LINAC2018 - Table of Session: TUPO (Tuesday Poster Session)

Paper	Title	Page
TUPO001	About the Limits for the Accelerated Beam Current in the LUE-200 Linac of the IREN Facility	320
	A.P. Sumbaev JINR, Dubna, Moscow Region, Russia A.M. Barnyakov, A.E. Levichev BINP SB RAS, Novosibirsk, Russia
	The beam current loading of the accelerating fields is discussed for the linear accelerator LUE-200 of IREN facility. LUE-200 electron Linac consits of two disk loaded travelling wave accelerating structure with the operating frequency of 2856 MHz and power compression SLED-type system. The limits by the accelerated beam current are defined for different pulse durations of the beam current and RF power. The calculated results are discussed and compared with the measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO001
About •	paper received ※ 12 September 2018 paper accepted ※ 22 January 2019 issue date ※ 18 January 2019
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TUPO002	Electron Gun for 100 MeV / 100 kW Linear Accelerator of Electrons as the Driver of Nuclear Subcritical Assembly Neutron Source	323
SPWR008	use link to see paper's listing under its alternate paper code
	M. Moisieienko, O. Bezditko, A. Mytsykov, A.Y. Zelinsky NSC/KIPT, Kharkov, Ukraine
	100 MeV / 100 kW linear electron accelerator of The "neutron source" nuclear subcritical assembly uses the 120 KW triode electron gun as the primary source of electrons. The gun is designed, manufactured and tested at IHEP, Beijing, China. At present, the gun is installed, tested. The maximum impulse current of the gun equal to 2 A. Under design operation, the impulse current of the gun equal to 0.55 A.The report describes the construction of a 120 kV triode electron gun, the results of testing and test operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO002
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO003	Development of CW Heavy Ion Linac at IMP	326
TUOP08	use link to see paper's listing under its alternate paper code
	X. Yin, H. Du, Y. He, Q.Y. Kong, X.N. Li, Z.S. Li, L.Z. Ma, J. Meng, C. Qian, L.T. Sun, K.D. Wang, J.X. Wu, J.W. Xia, W.J. Xie, Z. Xu, Y.Q. Yang, Q.G. Yao, Y.J. Yuan, W. Zhang, X.Z. Zhang, Y. Zhang, H.W. Zhao, Z.Z. Zhou IMP/CAS, Lanzhou, People’s Republic of China J.E. Chen, S.L. Gao, G. Liu, Y.R. Lu, Z. Wang, X.Q. Yan, K. Zhu PKU, Beijing, People’s Republic of China
	A new heavy ion linac as the injector for the Separated Sector Cyclotron (SSC), named SSC-Linac[1], is being under constructed at the national laboratory Heavy Ion Research Facility in Lanzhou (HIRFL). The SSC-Linac mainly consists of a 4-rod RFQ and three IH-DTL cavities which can accelerate ion of A⁄q≤7from 3.73 keV/u to 1.025 MeV/u. Both of themoperating at 53.667MHz had been developed. In the commissioning, ions weresuccessfully accelerated to 0.295MeV/u by IH-DTL1. The beam commissioningof the IH-DTL2 which can accelerate the ion to 0.586MeV/u will come soon. In this paper, the recent R&D progress of the SSC-Linac including the development of key components and the beam commissioning results arepresented.
	Slides TUPO003 [7.335 MB]
	Poster TUPO003 [0.810 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO003
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO004	RF Design and Cold Model Measurement of an IH-DTL for HIMM Injector	329
	H. Du, Q.Y. Kong, Z.S. Li, K.D. Wang, X. Yin IMP/CAS, Lanzhou, People’s Republic of China
	An interdigital H-mode drift tube linac (IH-DTL) will be constructed as a postinjector linac for the Heavy Ion Medical Machine (HIMM). Its resonant frequency, injec-tion and final energies are determined from beam dynamics and hardware parameters considerations of the entire machine to be 162.5MHz, 600keV/u and 4MeV/u, respectively. The beam duty cycle of the injector linac is less than 0.1% based on the injection requirements of the synchrotron. Beam dynamics and RF structure design and optimize of the IH-DTL has been finished. The maximum surface electric field is less than 2.0-times the Kilpatric limit for accelerating C⁴⁺ beam. This IH-DTL contains 42 accelerating gaps and two focusing quadrupole triplets. In order to examine the field distribution of the IH-DTL which reaches the length of 3.17m, an aluminum alloy 1:1 cold model cavity with 4 moveable tuners and 2 empty focusing magnet shell was constructed. The relative intertube-distance errors are less than ±50μm. The measurements show that the gap voltage values can match the CST-MWS simulating results within relative difference of ±3% by adjusting the 4 moveable tuners.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO004
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO005	Initial Beam Commissioning of LEAF at IMP	332
	Y. Yang, W.P. Dou, X. Fang, Y.H. Guo, H. Jia, L. Jing, X.J. Liu, L. Lu, W. Lu, W. Ma, L.T. Sun, L.P. Sun, W. Wei, H.W. Zhao, Y.H. Zhai IMP/CAS, Lanzhou, People’s Republic of China
	A Low Energy intense-highly-charged ion Accelerator Facility (LEAF), which mainly includes an ECR ion source, LEBT and an 81.25 MHz RFQ, was designed to produce and accelerate heavy ions, from helium to uranium with A/Q between 2 and 7, to the energy of 0.5 MeV/u. The typical beam intensity is designed up to 2 emA CW for the uranium beam. The facility has been successfully commissioned with He⁺ (A/Q=4) and N2+ (A/Q=7) beams and accelerated the beams in the CW regime to the designed energy of 0.5 MeV/u. Beam properties and transmission efficiencies were measured, indicating a good consistency with simulated data. After having briefly recalled the project scope and parameters, this paper describes the beam commissioning strategy and detailed commissioning results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO005
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO007	FRIB Fast Machine Protection System: Chopper Monitor System Design	336
TUOP02	use link to see paper's listing under its alternate paper code
	Z. Li, D. Chabot, S. Cogan, S.M. Lidia, R.C. Webber FRIB, East Lansing, USA
	Funding: Work supported by Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The Facility for Rare Isotope Beams tunes the beam power from 0 to 400KW by chopping the beam current with a beam chopper in the Low Energy Beam Transport. A chopper monitoring system is employed to verify proper chopper operation to avoid delivery of undesired high-powered beam and to inhibit beam for machine protection purposes. The system monitors the incoming beam gate time structure, the chopper switch high voltage pulses, the chopper electrode charge/discharge currents, and the status of machine protection system. It is designed to switch off the beam within tens of nanoseconds of a detected fault. Chal-lenges include a dynamic beam gate pulse structure with pulse lengths as short as 0.6 µs and high voltage power supply current pulses of ~25 ns. A high speed "integrate and hold circuit with reset", Field Program-mable Gate Array based digital control circuit and high speed ADC circuit were developed to fulfil the re-quired functions. Design approach, simulation, and test results with the beam are the focus of this paper.
	Slides TUPO007 [1.082 MB]
	Poster TUPO007 [1.321 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO007
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO009	Heat Treatment for a Prototype Half-Wave Resonator Cavity	339
	Y. Jung, B.H. Choi, J. Joo, H.C. Jung, H. Kim, J.W. Kim, Y. Kim, J. Lee, S. Lee IBS, Daejeon, Republic of Korea
	Heat treatment, 650C for 10hrs, was carried out to improve the performance of a half-wave resonator cavity. In this presentation, we report how the heat treatment was performed. X-ray diffraction analysis and residual gas analysis were performed to investigate the effect of the heat treatment on the cavity performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO009
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO010	Muon Acceleration Test with the RFQ Towards the Development of the Muon Linac	342
SPWR015	use link to see paper's listing under its alternate paper code
	R. Kitamura University of Tokyo, Tokyo, Japan S. Bae, S. Choi, B. Kim SNU, Seoul, Republic of Korea Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, T. Yamazaki KEK, Tsukuba, Japan K. Hasegawa, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T. Iijima, Y. Sue Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan H. Iinuma, Y. Nakazawa Ibaraki University, Hitachi, Ibaraki, Japan K. Ishida RIKEN Nishina Center, Wako, Japan S. Li The University of Tokyo, Graduate School of Science, Tokyo, Japan M. Otani, N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan G.P. Razuvaev Budker INP & NSU, Novosibirsk, Russia
	The muon linac to accelerate muons 212 MeV is planned in order to measure the muon dipole moments precisely in the J-PARC. The muon acceleration with a RF accelerator hasn’t been demonstrated yet in the world. Therefore the muon acceleration test with the RFQ as the feasibility test of the muon linac was demonstrated at the Muon D line in the J-PARC MLF. Conventional muons are cooled with producing ultra-slow muons using the muonium production and the ionization laser for the muon linac. However these apparatuses couldn’t be used because of the limitation of the experimental area in the acceleration test. Therefore the conventional muon was converted to the negative muonium ion (Mu-) with less than 2 keV using the thin aluminum foil target as the easy cooling method. The Mu- was finally accelerated to 90 keV using the RFQ. The accelerated Mu- was selected with a diagnostic beam line and identified with the Time-Of-Flight measurement using a MCP detector. The result of the world’s first muon acceleration test with the RFQ will be reported in this presentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO010
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO011	Upgrade of Heavy Ion Injector I-3 at ITEP	346
	N.N. Alexeev, P.N. Alekseev, V. Andreev, T. Kulevoy, A.D. Milyachenko, V.I. Nikolaev, Yu.A. Satov, A. Shumshurov, A. Zarubin ITEP, Moscow, Russia
	Heavy ion injector I-3 represents two-gap 2.5 MHz resonator with accelerating voltage 2x2 MV. It‘s used with laser ion source for acceleration of heavy ions in wide range of charge to mass ratio. As a result of modernization, injector structure will be supplemented by the second two-gap resonator, rf voltage will be increased to 3x4 MV and accelerated beam structure has to be improved by increasing accelerating frequency to 5 MHz. Design features of upgraded linac and peculiarity of beam dynamics for different types of ions are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO011
About •	paper received ※ 03 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO012	Compact Multipurpors Facility - BELA	349
	T. Kulevoy, R. Fatkullin, A.V. Kozlov, G. Kropachev, D.N. Selesnev, A.I. Semennikov, A. Sitnikov ITEP, Moscow, Russia T. Kulevoy MEPhI, Moscow, Russia T. Kulevoy NRC, Moscow, Russia
	In ITEP the project of multidiscipline facility Based on ECR ion source and Linear Accelerator (BELA) is started. The injector part of facility is based on combinations of ECR ion source and dc H⁺ and He⁺ source will provide the multi beams irradiation of the reactor materials for modeling experiments. The cw RFQ and following DTL will enable the set of experimental activity both for fun-damental physics and for practical applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO012
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO013	Commissioning Status of the LIGHT Development Machine	352
	G. De Michele, J. Adam, D. Aguilera Murciano, A. Benot-Morell, R. Bonomi, F. Cabaleiro Magallanes, M. Caldara, G. D’Auria, A. Degiovanni, M. Esposito, S. Fanella, D. Fazio, D.A. Fink, Y. Fusco, M. Gonzalez, P. Gradassi, L. Kobzeva, G. Levy, G. Magrin, A. Marraffa, A. Milla, R. Moser, P. Nadig, G. Nuessle, A. Patino-Revuelta, T. Rutter, F. Salveter, A. Samoshkin, L. Wallet A.D.A.M. SA, Meyrin, Switzerland M. Breitenfeldt, C. Candolfi, G. Castorina, M. Cerv, V.A. Dimov, M.T. Gallas, S. Gibson, A. S. Gonzalez, Ye. Ivanisenko, A. Jeff, V. F. Khan, S. Magnoni, J.L. Navarro Quirante, H. Pavetits, P. Paz Neira, S.G. Soriano, P. Stabile, K. Stachyra, A. Valloni, C. Zannini AVO-ADAM, Meyrin, Switzerland G. D’Auria Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	ADAM (Application of Detectors and Accelerators to Medicine) is a CERN spin-off company currently working on the construction and testing of the LIGHT (Linac for Image-Guided Hadron Therapy) machine. LIGHT is an innovative high-frequency linac based proton therapy system designed to accelerate protons up to 230 MeV: it consists of three different linac sections i.e. a 750 MHz Radio Frequency Quadrupole (RFQ) accelerating the beam up to 5 MeV; a 3 GHz Side Coupled Drift Tube Linac (SCDTL) up to 37.5 MeV; and a 3 GHz Coupled Cavity Linac (CCL) section up to 230 MeV. The compact and modular design is based on cutting edge technologies developed for particle colliders and adapted to the needs of hadron therapy beams. The LIGHT development machine is currently being built at CERN and this paper describes its design aspects and its different stages of installation and commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO013
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO014	TRIUMF ISAC LINAC Developments and Upgrades	355
	Z.T. Ang, T. Au, Y. Bylinskii, K. Fong, J.J. Keir, D. Lang, R.E. Laxdal, R. Leewe, B.S. Waraich, Z.Y. Yao, Q. Zheng, V. Zvyagintsev TRIUMF, Vancouver, Canada
	TRIUMF ISAC accelerator complex is in consists of ISAC-I room temperature linac and ISAC-II superconducting linac structure. ISAC-I linac has seventeen RF systems in operation for about twenty years, and ISAC-II linac has forty superconducting QWR RF cavities in operation for more than ten years. A small ISAC booster 3-gap structure at 11.78 MHz located in upstream of RFQ has been designed and installed for energy matching to RFQ. A sliding mode extremum seeking control for LLRF control was developed and implemented in operation. Six of DTL systems have been working in the control mode. Two of them had been commissioning and in operation one and half year reliably. RFQ, two more DTL system, HEBT rebuncher and DSB buncher system will be upgraded in the sliding mode control soon. Twenty ISAC-II SBC superconducting cavity RF power amplifiers were upgraded from YV-229 triode tube amplifier into solid state amplifier(SSA). The prototype and four SSAs have been commissioned in 2017 and in operation successfully. The rest of 16 SSA have been tested in RF lab and installed for operation at the mid of this year.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO014
About •	paper received ※ 04 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO015	The CW Beam Experiment of Window-type RFQ
TUOP11	use link to see paper's listing under its alternate paper code
	K. Zhu PKU, Beijing, People’s Republic of China
	Funding: work supported by NSFC. Grand No. 2014CB845503 A window-type RFQ is designed and fabricated by Peking University. It is planed to accelerate 50mA deuteron cw beam to 1MeV. The 60kV intervane voltage is designed to decrease the risk of high voltage discharge since the RFQ works in cw mode. High power test shows that the intervane voltage is over 60kV when the Cavity power consumption is 48kW. The beam experiment was done and 1.8mA cw beam was obtained at exit of RFQ with over 90% transmission efficiency. This paper will present the cold model measurement, high power RF conditioning and beam experiment result.
	Slides TUPO015 [2.051 MB]
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TUPO016	High Frequency RFQ Design and LEBT Matching for the CERN TwinEBIS Ion Source	358
SPWR013	use link to see paper's listing under its alternate paper code
	V. Bencini, J.-B. Lallement, A.M. Lombardi, H. Pahl, J. Pitters, F.J.C. Wenander CERN, Geneva, Switzerland M. Breitenfeldt AVO-ADAM, Meyrin, Switzerland A.I. Pikin BNL, Upton, Long Island, New York, USA
	An Electron Beam Ion Source (EBIS) is being developed at CERN for production of highly charged ions, for instance fully stripped 12C. The focus has so far been on the electron gun design, aiming for a high current compression, which results in a rapid ionisation process and thereby high repetition rate. Initial commissioning tests of such an electron gun, the so-called MEDeGUN, have already been performed and we are now in the process of designing a multi-purpose ion extraction and diagnostics line. The Low Energy Beam Transport (LEBT) line will transport the ions into the downstream Radio Frequency Quadrupole (RFQ) with a nominal energy of 15 keV/u. The 750 MHz RFQ is designed to accelerate ions from 15 keV/u up to the final energy of 2.5 MeV/u. After the RFQ design was finalized and its acceptance calculated, the beam matching to the RFQ was studied, finding a set of parameters for the LEBT that maximize the transmission through the RFQ. Details of the RFQ design, of the LEBT matching procedure and its final results are illustrated in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO016
About •	paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO017	The New Light Ion Injector for NICA	362
	B. Koubek, M. Basten, H. Hoeltermannpresenter, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede BEVATECH, Frankfurt, Germany A.V. Butenko, D.E. Donets, B.V. Golovenskiy, A. Govorov, K.A. Levterov, D.A. Lyuosev, A.A. Martynov, V.A. Monchinsky, D.O. Ponkin, K.V. Shevchenko, I.V. Shirikov, E. Syresin JINR, Dubna, Moscow Region, Russia C. K. Kampmeyer, H. Schlarb DESY, Hamburg, Germany
	Within the upgrade scheme of the injection complex of the NICA project and after a successful beam commissioning of a heavy ion linac, Bevatech GmbH will build a first part of a new light ion linac as an injector for the Nuclotron ring. The linac will provide a beam of polarised protons and light ions with a mass to charge ratio up to 3 and an energy of 7 MeV/u. The mandate of the Linac does not only include the hardware for the accelerating structures, focusing magnets and beam diagnostic devices, but also the LLRF control soft- and hardware based on the MicroTCA.4 standard in collaboration with the MicroTCA Technology Lab at DESY. An overview of the Linac is presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO017
About •	paper received ※ 10 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO019	SPIRAL2 Cryogenic System Thermodynamic Behavior Prediction Through Dynamic Modeling	366
	A.V. Vassal, P.-E. Bernaudin, A. Ghribi GANIL, Caen, France P.-E. Bernaudin CEA/DSM/IRFU, France P. Bonnay, F. Bonne CEA/INAC, Grenoble Cedex 9, France F. Millet CEA, Grenoble, France
	SPIRAL 2 (Caen, France) is a state of the art superconducting linear accelerator composed of 26 quarter wave accelerating cavities. Each cavity is plunged in a liquid helium bath at 4.4 K itself surrounded by a thermal shield at 70 K. In this paper, a dynamic model of the cryogenic systemof the LINAC is proposed. Thismodel simulates the dynamic behaviour of the 19 cryomodules and their respective valves box connected through the cryodistribution. Model accuracy is evaluated through a comparison between simulation and experimental data. Using the model we should be able to predict the behaviour of the cryogenic system for different beam operating conditions of the accelerator. The model also highlights the link between the cryogenic system and the cavity RF losses through a dynamic estimator of those RF losses in the cavity walls. The latter could be used as a rough estimator of the quality factor of a cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO019
About •	paper received ※ 13 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO020	Microphonics Investigation of ARIEL e-Linac Cryomodules	370
	Y. Ma, K. Fong, M. Keikha, J.J. Keir, D. Kishi, S.R. Koscielniak, D. Lang, R.E. Laxdalpresenter, R.R. Nagimov, Z.Y. Yao, Q. Zheng, V. Zvyagintsev TRIUMF, Vancouver, Canada L. Lilje DESY, Hamburg, Germany
	Now the stage of the 30MeV portion of ARIEL (The Advanced Rare Isotope Laboratory) e-Linac is under commissioning which includes an injector cryomodule (ICM) and the 1st accelerator cryomodule (ACM1) with two cavities configuration. In this paper, the progress of the microphonics investigation and suppression of ICM and ACM1 is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO020
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO022	Manufacturing of X-band Accelerating Structures: Metrology Analysis and Process Capability	374
	J. Sauza-Bedolla, S. Atieh, N. Catalán Lasheras CERN, Geneva, Switzerland
	The fabrication tolerances of RF components are essential for CLIC X-band accelerating structures to perform efficiently. On one hand, the capability of high power accelerating structures depends on the shape accuracy and the asperity of the inner surfaces, when microwaves pass through the cavity. On the other hand, surface flatness and dimensional tolerances are necessary to guarantee a correct assembly process. Hence, the discs that build up the structure require sub-micrometre specifications and, in order to meet all the needs, ultra-precision machining using single crystal diamond tools is mandatory. This paper shows the analysis of the metrology results of the fabrication of 118 discs (4 accelerating structures). Dimensional and form tolerances are studied following the production order to find drifts in the production and to predict the impact on the assembly process. Finally, process capability is evaluated.
	Poster TUPO022 [2.987 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO022
About •	paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO023	Preserving Micron Tolerances Through the Assembly Process of an X-band Accelerating Structure	377
	J. Sauza-Bedolla, N. Catalán Lasheras, A. Grudiev, S. Lebet, E. Rodriguez-Castro, P. Sobrino-Mompean, A. Solodko, K. T. Szypula CERN, Geneva, Switzerland H. Bursali IZTECH, Izmir, Turkey
	The CLIC structures are designed for operating at X-Band, 2π/3 traveling wave mode with a loaded 100 MV/m gradient. Mechanical tolerances, at the submicron level, are required to satisfy the RF design constraints and beam dynamics and are reachable using ultra-precision diamond machining. However, inherent to the manufacturing process, there is a deviation from the nominal specifications and as a result; incorrect cavity dimensions produce a less efficient linac. Moreover, the assembly process increase the difference from the original geometry. As part of a cost and manufacturability optimization of the structures for mass production, this study aims to identify a correlation between frequency deviations and geometrical errors of the individual discs of the accelerating structures caused by the production process. A sensitivity analysis has been carried out to determine the most critical parameters. Cell frequency deviations have been monitored by bead pull measurements before and after bonding. Several accelerating structure prototypes have been tested to determine our assumptions and to assess if the assembly process preserves the tight tolerances achieved by machining.
	Poster TUPO023 [1.443 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO023
About •	paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO027	Series Production of the Specific Waveguide Distribution for the European XFEL at DESY	380
TUPO024	use link to see paper's listing under its alternate paper code
	B. Yildirim, S. Choroba, V.V. Katalev, P. Morozov, Y. Nachtigal DESY, Hamburg, Germany E.M. Apostolov Technical University of Sofia, Sofia, Bulgaria
	Series Production of the Specific Waveguide Distribution for the European XFEL at DESY B.Yildirim, S.Choroba, V.Katalev, P.Morozov, Y.Nachtigal, E.Apostolov The European XFEL uses 100 accelerating cryomodules. One RF station with 10 MW klystron supplies four cryomodules, each with eight cavities, through a waveguide distribution system. The RF station operates at 1.3 GHz, 1.37 ms pulse width and 10 Hz repetition rate. The results of the cryomodule test have shown however different maximum gradients for each cavity. The maximum gradient has been measured between 11 MV/m and 31 MV/m, which requires the cavity power from 29 kW to 230 kW. To operate with the maximum energy for every cryomodule, it is necessary to supply individual power to the cavity. In this case the weakest cavity problem can be avoided. For this goal a specific waveguide distribution has been developed. 100 waveguide distributions have been successfully tailored, produced and tested at the Waveguide Assembly Test Facility (WATF) at DESY and finally assembled to the cryomodules. We present the series production of the specific waveguide distributions at the WATF.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO027
About •	paper received ※ 06 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO028	Retreatment of European XFEL Series Cavities at DESY as Part of the Repair of European XFEL Accelerating Modules	384
	S. Sievers, N. Krupka, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, N. Steinhau-Kühl, E. Vogel, H. Weise, B. van der Horst DESY, Hamburg, Germany M. Wiencek IFJ-PAN, Kraków, Poland
	For the European XFEL 10² accelerating modules were built and tested. Several accelerating modules had to be reworked due to different kinds of non-conformities. The extent of this rework varied greatly. At the end of production four accelerating modules could not be qualified in time before the tunnel installation was to be finished in September 2016. Meanwhile the cavity strings of two of these accelerating modules have been disassembled in the DESY clean room. The cavities have been retreated at DESY either by additional high pressure water rinsing or BCP flash chemical treatment. All cavities were vertically tested and 15 out of 16 were qualified for the reassembly of the cavity strings. One accelerating module will be reassembled completely and tested until the end of 2018; the other will follow in the first half of 2019. We report on retreatment procedures and performance of these cavities.
	Poster TUPO028 [1.662 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO028
About •	paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO029	Highlights of the XM-3 Cryomodule Tests at DESY	388
	J. Branlard, V. Ayvazyan, A. Bellandi, J. Eschke, C. Gumus, D. Kostin, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz DESY, Hamburg, Germany W. Cichalewski TUL-DMCS, Łódź, Poland
