LINAC2018 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MO1A01	CSNS Front End and Linac Commissioning	linac, MMI, DTL, rfq	1
	S. Fu, H.C. Liu, H.F. Ouyang, S. Wang IHEP, Beijing, People’s Republic of China J. Li, J. Peng CSNS, Guangdong Province, People’s Republic of China
	The China Spallation Neutron Source(CSNS) accelera-tor systems is designed to deliver a 1.6GeV, 100kW proton beam to a solid metal target for neutron scattering research. The accelerator consists of a front end, an 80MeV DTL linac, and a 1.6GeV Rapid Cycling Syn-chrotron (RCS). In August 2017 the first 1.6GeV proton beam hit on the tungsten target and production neutrons were monitored. This paper will report the major steps and results of the machine commissioning and beam commissioning of the CSNS front end and linac. In the first section, a brief introduction of the CSNS accelerator design and present status will be presented. Then, we will share our commissioning experience in the front end and the DTL linac in the following sections.
	Slides MO1A01 [9.123 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1A01
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MO1A02	An Overview of Recent Developments in SRF Technology	SRF, niobium, cryomodule, linac	6
	R.E. Laxdal TRIUMF, Vancouver, Canada
	Superconducting Radio-Frequency (SRF) is now the technology of choice for both large and small linac projects. Several challenging projects are in progress or planned that are pushing SRF technology and/or are enabled by SRF technology. This paper gives an overview of the present status of the field.
	Slides MO1A02 [4.202 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1A02
About •	paper received ※ 16 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019
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MO1P02	Approaches to High Power Operation of J-PARC Accelerator	linac, operation, rfq, ion-source	29
	H. Oguri JAEA/J-PARC, Tokai-mura, Japan
	Japan Proton Accelerator Research Complex (J-PARC) accelerators have been having over 10 years of operation experience. In 2006, the J-PARC linac started beam operation with an energy of 181 MeV. To realize the nominal performance of 1 MW at 3 GeV Rapid Cycling Synchrotron (RCS) and 0.75 MW at a 30 GeV Main Ring synchrotron (MR), the linac energy was upgrade to 400 MeV by adding an annular-ring coupled structure linac, and the beam current was also upgraded from 30 to 50 mA by replacing a new ion source and an RFQ. After the upgrade, the RCS demonstrated 1MW equivalent beam operation and currently operates 400 kW for the Material and Life Science Facility. The MR beam power is increasing and becomes about 480 kW beam to the Neutrino Facility and about 50 kW at the Hadron Experimental Facility. Further upgrade plan of 1.5 MW beam power from the RCS is now in consideration. To achieve the plan, it is necessary to increase by about 20 % both beam current and pulse length at the linac. The detail process in the past upgrade and the possibility for further upgrade at the linac will be presented in this talk.
	Slides MO1P02 [5.595 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1P02
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MO1P03	Status of the ESS Linac	linac, ion-source, controls, target	35
	A. Sunesson, P. Arnold, S.L. Birch, R. Garoby, M. Jensen, M. Lindroos, C.A. Martins, A. Nordt, T.J. Shea, J.G. Weisend ESS, Lund, Sweden
	The European Spallation Source under construction in Lund (Sweden) uses a 2 GeV-5MW pulsed superconducting linac as proton driver. Normal conducting accelerating structures are used up to 92 MeV and superconducting structures up to 2 GeV. Most linac components are designed and procured as in-kind contributions by institutes/laboratories in the European partner countries. Installation of the Ion source delivered by INFN-Catania started end 2017. Installation of more components and infrastructure progresses at a high pace. Commissioning of the normal conducting linac section will take place in parallel with installation of the superconducting section. Beam commissioning of the superconducting section will be done starting in 2021, interlaced with the installation of additional high beta cryomodules. Beam will be sent to the target in 2022, initially at an energy of 1.3 GeV. Start of the User Programme is scheduled in 2023, when some neutron instruments will be ready and end of construction is in 2025, with the full set of instruments operational. This paper reports the status of linac components construction, the progress with installation on site, and the overall project schedule.
	Slides MO1P03 [14.161 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1P03
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO004	Commissioning of the SRF Booster Cavity for LEReC	booster, SRF, gun, MMI	40
	W. Xu, A.V. Fedotov, T. Hayes, D. Holmes, G.T. McIntyre, K. Mernick, S.K. Seberg, F. Severino, K.S. Smith, R. Than, Q. Wu, B. P. Xiao, T. Xin, A. Zaltsman BNL, Upton, Long Island, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. One important component for LEReC project is a 704 MHz booster cavity, which was modified from the BNL ERL 704 MHz SRF gun cavity. The major modifications include converting the upstream cathode transportation to a proper beam pipe, adding a HOM coaxial line HOM damper to the downstream, retracting FPC insertions, and improvement of cryomodule layout. In the past one and half year, tremendous work was completed: the cavity was modified and tested vertically, FPC were conditioned, and HOM damper were designed and conditioned, cryomodule was re-assembled. The booster cavity cryomodule was successfully commissioned in mid October, and it was moved to LEReC location at RHIC tunnel 2 O’clock early November. This paper will report the configuration of the new cryomodule and its commissioning results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO004
About •	paper received ※ 22 August 2018 paper accepted ※ 22 September 2018 issue date ※ 18 January 2019
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MOPO005	Commissioning of the Normal Conducting Cavities for LEReC Project	booster, electron, MMI, vacuum	44
	B. P. Xiao, K. Mernick, F. Severino, K.S. Smith, T. Xin, A. Zaltsman BNL, Upton, Long Island, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is designed, and is currently under commissioning at BNL. The linac of LEReC consists of a DC photoemission gun, a 704 MHz superconducting radio frequency (SRF) booster cavity, a three-cell 2.1 GHz third harmonic cavity for RF curvature correction, a single-cell 704 MHz cavity for energy de-chirping and a 704 MHz deflecting cavity for diagnostic line. In this paper, we present the commissioning of three normal conducting cavities mentioned above.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO005
About •	paper received ※ 14 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO006	Crosstalk Effect in the LEReC Booster Cavity	resonance, booster, HOM, cathode	47
	B. P. Xiao, K. Mernick, F. Severino, K.S. Smith, T. Xin, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The Linac of Low Energy RHIC electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with peak-to-peak dp/p less than 7·10^-4. The booster cavity is the major accelerating component in LEReC, which is a 0.4 cell cavity operating at 2 K, with a maximum energy gain of 2.2 MeV. It is modified from the Energy Recovery Linac (ERL) photocathode gun, with fundamental power coupler, pickup coupler and HOM coupler close to each other. Crosstalk effect in this cavity is simulated and measured. Correction method is proposed to meet the energy spread requirement.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO006
About •	paper received ※ 14 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO008	The RF Gun Adopting the Dielectric Assist Accelerating Structure	electron, cathode, emittance, gun	54
	S. Mori, D. Satoh, M. Yoshida KEK, Ibaraki, Japan
	We apply the dielectric assist accelerating (DAA) structure to the RF gun, which is a candidate for a high average current and high brightness electron source. The DAA structure consists of ultralow-loss dielectric cylinders and disks which are periodically arranged in a metallic enclosure. Due to the high quality factor and the high shunt impedance of the DAA cavity, the RF gun adopting the DAA cavity can be a high-duty electron beam source at room temperature. We provide design work for RF gun adopting the DAA structure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO008
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO018	Development of an Improved Capture Section for the S-DALINAC Injector*	electron, linac, simulation, gun	68
	S. Weih, M. Arnold, J. Enders, N. Pietralla TU Darmstadt, Darmstadt, Germany D.B. Bazyl, H. De Gersem, W.F.O. Müller TEMF, TU Darmstadt, Darmstadt, Germany
	For the injector of the superconducting Darmstadt electron linear accelerator S-DALINAC, the design of a new capture cavity was recently completed. This beta-reduced structure will optimize the capture of low-energy electron bunches from the gun section and therefore improve the longitudinal beam quality of the injector beam, as simulations have shown. The existing cryomodule of the injector has to be modified for the installation of the new cavity. These modifications include adaptions of the tuner frame as well as modifications of other surrounding parts. To improve the diagnostics in the low-energy section, an energy-spread measurement setup is currently also under development. In this contribution the cryomodule modifications as well as simulation results for the longitudinal beam dynamics are presented. *Work supported by DFG through GRK 2128 "AccelencE"
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO018
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO019	Study on Cleaning of Copper Plated Bellows for LCLS-II	SRF, FEL, cryomodule, experiment	71
	L. Zhao, E. Daly, G.K. Davis, G.V. Eremeev, A.V. Reilly, A-M. Valente-Feliciano, K.M. Wilson JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515 for the LCLS-II Project. Inter-cavity copper plated bellows are part of the LCLS-II cryomodule beamline components. Since the bellows are close to superconducting radio frequency (SRF) cavities during accelerator operation, it is desirable that these bellows have similar cleanliness as SRF cavi-ties. Studies have been done to help evaluate bellows interior cleanliness after the standard bellows cleaning procedure at Jefferson Lab.
	Poster MOPO019 [1.326 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO019
About •	paper received ※ 28 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO026	The Resonance Frequency Shift After Applying the Cooling System for a Side Coupled Standing Wave Linac	controls, electron, coupling, radio-frequency	81
