flashes with a high brilliance in the near future. All LLRF stations of the injector, covering the normal conducting RF gun, A1 (8 1.3 GHz superconducting cavities (SCs) and AH1 (8 3.9 GHz SCs), were successfully commissioned by the end of 2015. The injector was operated with beam transmission to the injector dump since then. After the conclusion of the construction work in the XFEL accelerator tunnel (XTL), the commissioning of 22 LLRF stations (A2 to A23) started with the beginning of 2017. Every station consists of a semi-distributed LLRF system controlling 32 1.3 GHz SCs. Stable operation with beam transport to the main dump (TLD) was achieved. The commissioning procedure applied, experience gained and performance reached are described.

Slides FRXBA01 [2.159 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-FRXBA01

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