	To investigate the feasibility of the continuous wave (cw) upgrade of the European XFEL (E-XFEL) DESY, on-going tests are performed on E-XFEL prototype and production cryomodules since 2011. For these studies, DESY’s Cryo-Module Test Bench (CMTB) has been equipped with a 10⁵ kW cw operating IOT in addition to the 10MW pulsed klystron, making CMTB a very flexible test stand, enabling both cw and pulse operation. For these tests, E-XFEL-like LLRF electronics is used to stabilize amplitude and phase of the voltage Vector Sum (VS) of all 8 cavities of the cryomodule under test. The cryomodule most often tested is the pre-series XM-3, unique since it is housing one fine grain niobium and seven large grain niobium cavities. In autumn 2017, additional spacers were installed on all 8 input couplers to increase the maximum reachable loaded quality factor Ql beyond 2·10⁷. With higher Ql, up to 6·10⁷ for 6 cavities and 2.7·10⁷ for 2 cavities, we have investigated the VS stability and SRF-performance of this cryomodule under various conditions of cooling down rate and operation temperature 1.65K, 1.8K and 2K, at gradients up to ca. 18MV/m. The results of these tests are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO029
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO030	Precise Evaluation of Characteristic of the Multi-layer Thin-film Superconductor Consisting of NbN and Insulator on Pure Nb Substrate	391
TUOP03	use link to see paper's listing under its alternate paper code
	R. Katayama, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan C.Z. Antoine CEA/IRFU, Gif-sur-Yvette, France A. Four CEA/DRF/IRFU, Gif-sur-Yvette, France H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan R. Ito, T. Nagata ULVAC, Inc, Chiba, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	In recent years, it has been pointed out that the maximum accelerating gradient of a superconducting RF cavity can be pushed up by coating the inner surface of the cavity with a multilayer thin-film structure that consists of alternating insulating and superconducting layers. In this structure, the principal parameter that limits the performance of the cavity is the critical magnetic field or effective Hc1 at which vortices start penetrating into the superconductor layer, and it is predicted to depend on the combination of the film thickness. We made samples that have NbN/SiO2 thin-film structure on pure Nb substrate with several thicknesses of NbN film deposited using DC magnetron sputtering method. Here, we report the measurement results of effective Hc1 of the NbN sample with a thickness of 200 nm by using the third-harmonic voltage method. In addition, we report the preliminary results to evaluate the dependence of the effective Hc1 on the thickness of the NbN film in the range 50 nm-200 nm.
	Slides TUPO030 [0.305 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO030
About •	paper received ※ 18 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO031	Investigation of the Surface Resistance of Niobium Between 325 MHz and 1300 MHz Using a Coaxial Half-wave Cavity	395
TUOP04	use link to see paper's listing under its alternate paper code
	H. Park, S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA
	The Center for Accelerator Science at Old Dominion University has built a half-wave coaxial cavity () to measure the surface resistance of niobium as a function of frequency, temperature, rf field, preparation techniques, over a wide range of frequencies of interest for particle accelerators. The characteristics of the half-wave coaxial cavity provide these information on a same surface. The preliminary results showed clearly the frequency dependence of residual surface resistance (). After establishing baseline, we have conducted a study of low temperature baking effect on the surface resistance under controlled environment. This paper will describe the details of the test procedure, results and we will explore underlying physics of the phenomenon. H. Park et al., MOPB003, Proc. SRF2015, http://jacow.org/ ** H. Park et al., THPB080, Proc. SRF2017, http://jacow.org/
	Slides TUPO031 [0.966 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO031
About •	paper received ※ 17 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO032	First Test Results of Superconducting Twin Axis Cavity for ERL Applications	398
	H. Park, S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA A. Hutton, F. Marhauser, H. Park JLab, Newport News, Virginia, USA
	Superconducting cavities with two beam pipes had been proposed in the past for energy recovery linac applications. The relatively complex geometry of those cavities presented a serious challenge for fabrication and surface processing. Main concerns have now been overcome with the production and successful RF testing of a new elliptical twin-axis cavity proposed by Jefferson Lab and optimized by the Center for Accelerator Science at Old Dominion University in the frame of a DoE accelerator stewardship program. The cavity design provides uniform accelerating or decelerating fields for both beams. This paper describes the cavity design, fabrication experience, and the first cold RF test results and explores potential applications especially for Jefferson Lab s EIC (JLEIC).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO032
About •	paper received ※ 20 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO033	Cryogenic Test Results of the SPS Prototype RF-dipole Crabbing Cavity with Higher Order Mode Couplers	402
TUOP05	use link to see paper's listing under its alternate paper code
	S.U. De Silva, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA Z. Li SLAC, Menlo Park, California, USA H. Park JLab, Newport News, Virginia, USA
	The rf-dipole crabbing cavity planned for the LHC High Luminosity Upgrade is designed to deliver a transverse kick of 3.34 MV; crabbing the proton beam in the horizontal plane. The proton beams of the LHC machine operating at 7 TeV each sets high impedance thresholds on the crabbing cavity systems. The rf-dipole crabbing cavity is designed with a two higher order mode couplers to suppress those HOMs. The first prototype of the HOM couplers are fabricated at Jefferson Lab. This paper reports the cryogenic test results of the HOM couplers with the SPS prototype rf-dipole cavity.
	Slides TUPO033 [0.859 MB]
	Poster TUPO033 [1.838 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO033
About •	paper received ※ 17 September 2018 paper accepted ※ 09 November 2018 issue date ※ 18 January 2019
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TUPO035	Determination of the Field-dependence of the Surface Resistance of Superconductors from Cavity Tests	405
TUOP12	use link to see paper's listing under its alternate paper code
	J.R. Delayen, S.U. De Silva, H. Park ODU, Norfolk, Virginia, USA
	Cryogenic tests of superconducting cavities yield an average surface resistance as a function of the peak surface magnetic field. An analytical formalism has been developed to extract the actual field dependence of the surface resistance from cavity tests and is applied to coaxial cavities and cavities of more complex geometries.
	Slides TUPO035 [0.524 MB]
	Poster TUPO035 [1.002 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO035
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO036	Vertical Test Results of Plasma In-situ Cleaning on Low Beta HWR Cavity	408
TUOP06	use link to see paper's listing under its alternate paper code
	A.D. Wu, H. Guo, Y. He, C.F. Hu, S.C. Huang, C.L. Li, Y.M. Li, X. Liu, F. Pan, Y.K. Song, P.R. Xiong, L. Yang, W.M. Yue, C. Zhang, S.H. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	Field emission occurred in SRF cavity is the major limitation to operate at high gradient with stability. The plasma in-situ cleaning for the low beta HWR cavity was carried out to remove the hydrocarbons contaminants on the inner cavity surface. And the vertical test results indicated that the field emission effect was relieved with the increasing of the quench point and emission set-on point. Thus, oxygen active plasma processing can be an effective method to solve the field emission issues for the low beta HWR cavity.
	Slides TUPO036 [1.281 MB]
	Poster TUPO036 [0.672 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO036
About •	paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO038	Several Experimental Phenomena of Sn Nucleation on Nb Surface Observed at IMP	412
TUPO037	use link to see paper's listing under its alternate paper code
	Z.Q. Yang, Y. He, F. Pan IMP/CAS, Lanzhou, People’s Republic of China
	Nucleation process is an important step that affects the quality of Nb3Sn films coated by vapor diffusion method. A uniform distribution of nucleation centers is essential to the uniformity of Nb3Sn films. In this paper we report several experimental phenomena on the Sn nucleation on Nb surface. Better nucleation in the downstream of the pumping direction was observed. Influence of SnCl2 partial pressure inhomogeneity was studied. Samples with higher SnCl2 partial pressure have denser nucleation, which means homogeneous SnCl2 pressure is a critical factor to the uniform nucleation. Less-nuclear zones, mainly distributed at cracks, grain boundaries and even some whole grain surfaces, were found on the surfaces of all samples. The less-nuclear zones may result in the low tin regions of the Nb3Sn cavities. The specific solution to the less-nuclear problem was proposed. These studies help to better understanding of the mechanism underlying the nucleation process and will be useful foundation for the follow-up Nb3Sn/Nb project at IMP.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO038
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO039	Tests of the Balloon Single Spoke Resonator	417
TUOP07	use link to see paper's listing under its alternate paper code
	Z.Y. Yao, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, H. Liu, Y. Ma, B. Matheson, B.S. Waraich, Q. Zheng, V. Zvyagintsev TRIUMF, Vancouver, Canada
	A balloon variant of the single spoke resonator (SSR) has been designed, fabricated and tested. The cavity is the SSR1 prototype for the Rare Isotope Science Project (RISP) in Korea. It is specifically designed to reduce the likelihood of multipacting barriers near the operating point. A systematic multipacting study leads to a novel geometry, a spherical cavity with re-entrant irises and a spoke. Other than eliminating multipacting around operational gradient, the balloon shape also provides competitive RF parameters and robust mechanical structure. Cryostat cold tests demonstrated cavity performance on each design aspect. The cold tests will be reported in this paper.
	Slides TUPO039 [25.279 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO039
About •	paper received ※ 17 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO040	Tests of Multi-frequency Coaxial Resonators	420
	Z.Y. Yao, J.J. Keir, P. Kolb, A. Kong, R.E. Laxdal, B. Matheson, E. Thoeng, B.S. Waraich, Q. Zheng, V. Zvyagintsev TRIUMF, Vancouver, Canada
	A significant issue in low beta resonators is medium field Q-slope (MFQS) at 4K. To study the MFQS and the field dependence of surface resistance in low beta resonators, a quarter-wave resonator (QWR) and a half-wave resonator (HWR) were designed to be tested at integer harmonic frequencies of 200MHz, and up to 1.2GHz. A series of chemistry and heat treatments are proposed to these cavities. A systemic study on the surface resistance of the coaxial resonators associating with post-processing, RF field, and frequency is in progress. The cavities were designed and fabricated. The cold test results will be discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO040
About •	paper received ※ 17 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO041	LCLS-II Cavity Higher Order Modes Coupler Tuning Optimization and Challenges at Jefferson Lab	423
	A.D. Solopova, D. Forehand, A.D. Palczewski JLab, Newport News, Virginia, USA T.N. Khabiboulline Fermilab, Batavia, Illinois, USA
	LCLS-II is a new XFEL linac based on 1.3GHz SRF linac. Half of the LCLS-II cryomodules are being produced at Jefferson Lab. This paper summarizes the Higher Order Mode filter tuning challenges at Jefferson Lab and describes optimization of the procedure for a 9-cell Tesla type cavity and its integration into a cryomodule production line.
	Poster TUPO041 [0.719 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO041
About •	paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO042	RF Results of Nb Coated SRF Accelerator Cavities via HiPIMS	427
	M.C. Burton, A.D. Palczewski, H.L. Phillips, C.E. Reecepresenter, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA R.A. Lukaszew The College of William and Mary, Williamsburg, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. Bulk Niobium (Nb) SRF (superconducting radio frequency) cavities are currently the preferred method for acceleration of charged particles at accelerator facilities around the world. Since the SRF phenomena occurs within a shallow depth of 40 nm (for Nb), a proposed option has been to deposit a superconducting Nb thin film on the interior of a cavity made of a suitable alternative material such as copper or aluminum. While this approach has been attempted in the past using DC magnetron sputtering (DCMS), such cavities have never performed at the bulk Nb level. However, new energetic condensation techniques for film deposition offer the opportunity to create suitably thick Nb films with improved density, microstructure and adhesion compared to traditional DCMS. One such technique that has been developed somewhat recently is ’High Power Impulse Magnetron Sputtering’ (HiPIMS). Here we report early results from various thin film coatings carried out on 1.3 GHz Cu Cavities, a 1.5 GHz Nb cavity and small Cu coupon samples coated at Jefferson Lab using HiPIMS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO042
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO043	New Progress with HF-free Chemical Finishing for Nb SRF Cavities	431
	H. Tian, J. Carroll, C.E. Reecepresenter, B. Straka JLab, Newport News, Virginia, USA T.D. Hall, M.E. Inman, R. Radhakrishnan, E.J. Taylor Faraday Technology, Inc., Clayton, Ohio, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. Jefferson Lab has implemented a bipolar pulsed electropolishing system for final chemical processing of niobium SRF cavities. This FARADAYIC bi-polar electropolishing (BPEP) has been applied to single cells, a 7-cell CEBAF C100 cavity, and to 9-cell TESLA-style cavities.* As a mechanistic characterization of the process emerges, the critical role played by the local current density during each cathodic pulse is becoming clear. This influences system and operational parameter refinement. We present current process parameters, removal characterization, and rf performance of the processed cavities. This is the fruit of collaborative work between Jefferson Lab and Faraday Technology, Inc. directed toward the routine commercialization and industrialization of niobium cavity processing. We also present supporting data from controlled-parameter coupon studies * E.J. Taylor, et al. "Electrochemical system and method for electropolishing superconductive radio frequency cavities" U.S. Pat. No. 9,006, 147 (& international counterparts) issued April 14, 2015.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO043
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO045	Optimization of Dual Axis Asymmetric Cavity for Energy Recovery Linac	435
SPWR022	use link to see paper's listing under its alternate paper code
	Ya.V. Shashkov, A.M. Bulygin, M. Gusarova MEPhI, Moscow, Russia I.V. Konoplev JAI, Oxford, United Kingdom F. Marhauser JLab, Newport News, Virginia, USA A. Seryi SLAC, Menlo Park, California, USA
	Funding: The reported study was funded by RFBR according to the research project № 18-302-00990 Optimization of the dual axis asymmetric cavity was performed to minimize the ratio of the peak magnetic and electric fields values to the accelerating voltage, to increase the distance between operating and neighbouring modes as well as to reduce the manufacturing cost of the cavity. To reach the goals several solutions have been suggested bringing the ratios to the acceptable values and leading to simplification of the manufacturing of the structure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO045
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO048	Study Progress of Pulse Laser Annealing for Niobium Film on Copper	438
SPWR021	use link to see paper's listing under its alternate paper code
	Y. Yang, B.T. Li, X.Y. Lu, W.W. Tan, L. Xiao, D. Xie, D.Y. Yang PKU, Beijing, People’s Republic of China
	Funding: Work supported by Major Research Plan of National Natural Science Foundation of China (No. 91026001). The recent studies of laser annealing on niobium films on copper are reported. Annealing is normally used to deal with the surface, reducing defects and even chang-ing the microstructure of the coating film. Short pulse laser can produce a sharp step temperature field on the film thickness scale (μm), which anneals the surface without substrate heated. The laser annealing experi-ments of niobium thin film sample have been carried out, and according to SEM and FIB results, Nb films melted and recrystallization occurred. Grains growing up can be observed while the power density of laser pulse in-creased.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO048
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO049	Nitrogen Doping Study With 1.3 GHz Single Cell Superconducting Cavities	442
	S. Chen, M. Chen, L.W. Feng, J.K. Hao, L. Lin, K.X. Liu, S.W. Quan, F. Wang, F. Zhu PKU, Beijing, People’s Republic of China
	Nitrogen doping studies were carried out at Peking University. A series of 1.3 GHz single cell cavities fabricated with OTIC large grain niobium material were annealed and doped in the furnace of Peking University, and electropolished by a simple EP device. Light doping recipe and heavy doping recipe are both adopted for comparison. The results and analysis are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO049
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO050	Construction of Thin-film Coating System Toward the Realization of Superconducting Multilayered Structure	445
	R. Ito, T. Nagata ULVAC, Inc, Chiba, Japan H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan Y. Iwashita, R. Katayama Kyoto ICR, Uji, Kyoto, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	Although S-I-S (superconductor-insulator-superconductor) multilayered structure is expected to increase the maximum acceleration gradient of SRF cavities, in order for it to function in reality, it is necessary to develop a coating processing that can realize high purity and quality superconducting thin-films. We launched the co-sputtering system to create superconducting alloy thin-films such as Nb3Sn and to research how the characteristics of them change depending on the coating conditions. The deposition rate of two elements was optimized by adjusting each input power, so we successfully obtained an alloy thin-film having appropriate composition ratio. In addition, we developed another experimental equipment for coating on the inner surface of the 3GHz TESLA type small cavities. A cylindrical shape Nb in which some permanent magnets are inserted was adopted as the sputtering target. Glow discharge of the target was confirmed, and the inner-sputtering test was conducted. This presentation reports the specifications of the two sputtering apparatuses and the results of the coating test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO050
About •	paper received ※ 18 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO051	Design Considerations of a Balloon-shaped SSR Superconducting Cavity	448
	H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, S. H. Park, J.Y. Yoon Korea University Sejong Campus, Sejong, Republic of Korea
	A single spoke resonator (SSR, β = 0.51 and f = 325 MHz) is being developed at Korea University. It is well-known that a traditional spoke cavity having flat or round end walls has broad multipacting ranges in acceleration gradient, sometimes including operation region. In general, quite long conditioning time is consumed to overcome such multipacting barriers. In this study, we introduce a balloon-shaped SSR superconducting cavity for the multipacting mitigation due to structural simplicity. The electromagnetic modeling of the SSR was made based on the RF parameter optimization. The simulation results show much narrower multipacting bandwidth, compared to those for the traditional spoke cavity. Mechanical analyses with stiffening structure at maximum allowable working pressures indicate acceptable stresses at the SSR cavity wall. In addition, the resonant frequency shifts due to fabrication and processing for cold tests are predicted and power coupling and tuning mechanism are also investigated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO051
About •	paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO052	Design Study of a Prototype 325MHz RF Power Coupler for Superconducting Cavity	451
	J.Y. Yoon, J.B. Bhang, H.J. Chapresenter, S.W. Jang, E.-S. Kim, K.R. Kim, C.S. Park, S. H. Park Korea University Sejong Campus, Sejong, Republic of Korea E. Kako KEK, Ibaraki, Japan D.Y. Kim, J. Lee Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea I. Shin IBS, Daejeon, Republic of Korea
	Funding: Korea University (Sejong Campus) in South KOREA We present design studies of a prototype RF input power coupler, which provides RF powers to 325MHz cavities up to 18.5 kW in CW mode. The prototype power coupler is a coaxial capacitive type with single ceramic window. In order to optimize the RF coupler design, we performed multi-physics simulations, including electromagnetic, thermal, and mechanical analyses.
	Poster TUPO052 [1.607 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO052
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO053	Fabrication of Nb Mushroom Shaped Cavity for Evaluation of Multi-layer Thin-film Superconductor	454
	H. Oikawa Utsunomiya University, Utsunomiya, Japan K. Enami, H. Hayano, H. Inoue KEK, Ibaraki, Japan T. Higashiguchi Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan
	The accelerating gradient of the Nb superconducting RF cavity seems to reach the limit due to the RF critical magnetic field of the Nb material. To obtain more higher gradient, there has been proposed a method of increasing an RF critical magnetic field of the cavity inner surface by coating of multi-layer thin-film superconductor. It is needed to demonstrate improvement RF critical magnetic field of the RF cavity coated with multi-layer thin-film superconductor. To optimize thin-film superconductor, sample tests are required. A cavity for sample test is necessary to produce a strong RF magnetic field parallel to the surface of the sample for evaluating RF critical magnetic field. For such a cavity, we designed a mushroom shaped cavity made of Nb which is operated in cryogenic temperature. Input and pick up antenna coupler are also designed electrically and mechanically. The connection design of sample plate and cavity bottom plate in superconducting state is also designed. The Nb mushroom shaped cavity is under fabrication. Fabrication method and status are reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO053
About •	paper received ※ 17 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO054	Fundamental Studies of Impurity Doping in 1.3 GHz and Higher Frequency SRF Cavities	458
SPWR018	use link to see paper's listing under its alternate paper code
TUOP01	use link to see paper's listing under its alternate paper code
	J.T. Maniscalco, P.N. Koufalis, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	As the demand for more powerful, more efficient, and smaller superconducting RF accelerators continues to increase, both impurity doping and high-frequency cavities (> 1.3 GHz) have become hot topics for fundamental research because of their potential to significantly decrease surface losses and cost respectively. In this report, we present recent experimental and theoretical results on undoped and nitrogen-doped high-frequency cavities and on alternative doping agents in traditional 1.3 GHz cavities, with a focus on understanding the fundamental science of impurity doping.
	Slides TUPO054 [1.956 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO054
About •	paper received ※ 16 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO055	Next Generation Nb3Sn SRF Cavities for Linear Accelerators	462
	R.D. Porter, D.L. Hall, M. Liepe, J.T. Maniscalcopresenter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Arias, P. Cueva, D.A. Muller, N. Sitaraman Cornell University, Ithaca, New York, USA
	Niobium-3 Tin (Nb3Sn) is a very promising alternative material for SRF accelerator cavities. The material can achieve higher quality factors, higher temperature operation and potentially higher accelerating gradients (~ 96 MV/m) compared to conventional niobium. This material is formed by vaporizing Sn in a high temperature vacuum furnace and letting the Sn absorb into a Nb substrate to form a 2-3 um Nb3Sn layer. Current Nb3Sn cavities produced at Cornell achieve Q ~ 10¹⁰ at 4.2 K and 17 MV/m. Here we present a summary of the current performance of Nb₃Sn cavities at Cornell and recent progress in improving the accelerating gradient.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO055
About •	paper received ※ 20 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO057	Low-temperature Baking and Infusion Studies for High-gradient ILC SRF Cavities	466
	M. Ge, P.N. Koufalis, G. Kulina, M. Liepe, J.T. Maniscalco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Low-temperature infusion has become a hot-topic in SRF researches recently. Past results show that low-temperature infusion can produce high quality factor at medium accelerating fields. Also, 75°C baking recently has been shown to improve accelerating gradients of SRF cavities. Hence these treatments are very promising for reducing cost of the ILC. In this work, we present latest results of low temperature infusion and baking, showing that these treatments can improve SRF cavities performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO057
About •	paper received ※ 19 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO058	Cool Down Studies for the LCLS-II Project	470
	M. Ge, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D. Gonnella SLAC, Menlo Park, California, USA J. Sears Cornell University, Ithaca, New York, USA