	M. Mohseni Kejani, F. Abbasi Davani Shahid Beheshti University, Tehran, Iran S. Ahmadiannamin ILSF, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran S. Zarei Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
	A radio frequency accelerator tube used in linear medical accelerators includes three main sections of the radio frequency cavity, an electron gun and the X-ray target, which is vacuumed by a pump inside it. The electromagnetic energy loss in the structure of the cavity can increase the temperature of the tube, resulting in changes in the geometric dimensions and then changes in some of the cavity characteristics, such as the resonance frequency. A cooling system is required to prevent excessive change in the resonant frequency due to thermal loss. Also, it is necessary to perform some computer simulations to stabilize the cavity’s performance in the presence of electromagnetic energy thermal dissipation and the cooling system. In this paper, the simulation results of resonant frequency shifts after applying the cooling system have been reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO026
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO037	SRF Gun Development at DESY	gun, cathode, SRF, laser	105
	E. Vogel, S. Barbanotti, I. Hartl, K. Jensch, D. Klinke, D. Kostin, W.-D. Möller, M. Schmökel, J.K. Sekutowicz, S. Sievers, N. Steinhau-Kühl, A.A. Sulimov, J.H. Thie, H. Weise, L. Winkelmann, B. van der Horst DESY, Hamburg, Germany J.A. Lorkiewicz, R. Nietubyć NCBJ, Świerk/Otwock, Poland J. Smedley BNL, Upton, Long Island, New York, USA J. Teichert HZDR, Dresden, Germany M. Wiencek IFJ-PAN, Kraków, Poland
	A future upgrade of the European XFEL (E-XFEL) foresees an additional cw operation mode increasing the flexibility in the photon beam time structure. This mode requires among others a cw operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating cw. Since more than a decade DESY in collaboration with TJNAF, NCBJ, BNL, HZB and HZDR performs R&D to develop an all superconducting RF gun with a lead cathode. In the frame of E-XFEL cw upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping the gun cavity in a clean room to exchange the cathode. Thus it is practical only when the life time of the cathode is at least several months. In this paper we present the actual status of the R&D program, next steps and the longer term plans.
	Slides MOPO037 [1.966 MB]
	Poster MOPO037 [3.774 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO037
About •	paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO038	RF Operation Experience at the European XFEL	FEL, MMI, operation, LLRF	109
	J. Branlard, V. Ayvazyan, L. Butkowski, M.K. Grecki, M. Hierholzer, M.G. Hoffmann, M. Hoffmann, M. Killenberg, D. Kostin, T. Lamb, L. Lilje, U. Mavrič, M. Omet, S. Pfeiffer, R. Rybaniec, H. Schlarb, Ch. Schmidt, N. Shehzad, V. Vogel, N. Walker DESY, Hamburg, Germany
	After its successful commissioning which took place during the first half of 2017, the European X-ray free electron laser is in now in regular operation delivering photons to users since September 2017. This paper presents an overview on the experience gathered during the first couple of years of operation. In particular, the focus is set on RF operation, maintenance activities, availability and typical failures. A first look on machine performance in terms of RF and beam stability, energy reach, radiation related investigations and microphonics studies will also be presented.
	Slides MOPO038 [2.421 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO038
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO039	Status Update of the Fast Energy Corrector Cavity at FLASH	electron, laser, coupling, free-electron-laser	112
	S. Pfeiffer, J. Branlard, L. Butkowski, M. Hierholzer, M. Hoffmann, K. Honkavaara, H. Schlarb, Ch. Schmidt, S. Schreiber, M. Vogt, J. Zemella DESY, Hamburg, Germany M. Fakhari CFEL, Hamburg, Germany
	Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453. Linear accelerator facilities driving a free-electron laser require femtosecond precision synchronization between external laser systems and the electron beam. Such high precision is required for pump-probe experiments and also for example for the electron bunch injection into a plasma bubble for laser plasma acceleration. An upgrade of the fast intra-train beam-based feedback system is planned at the Free-Electron Laser FLASH in Hamburg, Germany. This linear accelerator is based on superconducting (SRF) technology operating with pulse trains of maximum 1 MHz bunch repetition rate. Arrival time fluctuations of the electron beam are correctable by introducing small energy modulations prior to the magnetic bunch compressor. This contribution focuses on the design and the characterization of a normal-conducting RF (NRF) cavity with large bandwidth, mandatory to correct fast arrival time fluctuations. The cavity has recently been installed in the FLASH beamline. First measurements with the new cavity will be presented.
	Poster MOPO039 [1.884 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO039
About •	paper received ※ 13 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO059	Choke-Type Resonator for a Compact Storage Ring	storage-ring, ECR, ISOL, higher-order-mode	126
	L. Ovchinnikova, V.I. Shvedunov SINP MSU, Moscow, Russia L. Ovchinnikova, V.I. Shvedunov LEA MSU, Moscow, Russia A. Ryabov IHEP, Moscow Region, Russia
	We present the results of calculations and measurements the electrodynamic characteristics of the operating and high order modes of a choke-type resonator, intended for a 35-50 MeV storage ring, which is part of the Thomson X-ray generator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO059
About •	paper received ※ 09 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO063	Development of Side-coupled X-band Medical Linear Accelerator for Radiotherapy	linac, electron, gun, target	139
	Y.S. Lee, Y.W. Choi, G.J. Kim, I.S. Kim, J.I. Kim, S. Kim, J.H. Lee KERI, Changwon, Republic of Korea J.H. Hwang, Y.N. Kang, A.R. Kim, J.N. Kim, T.G. Oh, Y.A. Oh, Y. J. Seol, J.S. Shin The Catholic University of Korea, Seoul, Republic of Korea
	Recently, LINAC-based radiotherapy equipment are being developed by combining with imaging devices such as CT or MRI, so that it is possible to precisely focus high dose radiation on tumor tissues while minimizing the normal tissue damage. In order to place the diagnostic and treatment devices simultaneously in a confined space, constraints related to interference and volume between the subsystems must be considered. To meet these requirements, the size and weight of the LINAC system need to be reduced, which can be achieved by applying X-band technology. For the purpose of use in IMRT based on image guided radiotherapy, we developed a 9.3 GHz X-band medical LINAC using side-coupled structure. The LINAC is designed to have the accelerating field strength of 16.8 MV/m, and the beam current transmission efficiency of 26 % at the end of accelerating cell when the supplied RF power is at 1.7 MW. Therefore, it can accelerate the electron beam up to 6.2 MeV with having about 90 mA beam current. We plan to carry out the performance test using beam diagnostics system and X-ray measurement system, and the details of design and experimental results of LINAC will be described in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO063
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO070	Construction of the Side-coupled Standing-wave e-Linac	simulation, linac, coupling, electron	151
	S. Zarei Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran F. Abbasi Shahid Beheshti University, Tehran, Iran M. Bahrami, M. Lamehi IPM, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran
	Due to Iran’s growing need for accelerators in various applications, NSTRI electron linear accelerator project has been defined for medical and inspection applications. This accelerator is a 6 MeV side-coupled standing-wave that operate is π /2 mode in the frequency of 2998.5 MHz. In this paper the construction and measurement results of the tube of this accelerator are presented. The prototype tube was constructed from aluminum and was clamped with bolts. By using a network analyzer, electric and magnetic probes and a side-coupled cavity tuning method and a bead-pull measurement technique, RF measurements were carried out. The resonant frequency and quality factor have been achieved 2998.5 MHz and 7940 respectively . low-energy accelerator, construction of linac, standing-wave linac
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO070
About •	paper received ※ 12 September 2018 paper accepted ※ 09 November 2018 issue date ※ 18 January 2019
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MOPO073	Coherent Edge Radiation Sources in Linac-Based Infrared Free-Electron Laser Facilities	FEL, electron, radiation, undulator	154
	N. Sei, H. Ogawa AIST, Tsukuba, Ibaraki, Japan K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo, T. Tanaka LEBRA, Funabashi, Japan H. Ohgaki, H. Zen Kyoto University, Kyoto, Japan
	Funding: This study was financially supported by JSPS KAKENHI Grant Number JP16H03912. National Institute of Advanced Industrial Science and Technology has been studied far-infrared coherent radiation at Linac-based infrared free-electron laser (FEL) facilities in col-laboration with Nihon University and Kyoto University. To obtain high FEL gain at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University and at Kyoto Uni-versity Free Electron Laser (KU-FEL), the electron-bunch length is compressed to less than 1 ps in their undulator sections. Short electron bunches are suitable for generating intense coher-ent radiation, and we have already developed some terahertz-wave sources based on the coher-ent synchrotron radiation and the coherent transition radiation [1-3]. However, it was difficult to observe them with sufficient intensity without disturbing the infrared FEL oscillations. Then, we now develop coherent edge radiation emitted from downstream bending magnets in the un-dulator sections. It can be extracted from the undulator sections without disturbing the FEL os-cillations. In this presentation, the observed coherent radiation at LEBRA and KU-FEL will be reported on. [1] N. Sei et al., J. Phys. D: Appl. Phys. 46, (2013) 045104. [2] N. Sei et al., Nucl. Instr. and Meth. A, 832, (2016) 208. [3] N. Sei et al., Jpn. J. Appl. Phys.: 56, (2017) 032401.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO073
About •	paper received ※ 29 August 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO079	Cavity Design of a 7 MeV 325 MHz Proton APF IH-DTL for a Compact Injector	DTL, proton, linac, focusing	163
	X. Li University of Chinese Academy of Sciences, Beijing, People’s Republic of China X. Li, Y.H. Pu, X.C. Xie, M.H. Zhao SINAP, Shanghai, People’s Republic of China F. Yang Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China
	Funding: National Key Research and Development Program of China (grant number 2016YFC0105408) An Interdigit H-mode Drift-Tube-Linac (IH-DTL) with Alternating-Phase-Focusing (APF) method working at 325MHz was designed. With the RF field established properly in the cavity, protons can be accelerated from 3MeV to 7MeV successfully. In this paper, the process of designing such an APF IH-DTL cavity is going to be presented. Also, the characteristics of the cavity and pa-rameters studying of RF are going to be demonstrated.
	Poster MOPO079 [0.433 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO079
About •	paper received ※ 02 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO080	The Manufacturing of the CSNS DTL Tank	DTL, vacuum, linac, factory	167
	X.L. Wu, T. Luo CSNS, Guangdong Province, People’s Republic of China L. Dong, K.Y. Gong, H.C. Liu, H. Song IHEP, Beijing, People’s Republic of China S.M. Liu DNSC, Dongguan, People’s Republic of China
	The DTL tank is a crucial component of the China Spallation Neutron Source (CSNS) linear accelerator (LINAC), which mainly use the technology of oxygen-free copper (OFC) electroplating on the inner surface of the 20# carbon steel tube. It is the first time to perform OFC electroplating with high electrical conductivity in the high intensity beam accelerator in China. In the process of cavity manufacturing, problems such as machining deformation, plating surface nodule and plating peeling are encountered. In this project, based on pre-research and information from literature, the formula of acid solution was improved to construct a stable pickling process protocol. The manufacturing process of DTL tank and the measurement details are introduced in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO080
About •	paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO081	Light Proton Therapy Linac LLRF System Development	LLRF, controls, proton, interface	171
	B.B. Baricevic, A. Bardorfer, R. Cerne I-Tech, Solkan, Slovenia G. De Michele, Ye. Ivanisenko AVO-ADAM, Meyrin, Switzerland
	Proton cancer therapy is a state-of-the-art medical treatment technique based on an accelerator beam production facility. The LIGHT linear accelerator design by AVO-ADAM offers a modular compact solution for precise control of the treatment dose delivery, both position and energy wise. Proton energy can be modulated at up to 200 Hz in a range from 70 to 230 MeV by varying the gradient of the accelerating structures. The normal conducting LINAC RF system is based on a 750 MHz RFQ and 12 S band stations individually controlled. A customized LLRF system is being developed on the Libera LLRF platform for the LIGHT project. The paper is describing the required cavity field control functionality and the other subsystems such as master oscillator reference, cavity tuning, real-time control, data acquisition, control system and synchronization interfaces.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO081
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO084	The Simulation and Manufacture of the Room Temperature CH-DTL	impedance, DTL, linac, rfq	177
	J.H. Li, G. Han China Institute of Atomic Energy, Beijing, People’s Republic of China C.G. Li CIAE, Beijing, People’s Republic of China Z. Li SCU, Chengdu, People’s Republic of China
	The room temperature Cross-bar H Type Drift Tube Linac (CH-DTL) is one of the candidate acceleration structures working in CW mode. In order to optimize the parameters, the 3 dimensional electromagnetic field of the CH-DTL cavity is simulated. The method of parameter sweeping with constraint variable is better than the method of parameter sweeping with only one variable during the optimization. In order to simplify the manufacture, the drift tube surface can be designed as spherical shape. The CH-DTL cavity has been manufactured and tested.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO084
About •	paper received ※ 31 August 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO085	Prototype of an Inter-digital H-mode Drift-tube Linac for Muon Linac	linac, focusing, DTL, experiment	180
	Y. Nakazawa, H. Iinuma Ibaraki University, Ibaraki, Japan K. Hasegawa, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-mura, Japan N. Hayashizaki RLNR, Tokyo, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan Y. Iwata NIRS, Chiba-shi, Japan N. Kawamura, T. Mibe, M. Otani, T. Yamazaki, M. Yoshida KEK, Ibaraki, Japan R. Kitamura, H.Y. Yasuda University of Tokyo, Tokyo, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Sue Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
	An inter-digital H-mode (IH) drift-tube linac (DTL) is developed for a low velocity part in a muon linac at the J-PARC E34 experiment. It will accelerate muons from v/c = 0.08 to 0.28 at an operational frequency of 324 MHz. In order to achieve higher acceleration efficiency and make cost lower, an alternative phase focusing (APF) scheme is adopted. A prototype with 6 cells of 0.45 m length was manufactured. The prototype accelerates muons from v/c = 0.08 to 0.15 stage. We conducted frequency measurement and bead-pull measurement as a low-power measurement, in order to evaluate the prototype product. In this paper, the results of the low-power measurement for prototype cavity will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO085
About •	paper received ※ 10 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO087	Cold Test of Hybrid RFQ Prototype	rfq, quadrupole, simulation, linac	184
	P.Y. Yu, Y. He, C.X. Li, F.F. Wang, Z.J. Wang, B. Zhang IMP/CAS, Lanzhou, People’s Republic of China
	Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator, which is combined by four-vane RFQ structure and CH-DTL structure. It has higher energy gain rate compared to conventional RFQ, and it is more compact than traditional DTL. In order to research on process exploration and RF parameters of this structure, an aluminium prototype is developed. The cold test of Hybrid RFQ prototype is completed. This paper will present the results and analysis of the test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO087
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO088	Study on a 325 MHz HOM Drift Tube Linac	DTL, HOM, linac, impedance	187
	L. Lu, T. He, W. Ma, C.C. Xing, L. Yang IMP/CAS, Lanzhou, People’s Republic of China
	Normally, drift tube linacs (DTL) are used following RFQ linacs for beam acceleration in middle and high beam energy region. but acceleration efficiency of DTLs is decreasing with beam energy increasing. Using resonated higher order mode (HOM) of cavity, DTL can get higher effective shunt impedance. we proposed a 325MHz DTL with TE115 mode. In this paper, the dynamics calculation and electromagnetic design of the HOM-DTL will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO088
About •	paper received ※ 13 September 2018 paper accepted ※ 17 October 2018 issue date ※ 18 January 2019
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MOPO090	Measurements of the First Room Temperature CH Cavity for MYRRHA at IAP Frankfurt	simulation, resonance, status, rfq	193
	K. Kümpel, S. Lamprecht, P. Müller, N.F. Petry, H. Podlech, S. Zimmermann IAP, Frankfurt am Main, Germany
	Funding: This work has been supported by MYRTE which is funded by the European Commission under Project-ID 662186. The MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project is a planned accelerator driven system (ADS) for the transmutation of long-living radioactive waste. A critical passage for the beam quality and especially for the emittance is the injector, which for the MYRRHA project consists of a 4-Rod RFQ, two Quarter Wave Rebunchers (QWR) and a total of 16 normal conducting CH-DTL cavities. The first installment of the MYRRHA injector in Louvein-La-Neuve (Belgium) will include an ion source, a RFQ, the QWRs and the first seven CH DTL cavities. This paper will report on the status of the low level tests on CHs 1 and 2 as well as on further developments on CHs 8-15.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO090
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO093	A Study of a Cooling Configuration for an OFHC Copper Rebuncher	simulation, linac, pick-up, vacuum	200
	O. Mazor, M. Bukai, D. Nusbaum, J. Rodnizki Soreq NRC, Yavne, Israel E. Dyunin Ariel University, Ariel, Israel G. Ziskind Ben-Gurion University in the Negev, Beer Sheva, Israel
	Funding: Pazy Fund (Israel Atomic Energy commission) https://pazy.org.il A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction for the MEBT of SARAF Phase II proton/ deuteron linac. The rebuncher is designed to bunch a 5 mA CW beam at 176 MHz. The required cavity voltage according to beam dynamics evaluation is 150 kV with a beam aperture diameter of 40 mm at a beam energy of 1.3 MeV/u with a Q value of 8000. Considering utilizing this cavity for enhancing the beam energy, the cooling configuration is explored for a cavity voltage of 300 kV, consuming 20 kW dissipated power, at a peak electric field of 16 MV/m, equivalent to the Kilpatrick limit. The electro magnetic study conducted with the CST RF simulation package was reproduced at ANSYS HFSS. The simulated dissipated power along the rebuncher for 20 kW forward power injected through the coupler port with the HFSS driven model were assigned to the ANSYS Fluent model to explore the resulted temperature map. Several evolved cooling configurations were studied, including cooling of the drift tubes. In this configuration the temperature rise along the cavity is in the range of 30 K. A detailed design of the four gap rebuncher is following this study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO093
About •	paper received ※ 03 September 2018 paper accepted ※ 22 September 2018 issue date ※ 18 January 2019
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MOPO094	RF Stability Test of RFQ Cavity with Prototype Low-level Radio Frequency in RAON	rfq, LLRF, controls, experiment	204
	D.Y. Lee, B.H. Choi, C.O. Choi, H. Jang, H.C. Jung, K.T. Son IBS, Daejeon, Republic of Korea
	RAON is a heavy ion accelerator of the Institute for Basic Sciences (IBS) in Korea. The prototype Low-Level Radio Frequency (LLRF) operated at 81.25 MHz has been designed and fabricated for a prototype Radio Fre-quency Quadrupole (RFQ) cavity in RAON. Stabilities of ±1 % in amplitude and ±1 degree in phase are required for specifications of the RFQ system. The prototype LLRF controls the RF amplitude and phase in the cavity by PID feedback loop. The prototype LLRF has been tested with one RFQ cavity and stabilities have been measured. In this paper, we present the design and results of stability test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO094
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO101	LINAC-multitool - an Open Source Java-toolkit	linac, GUI, simulation, MMI	217