	The quality factor of the nitrogen-doped SRF cavities for the LCLS-II project are strongly impacted by cool down speed. A sufficiently fast cool down speed can produce large thermal gradient across a cavity and sufficiently expel magnetic flux when the cavity wall passes from the normal-conducting to the superconducting state. However, instrumentation in LCLS-II production cryomodules has been kept at a minimum, and additional information during the cool down of the modules is therefore desirable. In this work, we study if and how RF data can be used during cavity cool-down to determine the transition speeds of the individual cavities in the LCLS-II linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO058
About •	paper received ※ 19 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO059	Latest Results of Salt Based Bipolar Electro-polishing R&D at Cornell	473
	M. Ge, F. Furuta, T. Gruber, J.J. Kaufman, M. Liepe, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T.D. Hall, R. Radhakrishnan, S.T. Snyder, E.J. Taylor Faraday Technology, Inc., Clayton, Ohio, USA
	Acid free electropolishing would be safer to use and friendlier to the environment. A collaboration, sup-ported by the DOE SBIR Phase-II program, between Faraday Technology Inc. and Cornell University focused on salt-based bipolar electropolishing (BEP). In this paper, we present the latest salt-based BEP results. The superconducting performance of a single-cell 1.3GHz cavity has been carefully analyzed, showing that salt-based BEP is promising, but still has large room for improvement.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO059
About •	paper received ※ 19 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO064	Pre-study of CEPC SRF Cavity	476
	P. Sha Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People’s Republic of China J. Dai, C. Dong, H.F.S. Feisi, S. Jin, Z.Q. Li, B.Q. Liu, Z.H. Mi, J.Y. Zhai, X.Y. Zhang, H.J. Zheng IHEP, Beijing, People’s Republic of China J.K. Hao, F. Wang PKU, Beijing, People’s Republic of China
	Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400) and National Natural Science Foundation of China (Grant NO.:11505197). CEPC will use 650 MHz cavities for the collider and 1.3 GHz cavities for the Booster. Each booster cryomod-ule contains eight 1.3 GHz 9-cell cavities, which is simi-lar as LCLS-II, E-XFEL and ILC. Each collider cryo-module contains six 650 MHz 2-cell cavities, which is totally new. Therefore, the pre-study mainly focuses on the 650 MHz 2-cell cavity. N-doping and vertical tests of 650 MHz 1-cell and 2-cell cavities have been carried out at IHEP, which have achieved good results. A test cryomodule, which consists of two 650 MHz 2-cell cavities, has also begun as the first step to the full-scale cryomodule.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO064
About •	paper received ※ 31 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO065	Improvement of Cavity Performance by Nitrogen Doping at KEK	480
SPWR019	use link to see paper's listing under its alternate paper code
	T. Okada, Y. Hori, E. Kako, T. Konomi, H. Sakai, K. Umemori, Y. Yamamoto Sokendai, Ibaraki, Japan T. Dohmae, Y. Hori, E. Kako, T. Konomi, T. Saeki, T. Saeki, H. Sakai, K. Umemori, Y. Yamamoto KEK, Ibaraki, Japan J. Kamiya JAEA/J-PARC, Tokai-mura, Japan S. Kurosawa, K. Takeishi JAEA, Ibaraki-ken, Japan
	Nitrogen doping experiments in single-cell and 3-cell niobium cavities were carried out at KEK. After annealing at 800 deg C for 3 hours, pure nitrogen gas with a pressure of 3 Pa for 20 minutes and 3 minutes were introduced for doping in a furnace in J-PARC, respectively. Removing surface in 5 um and 20 um by electropolishing were performed prior to the vertical tests, respectively. Increases of a quality factor at 2K and reduction of the BCS resistance with respect to an accelerating gradient were observed in both cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO065
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO066	Lower Critical Field Measurement of Thin Film Superconductor	484
	H. Ito Sokendai, Ibaraki, Japan C.Z. Antoine CEA/IRFU, Gif-sur-Yvette, France A. Four CEA/DRF/IRFU, Gif-sur-Yvette, France H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan R. Ito, T. Nagata ULVAC, Inc, Chiba, Japan Y. Iwashita, R. Katayama, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	Funding: The work is supported by Japan Society for the Promotion of Science Grant-in-Aid for Young Scientist (A) No.17H04839. Superconducting thin film is the promising technology to increase the performance of SRF cavities. The lower critical field Hc1, which is one of the important physical parameters characterizing a superconducting material, will be enhanced by coating Nb with thin film superconductor such as NbN. To investigate the Hc1, we developed the Hc1 measurement system using the third harmonic response of applied AC magnetic field. The measurement system consists of helium cryostat with two of GM refrigerators, sample Cu stage, solenoid coil Cu mount, solenoid coil, temperature sensors, and liquid helium level meter. AC magnetic field is produced by a coil which is driven by function generator and power amplifier at around 1 kHz. In order to control the temperature of the sample, we installed heaters and thermal anchors which could be moved by the motor. By this temperature control the sample state can be easily transferred from Meissner state to mixed state. So that the measurement is repeated for various applied magnetic field, and the transition curve can be made. In this report, measurement result of the bulk Nb sample and NbN-SiO2 multilayer thin film sample will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO066
About •	paper received ※ 19 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO067	Study on New Removal Thickness Distribution Improvement Methods for Niobium 9-cell Cavity Vertical Electropolishing with Ninja Cathode	488
	K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	Marui Galvanizing Co., Ltd. has been developing niobium 9-cell cavity vertical electropolishing (VEP) technologies with Ninja cathode in collaboration with KEK. Conventional 9-cell cavity VEP had a serious problem, which was asymmetry of removal thickness distribution. Usually removal thickness of upper side became larger than lower side in case of both in-cell and inter-cell. So far, as one solution, we proposed bubble diffusion prevention method and proved it was effective for uniform removal. This time, as other new solution, we tried cavity flip upside down and Ninja cathode masking VEP methods. In this article we will report the purpose, intention and VEP experiment result of these methods.
	Poster TUPO067 [0.858 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO067
About •	paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO068	Vertical Electropolishing of 1.3 GHz Niobium Nine-cell SRF Cavity: Bulk Removal and RF Performance	491
	V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	Vertical electropolishing (VEP) technique have been successfully developed for 1.3 GHz niobium (Nb) single cell cavity to achieve a smooth surface with uniform removal and better RF performance as achieved after horizontal EP (HEP) process. VEP parameters for 1.3 GHz Nb nine-cell cavities are being studied using a nine-cell coupon cavity and our unique Ninja cathode. The investigated VEP parameters heretofore were applied on a 1.3 GHz Tesla shape nine-cell superconducting RF cavity for bulk removal of 100 µm followed by fine removal of 20 and 10 µm. The interior surface was found to be smooth and shiny after the VEP process. Our recently developed dual flow technique, in which the EP acid is flown separately in the Ninja cathode housing and cavity, yielded lower asymmetry in removal along the cavity length. The cavity was tested in a vertical cryostat after the final VEP process. The cavity achieved 28.3 MV/m at Q0 value of 6.7x109. The cavity performance was almost the same as in the baseline vertical test performed after the HEP process.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO068
About •	paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO069	Development of Vertical Electropolishing Facility for Nb 9-cell Cavity (2)	494
	Y.I. Ida, V. Chouhan, K.N. Nii MGH, Hyogo-ken, Japan T. Akabori, G.M. Mitoya, K. Miyano HKK, Morioka, Japan Y. Anetai, F. Takahashi WING. Co.Ltd, Iwate-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	In IPAC18 (Vancouver, Canada), we reported our first step of development of niobium 9-cell cavity vertical electropolishing (VEP) facility. In this article, we will report the method, system for uniform polishing for niobium 9-cell cavities and the current situation of our 9-cell cavity VEP facility (The result of polishing uniformity, vertical test will be presented in other posters of this conference). In addition, we will show the movie of experiments of VEP-3 with Ninja cathode. This facility aims not only for test VEP but also for mass production and long-time operation.
	Poster TUPO069 [0.316 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO069
About •	paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO070	Design and Commissioning of KEK New Vacuum Furnace for SRF Cavity Development	496
	K. Umemori, M. Egi, E. Kako, T. Konomi, S. Michizono, H. Sakai KEK, Ibaraki, Japan
	Recently new techniques such as Nitrogen-doping and Nitrogen-infusion have been developed to improve performance of SRF (Superconducting RF) cavities. We purchased a new vacuum furnace, which is key to realize these techniques. Cleanness of the furnace is most important issue. The furnace has a cryo-pump and whole of vacuum system is oil-free system. Target vacuum level after cooling down is 1x10^-6 Pa. Heater, reflectors and support table were made from Molybdenum to avoid contamination during heat treatment. Metal gaskets are used for all vacuum seals, except big doors. Maximum operation temperature is 1150 degree C. Size is around 1 m diameter and 2m long for a 1.3 GHz 9-cell cavity. Entrance of furnace is covered by a clean booth. The furnace was fabricated, assembled at KEK COI building and commissioned this year. After several burning runs, target vacuum pressure was achieved after cooling down to room temperature. Design of the furnace and performance during commissioning runs are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO070
About •	paper received ※ 19 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO071	Study on Nitrogen Infusion for 1.3 GHz SRF Cavities Using J-PARC Furnace	499
	K. Umemori, T. Dohmae, M. Egi, Y. Hori, E. Kako, T. Konomi, S. Michizono, T. Saeki, H. Sakai, Y. Yamamoto KEK, Ibaraki, Japan J. Kamiya JAEA/J-PARC, Tokai-mura, Japan S. Kurosawa, K. Takeishi JAEA, Ibaraki-ken, Japan T. Okada Sokendai, Ibaraki, Japan
	Nitrogen infusion (N-infusion) is new surface treatment technique for niobium SRF (Superconducting RF) cavities. After cooling down from 800 degree C heat treatment, a vacuum furnace and cavities are kept 120 degree C, 48 hours with about 3 Pa Nitrogen. Improvement of Q-value and accelerating gradient is expected. We used J-PARC furnace, since N-infusion procedure requires clean vacuum furnace. It has a cryo-pump and turbo molecular pumps and its vacuum system is oil-free system. Six times of N-infusion tests were carried out, while changing vacuum condition, N-infusion temperature, Nitrogen pressure, niobium material and so on. Niobium caps were mounted on cavities to avoid contaminations on inner surfaces. Some of trials were successful and vertical test results showed improvement of Q-values and accelerating gradient. However, some of them were not. Most of bad cases showed degradation of Q-values above 5 MV/m. Details of heat treatment procedure including N-infusion and vertical test results are shown in this presentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO071
About •	paper received ※ 20 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO072	First Trial of the In-situ Nitrogen Infusion at KEK	503
	T. Konomi, T. Dohmae, E. Kako, S. Michizono, H. Sakai, K. Umemori KEK, Ibaraki, Japan T. Okada Sokendai, Ibaraki, Japan
	The nitrogen infusion is the new surface treatment technique for improving the RF loss and the maximum accelerating gradient of superconducting cavity. In this process, it is important to be carried out continuously both the 800 C annealing in vacuum and 120 C nitrogen infusion without exposure to the atmosphere. The annealing serves activation process by removing the oxide layer. The in-situ nitrogen infusion system was prepared to investigate whether nitrogen infusion effect or something changes happen in the case of applying nitrogen infusion technique without removing the oxide layer. It can only introduce nitrogen into a cavity during 120 C low temperature baking and transport a cavity to the vertical test system without exposure to the atmosphere. We tried to infuse nitrogen to a single cell by keeping 120 C and 48 hours with 3 Pa nitrogen. The cavity was annealed in another furnace and applied high pressure rinsing before nitrogen infusion. The vertical test result was same Q as the normal 120 C baking without nitrogen. It suggests that oxide layer prevents infusion of nitrogen. In this poster, the in-situ nitrogen infusion system and vertical test results will be reported.
	Poster TUPO072 [4.653 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO072
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO073	Niobium Sample Analysis for Nitrogen Infusion and Doping	506
	T. Konomi, E. Kako, S. Michizono, H. Sakai, K. Umemori KEK, Ibaraki, Japan T. Nagata ULVAC, Inc., Tsukuba, Japan T. Nojima Tohoku University, Sendai, Japan
	KEK has been investigating the better conditions of the heat treatment in nitrogen, which are called as nitrogen doping and nitrogen infusion. We have tried to understand the high gradient performance of the cavity from the analyses of samples which were prepared in the same conditions for the cavity. The main tools are D-SIMS for the depth profile of the elemental concentration, XPS for composition analysis and SQUID magnetometry for the critical DC magnetic field measurement. The difference in the depth profiles of the nitrogen, carbon and oxygen between the heat treatment conditions was observed in vacuum and furnace temperature of nitrogen infusion by D-SIMS and XPS. Such a difference correlates with the vortex penetration field measured by SQUID. In particular, that of nitrogen doping sample was greatly degraded, while that of nitrogen infusion sample was slightly improved. The tendency is similar to the RF high gradient test results. Details of the sample analysis are shown in this presentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO073
About •	paper received ※ 18 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO074	Design and Fabrication of KEK Superconducting RF Gun #2	510
	T. Konomi, Y. Honda, E. Kako, Y. Kobayashi, S. Michizono, T. Miyajima, H. Sakai, K. Umemori, S. Yamaguchi, M. Yamamoto KEK, Ibaraki, Japan
	Superconducting RF gun can realize high acceleration voltage and high beam repetition. KEK has been developing the 1.3 GHz elliptical type 1.5 cell superconducting RF gun to investigate fundamental performance. A surface cleaning method and tools are developed by using KEK SRFGUN #1 and high surface peak gradient 75 MV/m was achieved without field emission. SRFGUN #2 which equips the helium jacket and can be operated with electron beam was designed based on the SRFGUN #1. It can be operated with transmit type photocathode which include superconducting transparent material. The cathode plug is cooled by thermal conducting from the 2 K helium jacket and photocathode will be kept around 2K to maintain superconductivity. Bulk niobium photocathode plug and substrate will used for the fundamental performance test. In parallel, the photocathode deposition chamber for multi-alkali photocathode will be prepared.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO074
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO076	An Innovative Nb3Sn Film Approach and Its Potential for SRF Applications	513
	E.Z. Barzi, D. Turrioni, C. Ciaccia Fermilab, Batavia, Illinois, USA G.V. Eremeev, R.L. Geng, R.A. Rimmer, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA S. Falletta Politecnico di Torino, Torino, Italy H. Hayanopresenter, T. Saeki KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan A. Kikuchi NIMS, Tsukuba, Ibaraki, Japan
	Funding: Work supported by U.S. DOE contract No. DE-AC02-07CH11359 A novel electro-chemical technique to produce Nb3Sn films on Nb substrates was developed and optimized at Fermilab. The Nb3Sn phase is obtained in a two-electrode cell, by electrodeposition from aqueous solutions of Sn layers and Cu intermediate layers onto Nb substrates. Subsequent thermal treatments in inert atmosphere are realized at a maximum temperature of 700°C to obtain the Nb3Sn superconducting phase. Several superconduct-ing Nb3Sn films were obtained on Nb substrates by study-ing and optimizing most parameters of the electro-plating process. Samples were characterized at Fermilab, NIMS, KEK and JLAB, including EPMA analyses, DC and in-ductive tests of critical temperature Tc0, and lower critical field Hc1(4.2 K) by SQUID. In parallel to sample devel-opment and fabrication at FNAL, at JLAB and KEK effort was put into etching and electro-polishing techniques adequate to remove the Cu and bronze phases from the samples’ outer surface. This is necessary prior to meas-urements at JLAB of the surface impedance of flat sam-ples in a setup that make use of an RF host cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO076
About •	paper received ※ 21 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO078	Extension of Busch’s Theorem to Particle Beams	516
TUOP09	use link to see paper's listing under its alternate paper code
	L. Groening, C. Xiao GSI, Darmstadt, Germany M. Chung UNIST, Ulsan, Republic of Korea
	In 1926, H. Busch formulated a theorem for one single charged particle moving along a region with longitudinal magnetic field. The theorem relates particle angular momentum to the amount of field lines being enclosed by the particle cyclotron motion. Recently it has been extended to accelerated particle beams [Phys. Rev. Accel. Beams 21 014201 (2018)]. This contribution sketches this extension and applies the extended theorem to successfully performed emittance manipulations with electron and ion beams.
	Slides TUPO078 [0.999 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO078
About •	paper received ※ 24 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO079	Numerical and Experimental Study of H⁻ Beam Dynamics in J-PARC LEBT	519
TUOP10	use link to see paper's listing under its alternate paper code
	T. Shibata, K. Ikegami, Y. Liu, K. Ohkoshi, M. Otani J-PARC, KEK & JAEA, Ibaraki-ken, Japan A. Miura, H. Oguri, K. Shinto JAEA/J-PARC, Tokai-mura, Japan F. Naito, K. Nanmo, A. Takagi KEK, Tokai, Ibaraki, Japan
	Negative hydrogen ion (H⁻) beam dynamics in J-PARC Low Energy Beam Transport (LEBT) has been investigated by numerical modeling which calculates particle transport with effect of space charge and collision processes. Understandings of H⁻ beam transport in LEBT is important for high transmission rate from Ion Source (IS) to Radio Frequency Quadrupole (RFQ) in J-PARC in higher beam current in future. In 2017, 45 mA beam current of H⁻ has been extracted from IS in J-PARC user operation which has been increased from 30 mA in last 2 years. The beam current is planned to be increased to 50 mA in the next upgrade. As the beam current increase, IS/LEBT commissioning becomes more difficult because of the higher space charge (SC). Especially in J-PARC, vacuum pressure is around 10^-5 Pa by 15 mmf orifice located in the center of LEBT. The orifice prevents residual gas injection from IS to LEBT/RFQ and thus produces stronger SC effect. In the presentation, numerical results are compared with actual results from J-PARC Linac beam commissioning. A comparison of the results shows that location of the 15 mmf orifice results in two peaks of RFQ transmission rate against SOL currents.
	Slides TUPO079 [0.968 MB]
	Poster TUPO079 [1.699 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO079
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO083	Beam Dynamics for the FAIR p-Linac Ladder RFQ	522
SPWR033	use link to see paper's listing under its alternate paper code
	M. Syha, U. Ratzinger, M. Schuett IAP, Frankfurt am Main, Germany
	After the successful measurements with a 0.8 m prototype a 3.3 m Ladder-RFQ is under construction at IAP, Goethe University Frankfurt. It is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the p-Linac at FAIR. Along the acceleration section modulation parameter, aperture and synchronous phase all course (quasi-)linear, which differentiates this design approach from other designs developed at IAP. The ratio of transversal vane curvature radius to mid-cell radial aperture as well as the vane radius itself are constant, which favors a flat voltage distribution along the RFQ. This was verified by implantation of the modulated vane geometry into MWS-CST RF field simulations. The development of adequate beam dynamics was done in close collaboration with the IAP resonator design team. The Los Alamos RFQGen-code was used for the RFQ design and the beam dynamics simulations.
	Poster TUPO083 [0.932 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO083
About •	paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO084	Beam Dynamics Simulations for the New Superconducting CW Heavy Ion LINAC at GSI	525
SPWR034	use link to see paper's listing under its alternate paper code
	M. Schwarz, M. Basten, M. Busch, H. Podlech IAP, Frankfurt am Main, Germany K. Aulenbacher IKP, Mainz, Germany K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu HIM, Mainz, Germany W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev GSI, Darmstadt, Germany
	Funding: Work supported by BMBF contr. No. 05P15RFRBA, EU Framework Programme H2020 662186 (MYRTE) and HIC for FAIR For future experiments with heavy ions near the coulomb barrier within the super-heavy element (SHE) research project a multi-stage R&D program of GSI/HIM and IAP is currently in progress. It aims for developing a supercon-ducting (sc) continuous wave (CW) LINAC with multiple CH cavities as key components downstream the High Charge State Injector (HLI) at GSI. The LINAC design is challenging due to the requirement of intense beams in CW mode up to a mass-to-charge ratio of 6, while covering a broad output energy range from 3.5 to 7.3 MeV/u with unchanged minimum energy spread. Testing of the first CH-cavity in 2016 demonstrated a promising maximum accelerating gradient of E_a = 9.6 MV/m; the worldwide first beam test with this sc multi-gap CH-cavity in 2017 was a milestone in the R&D work of GSI/HIM and IAP. In the light of experience gained in this research so far, the beam dynamics layout for the entire LINAC has recently been updated and optimized.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO084
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO085	Modelling of Beam Parameters of RF Linac for GBS-ELI-NP	528
	P.S. Tracz IFIN-HH, Bucharest - Magurele, Romania
	The Gamma Beam System at the ELI-NP (Extreme Light Infrastructure - Nuclear Physics) currently being constructed in Magurele/Bucharest, Romania will be a high-brilliance advanced source of gamma rays based on laser Compton back-scattering. For a successful operation of the GBS a high brightness low emittance electron beam is of crucial importance. The warm RF linac is designed in two stages - one with the beam up to 300 MeV, and another one about 720 MeV. The S-band photo-injector is combined with a C-band linac. The beam is transported by transfer lines to the interaction points. In this paper we report the results of computer simulations of the electron beam transport in the low energy linac and transfer line up to the low energy interaction point (IP1). The simulation model makes it possible to predict the beam parameters to be recuperated in case of failure of any magnetic or accelerating elements as well as it enables to determine the optimal parameters of replaced components. It will be used for the development of the Gamma Beam System in the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO085
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TUPO088	Measurement of Diagnostics Response by RF Parameters for Hard X-ray Line in PAL-XFEL*	531
	H. Yang PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: *This work is supported by MSIP, Korea. PAL-XFEL is a hard x-ray (HX) and soft x-ray (SX) FEL machine to generate 2.5 - 15 keV FEL in the HX line and 0.28 - 1.2 keV FEL in the SX line. The HX line consists of an e-gun, a laser heater, S-band accelerators, an X-band linearizer, three bunch compressors (BC), and a dog-leg line. PAL-XFEL maintains the stable operation and FEL delivery with more than 98% availability due to machine stabilities including RF modules. In order to investigate the stable operation, we measure the diagnostics response for bunch charge monitors, energy beam position monitors, bunch length monitors, and a FEL intensity with a photon beam position monitor by RF parameters - RF amplitude and phase for an e-gun, accelerators, and a linearizer. In this paper, we present mainly corresponding RF parameters for e-beam and FEL jitters by this measurement and matrix analysis.
	Poster TUPO088 [0.281 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO088
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TUPO090	Electron-beam Matching to Solenoid Magnetic Field in a Klystron	534
	S.J. Park, Y.J. Park PAL, Pohang, Kyungbuk, Republic of Korea J.H. Hwangpresenter, S.-G. Shin POSTECH, Pohang, Kyungbuk, Republic of Korea S.Y. Hyun, D.H. Yu Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea
	Funding: The work was supported by the National R&D Program (grant number: 2016R1A6B2A01016828) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT, Korea. High-power klystrons for particle accelerators employ high-perveance electron guns which are usually focused by Solenoid magnets. The electron beam should be optically matched to the downstream magnetic field to prevent the beam from scalloping. The task usually requires a series of computer simulations with many design parameters, and therefore requires extensive(sometimes exhaustive) efforts if not aided by a priori experiences. In order to alleviate the difficulties we have developed a matching procedure which is systematic and reliable. In this article we describe the procedure with an example design of a 400-kV 500-A electron beam with radius 8 - 11 mm.