	M. Schwarz, D. Bade, J. Corbet, H. Podlech IAP, Frankfurt am Main, Germany
	Funding: Work supported by BMBF contr. No. 05P15RFRBA and HIC for FAIR Dedicating more precious time to advanced research instead of spending it towards timeconsuming routine tasks is a desirable goal in particle accelerator simulation and development. Requirements engineering was started at IAP in order to identify routine processes at our institute’s R&D that can be automated or simplified. Results indicated that there were several areas to consider: Bead pull measurements, data processing and visualization for the beam dynamics code LORASR, CST field map processing for the use with TraceWin, conversion between different particle distribution data formats and more. Subsequently development of the LINAC-Multitool started to rationalize these processes and replace preexisting scripts also to ensure consistency of results and increase transparency and reliability of computation. In order to guarantee maintainability, expandability and platform independence, LINAC-Multitool is programmed using Java and will be open source. This contribution presents the current state of development.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO101
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO102	Progress of MicroTCA.4 based LLRF System of TARLA	LLRF, controls, hardware, operation	220
	C. Gumus, M. Hierholzer, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany A.A. Aksoy, A. Aydin, C. Kaya Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey O.F. Elcim Ankara University Institute of Accelerator Technologies, Golbasi, Turkey
	The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is constructing a 40 MeV Free Electron Laser with continuous wave RF operation. DESY is responsible for delivering a turnkey LLRF system based on MicroTCA.4 standard that will be used to control four superconducting (SC) TESLA type cavities as well as the two normal conducting buncher cavities. This highly modular system is further used to control the mechanical tuning of the SC cavities by control of piezo actuators and mechanical motor tuners. With the usage of ChimeraTK framework, integration to EPICS control system is also implemented. This poster describes the system setup and integration to the existing accelerator environment with hardware and software components along with the latest updates from the facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO102
About •	paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO104	LLRF R&D Towards CW Operation of the European XFEL	FEL, controls, LLRF, resonance	223
	A. Bellandi, V. Ayvazyan, J. Branlard, C. Gumus, S. Pfeiffer, K.P. Przygoda, R. Rybaniec, H. Schlarb, Ch. Schmidt, J.K. Sekutowicz DESY, Hamburg, Germany W. Cichalewski TUL-DMCS, Łódź, Poland
	The ever growing request for machines with a higher average beam pulse rate and also with a relaxed (< 1 MHz) pulse separation calls for superconducting linacs that operate in Long Pulse (LP) or Continuous Wave (CW) mode. For this purpose the European X-ray Free Electron Laser (European XFEL) could be upgraded to add the ability to run in CW/LP mode. Cryo Module Test Bench (CMTB) is a facility used to perform tests on superconducting cavity cryomodules. Because of the interest in upgrading European XFEL to a CW machine, CMTB is now used to perform studies on XM-3, a 1.3 GHz European XFEL-like cryomodule with modified coupling that is able to run with very high quality factor (QL = 10E7…10E8) values. The RF power source allows running the cavities at gradients larger than 16 MV/m. Because of the QL and gradient values involved in these tests, detuning effects like mechanical resonances and microphonics became more challenging to regulate. The goal is then to determine the appropriate set of parameters for the LLRF control system to keep the error to be less than 0.01° in phase and 0.01% in amplitude.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO104
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO106	New Digital LLRF System for HIT	controls, LLRF, linac, feedback	227
	E. Feldmeier, Th. Haberer, A. Peters HIT, Heidelberg, Germany
	The Heidelberg Ion Therapy Center HIT is in clinical operation since 2009. The accelerator complex consists of a linear accelerator and a synchrotron to provide carbon ions and protons for clinical use as well as helium and oxygen ions. The analog LLRF system for the linac should be replaced after more than 10 years of continuous operation. In its life-time the LLRF caused no interruption of the clinical operation with a downtime of more than 15 minutes. In order to keep the reliability in the next 10 years at least as high, a new digital LLRF system is planned. Further difficulties for the installation of a new system are due to the clinical full time usage of the accelerator and the short maintenance slots of only two days in series.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO106
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO118	Optimized Design for a Compact Linac with Collinear Absorbing Loads at the Hust FEL-THz	linac, FEL, radiation, electron	242
	J. Jiang, G. Feng, T. Hu, Y. Lu, X.D. Tu, Y.Q. Xiong HUST, Wuhan, People’s Republic of China Y.J. Pei USTC/NSRL, Hefei, Anhui, People’s Republic of China
	To meet the requirement of miniaturization for high power THz radiation in the field of commercial and civil use, RF Linacs have been applied widely as beam injectors, and the Linac with collinear absorbing loads reveals the potential to achieve a tradeoff between performance and compactness. Under overall consideration of systematic conflicts, optimization choices for such Linacs involving power absorbing ability, accelerating efficiency, as well as beamline length were described in this context. Meanwhile, cold testing has been conducted to verify design parameters for the collinear absorbing loads. Furthermore, elaborated calculation of thermal power loss and integrated helical water channel cooling has been performed for the 14MeV Linac with collinear absorbing loads installed on the HUST FEL-THz, and online experiments demonstrated that both the accelerating efficiency and the water cooling performance fulfilled operation demands.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO118
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO119	Design of a Fully Automated Test Bench for Measuring the Field Distribution in Standing Wave Cavity	simulation, coupling, controls, network	246
	Y. Lu, G. Feng, T. Hu, J. Jiang, X.D. Tu, Y.Q. Xiong HUST, Wuhan, People’s Republic of China
	The resonant cavity plays a great role in the linear accelerator. An accurate measurement of the cavity field distribution is very important to design linear accelerators. A fully computer controlled bench for the electric field distribution has been developed in this context. Based on the perturbation theory, the acquisition of the resonant frequency shift is proportional to the square of E (electric field). In order to verify the reliability of the test bench, a standard cylindrical cavity has been tested in this measurement system. The simulation by HFSS (High Frequency Structure Simulator) and the practice will be both presented in this paper. And the result demonstrates that, because of its high concentricity, the automated test bench achieves high precision in measuring the distribution of electric field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO119
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO120	Improvement of the Linear Part in the Tuner System of ADS 25 MeV Linac	linac, experiment, proton, superconducting-cavity	250
	L. Zhang, Z. Gao, L.B. Liu, F.F. Wang, B. Zhang IMP/CAS, Lanzhou, People’s Republic of China
	Tuner system is the indispensable part of ADS high current proton superconducting linac. It influences the working frequency of superconducting cavity of particle accelerator. To completely understand the working situa-tion of the tuner system and analyses the problems existing in it, experiments of linear part were fully conducted.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO120
About •	paper received ※ 09 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO130	Magnetic Flux Generated by Thermal Current in CEBAF 5-Cell Cavity System	cryomodule, experiment, niobium, operation	273
	R.L. Geng JLab, Newport News, Virginia, USA S.C. Huang IMP/CAS, Lanzhou, People’s Republic of China
	The unloaded quality factor Q0 of many 5-cell CEBAF cavities were lowered by a factor of ~2 from their vertical qualification testing to their beam operation in CEBAF tunnel. Causes of this Q0 degradation were studied previously, including a more recent one addressing static fluxes arising from magnetic components near a 5-cell cavity. This paper reports on a preliminary study of the dynamic fluxes generated by a thermal current. Such a thermal current arises from the Seebeck effect and flows in closed loops formed by a niobium cavity and its surrounding tuner rods and liquid helium vessel that are made of stainless-steel. The behaviors of magnetic fluxes in response to various thermal profiles on a 5-cell CEBAF cavity with integrated tuner rods were studied in a JLAB VTA dewar. An outcome of this study is a proposed cool-down procedure for eliminating the thermal current generated magnetic fluxes around 5-cell cavities placed in CEBAF tunnels. This procedure may be useful to improve cavity Q0 in a cost-effective manner, which in turn saves cryogenic expenditures for sustaining CEBAF operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO130
About •	paper received ※ 01 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TU1A01	Challenges in Superconducting Accelerating Module Design and Construction for High Power Proton Accelerators	cryomodule, linac, vacuum, alignment	280
	C. Madec CEA/DSM/IRFU, France
	CEA is engaged in the construction of the IFMIF, SARAF and ESS superconducting linacs and in particular in the design and production of a their accelerating cryomodules: 1 low-beta half-wave 176 MHz resonators for IFMIF, 4 low-beta half-wave 176 MHz resonators for SARAF and 30 medium and high-beta elliptical cavity resonators for ESS. The developments of these RF cryomodules, although at various stages, are led in parallel by the cryomodule team at CEA-Saclay, including all RF, mechanical, thermal, cryogenic, integration and QA-QC aspects in a global approach which attempts to optimise synergies and lessons learnt between these projects. A status report will be presented describing the common approaches and methods, and the systemic particularities of each project.
	Slides TU1A01 [11.896 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1A01
About •	paper received ※ 14 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TU1A03	Status and Issues (Microphonics, LFD, MPS) with TRIUMF ARIEL e-Linac Commissioning	linac, TRIUMF, MMI, electron	286
	S.R. Koscielniak, M. Alcorta, F. Ames, E. Chapman, K. Fong, B. Humphries, O.K. Kester, D. Kishi, R.E. Laxdal, Y. Ma, T. Planche, M. Rowe, S.D. Rädel, V.A. Verzilov, Z.Y. Yao TRIUMF, Vancouver, Canada
	The ARIEL electron linac (e-linac) is designed to generate cw beams of up to 30 MeV and 10 mA for delivery to a photo-convertor. Bremsstrahlung induced fission of a production target yields neutron-rich rare isotope beams to be supplied to the ISAC experimental facilities. The beam power will eventually reach 300 kW, and a machine protection system (MPS) with 10 μs rapidity is essential. The e-linac, which adopts 1.3 GHz, 2K SRF technology, is composed of a 10 MeV single-cavity injector cryomodule (EINJ) and a 20 MeV two-cavity accelerator cryomodule (EACA). The latter has vector-sum control of two cavities driven from a single klystron. Beam commissioning of these systems is ongoing since 2016. The magnetic optics and MPS commissioning to 10 MeV is reported herein. Beam has been accelerated up to 25 MeV, and thread-ed to the high energy dump (EHD). A campaign to investigate microphonics driving terms, LN2 disturb-ances, and a ponderomotive instability in the EACA, is underway.
	Slides TU1A03 [9.683 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1A03
About •	paper received ※ 17 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TU1A05	Seamless Quarter Wave Resonators for HIE ISOLDE	ISOL, niobium, linac, cryomodule	292
	W. Venturini Delsolaro, A. Miyazaki CERN, Geneva, Switzerland
	The HIE-ISOLDE post accelerator consists of 4 cryomodules with 5 niobium-coated Quarter Wave Reso-nators (QWR) each. The standard manufacturing tech-nique was to machine the inner and outer conductor sepa-rately, to shrink-fit the 2 pieces and to apply an electron beam welding at the interface. Due toμcracks, ob-served on some of the cavities around the welds, we took the decision to explore the possibility of a seamless de-sign. First cavities became available in late 2017 and were then cold-tested in the vertical cryostat. These seam-less coated quarter wave resonators have shown some of the highest Q-values of all HIE-ISOLDE cavities in the acceptance tests. Furthermore, we studied the cavity per-formance with different compensations of the earth mag-netic field and different temperature gradients upon cool down. These tests have demonstrated record-breaking RF surface fields for the Nb/Cu technology. This paper re-views the design and fabrication and reports on the cold tests results of seamless quarter wave resonators, and of possible future applications
	Slides TU1A05 [30.518 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1A05
About •	paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TU2A01	First Acceleration of Heavy Ion Beams with a Superconducting Continuous Wave HIM/GSI CW-linac	linac, heavy-ion, acceleration, emittance	297
	W.A. Barth, K. Aulenbacher, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev GSI, Darmstadt, Germany M. Basten, M. Busch, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany
	First acceleration of heavy ion beams with a superconducting continuous wave HIM/GSI CW-Linac After successful RF-testing of a new superconducting Linac RF-cavity at GSI Helmholtzzentrum für Schwerionenforschung and a short commissioning and ramp up time of some days, this 15-gaps Crossbar H-cavity accelerated first time heavy ion beams with full transmission up to the design beam energy. The design acceleration gain of 3.5 MV inside a length of less than 70 cm has been verified with heavy ion beam of up to 1.5 particle mkA. The measured beam parameters show a nice beam quality. The machine commissioning with beam is a milestone of the R&D work of Helmholtz Institute Mainz and GSI in collaboration with Goethe University Frankfurt in development of the superconducting heavy ion continuous wave linear accelerator CW-Linac.
	Slides TU2A01 [3.385 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU2A01
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TU2A03	Layout of the New FAIR Post-stripper DTL for Intense Heavy Ion Beams	DTL, quadrupole, operation, emittance	303
	S. Mickat, X. Du, P. Gerhard, L. Groening, M. Heilmann, M. Kaiser, A. Rubin, V. Srinivasan, W. Sturm GSI, Darmstadt, Germany
	The new post-stripper DTL at GSI shall accelerate uranium beams with space charge induced tune depressions of up to 37% to 11.4 MeV/u. Emittance dilution must be kept below few percent. However, the layout must also allow for delivery of lightest ions to just 3.0 MeV/u. This broad-banded range of requirements imposes huge challenges on the layout and fabrication especially of the cavities and drift tube magnets.
	Slides TU2A03 [4.777 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU2A03
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TU2A04	Progress Report on LIPAC	rfq, MMI, linac, SRF	308
	M. Sugimoto, T. Akagi, T. Ebisawa, Y. Hirata, R. Ichimiya, A. Kasugai, K. Kondo, S. Maebara, K. Sakamoto, T. Shinya QST, Aomori, Japan P. Abbon, N. Bazin, B. Bolzon, N. Chauvin, S. Chel, R. Gobin, J. Marroncle, B. Renard CEA/IRFU, Gif-sur-Yvette, France L. Antoniazzi, L. Bellan, D. Bortolato, M. Comunian, E. Fagotti, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo INFN/LNL, Legnaro (PD), Italy P.-Y. Beauvais, H. Dzitko, D. Gex, R. Heidinger, A. Jokinen, I. Moya, G. Phillips Fusion for Energy, Garching, Germany P. Cara IFMIF/EVEDA, Rokkasho, Japan D. Gavela, D. Jiménez-Rey, I. Kirpitchev, J. Mollá, P. Méndez, I. Podadera, D. Regidor, R. Varela, M. Weber CIEMAT, Madrid, Spain J. Knaster F4E, Barcelona, Spain G. Pruneri Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy
	International Fusion Materials Irradiation Facility (IFMIF) is the neutron source for simulating fusion reactor environment using two 40 MeV/125 mA CW D⁺ beams. LIPAc facility is under construction in Rokkasho for validating 9 MeV/125 mA CW linac technology as a prototype of the IFMIF accelerator. Commissioning of 5 MeV CW RFQ is underway after the completion of installation of RFQ, MEBT, diagnostic plate. low power beam dump, RF power system and their auxiliaries. As the first step, high power RF conditioning is planned to complete in early 2018 and beam commissioning will start with stepwise approach at the same time. The status of LIPAc construction for preparing 9 MeV acceleration and results of RFQ beam commissioning are presented.
	Slides TU2A04 [9.651 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU2A04
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TU1P01	Extreme High Brightness Electron Beam Generation in a Space Charge Regime	emittance, electron, space-charge, bunching	314
	A. Bacci Istituto Nazionale di Fisica Nucleare, Milano, Italy L. Faillace, M. Rossetti Conti Universita’ degli Studi di Milano & INFN, Milano, Italy
	The generation of ultra-short, low emittance and low energy spread electron bunches is nowadays a critical requirement for accelerators in plasma wave or for femto-second light sources. A new longitudinal compression scheme, based on velocity and ballistic bunching tech-niques in presence of space charge forces, allows to enter in a peculiar regime, so-called laminar bunching (LB). In this regime, the bunch is longitudinally compressed, at the expense of its transverse size, and the over-bunching is forbidden by the laminarity: going to the minimal longi-tudinal dimension the bunch is adiabatically frozen and transversally refocused. Furthermore this technique heats slightly the uncorrelated energy spread resulting in elec-tron distributions that, in case of bending paths, does not require Laser Heater devices.
	Slides TU1P01 [1.720 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1P01
About •	paper received ※ 12 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019
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TUPO003	Development of CW Heavy Ion Linac at IMP	DTL, linac, MMI, rfq	326
	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	DTL, linac, simulation, quadrupole	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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TUPO009	Heat Treatment for a Prototype Half-Wave Resonator Cavity	niobium, vacuum, SRF, lattice	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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TUPO017	The New Light Ion Injector for NICA	linac, diagnostics, LLRF, rfq	362
	B. Koubek, M. Basten, H. Höltermann, 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	cryomodule, cryogenics, controls, experiment	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	cryomodule, pick-up, damping, linac	370
	Y. Ma, K. Fong, M. Keikha, J.J. Keir, D. Kishi, S.R. Koscielniak, D. Lang, R.E. Laxdal, 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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TUPO023	Preserving Micron Tolerances Through the Assembly Process of an X-band Accelerating Structure	simulation, HOM, linac, software	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	GUI, cryomodule, FEL, LLRF	380
	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	FEL, vacuum, SRF, linac	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	cryomodule, FEL, operation, feedback	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	superconducting-RF, radio-frequency, linac, SRF	391
	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	SRF, niobium, electromagnetic-fields, pick-up	395
	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	HOM, SRF, linac, operation	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	HOM, dipole, luminosity, ECR	402
	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	experiment, electromagnetic-fields, SRF, superconducting-cavity	405
	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	plasma, electron, experiment, SRF	408
	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	experiment, SRF, HOM, niobium	412
	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	multipactoring, linac, TRIUMF, simulation	417
	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	TRIUMF, LLRF, controls, niobium	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	HOM, cryomodule, vacuum, target	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	SRF, site, superconductivity, lattice	427
	M.C. Burton, A.D. Palczewski, H.L. Phillips, C.E. Reece, 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	SRF, niobium, controls, operation	431
	H. Tian, J. Carroll, C.E. Reece, 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	linac, HOM, coupling, SRF	435
	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	laser, ECR, niobium, experiment	438
	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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Paper