Paper

Title

Page

About the Limits for the Accelerated Beam Current in the LUE-200 Linac of the IREN Facility

320

A.P. Sumbaev
JINR, Dubna, Moscow Region, Russia
A.M. Barnyakov, A.E. Levichev
BINP SB RAS, Novosibirsk, Russia

The beam current loading of the accelerating fields is discussed for the linear accelerator LUE-200 of IREN facility. LUE-200 electron Linac consits of two disk loaded travelling wave accelerating structure with the operating frequency of 2856 MHz and power compression SLED-type system. The limits by the accelerated beam current are defined for different pulse durations of the beam current and RF power. The calculated results are discussed and compared with the measurements.

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paper received ※ 12 September 2018 paper accepted ※ 22 January 2019 issue date ※ 18 January 2019

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TUPO002

Electron Gun for 100 MeV / 100 kW Linear Accelerator of Electrons as the Driver of Nuclear Subcritical Assembly Neutron Source

323

SPWR008

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

M. Moisieienko, O. Bezditko, A. Mytsykov, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine

100 MeV / 100 kW linear electron accelerator of The "neutron source" nuclear subcritical assembly uses the 120 KW triode electron gun as the primary source of electrons. The gun is designed, manufactured and tested at IHEP, Beijing, China. At present, the gun is installed, tested. The maximum impulse current of the gun equal to 2 A. Under design operation, the impulse current of the gun equal to 0.55 A.The report describes the construction of a 120 kV triode electron gun, the results of testing and test operation.

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO003

Development of CW Heavy Ion Linac at IMP

326

TUOP08

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

X. Yin, H. Du, Y. He, Q.Y. Kong, X.N. Li, Z.S. Li, L.Z. Ma, J. Meng, C. Qian, L.T. Sun, K.D. Wang, J.X. Wu, J.W. Xia, W.J. Xie, Z. Xu, Y.Q. Yang, Q.G. Yao, Y.J. Yuan, W. Zhang, X.Z. Zhang, Y. Zhang, H.W. Zhao, Z.Z. Zhou
IMP/CAS, Lanzhou, People’s Republic of China
J.E. Chen, S.L. Gao, G. Liu, Y.R. Lu, Z. Wang, X.Q. Yan, K. Zhu
PKU, Beijing, People’s Republic of China

A new heavy ion linac as the injector for the Separated Sector Cyclotron (SSC), named SSC-Linac[1], is being under constructed at the national laboratory Heavy Ion Research Facility in Lanzhou (HIRFL). The SSC-Linac mainly consists of a 4-rod RFQ and three IH-DTL cavities which can accelerate ion of A⁄q≤7from 3.73 keV/u to 1.025 MeV/u. Both of themoperating at 53.667MHz had been developed. In the commissioning, ions weresuccessfully accelerated to 0.295MeV/u by IH-DTL1. The beam commissioningof the IH-DTL2 which can accelerate the ion to 0.586MeV/u will come soon. In this paper, the recent R&D progress of the SSC-Linac including the development of key components and the beam commissioning results arepresented.

Slides TUPO003 [7.335 MB]

Poster TUPO003 [0.810 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO003

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO004

RF Design and Cold Model Measurement of an IH-DTL for HIMM Injector

329

H. Du, Q.Y. Kong, Z.S. Li, K.D. Wang, X. Yin
IMP/CAS, Lanzhou, People’s Republic of China

An interdigital H-mode drift tube linac (IH-DTL) will be constructed as a postinjector linac for the Heavy Ion Medical Machine (HIMM). Its resonant frequency, injec-tion and final energies are determined from beam dynamics and hardware parameters considerations of the entire machine to be 162.5MHz, 600keV/u and 4MeV/u, respectively. The beam duty cycle of the injector linac is less than 0.1% based on the injection requirements of the synchrotron. Beam dynamics and RF structure design and optimize of the IH-DTL has been finished. The maximum surface electric field is less than 2.0-times the Kilpatric limit for accelerating C⁴⁺ beam. This IH-DTL contains 42 accelerating gaps and two focusing quadrupole triplets. In order to examine the field distribution of the IH-DTL which reaches the length of 3.17m, an aluminum alloy 1:1 cold model cavity with 4 moveable tuners and 2 empty focusing magnet shell was constructed. The relative intertube-distance errors are less than ±50μm. The measurements show that the gap voltage values can match the CST-MWS simulating results within relative difference of ±3% by adjusting the 4 moveable tuners.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO004

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO005

Initial Beam Commissioning of LEAF at IMP

332

Y. Yang, W.P. Dou, X. Fang, Y.H. Guo, H. Jia, L. Jing, X.J. Liu, L. Lu, W. Lu, W. Ma, L.T. Sun, L.P. Sun, W. Wei, H.W. Zhao, Y.H. Zhai
IMP/CAS, Lanzhou, People’s Republic of China

A Low Energy intense-highly-charged ion Accelerator Facility (LEAF), which mainly includes an ECR ion source, LEBT and an 81.25 MHz RFQ, was designed to produce and accelerate heavy ions, from helium to uranium with A/Q between 2 and 7, to the energy of 0.5 MeV/u. The typical beam intensity is designed up to 2 emA CW for the uranium beam. The facility has been successfully commissioned with He⁺ (A/Q=4) and N2+ (A/Q=7) beams and accelerated the beams in the CW regime to the designed energy of 0.5 MeV/u. Beam properties and transmission efficiencies were measured, indicating a good consistency with simulated data. After having briefly recalled the project scope and parameters, this paper describes the beam commissioning strategy and detailed commissioning results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO005

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO007

FRIB Fast Machine Protection System: Chopper Monitor System Design

336

TUOP02

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

Z. Li, D. Chabot, S. Cogan, S.M. Lidia, R.C. Webber
FRIB, East Lansing, USA

Funding: Work supported by Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The Facility for Rare Isotope Beams tunes the beam power from 0 to 400KW by chopping the beam current with a beam chopper in the Low Energy Beam Transport. A chopper monitoring system is employed to verify proper chopper operation to avoid delivery of undesired high-powered beam and to inhibit beam for machine protection purposes. The system monitors the incoming beam gate time structure, the chopper switch high voltage pulses, the chopper electrode charge/discharge currents, and the status of machine protection system. It is designed to switch off the beam within tens of nanoseconds of a detected fault. Chal-lenges include a dynamic beam gate pulse structure with pulse lengths as short as 0.6 µs and high voltage power supply current pulses of ~25 ns. A high speed "integrate and hold circuit with reset", Field Program-mable Gate Array based digital control circuit and high speed ADC circuit were developed to fulfil the re-quired functions. Design approach, simulation, and test results with the beam are the focus of this paper.

Slides TUPO007 [1.082 MB]

Poster TUPO007 [1.321 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO007

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO009

Heat Treatment for a Prototype Half-Wave Resonator Cavity

339

Y. Jung, B.H. Choi, J. Joo, H.C. Jung, H. Kim, J.W. Kim, Y. Kim, J. Lee, S. Lee
IBS, Daejeon, Republic of Korea

Heat treatment, 650C for 10hrs, was carried out to improve the performance of a half-wave resonator cavity. In this presentation, we report how the heat treatment was performed. X-ray diffraction analysis and residual gas analysis were performed to investigate the effect of the heat treatment on the cavity performance.