Title

Other Keywords

Page

MO1A01

CSNS Front End and Linac Commissioning

linac, MMI, DTL, rfq

1

S. Fu, H.C. Liu, H.F. Ouyang, S. Wang
IHEP, Beijing, People’s Republic of China
J. Li, J. Peng
CSNS, Guangdong Province, People’s Republic of China

The China Spallation Neutron Source(CSNS) accelera-tor systems is designed to deliver a 1.6GeV, 100kW proton beam to a solid metal target for neutron scattering research. The accelerator consists of a front end, an 80MeV DTL linac, and a 1.6GeV Rapid Cycling Syn-chrotron (RCS). In August 2017 the first 1.6GeV proton beam hit on the tungsten target and production neutrons were monitored. This paper will report the major steps and results of the machine commissioning and beam commissioning of the CSNS front end and linac. In the first section, a brief introduction of the CSNS accelerator design and present status will be presented. Then, we will share our commissioning experience in the front end and the DTL linac in the following sections.

Slides MO1A01 [9.123 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1A01

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

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MO1A02

An Overview of Recent Developments in SRF Technology

SRF, niobium, cryomodule, linac

6

R.E. Laxdal
TRIUMF, Vancouver, Canada

Superconducting Radio-Frequency (SRF) is now the technology of choice for both large and small linac projects. Several challenging projects are in progress or planned that are pushing SRF technology and/or are enabled by SRF technology. This paper gives an overview of the present status of the field.

Slides MO1A02 [4.202 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1A02

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paper received ※ 16 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019

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MO1P02

Approaches to High Power Operation of J-PARC Accelerator

linac, operation, rfq, ion-source

29

H. Oguri
JAEA/J-PARC, Tokai-mura, Japan

Japan Proton Accelerator Research Complex (J-PARC) accelerators have been having over 10 years of operation experience. In 2006, the J-PARC linac started beam operation with an energy of 181 MeV. To realize the nominal performance of 1 MW at 3 GeV Rapid Cycling Synchrotron (RCS) and 0.75 MW at a 30 GeV Main Ring synchrotron (MR), the linac energy was upgrade to 400 MeV by adding an annular-ring coupled structure linac, and the beam current was also upgraded from 30 to 50 mA by replacing a new ion source and an RFQ. After the upgrade, the RCS demonstrated 1MW equivalent beam operation and currently operates 400 kW for the Material and Life Science Facility. The MR beam power is increasing and becomes about 480 kW beam to the Neutrino Facility and about 50 kW at the Hadron Experimental Facility. Further upgrade plan of 1.5 MW beam power from the RCS is now in consideration. To achieve the plan, it is necessary to increase by about 20 % both beam current and pulse length at the linac. The detail process in the past upgrade and the possibility for further upgrade at the linac will be presented in this talk.

Slides MO1P02 [5.595 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1P02

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

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MO1P03

Status of the ESS Linac

linac, ion-source, controls, target

35

A. Sunesson, P. Arnold, S.L. Birch, R. Garoby, M. Jensen, M. Lindroos, C.A. Martins, A. Nordt, T.J. Shea, J.G. Weisend
ESS, Lund, Sweden

The European Spallation Source under construction in Lund (Sweden) uses a 2 GeV-5MW pulsed superconducting linac as proton driver. Normal conducting accelerating structures are used up to 92 MeV and superconducting structures up to 2 GeV. Most linac components are designed and procured as in-kind contributions by institutes/laboratories in the European partner countries. Installation of the Ion source delivered by INFN-Catania started end 2017. Installation of more components and infrastructure progresses at a high pace. Commissioning of the normal conducting linac section will take place in parallel with installation of the superconducting section. Beam commissioning of the superconducting section will be done starting in 2021, interlaced with the installation of additional high beta cryomodules. Beam will be sent to the target in 2022, initially at an energy of 1.3 GeV. Start of the User Programme is scheduled in 2023, when some neutron instruments will be ready and end of construction is in 2025, with the full set of instruments operational. This paper reports the status of linac components construction, the progress with installation on site, and the overall project schedule.

Slides MO1P03 [14.161 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1P03

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

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MOPO004

Commissioning of the SRF Booster Cavity for LEReC

booster, SRF, gun, MMI

40

W. Xu, A.V. Fedotov, T. Hayes, D. Holmes, G.T. McIntyre, K. Mernick, S.K. Seberg, F. Severino, K.S. Smith, R. Than, Q. Wu, B. P. Xiao, T. Xin, A. Zaltsman
BNL, Upton, Long Island, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
One important component for LEReC project is a 704 MHz booster cavity, which was modified from the BNL ERL 704 MHz SRF gun cavity. The major modifications include converting the upstream cathode transportation to a proper beam pipe, adding a HOM coaxial line HOM damper to the downstream, retracting FPC insertions, and improvement of cryomodule layout. In the past one and half year, tremendous work was completed: the cavity was modified and tested vertically, FPC were conditioned, and HOM damper were designed and conditioned, cryomodule was re-assembled. The booster cavity cryomodule was successfully commissioned in mid October, and it was moved to LEReC location at RHIC tunnel 2 O’clock early November. This paper will report the configuration of the new cryomodule and its commissioning results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO004

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

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MOPO005

Commissioning of the Normal Conducting Cavities for LEReC Project

booster, electron, MMI, vacuum

44

B. P. Xiao, K. Mernick, F. Severino, K.S. Smith, T. Xin, A. Zaltsman
BNL, Upton, Long Island, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is designed, and is currently under commissioning at BNL. The linac of LEReC consists of a DC photoemission gun, a 704 MHz superconducting radio frequency (SRF) booster cavity, a three-cell 2.1 GHz third harmonic cavity for RF curvature correction, a single-cell 704 MHz cavity for energy de-chirping and a 704 MHz deflecting cavity for diagnostic line. In this paper, we present the commissioning of three normal conducting cavities mentioned above.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO005

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paper received ※ 14 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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MOPO006

Crosstalk Effect in the LEReC Booster Cavity

resonance, booster, HOM, cathode

47

B. P. Xiao, K. Mernick, F. Severino, K.S. Smith, T. Xin, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Linac of Low Energy RHIC electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with peak-to-peak dp/p less than 7·10^-4. The booster cavity is the major accelerating component in LEReC, which is a 0.4 cell cavity operating at 2 K, with a maximum energy gain of 2.2 MeV. It is modified from the Energy Recovery Linac (ERL) photocathode gun, with fundamental power coupler, pickup coupler and HOM coupler close to each other. Crosstalk effect in this cavity is simulated and measured. Correction method is proposed to meet the energy spread requirement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO006

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paper received ※ 14 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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MOPO008

The RF Gun Adopting the Dielectric Assist Accelerating Structure

electron, cathode, emittance, gun

54

S. Mori, D. Satoh, M. Yoshida
KEK, Ibaraki, Japan

We apply the dielectric assist accelerating (DAA) structure to the RF gun, which is a candidate for a high average current and high brightness electron source. The DAA structure consists of ultralow-loss dielectric cylinders and disks which are periodically arranged in a metallic enclosure. Due to the high quality factor and the high shunt impedance of the DAA cavity, the RF gun adopting the DAA cavity can be a high-duty electron beam source at room temperature. We provide design work for RF gun adopting the DAA structure.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO008

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

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MOPO018

Development of an Improved Capture Section for the S-DALINAC Injector*

electron, linac, simulation, gun

68

S. Weih, M. Arnold, J. Enders, N. Pietralla
TU Darmstadt, Darmstadt, Germany
D.B. Bazyl, H. De Gersem, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany

For the injector of the superconducting Darmstadt electron linear accelerator S-DALINAC, the design of a new capture cavity was recently completed. This beta-reduced structure will optimize the capture of low-energy electron bunches from the gun section and therefore improve the longitudinal beam quality of the injector beam, as simulations have shown. The existing cryomodule of the injector has to be modified for the installation of the new cavity. These modifications include adaptions of the tuner frame as well as modifications of other surrounding parts. To improve the diagnostics in the low-energy section, an energy-spread measurement setup is currently also under development. In this contribution the cryomodule modifications as well as simulation results for the longitudinal beam dynamics are presented.
*Work supported by DFG through GRK 2128 "AccelencE"

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO018

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MOPO019

Study on Cleaning of Copper Plated Bellows for LCLS-II

SRF, FEL, cryomodule, experiment

71

L. Zhao, E. Daly, G.K. Davis, G.V. Eremeev, A.V. Reilly, A-M. Valente-Feliciano, K.M. Wilson
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515 for the LCLS-II Project.
Inter-cavity copper plated bellows are part of the LCLS-II cryomodule beamline components. Since the bellows are close to superconducting radio frequency (SRF) cavities during accelerator operation, it is desirable that these bellows have similar cleanliness as SRF cavi-ties. Studies have been done to help evaluate bellows interior cleanliness after the standard bellows cleaning procedure at Jefferson Lab.

Poster MOPO019 [1.326 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO019

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paper received ※ 28 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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MOPO026

The Resonance Frequency Shift After Applying the Cooling System for a Side Coupled Standing Wave Linac

controls, electron, coupling, radio-frequency

81

M. Mohseni Kejani, F. Abbasi Davani
Shahid Beheshti University, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran

A radio frequency accelerator tube used in linear medical accelerators includes three main sections of the radio frequency cavity, an electron gun and the X-ray target, which is vacuumed by a pump inside it. The electromagnetic energy loss in the structure of the cavity can increase the temperature of the tube, resulting in changes in the geometric dimensions and then changes in some of the cavity characteristics, such as the resonance frequency. A cooling system is required to prevent excessive change in the resonant frequency due to thermal loss. Also, it is necessary to perform some computer simulations to stabilize the cavity’s performance in the presence of electromagnetic energy thermal dissipation and the cooling system. In this paper, the simulation results of resonant frequency shifts after applying the cooling system have been reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO026

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MOPO037

SRF Gun Development at DESY

gun, cathode, SRF, laser

105

E. Vogel, S. Barbanotti, I. Hartl, K. Jensch, D. Klinke, D. Kostin, W.-D. Möller, M. Schmökel, J.K. Sekutowicz, S. Sievers, N. Steinhau-Kühl, A.A. Sulimov, J.H. Thie, H. Weise, L. Winkelmann, B. van der Horst
DESY, Hamburg, Germany
J.A. Lorkiewicz, R. Nietubyć
NCBJ, Świerk/Otwock, Poland
J. Smedley
BNL, Upton, Long Island, New York, USA
J. Teichert
HZDR, Dresden, Germany
M. Wiencek
IFJ-PAN, Kraków, Poland

A future upgrade of the European XFEL (E-XFEL) foresees an additional cw operation mode increasing the flexibility in the photon beam time structure. This mode requires among others a cw operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating cw. Since more than a decade DESY in collaboration with TJNAF, NCBJ, BNL, HZB and HZDR performs R&D to develop an all superconducting RF gun with a lead cathode. In the frame of E-XFEL cw upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping the gun cavity in a clean room to exchange the cathode. Thus it is practical only when the life time of the cathode is at least several months. In this paper we present the actual status of the R&D program, next steps and the longer term plans.

Slides MOPO037 [1.966 MB]

Poster MOPO037 [3.774 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO037

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

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MOPO038

RF Operation Experience at the European XFEL

FEL, MMI, operation, LLRF

109

J. Branlard, V. Ayvazyan, L. Butkowski, M.K. Grecki, M. Hierholzer, M.G. Hoffmann, M. Hoffmann, M. Killenberg, D. Kostin, T. Lamb, L. Lilje, U. Mavrič, M. Omet, S. Pfeiffer, R. Rybaniec, H. Schlarb, Ch. Schmidt, N. Shehzad, V. Vogel, N. Walker
DESY, Hamburg, Germany

After its successful commissioning which took place during the first half of 2017, the European X-ray free electron laser is in now in regular operation delivering photons to users since September 2017. This paper presents an overview on the experience gathered during the first couple of years of operation. In particular, the focus is set on RF operation, maintenance activities, availability and typical failures. A first look on machine performance in terms of RF and beam stability, energy reach, radiation related investigations and microphonics studies will also be presented.

Slides MOPO038 [2.421 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO038

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

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MOPO039

Status Update of the Fast Energy Corrector Cavity at FLASH

electron, laser, coupling, free-electron-laser

112

S. Pfeiffer, J. Branlard, L. Butkowski, M. Hierholzer, M. Hoffmann, K. Honkavaara, H. Schlarb, Ch. Schmidt, S. Schreiber, M. Vogt, J. Zemella
DESY, Hamburg, Germany
M. Fakhari
CFEL, Hamburg, Germany

Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453.
Linear accelerator facilities driving a free-electron laser require femtosecond precision synchronization between external laser systems and the electron beam. Such high precision is required for pump-probe experiments and also for example for the electron bunch injection into a plasma bubble for laser plasma acceleration. An upgrade of the fast intra-train beam-based feedback system is planned at the Free-Electron Laser FLASH in Hamburg, Germany. This linear accelerator is based on superconducting (SRF) technology operating with pulse trains of maximum 1 MHz bunch repetition rate. Arrival time fluctuations of the electron beam are correctable by introducing small energy modulations prior to the magnetic bunch compressor. This contribution focuses on the design and the characterization of a normal-conducting RF (NRF) cavity with large bandwidth, mandatory to correct fast arrival time fluctuations. The cavity has recently been installed in the FLASH beamline. First measurements with the new cavity will be presented.

Poster MOPO039 [1.884 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO039

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

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MOPO059

Choke-Type Resonator for a Compact Storage Ring

storage-ring, ECR, ISOL, higher-order-mode

126

L. Ovchinnikova, V.I. Shvedunov
SINP MSU, Moscow, Russia
L. Ovchinnikova, V.I. Shvedunov
LEA MSU, Moscow, Russia
A. Ryabov
IHEP, Moscow Region, Russia

We present the results of calculations and measurements the electrodynamic characteristics of the operating and high order modes of a choke-type resonator, intended for a 35-50 MeV storage ring, which is part of the Thomson X-ray generator.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO059

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paper received ※ 09 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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MOPO063

Development of Side-coupled X-band Medical Linear Accelerator for Radiotherapy

linac, electron, gun, target

139

Y.S. Lee, Y.W. Choi, G.J. Kim, I.S. Kim, J.I. Kim, S. Kim, J.H. Lee
KERI, Changwon, Republic of Korea
J.H. Hwang, Y.N. Kang, A.R. Kim, J.N. Kim, T.G. Oh, Y.A. Oh, Y. J. Seol, J.S. Shin
The Catholic University of Korea, Seoul, Republic of Korea

Recently, LINAC-based radiotherapy equipment are being developed by combining with imaging devices such as CT or MRI, so that it is possible to precisely focus high dose radiation on tumor tissues while minimizing the normal tissue damage. In order to place the diagnostic and treatment devices simultaneously in a confined space, constraints related to interference and volume between the subsystems must be considered. To meet these requirements, the size and weight of the LINAC system need to be reduced, which can be achieved by applying X-band technology. For the purpose of use in IMRT based on image guided radiotherapy, we developed a 9.3 GHz X-band medical LINAC using side-coupled structure. The LINAC is designed to have the accelerating field strength of 16.8 MV/m, and the beam current transmission efficiency of 26 % at the end of accelerating cell when the supplied RF power is at 1.7 MW. Therefore, it can accelerate the electron beam up to 6.2 MeV with having about 90 mA beam current. We plan to carry out the performance test using beam diagnostics system and X-ray measurement system, and the details of design and experimental results of LINAC will be described in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO063

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

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MOPO070

Construction of the Side-coupled Standing-wave e-Linac

simulation, linac, coupling, electron

151

S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
F. Abbasi
Shahid Beheshti University, Tehran, Iran
M. Bahrami, M. Lamehi
IPM, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran

Due to Iran’s growing need for accelerators in various applications, NSTRI electron linear accelerator project has been defined for medical and inspection applications. This accelerator is a 6 MeV side-coupled standing-wave that operate is π /2 mode in the frequency of 2998.5 MHz. In this paper the construction and measurement results of the tube of this accelerator are presented. The prototype tube was constructed from aluminum and was clamped with bolts. By using a network analyzer, electric and magnetic probes and a side-coupled cavity tuning method and a bead-pull measurement technique, RF measurements were carried out. The resonant frequency and quality factor have been achieved 2998.5 MHz and 7940 respectively .
low-energy accelerator, construction of linac, standing-wave linac

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO070

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paper received ※ 12 September 2018 paper accepted ※ 09 November 2018 issue date ※ 18 January 2019

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MOPO073

Coherent Edge Radiation Sources in Linac-Based Infrared Free-Electron Laser Facilities

FEL, electron, radiation, undulator

154

N. Sei, H. Ogawa
AIST, Tsukuba, Ibaraki, Japan
K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo, T. Tanaka
LEBRA, Funabashi, Japan
H. Ohgaki, H. Zen
Kyoto University, Kyoto, Japan

Funding: This study was financially supported by JSPS KAKENHI Grant Number JP16H03912.
National Institute of Advanced Industrial Science and Technology has been studied far-infrared coherent radiation at Linac-based infrared free-electron laser (FEL) facilities in col-laboration with Nihon University and Kyoto University. To obtain high FEL gain at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University and at Kyoto Uni-versity Free Electron Laser (KU-FEL), the electron-bunch length is compressed to less than 1 ps in their undulator sections. Short electron bunches are suitable for generating intense coher-ent radiation, and we have already developed some terahertz-wave sources based on the coher-ent synchrotron radiation and the coherent transition radiation [1-3]. However, it was difficult to observe them with sufficient intensity without disturbing the infrared FEL oscillations. Then, we now develop coherent edge radiation emitted from downstream bending magnets in the un-dulator sections. It can be extracted from the undulator sections without disturbing the FEL os-cillations. In this presentation, the observed coherent radiation at LEBRA and KU-FEL will be reported on.
[1] N. Sei et al., J. Phys. D: Appl. Phys. 46, (2013) 045104.
[2] N. Sei et al., Nucl. Instr. and Meth. A, 832, (2016) 208.
[3] N. Sei et al., Jpn. J. Appl. Phys.: 56, (2017) 032401.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO073

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paper received ※ 29 August 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO079

Cavity Design of a 7 MeV 325 MHz Proton APF IH-DTL for a Compact Injector

DTL, proton, linac, focusing

163

X. Li
University of Chinese Academy of Sciences, Beijing, People’s Republic of China
X. Li, Y.H. Pu, X.C. Xie, M.H. Zhao
SINAP, Shanghai, People’s Republic of China
F. Yang
Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China

Funding: National Key Research and Development Program of China (grant number 2016YFC0105408)
An Interdigit H-mode Drift-Tube-Linac (IH-DTL) with Alternating-Phase-Focusing (APF) method working at 325MHz was designed. With the RF field established properly in the cavity, protons can be accelerated from 3MeV to 7MeV successfully. In this paper, the process of designing such an APF IH-DTL cavity is going to be presented. Also, the characteristics of the cavity and pa-rameters studying of RF are going to be demonstrated.