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TUPO010

Muon Acceleration Test with the RFQ Towards the Development of the Muon Linac

342

SPWR015

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

R. Kitamura
University of Tokyo, Tokyo, Japan
S. Bae, S. Choi, B. Kim
SNU, Seoul, Republic of Korea
Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, T. Yamazaki
KEK, Tsukuba, Japan
K. Hasegawa, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Iijima, Y. Sue
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
H. Iinuma, Y. Nakazawa
Ibaraki University, Hitachi, Ibaraki, Japan
K. Ishida
RIKEN Nishina Center, Wako, Japan
S. Li
The University of Tokyo, Graduate School of Science, Tokyo, Japan
M. Otani, N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
G.P. Razuvaev
Budker INP & NSU, Novosibirsk, Russia

The muon linac to accelerate muons 212 MeV is planned in order to measure the muon dipole moments precisely in the J-PARC. The muon acceleration with a RF accelerator hasn’t been demonstrated yet in the world. Therefore the muon acceleration test with the RFQ as the feasibility test of the muon linac was demonstrated at the Muon D line in the J-PARC MLF. Conventional muons are cooled with producing ultra-slow muons using the muonium production and the ionization laser for the muon linac. However these apparatuses couldn’t be used because of the limitation of the experimental area in the acceleration test. Therefore the conventional muon was converted to the negative muonium ion (Mu-) with less than 2 keV using the thin aluminum foil target as the easy cooling method. The Mu- was finally accelerated to 90 keV using the RFQ. The accelerated Mu- was selected with a diagnostic beam line and identified with the Time-Of-Flight measurement using a MCP detector. The result of the world’s first muon acceleration test with the RFQ will be reported in this presentation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO010

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TUPO011

Upgrade of Heavy Ion Injector I-3 at ITEP

346

N.N. Alexeev, P.N. Alekseev, V. Andreev, T. Kulevoy, A.D. Milyachenko, V.I. Nikolaev, Yu.A. Satov, A. Shumshurov, A. Zarubin
ITEP, Moscow, Russia

Heavy ion injector I-3 represents two-gap 2.5 MHz resonator with accelerating voltage 2x2 MV. It‘s used with laser ion source for acceleration of heavy ions in wide range of charge to mass ratio. As a result of modernization, injector structure will be supplemented by the second two-gap resonator, rf voltage will be increased to 3x4 MV and accelerated beam structure has to be improved by increasing accelerating frequency to 5 MHz. Design features of upgraded linac and peculiarity of beam dynamics for different types of ions are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO011

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paper received ※ 03 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO012

Compact Multipurpors Facility - BELA

349

T. Kulevoy, R. Fatkullin, A.V. Kozlov, G. Kropachev, D.N. Selesnev, A.I. Semennikov, A. Sitnikov
ITEP, Moscow, Russia
T. Kulevoy
MEPhI, Moscow, Russia
T. Kulevoy
NRC, Moscow, Russia

In ITEP the project of multidiscipline facility Based on ECR ion source and Linear Accelerator (BELA) is started. The injector part of facility is based on combinations of ECR ion source and dc H⁺ and He⁺ source will provide the multi beams irradiation of the reactor materials for modeling experiments. The cw RFQ and following DTL will enable the set of experimental activity both for fun-damental physics and for practical applications.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO012

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO013

Commissioning Status of the LIGHT Development Machine

352

G. De Michele, J. Adam, D. Aguilera Murciano, A. Benot-Morell, R. Bonomi, F. Cabaleiro Magallanes, M. Caldara, G. D’Auria, A. Degiovanni, M. Esposito, S. Fanella, D. Fazio, D.A. Fink, Y. Fusco, M. Gonzalez, P. Gradassi, L. Kobzeva, G. Levy, G. Magrin, A. Marraffa, A. Milla, R. Moser, P. Nadig, G. Nuessle, A. Patino-Revuelta, T. Rutter, F. Salveter, A. Samoshkin, L. Wallet
A.D.A.M. SA, Meyrin, Switzerland
M. Breitenfeldt, C. Candolfi, G. Castorina, M. Cerv, V.A. Dimov, M.T. Gallas, S. Gibson, A. S. Gonzalez, Ye. Ivanisenko, A. Jeff, V. F. Khan, S. Magnoni, J.L. Navarro Quirante, H. Pavetits, P. Paz Neira, S.G. Soriano, P. Stabile, K. Stachyra, A. Valloni, C. Zannini
AVO-ADAM, Meyrin, Switzerland
G. D’Auria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

ADAM (Application of Detectors and Accelerators to Medicine) is a CERN spin-off company currently working on the construction and testing of the LIGHT (Linac for Image-Guided Hadron Therapy) machine. LIGHT is an innovative high-frequency linac based proton therapy system designed to accelerate protons up to 230 MeV: it consists of three different linac sections i.e. a 750 MHz Radio Frequency Quadrupole (RFQ) accelerating the beam up to 5 MeV; a 3 GHz Side Coupled Drift Tube Linac (SCDTL) up to 37.5 MeV; and a 3 GHz Coupled Cavity Linac (CCL) section up to 230 MeV. The compact and modular design is based on cutting edge technologies developed for particle colliders and adapted to the needs of hadron therapy beams. The LIGHT development machine is currently being built at CERN and this paper describes its design aspects and its different stages of installation and commissioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO013

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TUPO014

TRIUMF ISAC LINAC Developments and Upgrades

355

Z.T. Ang, T. Au, Y. Bylinskii, K. Fong, J.J. Keir, D. Lang, R.E. Laxdal, R. Leewe, B.S. Waraich, Z.Y. Yao, Q. Zheng, V. Zvyagintsev
TRIUMF, Vancouver, Canada

TRIUMF ISAC accelerator complex is in consists of ISAC-I room temperature linac and ISAC-II superconducting linac structure. ISAC-I linac has seventeen RF systems in operation for about twenty years, and ISAC-II linac has forty superconducting QWR RF cavities in operation for more than ten years. A small ISAC booster 3-gap structure at 11.78 MHz located in upstream of RFQ has been designed and installed for energy matching to RFQ. A sliding mode extremum seeking control for LLRF control was developed and implemented in operation. Six of DTL systems have been working in the control mode. Two of them had been commissioning and in operation one and half year reliably. RFQ, two more DTL system, HEBT rebuncher and DSB buncher system will be upgraded in the sliding mode control soon. Twenty ISAC-II SBC superconducting cavity RF power amplifiers were upgraded from YV-229 triode tube amplifier into solid state amplifier(SSA). The prototype and four SSAs have been commissioned in 2017 and in operation successfully. The rest of 16 SSA have been tested in RF lab and installed for operation at the mid of this year.

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paper received ※ 04 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO015

The CW Beam Experiment of Window-type RFQ

TUOP11

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K. Zhu
PKU, Beijing, People’s Republic of China

Funding: work supported by NSFC. Grand No. 2014CB845503
A window-type RFQ is designed and fabricated by Peking University. It is planed to accelerate 50mA deuteron cw beam to 1MeV. The 60kV intervane voltage is designed to decrease the risk of high voltage discharge since the RFQ works in cw mode. High power test shows that the intervane voltage is over 60kV when the Cavity power consumption is 48kW. The beam experiment was done and 1.8mA cw beam was obtained at exit of RFQ with over 90% transmission efficiency. This paper will present the cold model measurement, high power RF conditioning and beam experiment result.

Slides TUPO015 [2.051 MB]

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TUPO016

High Frequency RFQ Design and LEBT Matching for the CERN TwinEBIS Ion Source

358

SPWR013

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V. Bencini, J.-B. Lallement, A.M. Lombardi, H. Pahl, J. Pitters, F.J.C. Wenander
CERN, Geneva, Switzerland
M. Breitenfeldt
AVO-ADAM, Meyrin, Switzerland
A.I. Pikin
BNL, Upton, Long Island, New York, USA

An Electron Beam Ion Source (EBIS) is being developed at CERN for production of highly charged ions, for instance fully stripped 12C. The focus has so far been on the electron gun design, aiming for a high current compression, which results in a rapid ionisation process and thereby high repetition rate. Initial commissioning tests of such an electron gun, the so-called MEDeGUN, have already been performed and we are now in the process of designing a multi-purpose ion extraction and diagnostics line. The Low Energy Beam Transport (LEBT) line will transport the ions into the downstream Radio Frequency Quadrupole (RFQ) with a nominal energy of 15 keV/u. The 750 MHz RFQ is designed to accelerate ions from 15 keV/u up to the final energy of 2.5 MeV/u. After the RFQ design was finalized and its acceptance calculated, the beam matching to the RFQ was studied, finding a set of parameters for the LEBT that maximize the transmission through the RFQ. Details of the RFQ design, of the LEBT matching procedure and its final results are illustrated in this paper.

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TUPO017

The New Light Ion Injector for NICA

362

B. Koubek, M. Basten, H. Hoeltermannpresenter, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede
BEVATECH, Frankfurt, Germany
A.V. Butenko, D.E. Donets, B.V. Golovenskiy, A. Govorov, K.A. Levterov, D.A. Lyuosev, A.A. Martynov, V.A. Monchinsky, D.O. Ponkin, K.V. Shevchenko, I.V. Shirikov, E. Syresin
JINR, Dubna, Moscow Region, Russia
C. K. Kampmeyer, H. Schlarb
DESY, Hamburg, Germany

Within the upgrade scheme of the injection complex of the NICA project and after a successful beam commissioning of a heavy ion linac, Bevatech GmbH will build a first part of a new light ion linac as an injector for the Nuclotron ring. The linac will provide a beam of polarised protons and light ions with a mass to charge ratio up to 3 and an energy of 7 MeV/u. The mandate of the Linac does not only include the hardware for the accelerating structures, focusing magnets and beam diagnostic devices, but also the LLRF control soft- and hardware based on the MicroTCA.4 standard in collaboration with the MicroTCA Technology Lab at DESY. An overview of the Linac is presented in this paper.

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paper received ※ 10 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO019

SPIRAL2 Cryogenic System Thermodynamic Behavior Prediction Through Dynamic Modeling

366

A.V. Vassal, P.-E. Bernaudin, A. Ghribi
GANIL, Caen, France
P.-E. Bernaudin
CEA/DSM/IRFU, France
P. Bonnay, F. Bonne
CEA/INAC, Grenoble Cedex 9, France
F. Millet
CEA, Grenoble, France

SPIRAL 2 (Caen, France) is a state of the art superconducting linear accelerator composed of 26 quarter wave accelerating cavities. Each cavity is plunged in a liquid helium bath at 4.4 K itself surrounded by a thermal shield at 70 K. In this paper, a dynamic model of the cryogenic systemof the LINAC is proposed. Thismodel simulates the dynamic behaviour of the 19 cryomodules and their respective valves box connected through the cryodistribution. Model accuracy is evaluated through a comparison between simulation and experimental data. Using the model we should be able to predict the behaviour of the cryogenic system for different beam operating conditions of the accelerator. The model also highlights the link between the cryogenic system and the cavity RF losses through a dynamic estimator of those RF losses in the cavity walls. The latter could be used as a rough estimator of the quality factor of a cavity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO019

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paper received ※ 13 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO020

Microphonics Investigation of ARIEL e-Linac Cryomodules

370

Y. Ma, K. Fong, M. Keikha, J.J. Keir, D. Kishi, S.R. Koscielniak, D. Lang, R.E. Laxdalpresenter, R.R. Nagimov, Z.Y. Yao, Q. Zheng, V. Zvyagintsev
TRIUMF, Vancouver, Canada
L. Lilje
DESY, Hamburg, Germany

Now the stage of the 30MeV portion of ARIEL (The Advanced Rare Isotope Laboratory) e-Linac is under commissioning which includes an injector cryomodule (ICM) and the 1st accelerator cryomodule (ACM1) with two cavities configuration. In this paper, the progress of the microphonics investigation and suppression of ICM and ACM1 is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO020

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO022

Manufacturing of X-band Accelerating Structures: Metrology Analysis and Process Capability

374

J. Sauza-Bedolla, S. Atieh, N. Catalán Lasheras
CERN, Geneva, Switzerland

The fabrication tolerances of RF components are essential for CLIC X-band accelerating structures to perform efficiently. On one hand, the capability of high power accelerating structures depends on the shape accuracy and the asperity of the inner surfaces, when microwaves pass through the cavity. On the other hand, surface flatness and dimensional tolerances are necessary to guarantee a correct assembly process. Hence, the discs that build up the structure require sub-micrometre specifications and, in order to meet all the needs, ultra-precision machining using single crystal diamond tools is mandatory. This paper shows the analysis of the metrology results of the fabrication of 118 discs (4 accelerating structures). Dimensional and form tolerances are studied following the production order to find drifts in the production and to predict the impact on the assembly process. Finally, process capability is evaluated.

Poster TUPO022 [2.987 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO022

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paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO023

Preserving Micron Tolerances Through the Assembly Process of an X-band Accelerating Structure

377

J. Sauza-Bedolla, N. Catalán Lasheras, A. Grudiev, S. Lebet, E. Rodriguez-Castro, P. Sobrino-Mompean, A. Solodko, K. T. Szypula
CERN, Geneva, Switzerland
H. Bursali
IZTECH, Izmir, Turkey

The CLIC structures are designed for operating at X-Band, 2π/3 traveling wave mode with a loaded 100 MV/m gradient. Mechanical tolerances, at the submicron level, are required to satisfy the RF design constraints and beam dynamics and are reachable using ultra-precision diamond machining. However, inherent to the manufacturing process, there is a deviation from the nominal specifications and as a result; incorrect cavity dimensions produce a less efficient linac. Moreover, the assembly process increase the difference from the original geometry. As part of a cost and manufacturability optimization of the structures for mass production, this study aims to identify a correlation between frequency deviations and geometrical errors of the individual discs of the accelerating structures caused by the production process. A sensitivity analysis has been carried out to determine the most critical parameters. Cell frequency deviations have been monitored by bead pull measurements before and after bonding. Several accelerating structure prototypes have been tested to determine our assumptions and to assess if the assembly process preserves the tight tolerances achieved by machining.

Poster TUPO023 [1.443 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO023

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paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO027

Series Production of the Specific Waveguide Distribution for the European XFEL at DESY

380

TUPO024

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

B. Yildirim, S. Choroba, V.V. Katalev, P. Morozov, Y. Nachtigal
DESY, Hamburg, Germany
E.M. Apostolov
Technical University of Sofia, Sofia, Bulgaria

Series Production of the Specific Waveguide Distribution for the European XFEL at DESY B.Yildirim, S.Choroba, V.Katalev, P.Morozov, Y.Nachtigal, E.Apostolov The European XFEL uses 100 accelerating cryomodules. One RF station with 10 MW klystron supplies four cryomodules, each with eight cavities, through a waveguide distribution system. The RF station operates at 1.3 GHz, 1.37 ms pulse width and 10 Hz repetition rate. The results of the cryomodule test have shown however different maximum gradients for each cavity. The maximum gradient has been measured between 11 MV/m and 31 MV/m, which requires the cavity power from 29 kW to 230 kW. To operate with the maximum energy for every cryomodule, it is necessary to supply individual power to the cavity. In this case the weakest cavity problem can be avoided. For this goal a specific waveguide distribution has been developed. 100 waveguide distributions have been successfully tailored, produced and tested at the Waveguide Assembly Test Facility (WATF) at DESY and finally assembled to the cryomodules. We present the series production of the specific waveguide distributions at the WATF.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO027

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paper received ※ 06 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO028

Retreatment of European XFEL Series Cavities at DESY as Part of the Repair of European XFEL Accelerating Modules

384

S. Sievers, N. Krupka, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, N. Steinhau-Kühl, E. Vogel, H. Weise, B. van der Horst
DESY, Hamburg, Germany
M. Wiencek
IFJ-PAN, Kraków, Poland

For the European XFEL 10² accelerating modules were built and tested. Several accelerating modules had to be reworked due to different kinds of non-conformities. The extent of this rework varied greatly. At the end of production four accelerating modules could not be qualified in time before the tunnel installation was to be finished in September 2016. Meanwhile the cavity strings of two of these accelerating modules have been disassembled in the DESY clean room. The cavities have been retreated at DESY either by additional high pressure water rinsing or BCP flash chemical treatment. All cavities were vertically tested and 15 out of 16 were qualified for the reassembly of the cavity strings. One accelerating module will be reassembled completely and tested until the end of 2018; the other will follow in the first half of 2019. We report on retreatment procedures and performance of these cavities.

Poster TUPO028 [1.662 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO028

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paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO029

Highlights of the XM-3 Cryomodule Tests at DESY

388

J. Branlard, V. Ayvazyan, A. Bellandi, J. Eschke, C. Gumus, D. Kostin, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz
DESY, Hamburg, Germany
W. Cichalewski
TUL-DMCS, Łódź, Poland

To investigate the feasibility of the continuous wave (cw) upgrade of the European XFEL (E-XFEL) DESY, on-going tests are performed on E-XFEL prototype and production cryomodules since 2011. For these studies, DESY’s Cryo-Module Test Bench (CMTB) has been equipped with a 10⁵ kW cw operating IOT in addition to the 10MW pulsed klystron, making CMTB a very flexible test stand, enabling both cw and pulse operation. For these tests, E-XFEL-like LLRF electronics is used to stabilize amplitude and phase of the voltage Vector Sum (VS) of all 8 cavities of the cryomodule under test. The cryomodule most often tested is the pre-series XM-3, unique since it is housing one fine grain niobium and seven large grain niobium cavities. In autumn 2017, additional spacers were installed on all 8 input couplers to increase the maximum reachable loaded quality factor Ql beyond 2·10⁷. With higher Ql, up to 6·10⁷ for 6 cavities and 2.7·10⁷ for 2 cavities, we have investigated the VS stability and SRF-performance of this cryomodule under various conditions of cooling down rate and operation temperature 1.65K, 1.8K and 2K, at gradients up to ca. 18MV/m. The results of these tests are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO029

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO030

Precise Evaluation of Characteristic of the Multi-layer Thin-film Superconductor Consisting of NbN and Insulator on Pure Nb Substrate

391

TUOP03

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

R. Katayama, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
C.Z. Antoine
CEA/IRFU, Gif-sur-Yvette, France
A. Four
CEA/DRF/IRFU, Gif-sur-Yvette, France
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

In recent years, it has been pointed out that the maximum accelerating gradient of a superconducting RF cavity can be pushed up by coating the inner surface of the cavity with a multilayer thin-film structure that consists of alternating insulating and superconducting layers. In this structure, the principal parameter that limits the performance of the cavity is the critical magnetic field or effective Hc1 at which vortices start penetrating into the superconductor layer, and it is predicted to depend on the combination of the film thickness. We made samples that have NbN/SiO2 thin-film structure on pure Nb substrate with several thicknesses of NbN film deposited using DC magnetron sputtering method. Here, we report the measurement results of effective Hc1 of the NbN sample with a thickness of 200 nm by using the third-harmonic voltage method. In addition, we report the preliminary results to evaluate the dependence of the effective Hc1 on the thickness of the NbN film in the range 50 nm-200 nm.

Slides TUPO030 [0.305 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO030

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paper received ※ 18 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO031

Investigation of the Surface Resistance of Niobium Between 325 MHz and 1300 MHz Using a Coaxial Half-wave Cavity

395

TUOP04

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

H. Park, S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA

The Center for Accelerator Science at Old Dominion University has built a half-wave coaxial cavity (*) to measure the surface resistance of niobium as a function of frequency, temperature, rf field, preparation techniques, over a wide range of frequencies of interest for particle accelerators. The characteristics of the half-wave coaxial cavity provide these information on a same surface. The preliminary results showed clearly the frequency dependence of residual surface resistance (**). After establishing baseline, we have conducted a study of low temperature baking effect on the surface resistance under controlled environment. This paper will describe the details of the test procedure, results and we will explore underlying physics of the phenomenon.
* H. Park et al., MOPB003, Proc. SRF2015, http://jacow.org/
** H. Park et al., THPB080, Proc. SRF2017, http://jacow.org/

Slides TUPO031 [0.966 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO031

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paper received ※ 17 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO032

First Test Results of Superconducting Twin Axis Cavity for ERL Applications

398

H. Park, S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Hutton, F. Marhauser, H. Park
JLab, Newport News, Virginia, USA

Superconducting cavities with two beam pipes had been proposed in the past for energy recovery linac applications. The relatively complex geometry of those cavities presented a serious challenge for fabrication and surface processing. Main concerns have now been overcome with the production and successful RF testing of a new elliptical twin-axis cavity proposed by Jefferson Lab and optimized by the Center for Accelerator Science at Old Dominion University in the frame of a DoE accelerator stewardship program. The cavity design provides uniform accelerating or decelerating fields for both beams. This paper describes the cavity design, fabrication experience, and the first cold RF test results and explores potential applications especially for Jefferson Lab s EIC (JLEIC).

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO032

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paper received ※ 20 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO033

Cryogenic Test Results of the SPS Prototype RF-dipole Crabbing Cavity with Higher Order Mode Couplers

402

TUOP05

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

S.U. De Silva, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
Z. Li
SLAC, Menlo Park, California, USA
H. Park
JLab, Newport News, Virginia, USA

The rf-dipole crabbing cavity planned for the LHC High Luminosity Upgrade is designed to deliver a transverse kick of 3.34 MV; crabbing the proton beam in the horizontal plane. The proton beams of the LHC machine operating at 7 TeV each sets high impedance thresholds on the crabbing cavity systems. The rf-dipole crabbing cavity is designed with a two higher order mode couplers to suppress those HOMs. The first prototype of the HOM couplers are fabricated at Jefferson Lab. This paper reports the cryogenic test results of the HOM couplers with the SPS prototype rf-dipole cavity.

Slides TUPO033 [0.859 MB]

Poster TUPO033 [1.838 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO033

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paper received ※ 17 September 2018 paper accepted ※ 09 November 2018 issue date ※ 18 January 2019

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TUPO035

Determination of the Field-dependence of the Surface Resistance of Superconductors from Cavity Tests

405

TUOP12

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

J.R. Delayen, S.U. De Silva, H. Park
ODU, Norfolk, Virginia, USA

Cryogenic tests of superconducting cavities yield an average surface resistance as a function of the peak surface magnetic field. An analytical formalism has been developed to extract the actual field dependence of the surface resistance from cavity tests and is applied to coaxial cavities and cavities of more complex geometries.

Slides TUPO035 [0.524 MB]

Poster TUPO035 [1.002 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO035

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO036

Vertical Test Results of Plasma In-situ Cleaning on Low Beta HWR Cavity

408

TUOP06

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

A.D. Wu, H. Guo, Y. He, C.F. Hu, S.C. Huang, C.L. Li, Y.M. Li, X. Liu, F. Pan, Y.K. Song, P.R. Xiong, L. Yang, W.M. Yue, C. Zhang, S.H. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

Field emission occurred in SRF cavity is the major limitation to operate at high gradient with stability. The plasma in-situ cleaning for the low beta HWR cavity was carried out to remove the hydrocarbons contaminants on the inner cavity surface. And the vertical test results indicated that the field emission effect was relieved with the increasing of the quench point and emission set-on point. Thus, oxygen active plasma processing can be an effective method to solve the field emission issues for the low beta HWR cavity.

Slides TUPO036 [1.281 MB]

Poster TUPO036 [0.672 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO036

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paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO038

Several Experimental Phenomena of Sn Nucleation on Nb Surface Observed at IMP

412

TUPO037

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

Z.Q. Yang, Y. He, F. Pan
IMP/CAS, Lanzhou, People’s Republic of China

Nucleation process is an important step that affects the quality of Nb3Sn films coated by vapor diffusion method. A uniform distribution of nucleation centers is essential to the uniformity of Nb3Sn films. In this paper we report several experimental phenomena on the Sn nucleation on Nb surface. Better nucleation in the downstream of the pumping direction was observed. Influence of SnCl2 partial pressure inhomogeneity was studied. Samples with higher SnCl2 partial pressure have denser nucleation, which means homogeneous SnCl2 pressure is a critical factor to the uniform nucleation. Less-nuclear zones, mainly distributed at cracks, grain boundaries and even some whole grain surfaces, were found on the surfaces of all samples. The less-nuclear zones may result in the low tin regions of the Nb3Sn cavities. The specific solution to the less-nuclear problem was proposed. These studies help to better understanding of the mechanism underlying the nucleation process and will be useful foundation for the follow-up Nb3Sn/Nb project at IMP.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO038

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO039

Tests of the Balloon Single Spoke Resonator

417

TUOP07

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Z.Y. Yao, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, H. Liu, Y. Ma, B. Matheson, B.S. Waraich, Q. Zheng, V. Zvyagintsev
TRIUMF, Vancouver, Canada

A balloon variant of the single spoke resonator (SSR) has been designed, fabricated and tested. The cavity is the SSR1 prototype for the Rare Isotope Science Project (RISP) in Korea. It is specifically designed to reduce the likelihood of multipacting barriers near the operating point. A systematic multipacting study leads to a novel geometry, a spherical cavity with re-entrant irises and a spoke. Other than eliminating multipacting around operational gradient, the balloon shape also provides competitive RF parameters and robust mechanical structure. Cryostat cold tests demonstrated cavity performance on each design aspect. The cold tests will be reported in this paper.

Slides TUPO039 [25.279 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO039

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paper received ※ 17 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO040

Tests of Multi-frequency Coaxial Resonators

420

Z.Y. Yao, J.J. Keir, P. Kolb, A. Kong, R.E. Laxdal, B. Matheson, E. Thoeng, B.S. Waraich, Q. Zheng, V. Zvyagintsev
TRIUMF, Vancouver, Canada

A significant issue in low beta resonators is medium field Q-slope (MFQS) at 4K. To study the MFQS and the field dependence of surface resistance in low beta resonators, a quarter-wave resonator (QWR) and a half-wave resonator (HWR) were designed to be tested at integer harmonic frequencies of 200MHz, and up to 1.2GHz. A series of chemistry and heat treatments are proposed to these cavities. A systemic study on the surface resistance of the coaxial resonators associating with post-processing, RF field, and frequency is in progress. The cavities were designed and fabricated. The cold test results will be discussed in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO040

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paper received ※ 17 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO041

LCLS-II Cavity Higher Order Modes Coupler Tuning Optimization and Challenges at Jefferson Lab

423

A.D. Solopova, D. Forehand, A.D. Palczewski
JLab, Newport News, Virginia, USA
T.N. Khabiboulline
Fermilab, Batavia, Illinois, USA

LCLS-II is a new XFEL linac based on 1.3GHz SRF linac. Half of the LCLS-II cryomodules are being produced at Jefferson Lab. This paper summarizes the Higher Order Mode filter tuning challenges at Jefferson Lab and describes optimization of the procedure for a 9-cell Tesla type cavity and its integration into a cryomodule production line.

Poster TUPO041 [0.719 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO041

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paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO042

RF Results of Nb Coated SRF Accelerator Cavities via HiPIMS

427

M.C. Burton, A.D. Palczewski, H.L. Phillips, C.E. Reecepresenter, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA
R.A. Lukaszew
The College of William and Mary, Williamsburg, Virginia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Bulk Niobium (Nb) SRF (superconducting radio frequency) cavities are currently the preferred method for acceleration of charged particles at accelerator facilities around the world. Since the SRF phenomena occurs within a shallow depth of 40 nm (for Nb), a proposed option has been to deposit a superconducting Nb thin film on the interior of a cavity made of a suitable alternative material such as copper or aluminum. While this approach has been attempted in the past using DC magnetron sputtering (DCMS), such cavities have never performed at the bulk Nb level. However, new energetic condensation techniques for film deposition offer the opportunity to create suitably thick Nb films with improved density, microstructure and adhesion compared to traditional DCMS. One such technique that has been developed somewhat recently is ’High Power Impulse Magnetron Sputtering’ (HiPIMS). Here we report early results from various thin film coatings carried out on 1.3 GHz Cu Cavities, a 1.5 GHz Nb cavity and small Cu coupon samples coated at Jefferson Lab using HiPIMS.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO042

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO043

New Progress with HF-free Chemical Finishing for Nb SRF Cavities

431

H. Tian, J. Carroll, C.E. Reecepresenter, B. Straka
JLab, Newport News, Virginia, USA
T.D. Hall, M.E. Inman, R. Radhakrishnan, E.J. Taylor
Faraday Technology, Inc., Clayton, Ohio, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Jefferson Lab has implemented a bipolar pulsed electropolishing system for final chemical processing of niobium SRF cavities. This FARADAYIC bi-polar electropolishing (BPEP) has been applied to single cells, a 7-cell CEBAF C100 cavity, and to 9-cell TESLA-style cavities.* As a mechanistic characterization of the process emerges, the critical role played by the local current density during each cathodic pulse is becoming clear. This influences system and operational parameter refinement. We present current process parameters, removal characterization, and rf performance of the processed cavities. This is the fruit of collaborative work between Jefferson Lab and Faraday Technology, Inc. directed toward the routine commercialization and industrialization of niobium cavity processing. We also present supporting data from controlled-parameter coupon studies
* E.J. Taylor, et al. "Electrochemical system and method for electropolishing superconductive radio frequency cavities" U.S. Pat. No. 9,006, 147 (& international counterparts) issued April 14, 2015.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO043

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO045

Optimization of Dual Axis Asymmetric Cavity for Energy Recovery Linac

435

SPWR022

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Ya.V. Shashkov, A.M. Bulygin, M. Gusarova
MEPhI, Moscow, Russia
I.V. Konoplev
JAI, Oxford, United Kingdom
F. Marhauser
JLab, Newport News, Virginia, USA
A. Seryi
SLAC, Menlo Park, California, USA

Funding: The reported study was funded by RFBR according to the research project № 18-302-00990
Optimization of the dual axis asymmetric cavity was performed to minimize the ratio of the peak magnetic and electric fields values to the accelerating voltage, to increase the distance between operating and neighbouring modes as well as to reduce the manufacturing cost of the cavity. To reach the goals several solutions have been suggested bringing the ratios to the acceptable values and leading to simplification of the manufacturing of the structure.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO045

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO048

Study Progress of Pulse Laser Annealing for Niobium Film on Copper

438

SPWR021

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Y. Yang, B.T. Li, X.Y. Lu, W.W. Tan, L. Xiao, D. Xie, D.Y. Yang
PKU, Beijing, People’s Republic of China

Funding: Work supported by Major Research Plan of National Natural Science Foundation of China (No. 91026001).
The recent studies of laser annealing on niobium films on copper are reported. Annealing is normally used to deal with the surface, reducing defects and even chang-ing the microstructure of the coating film. Short pulse laser can produce a sharp step temperature field on the film thickness scale (μm), which anneals the surface without substrate heated. The laser annealing experi-ments of niobium thin film sample have been carried out, and according to SEM and FIB results, Nb films melted and recrystallization occurred. Grains growing up can be observed while the power density of laser pulse in-creased.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO048

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO049

Nitrogen Doping Study With 1.3 GHz Single Cell Superconducting Cavities

442

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

Nitrogen doping studies were carried out at Peking University. A series of 1.3 GHz single cell cavities fabricated with OTIC large grain niobium material were annealed and doped in the furnace of Peking University, and electropolished by a simple EP device. Light doping recipe and heavy doping recipe are both adopted for comparison. The results and analysis are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO049

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO050

Construction of Thin-film Coating System Toward the Realization of Superconducting Multilayered Structure

445

R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
Y. Iwashita, R. Katayama
Kyoto ICR, Uji, Kyoto, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Although S-I-S (superconductor-insulator-superconductor) multilayered structure is expected to increase the maximum acceleration gradient of SRF cavities, in order for it to function in reality, it is necessary to develop a coating processing that can realize high purity and quality superconducting thin-films. We launched the co-sputtering system to create superconducting alloy thin-films such as Nb3Sn and to research how the characteristics of them change depending on the coating conditions. The deposition rate of two elements was optimized by adjusting each input power, so we successfully obtained an alloy thin-film having appropriate composition ratio. In addition, we developed another experimental equipment for coating on the inner surface of the 3GHz TESLA type small cavities. A cylindrical shape Nb in which some permanent magnets are inserted was adopted as the sputtering target. Glow discharge of the target was confirmed, and the inner-sputtering test was conducted. This presentation reports the specifications of the two sputtering apparatuses and the results of the coating test.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO050

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paper received ※ 18 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO051

Design Considerations of a Balloon-shaped SSR Superconducting Cavity

448

H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, S. H. Park, J.Y. Yoon
Korea University Sejong Campus, Sejong, Republic of Korea

A single spoke resonator (SSR, β = 0.51 and f = 325 MHz) is being developed at Korea University. It is well-known that a traditional spoke cavity having flat or round end walls has broad multipacting ranges in acceleration gradient, sometimes including operation region. In general, quite long conditioning time is consumed to overcome such multipacting barriers. In this study, we introduce a balloon-shaped SSR superconducting cavity for the multipacting mitigation due to structural simplicity. The electromagnetic modeling of the SSR was made based on the RF parameter optimization. The simulation results show much narrower multipacting bandwidth, compared to those for the traditional spoke cavity. Mechanical analyses with stiffening structure at maximum allowable working pressures indicate acceptable stresses at the SSR cavity wall. In addition, the resonant frequency shifts due to fabrication and processing for cold tests are predicted and power coupling and tuning mechanism are also investigated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO051

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paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO052

Design Study of a Prototype 325MHz RF Power Coupler for Superconducting Cavity

451

J.Y. Yoon, J.B. Bhang, H.J. Chapresenter, S.W. Jang, E.-S. Kim, K.R. Kim, C.S. Park, S. H. Park
Korea University Sejong Campus, Sejong, Republic of Korea
E. Kako
KEK, Ibaraki, Japan
D.Y. Kim, J. Lee
Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea
I. Shin
IBS, Daejeon, Republic of Korea

Funding: Korea University (Sejong Campus) in South KOREA
We present design studies of a prototype RF input power coupler, which provides RF powers to 325MHz cavities up to 18.5 kW in CW mode. The prototype power coupler is a coaxial capacitive type with single ceramic window. In order to optimize the RF coupler design, we performed multi-physics simulations, including electromagnetic, thermal, and mechanical analyses.

Poster TUPO052 [1.607 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO052

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO053

Fabrication of Nb Mushroom Shaped Cavity for Evaluation of Multi-layer Thin-film Superconductor

454

H. Oikawa
Utsunomiya University, Utsunomiya, Japan
K. Enami, H. Hayano, H. Inoue
KEK, Ibaraki, Japan
T. Higashiguchi
Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan

The accelerating gradient of the Nb superconducting RF cavity seems to reach the limit due to the RF critical magnetic field of the Nb material. To obtain more higher gradient, there has been proposed a method of increasing an RF critical magnetic field of the cavity inner surface by coating of multi-layer thin-film superconductor. It is needed to demonstrate improvement RF critical magnetic field of the RF cavity coated with multi-layer thin-film superconductor. To optimize thin-film superconductor, sample tests are required. A cavity for sample test is necessary to produce a strong RF magnetic field parallel to the surface of the sample for evaluating RF critical magnetic field. For such a cavity, we designed a mushroom shaped cavity made of Nb which is operated in cryogenic temperature. Input and pick up antenna coupler are also designed electrically and mechanically. The connection design of sample plate and cavity bottom plate in superconducting state is also designed. The Nb mushroom shaped cavity is under fabrication. Fabrication method and status are reported in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO053

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paper received ※ 17 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO054

Fundamental Studies of Impurity Doping in 1.3 GHz and Higher Frequency SRF Cavities

458

SPWR018

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TUOP01

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

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

As the demand for more powerful, more efficient, and smaller superconducting RF accelerators continues to increase, both impurity doping and high-frequency cavities (> 1.3 GHz) have become hot topics for fundamental research because of their potential to significantly decrease surface losses and cost respectively. In this report, we present recent experimental and theoretical results on undoped and nitrogen-doped high-frequency cavities and on alternative doping agents in traditional 1.3 GHz cavities, with a focus on understanding the fundamental science of impurity doping.

Slides TUPO054 [1.956 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO054

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paper received ※ 16 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO055

Next Generation Nb3Sn SRF Cavities for Linear Accelerators

462

R.D. Porter, D.L. Hall, M. Liepe, J.T. Maniscalcopresenter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Arias, P. Cueva, D.A. Muller, N. Sitaraman
Cornell University, Ithaca, New York, USA

Niobium-3 Tin (Nb3Sn) is a very promising alternative material for SRF accelerator cavities. The material can achieve higher quality factors, higher temperature operation and potentially higher accelerating gradients (~ 96 MV/m) compared to conventional niobium. This material is formed by vaporizing Sn in a high temperature vacuum furnace and letting the Sn absorb into a Nb substrate to form a 2-3 um Nb3Sn layer. Current Nb3Sn cavities produced at Cornell achieve Q ~ 10¹⁰ at 4.2 K and 17 MV/m. Here we present a summary of the current performance of Nb₃Sn cavities at Cornell and recent progress in improving the accelerating gradient.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO055

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paper received ※ 20 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO057

Low-temperature Baking and Infusion Studies for High-gradient ILC SRF Cavities

466

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

Low-temperature infusion has become a hot-topic in SRF researches recently. Past results show that low-temperature infusion can produce high quality factor at medium accelerating fields. Also, 75°C baking recently has been shown to improve accelerating gradients of SRF cavities. Hence these treatments are very promising for reducing cost of the ILC. In this work, we present latest results of low temperature infusion and baking, showing that these treatments can improve SRF cavities performance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO057

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paper received ※ 19 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO058

Cool Down Studies for the LCLS-II Project

470

M. Ge, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D. Gonnella
SLAC, Menlo Park, California, USA
J. Sears
Cornell University, Ithaca, New York, USA

The quality factor of the nitrogen-doped SRF cavities for the LCLS-II project are strongly impacted by cool down speed. A sufficiently fast cool down speed can produce large thermal gradient across a cavity and sufficiently expel magnetic flux when the cavity wall passes from the normal-conducting to the superconducting state. However, instrumentation in LCLS-II production cryomodules has been kept at a minimum, and additional information during the cool down of the modules is therefore desirable. In this work, we study if and how RF data can be used during cavity cool-down to determine the transition speeds of the individual cavities in the LCLS-II linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO058

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paper received ※ 19 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO059

Latest Results of Salt Based Bipolar Electro-polishing R&D at Cornell

473

M. Ge, F. Furuta, T. Gruber, J.J. Kaufman, M. Liepe, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T.D. Hall, R. Radhakrishnan, S.T. Snyder, E.J. Taylor
Faraday Technology, Inc., Clayton, Ohio, USA

Acid free electropolishing would be safer to use and friendlier to the environment. A collaboration, sup-ported by the DOE SBIR Phase-II program, between Faraday Technology Inc. and Cornell University focused on salt-based bipolar electropolishing (BEP). In this paper, we present the latest salt-based BEP results. The superconducting performance of a single-cell 1.3GHz cavity has been carefully analyzed, showing that salt-based BEP is promising, but still has large room for improvement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO059

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paper received ※ 19 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO064

Pre-study of CEPC SRF Cavity

476

P. Sha
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People’s Republic of China
J. Dai, C. Dong, H.F.S. Feisi, S. Jin, Z.Q. Li, B.Q. Liu, Z.H. Mi, J.Y. Zhai, X.Y. Zhang, H.J. Zheng
IHEP, Beijing, People’s Republic of China
J.K. Hao, F. Wang
PKU, Beijing, People’s Republic of China

Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400) and National Natural Science Foundation of China (Grant NO.:11505197).
CEPC will use 650 MHz cavities for the collider and 1.3 GHz cavities for the Booster. Each booster cryomod-ule contains eight 1.3 GHz 9-cell cavities, which is simi-lar as LCLS-II, E-XFEL and ILC. Each collider cryo-module contains six 650 MHz 2-cell cavities, which is totally new. Therefore, the pre-study mainly focuses on the 650 MHz 2-cell cavity. N-doping and vertical tests of 650 MHz 1-cell and 2-cell cavities have been carried out at IHEP, which have achieved good results. A test cryomodule, which consists of two 650 MHz 2-cell cavities, has also begun as the first step to the full-scale cryomodule.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO064

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paper received ※ 31 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO065

Improvement of Cavity Performance by Nitrogen Doping at KEK

480

SPWR019

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T. Okada, Y. Hori, E. Kako, T. Konomi, H. Sakai, K. Umemori, Y. Yamamoto
Sokendai, Ibaraki, Japan
T. Dohmae, Y. Hori, E. Kako, T. Konomi, T. Saeki, T. Saeki, H. Sakai, K. Umemori, Y. Yamamoto
KEK, Ibaraki, Japan
J. Kamiya
JAEA/J-PARC, Tokai-mura, Japan
S. Kurosawa, K. Takeishi
JAEA, Ibaraki-ken, Japan

Nitrogen doping experiments in single-cell and 3-cell niobium cavities were carried out at KEK. After annealing at 800 deg C for 3 hours, pure nitrogen gas with a pressure of 3 Pa for 20 minutes and 3 minutes were introduced for doping in a furnace in J-PARC, respectively. Removing surface in 5 um and 20 um by electropolishing were performed prior to the vertical tests, respectively. Increases of a quality factor at 2K and reduction of the BCS resistance with respect to an accelerating gradient were observed in both cavities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO065

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO066

Lower Critical Field Measurement of Thin Film Superconductor

484

H. Ito
Sokendai, Ibaraki, Japan
C.Z. Antoine
CEA/IRFU, Gif-sur-Yvette, France
A. Four
CEA/DRF/IRFU, Gif-sur-Yvette, France
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
Y. Iwashita, R. Katayama, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Funding: The work is supported by Japan Society for the Promotion of Science Grant-in-Aid for Young Scientist (A) No.17H04839.
Superconducting thin film is the promising technology to increase the performance of SRF cavities. The lower critical field Hc1, which is one of the important physical parameters characterizing a superconducting material, will be enhanced by coating Nb with thin film superconductor such as NbN. To investigate the Hc1, we developed the Hc1 measurement system using the third harmonic response of applied AC magnetic field. The measurement system consists of helium cryostat with two of GM refrigerators, sample Cu stage, solenoid coil Cu mount, solenoid coil, temperature sensors, and liquid helium level meter. AC magnetic field is produced by a coil which is driven by function generator and power amplifier at around 1 kHz. In order to control the temperature of the sample, we installed heaters and thermal anchors which could be moved by the motor. By this temperature control the sample state can be easily transferred from Meissner state to mixed state. So that the measurement is repeated for various applied magnetic field, and the transition curve can be made. In this report, measurement result of the bulk Nb sample and NbN-SiO2 multilayer thin film sample will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO066

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paper received ※ 19 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO067

Study on New Removal Thickness Distribution Improvement Methods for Niobium 9-cell Cavity Vertical Electropolishing with Ninja Cathode

488

K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

Marui Galvanizing Co., Ltd. has been developing niobium 9-cell cavity vertical electropolishing (VEP) technologies with Ninja cathode in collaboration with KEK. Conventional 9-cell cavity VEP had a serious problem, which was asymmetry of removal thickness distribution. Usually removal thickness of upper side became larger than lower side in case of both in-cell and inter-cell. So far, as one solution, we proposed bubble diffusion prevention method and proved it was effective for uniform removal. This time, as other new solution, we tried cavity flip upside down and Ninja cathode masking VEP methods. In this article we will report the purpose, intention and VEP experiment result of these methods.

Poster TUPO067 [0.858 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO067

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paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO068

Vertical Electropolishing of 1.3 GHz Niobium Nine-cell SRF Cavity: Bulk Removal and RF Performance

491

V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Vertical electropolishing (VEP) technique have been successfully developed for 1.3 GHz niobium (Nb) single cell cavity to achieve a smooth surface with uniform removal and better RF performance as achieved after horizontal EP (HEP) process. VEP parameters for 1.3 GHz Nb nine-cell cavities are being studied using a nine-cell coupon cavity and our unique Ninja cathode. The investigated VEP parameters heretofore were applied on a 1.3 GHz Tesla shape nine-cell superconducting RF cavity for bulk removal of 100 µm followed by fine removal of 20 and 10 µm. The interior surface was found to be smooth and shiny after the VEP process. Our recently developed dual flow technique, in which the EP acid is flown separately in the Ninja cathode housing and cavity, yielded lower asymmetry in removal along the cavity length. The cavity was tested in a vertical cryostat after the final VEP process. The cavity achieved 28.3 MV/m at Q0 value of 6.7x109. The cavity performance was almost the same as in the baseline vertical test performed after the HEP process.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO068

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paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO069

Development of Vertical Electropolishing Facility for Nb 9-cell Cavity (2)

494

Y.I. Ida, V. Chouhan, K.N. Nii
MGH, Hyogo-ken, Japan
T. Akabori, G.M. Mitoya, K. Miyano
HKK, Morioka, Japan
Y. Anetai, F. Takahashi
WING. Co.Ltd, Iwate-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

In IPAC18 (Vancouver, Canada), we reported our first step of development of niobium 9-cell cavity vertical electropolishing (VEP) facility. In this article, we will report the method, system for uniform polishing for niobium 9-cell cavities and the current situation of our 9-cell cavity VEP facility (The result of polishing uniformity, vertical test will be presented in other posters of this conference). In addition, we will show the movie of experiments of VEP-3 with Ninja cathode. This facility aims not only for test VEP but also for mass production and long-time operation.

Poster TUPO069 [0.316 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO069

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paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO070

Design and Commissioning of KEK New Vacuum Furnace for SRF Cavity Development

496

K. Umemori, M. Egi, E. Kako, T. Konomi, S. Michizono, H. Sakai
KEK, Ibaraki, Japan

Recently new techniques such as Nitrogen-doping and Nitrogen-infusion have been developed to improve performance of SRF (Superconducting RF) cavities. We purchased a new vacuum furnace, which is key to realize these techniques. Cleanness of the furnace is most important issue. The furnace has a cryo-pump and whole of vacuum system is oil-free system. Target vacuum level after cooling down is 1x10^-6 Pa. Heater, reflectors and support table were made from Molybdenum to avoid contamination during heat treatment. Metal gaskets are used for all vacuum seals, except big doors. Maximum operation temperature is 1150 degree C. Size is around 1 m diameter and 2m long for a 1.3 GHz 9-cell cavity. Entrance of furnace is covered by a clean booth. The furnace was fabricated, assembled at KEK COI building and commissioned this year. After several burning runs, target vacuum pressure was achieved after cooling down to room temperature. Design of the furnace and performance during commissioning runs are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO070

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paper received ※ 19 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO071

Study on Nitrogen Infusion for 1.3 GHz SRF Cavities Using J-PARC Furnace

499

K. Umemori, T. Dohmae, M. Egi, Y. Hori, E. Kako, T. Konomi, S. Michizono, T. Saeki, H. Sakai, Y. Yamamoto
KEK, Ibaraki, Japan
J. Kamiya
JAEA/J-PARC, Tokai-mura, Japan
S. Kurosawa, K. Takeishi
JAEA, Ibaraki-ken, Japan
T. Okada
Sokendai, Ibaraki, Japan

Nitrogen infusion (N-infusion) is new surface treatment technique for niobium SRF (Superconducting RF) cavities. After cooling down from 800 degree C heat treatment, a vacuum furnace and cavities are kept 120 degree C, 48 hours with about 3 Pa Nitrogen. Improvement of Q-value and accelerating gradient is expected. We used J-PARC furnace, since N-infusion procedure requires clean vacuum furnace. It has a cryo-pump and turbo molecular pumps and its vacuum system is oil-free system. Six times of N-infusion tests were carried out, while changing vacuum condition, N-infusion temperature, Nitrogen pressure, niobium material and so on. Niobium caps were mounted on cavities to avoid contaminations on inner surfaces. Some of trials were successful and vertical test results showed improvement of Q-values and accelerating gradient. However, some of them were not. Most of bad cases showed degradation of Q-values above 5 MV/m. Details of heat treatment procedure including N-infusion and vertical test results are shown in this presentation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO071

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paper received ※ 20 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO072

First Trial of the In-situ Nitrogen Infusion at KEK

503

T. Konomi, T. Dohmae, E. Kako, S. Michizono, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
T. Okada
Sokendai, Ibaraki, Japan

The nitrogen infusion is the new surface treatment technique for improving the RF loss and the maximum accelerating gradient of superconducting cavity. In this process, it is important to be carried out continuously both the 800 C annealing in vacuum and 120 C nitrogen infusion without exposure to the atmosphere. The annealing serves activation process by removing the oxide layer. The in-situ nitrogen infusion system was prepared to investigate whether nitrogen infusion effect or something changes happen in the case of applying nitrogen infusion technique without removing the oxide layer. It can only introduce nitrogen into a cavity during 120 C low temperature baking and transport a cavity to the vertical test system without exposure to the atmosphere. We tried to infuse nitrogen to a single cell by keeping 120 C and 48 hours with 3 Pa nitrogen. The cavity was annealed in another furnace and applied high pressure rinsing before nitrogen infusion. The vertical test result was same Q as the normal 120 C baking without nitrogen. It suggests that oxide layer prevents infusion of nitrogen. In this poster, the in-situ nitrogen infusion system and vertical test results will be reported.

Poster TUPO072 [4.653 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO072

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO073

Niobium Sample Analysis for Nitrogen Infusion and Doping

506

T. Konomi, E. Kako, S. Michizono, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
T. Nagata
ULVAC, Inc., Tsukuba, Japan
T. Nojima
Tohoku University, Sendai, Japan

KEK has been investigating the better conditions of the heat treatment in nitrogen, which are called as nitrogen doping and nitrogen infusion. We have tried to understand the high gradient performance of the cavity from the analyses of samples which were prepared in the same conditions for the cavity. The main tools are D-SIMS for the depth profile of the elemental concentration, XPS for composition analysis and SQUID magnetometry for the critical DC magnetic field measurement. The difference in the depth profiles of the nitrogen, carbon and oxygen between the heat treatment conditions was observed in vacuum and furnace temperature of nitrogen infusion by D-SIMS and XPS. Such a difference correlates with the vortex penetration field measured by SQUID. In particular, that of nitrogen doping sample was greatly degraded, while that of nitrogen infusion sample was slightly improved. The tendency is similar to the RF high gradient test results. Details of the sample analysis are shown in this presentation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO073

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paper received ※ 18 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO074

Design and Fabrication of KEK Superconducting RF Gun #2

510

T. Konomi, Y. Honda, E. Kako, Y. Kobayashi, S. Michizono, T. Miyajima, H. Sakai, K. Umemori, S. Yamaguchi, M. Yamamoto
KEK, Ibaraki, Japan

Superconducting RF gun can realize high acceleration voltage and high beam repetition. KEK has been developing the 1.3 GHz elliptical type 1.5 cell superconducting RF gun to investigate fundamental performance. A surface cleaning method and tools are developed by using KEK SRFGUN #1 and high surface peak gradient 75 MV/m was achieved without field emission. SRFGUN #2 which equips the helium jacket and can be operated with electron beam was designed based on the SRFGUN #1. It can be operated with transmit type photocathode which include superconducting transparent material. The cathode plug is cooled by thermal conducting from the 2 K helium jacket and photocathode will be kept around 2K to maintain superconductivity. Bulk niobium photocathode plug and substrate will used for the fundamental performance test. In parallel, the photocathode deposition chamber for multi-alkali photocathode will be prepared.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO074

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO076

An Innovative Nb3Sn Film Approach and Its Potential for SRF Applications

513

E.Z. Barzi, D. Turrioni, C. Ciaccia
Fermilab, Batavia, Illinois, USA
G.V. Eremeev, R.L. Geng, R.A. Rimmer, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA
S. Falletta
Politecnico di Torino, Torino, Italy
H. Hayanopresenter, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
A. Kikuchi
NIMS, Tsukuba, Ibaraki, Japan

Funding: Work supported by U.S. DOE contract No. DE-AC02-07CH11359
A novel electro-chemical technique to produce Nb3Sn films on Nb substrates was developed and optimized at Fermilab. The Nb3Sn phase is obtained in a two-electrode cell, by electrodeposition from aqueous solutions of Sn layers and Cu intermediate layers onto Nb substrates. Subsequent thermal treatments in inert atmosphere are realized at a maximum temperature of 700°C to obtain the Nb3Sn superconducting phase. Several superconduct-ing Nb3Sn films were obtained on Nb substrates by study-ing and optimizing most parameters of the electro-plating process. Samples were characterized at Fermilab, NIMS, KEK and JLAB, including EPMA analyses, DC and in-ductive tests of critical temperature Tc0, and lower critical field Hc1(4.2 K) by SQUID. In parallel to sample devel-opment and fabrication at FNAL, at JLAB and KEK effort was put into etching and electro-polishing techniques adequate to remove the Cu and bronze phases from the samples’ outer surface. This is necessary prior to meas-urements at JLAB of the surface impedance of flat sam-ples in a setup that make use of an RF host cavity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO076

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paper received ※ 21 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO078

Extension of Busch’s Theorem to Particle Beams

516

TUOP09

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

L. Groening, C. Xiao
GSI, Darmstadt, Germany
M. Chung
UNIST, Ulsan, Republic of Korea

In 1926, H. Busch formulated a theorem for one single charged particle moving along a region with longitudinal magnetic field. The theorem relates particle angular momentum to the amount of field lines being enclosed by the particle cyclotron motion. Recently it has been extended to accelerated particle beams [Phys. Rev. Accel. Beams 21 014201 (2018)]. This contribution sketches this extension and applies the extended theorem to successfully performed emittance manipulations with electron and ion beams.

Slides TUPO078 [0.999 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO078

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paper received ※ 24 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO079

Numerical and Experimental Study of H⁻ Beam Dynamics in J-PARC LEBT

519

TUOP10

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T. Shibata, K. Ikegami, Y. Liu, K. Ohkoshi, M. Otani
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
A. Miura, H. Oguri, K. Shinto
JAEA/J-PARC, Tokai-mura, Japan
F. Naito, K. Nanmo, A. Takagi
KEK, Tokai, Ibaraki, Japan

Negative hydrogen ion (H⁻) beam dynamics in J-PARC Low Energy Beam Transport (LEBT) has been investigated by numerical modeling which calculates particle transport with effect of space charge and collision processes. Understandings of H⁻ beam transport in LEBT is important for high transmission rate from Ion Source (IS) to Radio Frequency Quadrupole (RFQ) in J-PARC in higher beam current in future. In 2017, 45 mA beam current of H⁻ has been extracted from IS in J-PARC user operation which has been increased from 30 mA in last 2 years. The beam current is planned to be increased to 50 mA in the next upgrade. As the beam current increase, IS/LEBT commissioning becomes more difficult because of the higher space charge (SC). Especially in J-PARC, vacuum pressure is around 10^-5 Pa by 15 mmf orifice located in the center of LEBT. The orifice prevents residual gas injection from IS to LEBT/RFQ and thus produces stronger SC effect. In the presentation, numerical results are compared with actual results from J-PARC Linac beam commissioning. A comparison of the results shows that location of the 15 mmf orifice results in two peaks of RFQ transmission rate against SOL currents.

Slides TUPO079 [0.968 MB]

Poster TUPO079 [1.699 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO079

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO083

Beam Dynamics for the FAIR p-Linac Ladder RFQ

522

SPWR033

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

M. Syha, U. Ratzinger, M. Schuett
IAP, Frankfurt am Main, Germany

After the successful measurements with a 0.8 m prototype a 3.3 m Ladder-RFQ is under construction at IAP, Goethe University Frankfurt. It is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the p-Linac at FAIR. Along the acceleration section modulation parameter, aperture and synchronous phase all course (quasi-)linear, which differentiates this design approach from other designs developed at IAP. The ratio of transversal vane curvature radius to mid-cell radial aperture as well as the vane radius itself are constant, which favors a flat voltage distribution along the RFQ. This was verified by implantation of the modulated vane geometry into MWS-CST RF field simulations. The development of adequate beam dynamics was done in close collaboration with the IAP resonator design team. The Los Alamos RFQGen-code was used for the RFQ design and the beam dynamics simulations.

Poster TUPO083 [0.932 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO083

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paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO084

Beam Dynamics Simulations for the New Superconducting CW Heavy Ion LINAC at GSI

525

SPWR034

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M. Schwarz, M. Basten, M. Busch, H. Podlech
IAP, Frankfurt am Main, Germany
K. Aulenbacher
IKP, Mainz, Germany
K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
GSI, Darmstadt, Germany

Funding: Work supported by BMBF contr. No. 05P15RFRBA, EU Framework Programme H2020 662186 (MYRTE) and HIC for FAIR
For future experiments with heavy ions near the coulomb barrier within the super-heavy element (SHE) research project a multi-stage R&D program of GSI/HIM and IAP is currently in progress. It aims for developing a supercon-ducting (sc) continuous wave (CW) LINAC with multiple CH cavities as key components downstream the High Charge State Injector (HLI) at GSI. The LINAC design is challenging due to the requirement of intense beams in CW mode up to a mass-to-charge ratio of 6, while covering a broad output energy range from 3.5 to 7.3 MeV/u with unchanged minimum energy spread. Testing of the first CH-cavity in 2016 demonstrated a promising maximum accelerating gradient of E_a = 9.6 MV/m; the worldwide first beam test with this sc multi-gap CH-cavity in 2017 was a milestone in the R&D work of GSI/HIM and IAP. In the light of experience gained in this research so far, the beam dynamics layout for the entire LINAC has recently been updated and optimized.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO084

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO085

Modelling of Beam Parameters of RF Linac for GBS-ELI-NP

528

P.S. Tracz
IFIN-HH, Bucharest - Magurele, Romania

The Gamma Beam System at the ELI-NP (Extreme Light Infrastructure - Nuclear Physics) currently being constructed in Magurele/Bucharest, Romania will be a high-brilliance advanced source of gamma rays based on laser Compton back-scattering. For a successful operation of the GBS a high brightness low emittance electron beam is of crucial importance. The warm RF linac is designed in two stages - one with the beam up to 300 MeV, and another one about 720 MeV. The S-band photo-injector is combined with a C-band linac. The beam is transported by transfer lines to the interaction points. In this paper we report the results of computer simulations of the electron beam transport in the low energy linac and transfer line up to the low energy interaction point (IP1). The simulation model makes it possible to predict the beam parameters to be recuperated in case of failure of any magnetic or accelerating elements as well as it enables to determine the optimal parameters of replaced components. It will be used for the development of the Gamma Beam System in the future.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO085

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO088

Measurement of Diagnostics Response by RF Parameters for Hard X-ray Line in PAL-XFEL*

531

H. Yang
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: *This work is supported by MSIP, Korea.
PAL-XFEL is a hard x-ray (HX) and soft x-ray (SX) FEL machine to generate 2.5 - 15 keV FEL in the HX line and 0.28 - 1.2 keV FEL in the SX line. The HX line consists of an e-gun, a laser heater, S-band accelerators, an X-band linearizer, three bunch compressors (BC), and a dog-leg line. PAL-XFEL maintains the stable operation and FEL delivery with more than 98% availability due to machine stabilities including RF modules. In order to investigate the stable operation, we measure the diagnostics response for bunch charge monitors, energy beam position monitors, bunch length monitors, and a FEL intensity with a photon beam position monitor by RF parameters - RF amplitude and phase for an e-gun, accelerators, and a linearizer. In this paper, we present mainly corresponding RF parameters for e-beam and FEL jitters by this measurement and matrix analysis.

Poster TUPO088 [0.281 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO088

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paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO090

Electron-beam Matching to Solenoid Magnetic Field in a Klystron

534

S.J. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
J.H. Hwangpresenter, S.-G. Shin
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.Y. Hyun, D.H. Yu
Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea

Funding: The work was supported by the National R&D Program (grant number: 2016R1A6B2A01016828) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT, Korea.
High-power klystrons for particle accelerators employ high-perveance electron guns which are usually focused by Solenoid magnets. The electron beam should be optically matched to the downstream magnetic field to prevent the beam from scalloping. The task usually requires a series of computer simulations with many design parameters, and therefore requires extensive(sometimes exhaustive) efforts if not aided by a priori experiences. In order to alleviate the difficulties we have developed a matching procedure which is systematic and reliable. In this article we describe the procedure with an example design of a 400-kV 500-A electron beam with radius 8 - 11 mm.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO090

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO091

Beam Break Up Instability Analysis for Cavities, Linacs and Energy Recovery Linacs

537

V. Volkov, V.M. Petrov
BINP SB RAS, Novosibirsk, Russia

This analyze argue that BBU instability both in separate cavities and in Linacs or ERLs is going due to the consequence of fundamental property of dipole modes. ’Head-tail’ bunch instability has also the same nature. New BBU instability testing methods are described and analytically proved in the article.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO091

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paper received ※ 14 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO092

Beam Dynamics and Collimation Following MAGIX at MESA*

540

B. Ledroit, K. Aulenbacher
IKP, Mainz, Germany

Funding: * Supported by the DFG through GRK 2128
The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing operation in energy-recovery linac (ERL) mode, where beam energy is recovered by decelerating the beam in linac cryomodules and transferring kinetic energy to the RF. The ERL mode provides the opportunity to operate experiments at peak energy with thin targets, combining high luminosities typical for storage rings and high beam brightness typical for linacs. The MESA Internal Gas Target Experiment (MAGIX) aims to operate jet targets at high luminosities with different gases up to Xenon. As scattering effects in the beam rise with the atomic number, investigations on the impact of the target on beam dynamics and beam losses are required for machine safety. The goal of this work is to understand target induced halo, track halo particles through downstream sections and protect the machine with a suitable collimation system and shielding from direct and indirect damage through beam losses and radiation. The present status of the investigations is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO092

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paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO093

Excitation of Millimeter Wavelength Cavity Structure

543

SPWR030

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M.V. Arsentyeva
NSU, Novosibirsk, Russia
A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia

Excitation of millimeter wavelength cavity structure In this work excitation of W-band structure is studied. The structure consists of cylindrical cavities with the operating frequency of about 96 GHz. We plan to excite the structure by short bunches from the photocathode RF gun. In order to choose structure geometry and beam duration, we performed estimations and simulations; induced voltage was also estimated. Taking into account feasible parameters of the photocathode RF gun such as beam size and emittance, we studied exciting beam transverse dynamics to define its other characteristics (energy and charge). To lead the beam from the whole structure, focusing is needed. After estimation of required magnetic field, we considered possibility of focusing with help of permanent magnets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO093

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paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO095

Beam Loading with the First Rebuncher of Spiral2, First Measurements

546

M. Lechartier, R. Ferdinand, J.F. Leyge
GANIL, Caen, France

In the SPI2 project the middle energy line (LME) is equiped with a radio frequency qupole and three Rebunchers. The subject of this article is to measure and characterise the effect of the beam loading on the first Rebuncher cavity.

Poster TUPO095 [1.146 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO095

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paper received ※ 20 September 2018 paper accepted ※ 15 January 2019 issue date ※ 18 January 2019

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TUPO097

Design of C-band Electron Linear Accelerator for a Complex of Radiation Therapy

550

L. Ovchinnikova, V.I. Shvedunov
SINP MSU, Moscow, Russia
L. Ovchinnikova, V.I. Shvedunov
LEA MSU, Moscow, Russia

Funding: This material is based upon work supported by the Ministry of Education and Science of the Russian Federation, under Grant Agreement No. 14.582.21.0011, Grant Agreement Unique ID RFMEFI58217X0011.
The report presents the design of the linear electron accelerator for a complex of radiation therapy. The three-electrode electron gun and C-band accelerating structure are optimised to produce a therapeutic electron beam with an energy of 6 MeV and a dose rate of 10 Gy/min and a beam with an energy of 2.5 MeV to obtain a portal image. The beam size at the bremsstrahlung target in both modes does not exceed 2 mm. The total length of the accelerating system with the electron gun does not exceed 330 mm. The accelerating structure is fed by RF power from a multibeam klystron at a frequency of 5,712 MHz with a maximum pulsed power of 3.5 MW.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO097

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paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO098

Proof-of-Principle Tests for Slit-scan-based Slice Emittance Measurements at PITZ

553

R. Niemczyk, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, H.J. Qian, Y. Renier, C. Saisa-ard, F. Stephan, Q.T. Zhao
DESY Zeuthen, Zeuthen, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Transverse slice emittance is one of the most important properties of high-brightness electron beams for freeelectron lasers (FELs). The photo injector test facility at DESY in Zeuthen (PITZ) develops high-brightness electron sources for modern FELs. With a 23 MeV, 1 nC beam at PITZ the experimental slice emittance characterization with the quadrupole scan technique is complicated by strong space charge effects. Combining the slit scan technique with a transverse deflecting cavity (TDS) allows for timeresolved emittance measurements of such a space-chargedominated beam. The first proof-of-principle results of slice emittance measurements at PITZ based on the ’TDS + slit scan’-technique are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO098

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paper received ※ 04 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO101

Design of Practical HSC Type Injector for Cancer Therapy

557

C.C. Xing, T. He, C.X. Li, J. Li, L. Lu, L. Yang
IMP/CAS, Lanzhou, People’s Republic of China

The Hybrid single cavity(HSC), which is designed for 20 mA beam acceleration, is a new HSC Type Injector for Cancer Therapy. Its designed particle, resonant frequency, injection and final energies are designed from beam-optics considerations of the entire system to be C⁶⁺, 100MHz, 20keV/u and 0.6MeV/u. In order to achieve these requirements, keeping the Maximum surface electric field to less than 1.9-times the Kilpatrick limit, the RFQ becomes about 1.2 m long and the DTL is about 2.5 m long. The total efficiency of transmission is more than 80%.

Poster TUPO101 [0.345 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO101

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO106

Mathematical Principle and Numerical Reconstruction in Real Space Measurement with a Rotating BPM

560

P. Jiang, Y. He, Z.J. Wang
IMP/CAS, Lanzhou, People’s Republic of China

It is difficult to measure beam profiles and monitor the beam during beam supply for high intensity high power accelerators. Based on the button pick-ups, the mathematical principle of a rotating BPM is proposed. SVD method is used to reconstruct the beam in x-y real space, and the basic parameters used in beam reconstruction are argued. The beam distribution in x-y real space is reconstructed well and compared to the reference beam. The beam reconstruction is sensitive to the electrode radius. The meshing and the grid numbers in the solution window have an import effect on the beam reconstruction.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO106

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO109

Electron Cloud Estimates for the Jefferson Lab EIC

563

K.E. Deitrick, V.S. Morozov, T. Satogata
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In this work, we present preliminary estimates for electron cloud build-up and saturation for the ion ring of the Jefferson Laboratory Electron-Ion Collider (JLEIC) currently under development. Using the baseline ion ring design, we study the impact of various operational parameters on the behavior of the electron cloud for a 100 GeV proton beam, including estimated tune shifts.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO109

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO112

Calculation of Electron Beam Dynamics in Four Accelerating Stations for JINR Linear Electron Accelerator LINAC-200

566

SPWR032

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A. Sledneva, V. Aleksandrov, V.V. Kobets
JINR, Dubna, Moscow Region, Russia

In the Joint Institute for Nuclear Research a Test Stand with an electron beam generated by the linear accelerator LINAC-200 with the energy up to 200 MeV is being constructed to investigate properties of accelerating and semiconducting structures for advanced detectors, a radiation resistance of detectors based on gallium arsenide semiconductor, to study a free electron laser and to do other applied for work. The technical characteristics of the LINAC-200 accelerator make it possible to create an advanced system of test beams for scientific and methodological studies of detectors on its basis. Four accelerating stations with maximum beam energy up to 200 MeV are put into operation. The work is being carried out for experiments with electron test beams with energy up to 800 MeV. This work presents the calculation results of the magnetic field of the focusing solenoidal system and electron beam dynamics in accelerating stations. In addition, the results on the formation of the electron beam with optimal parameters to be captured in further accelerating sections.

Poster TUPO112 [1.176 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO112

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paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO113

Beam Dynamics Studies Through Dielectric THz Accelerating Structures

569

R. Apsimon, G. Burt, A.L. Healy, S.P. Jamison
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R.B. Appleby, E.J.H. Smith
UMAN, Manchester, United Kingdom
A. Latina
CERN, Geneva, Switzerland

As conventional RF accelerating schemes approach the physical limit of accelerating gradient, the accelerator community is increasingly looking at novel accelerating techniques to overcome these limitations. Moving from the RF to the THz frequency range, higher acceleration gradients of high energy beams can be achieved in compact structures. Beam dynamics studies are crucial as part of the design of novel accelerating structures to maximise the output beam current as well as the accelerating gradient. In this paper we present beam dynamics simulations through dielectric lined waveguide structures using novel techniques to simulate broadband signals for particle tracking studies in RF-Track. The beam parameters through the structure are optimised and we study the dynamics of general broadband accelerating structures.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO113

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paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO114

Beam Dynamics Studies for the CSNS DTL Due to a Quadrupole Fault

573

J. Peng, M.T. Li, Y.D. Liu, X.H. Lu, X.B. Luo
CSNS, Guangdong Province, People’s Republic of China
Y.W. An, S. Fu, L. Huang, M.Y. Huang, Y. Li, Z.P. Li, S. Wang, S.Y. Xu, Y. Yuan
IHEP, Beijing, People’s Republic of China

The China Spallation Neutron Source(CSNS) accelera-tor systems is designed to deliver a 1.6GeV, 100kW pro-ton beam to a solid metal target for neutron scattering research. It consists of a 50keV H⁻ Ion Source, a 3MeV Radio Frequency Quadrupole (RFQ), an 80MeV Drift Tube Linac (DTL), and a 1.6GeV Rapid-cycling Synchro-tron (RCS). The DTL consists of four tanks. In 2017, three of four tanks have been commissioned successfully, and beam has been accelerated to 61MeV with nearly 100% transmission. However, in July 2017, one quadrupole contained in the drift tube was found fault, the beam transmission decreased to 80%. A new lattice has been designed and the 100% transmission has recovered. In January 2018, the last tank of the DTL has been commissioned and accelerated the H⁻ beam to the design energy of 80MeV for the first time. The commissioning progress and the measurement results before and after lattice adjustment will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO114

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO115

Beam Parameters Measurement and Correction in CSNS Linac

576

Z.P. Li, Y. Li
IHEP, Beijing, People’s Republic of China
J. Pengpresenter
CSNS, Guangdong Province, People’s Republic of China

All the beam parameters of China Spallation Neutron Source (CSNS) linac had achieved the acceptance goals in January 2018 after a 2-year commissioning. Parameters of the H⁻ beam were carefully studied and corrected. Beam energy was measured and the energy dispersion are reduced. Transverse emittance are obtained by different tools and methods. Linear optics measurements and corrections were carried out under varied beam energies and peak intensities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO115

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO116

Particle Dynamics Optimization in DTL

579

SPWR031

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I. Skudnova
Saint Petersburg State University, Saint Petersburg, Russia

The research concerns ion dynamics in linear accelerators with drift tubes (DTL). Permanent quadrupole magnets are placed inside some of the drift tubes. Frequency of the field is 432 MHz. Electromagnetic fields and particle dynamics in the cavity are calculated using Comsol Multiphysics software. The input energy of the beam is 6 MeV, output 10 MeV. Initial beam is assumed to come from Radio Frequency Quadrupole accelerator (RFQ). The considered parameters are drift tubes radii, cavity diameter, gradient of the magnetic field from quadrupoles inside drift tubes and focusing lattice. Effectiveness is estimated by the emittance growth.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO116

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paper received ※ 14 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO119

A Diagnostics Box for the Linear Accelerator of Institute for Research in Fundamental Science (IPM)

581

S. Sanaye Hajari, M. Bahrami, H. Behnamian, S. Kasaei, H. Shaker
IPM, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran
F. Ghasemipresenter
NSTRI, Tehran, Iran

The IPM linac is an 8 MeV (up gradable to 11 MeV) electron linear accelerator under development at Institute for Research in Fundamental Sciences, Tehran, Iran. The design and construction of the linac is nearly finished and it is in the commissioning stage. The commissioning is planned in several phase of different energy ranging from 50 keV to 8 MeV. At each phase appropriate diagnostics is required in order to investigate the linac performance. A diagnostics box including a scintillator view screen, a dipole magnet, and a focusing solenoid is designed to diagnose the beam longitudinal and transverse parameters in wide range of energy. These parameters are the beam transverse profile, size, position, emittance and the energy spectrum.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO119

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paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO120

The Study of the Length and Shape of Beam in a High Power Electron Accelerator

584

M. Salehi, F. Abbasi Davani, B.G. Ghasemi
Shahid Beheshti University, Tehran, Iran
F. Ghasemipresenter, A.P. Poursaleh
NSTRI, Tehran, Iran

The output beam of a high-power linear accelerator, used for industrial purposes, is irradiated on products and scanning them. In order to improve the dosimetry of radiation which products received and to prevent loss of the attacked- beams to the edge of products, the exact evaluation of scanning length is necessary . One of the other challenges of the scanning beam is the lack of uniformity in dosimetry of received radiation . The scanning beam does not collide in parallel to the products, which is also a challenge to accelerator efficiency. To improve dosimetry of received radiation, the use of trajectory correction magnets is suggested. These magnets correct the beams that do not scan in parallel. Also, using the Monte Carlo code, the dosing rate of received radiation to products is simulated and compared in two non-uniform and uniform modes (corrected by trajectory correction magnets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO120

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO127

Activities at the Linac4 Test Stand

587

J.-B. Lallement, V. Bencini, S.B. Bertolo, F.D.L. Di Lorenzo, J. Lettry, A.M. Lombardi, C.M. Mastrostefano, D. Noll, M. O’Neil
CERN, Geneva, Switzerland

Linac4, the new CERN H⁻ injector to the Proton Synchrotron Booster, has been commissioned and has delivered a beam intensity and quality calculated to be sufficient to produce the standard beams for LHC and the high intensity beams for ISOLDE when connected. The beam current is nevertheless half of what is foreseen and the problem has been identified at the low energy end, between the extraction and the matching to the RFQ. The Linac4 test stand is being used to address this issue by testing different extraction geometries and different plasma generators. A fast method to access the current in the RFQ acceptance has been put in place. This paper reports the results of the measurements obtained so far.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO127

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO130

The Design of HEPS Magnet Database and Applications

591

Y.S. Qiao, F.S. Chen, C.P. Chu
IHEP, Beijing, People’s Republic of China

HEPS (High Energy Photon Source) is a planned ultra-bright and extremely low emittance synchrotron light source which will contain about 2500 magnets. The magnet related data including design, measurements, tests, and operation are typically scattered in various storages which can be hard to access for high-level purposes. For such a large number of magnets, it is very important to have essential magnet information systematically stored in relational databases for efficient management and applications. This paper outlines the conceptual and the functional design for the HEPS magnet database and its associated applications, mainly for design of the database schema and application software architecture. This database is developed with MySQL. To provide a better view and access function of magnet related data, a web-based management platform has been developed for data uploading, querying and data managing.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO130

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paper received ※ 10 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO132

Implementation of the Beam Loading Compensation Algorithm in the LLRF System of the European XFEL

594

Ł. Butkowski, J. Branlard, M. Omet, R. Rybaniec, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany

In the European XFEL, a maximum number of 2700 electron bunches per RF pulse with beam currents up to 4.5mA can be accelerated. Such large beam currents can cause a significant drop of the accelerating gradients, which results in large energy changes across the macro-pulse. But, the electron bunch energies should not deviate from the nominal energy to guarantee stable and reproducible generation of photon pulses for the European XFEL users. To overcome this issue, the Low Level RF system (LLRF) compensates in real-time the beam perturbation using a Beam Loading Compensation algorithm (BLC) minimizing the transient gradient variations. The algorithm takes the charge information obtained from beam diagnostic systems e.g. Beam Position Monitors (BPM) and information from the timing system. The BLC is a part of the LLRF controller implemented in the FPGA. The article presents the implementation of the algorithm in the FPGA and shows the results achieved with the BLC in the European XFEL.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO132

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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