Poster MOPO079 [0.433 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO079

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paper received ※ 02 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO080

The Manufacturing of the CSNS DTL Tank

DTL, vacuum, linac, factory

167

X.L. Wu, T. Luo
CSNS, Guangdong Province, People’s Republic of China
L. Dong, K.Y. Gong, H.C. Liu, H. Song
IHEP, Beijing, People’s Republic of China
S.M. Liu
DNSC, Dongguan, People’s Republic of China

The DTL tank is a crucial component of the China Spallation Neutron Source (CSNS) linear accelerator (LINAC), which mainly use the technology of oxygen-free copper (OFC) electroplating on the inner surface of the 20# carbon steel tube. It is the first time to perform OFC electroplating with high electrical conductivity in the high intensity beam accelerator in China. In the process of cavity manufacturing, problems such as machining deformation, plating surface nodule and plating peeling are encountered. In this project, based on pre-research and information from literature, the formula of acid solution was improved to construct a stable pickling process protocol. The manufacturing process of DTL tank and the measurement details are introduced in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO080

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

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MOPO081

Light Proton Therapy Linac LLRF System Development

LLRF, controls, proton, interface

171

B.B. Baricevic, A. Bardorfer, R. Cerne
I-Tech, Solkan, Slovenia
G. De Michele, Ye. Ivanisenko
AVO-ADAM, Meyrin, Switzerland

Proton cancer therapy is a state-of-the-art medical treatment technique based on an accelerator beam production facility. The LIGHT linear accelerator design by AVO-ADAM offers a modular compact solution for precise control of the treatment dose delivery, both position and energy wise. Proton energy can be modulated at up to 200 Hz in a range from 70 to 230 MeV by varying the gradient of the accelerating structures. The normal conducting LINAC RF system is based on a 750 MHz RFQ and 12 S band stations individually controlled. A customized LLRF system is being developed on the Libera LLRF platform for the LIGHT project. The paper is describing the required cavity field control functionality and the other subsystems such as master oscillator reference, cavity tuning, real-time control, data acquisition, control system and synchronization interfaces.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO081

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

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MOPO084

The Simulation and Manufacture of the Room Temperature CH-DTL

impedance, DTL, linac, rfq

177

J.H. Li, G. Han
China Institute of Atomic Energy, Beijing, People’s Republic of China
C.G. Li
CIAE, Beijing, People’s Republic of China
Z. Li
SCU, Chengdu, People’s Republic of China

The room temperature Cross-bar H Type Drift Tube Linac (CH-DTL) is one of the candidate acceleration structures working in CW mode. In order to optimize the parameters, the 3 dimensional electromagnetic field of the CH-DTL cavity is simulated. The method of parameter sweeping with constraint variable is better than the method of parameter sweeping with only one variable during the optimization. In order to simplify the manufacture, the drift tube surface can be designed as spherical shape. The CH-DTL cavity has been manufactured and tested.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO084

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paper received ※ 31 August 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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MOPO085

Prototype of an Inter-digital H-mode Drift-tube Linac for Muon Linac

linac, focusing, DTL, experiment

180

Y. Nakazawa, H. Iinuma
Ibaraki University, Ibaraki, Japan
K. Hasegawa, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-mura, Japan
N. Hayashizaki
RLNR, Tokyo, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
Y. Iwata
NIRS, Chiba-shi, Japan
N. Kawamura, T. Mibe, M. Otani, T. Yamazaki, M. Yoshida
KEK, Ibaraki, Japan
R. Kitamura, H.Y. Yasuda
University of Tokyo, Tokyo, Japan
N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Sue
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan

An inter-digital H-mode (IH) drift-tube linac (DTL) is developed for a low velocity part in a muon linac at the J-PARC E34 experiment. It will accelerate muons from v/c = 0.08 to 0.28 at an operational frequency of 324 MHz. In order to achieve higher acceleration efficiency and make cost lower, an alternative phase focusing (APF) scheme is adopted. A prototype with 6 cells of 0.45 m length was manufactured. The prototype accelerates muons from v/c = 0.08 to 0.15 stage. We conducted frequency measurement and bead-pull measurement as a low-power measurement, in order to evaluate the prototype product. In this paper, the results of the low-power measurement for prototype cavity will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO085

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

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MOPO087

Cold Test of Hybrid RFQ Prototype

rfq, quadrupole, simulation, linac

184

P.Y. Yu, Y. He, C.X. Li, F.F. Wang, Z.J. Wang, B. Zhang
IMP/CAS, Lanzhou, People’s Republic of China

Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator, which is combined by four-vane RFQ structure and CH-DTL structure. It has higher energy gain rate compared to conventional RFQ, and it is more compact than traditional DTL. In order to research on process exploration and RF parameters of this structure, an aluminium prototype is developed. The cold test of Hybrid RFQ prototype is completed. This paper will present the results and analysis of the test.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO087

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

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MOPO088

Study on a 325 MHz HOM Drift Tube Linac

DTL, HOM, linac, impedance

187

L. Lu, T. He, W. Ma, C.C. Xing, L. Yang
IMP/CAS, Lanzhou, People’s Republic of China

Normally, drift tube linacs (DTL) are used following RFQ linacs for beam acceleration in middle and high beam energy region. but acceleration efficiency of DTLs is decreasing with beam energy increasing. Using resonated higher order mode (HOM) of cavity, DTL can get higher effective shunt impedance. we proposed a 325MHz DTL with TE115 mode. In this paper, the dynamics calculation and electromagnetic design of the HOM-DTL will be reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO088

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paper received ※ 13 September 2018 paper accepted ※ 17 October 2018 issue date ※ 18 January 2019

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MOPO090

Measurements of the First Room Temperature CH Cavity for MYRRHA at IAP Frankfurt

simulation, resonance, status, rfq

193

K. Kümpel, S. Lamprecht, P. Müller, N.F. Petry, H. Podlech, S. Zimmermann
IAP, Frankfurt am Main, Germany

Funding: This work has been supported by MYRTE which is funded by the European Commission under Project-ID 662186.
The MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project is a planned accelerator driven system (ADS) for the transmutation of long-living radioactive waste. A critical passage for the beam quality and especially for the emittance is the injector, which for the MYRRHA project consists of a 4-Rod RFQ, two Quarter Wave Rebunchers (QWR) and a total of 16 normal conducting CH-DTL cavities. The first installment of the MYRRHA injector in Louvein-La-Neuve (Belgium) will include an ion source, a RFQ, the QWRs and the first seven CH DTL cavities. This paper will report on the status of the low level tests on CHs 1 and 2 as well as on further developments on CHs 8-15.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO090

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

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MOPO093

A Study of a Cooling Configuration for an OFHC Copper Rebuncher

simulation, linac, pick-up, vacuum

200

O. Mazor, M. Bukai, D. Nusbaum, J. Rodnizki
Soreq NRC, Yavne, Israel
E. Dyunin
Ariel University, Ariel, Israel
G. Ziskind
Ben-Gurion University in the Negev, Beer Sheva, Israel

Funding: Pazy Fund (Israel Atomic Energy commission) https://pazy.org.il
A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction for the MEBT of SARAF Phase II proton/ deuteron linac. The rebuncher is designed to bunch a 5 mA CW beam at 176 MHz. The required cavity voltage according to beam dynamics evaluation is 150 kV with a beam aperture diameter of 40 mm at a beam energy of 1.3 MeV/u with a Q value of 8000. Considering utilizing this cavity for enhancing the beam energy, the cooling configuration is explored for a cavity voltage of 300 kV, consuming 20 kW dissipated power, at a peak electric field of 16 MV/m, equivalent to the Kilpatrick limit. The electro magnetic study conducted with the CST RF simulation package was reproduced at ANSYS HFSS. The simulated dissipated power along the rebuncher for 20 kW forward power injected through the coupler port with the HFSS driven model were assigned to the ANSYS Fluent model to explore the resulted temperature map. Several evolved cooling configurations were studied, including cooling of the drift tubes. In this configuration the temperature rise along the cavity is in the range of 30 K. A detailed design of the four gap rebuncher is following this study.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO093

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paper received ※ 03 September 2018 paper accepted ※ 22 September 2018 issue date ※ 18 January 2019

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MOPO094

RF Stability Test of RFQ Cavity with Prototype Low-level Radio Frequency in RAON

rfq, LLRF, controls, experiment

204

D.Y. Lee, B.H. Choi, C.O. Choi, H. Jang, H.C. Jung, K.T. Son
IBS, Daejeon, Republic of Korea

RAON is a heavy ion accelerator of the Institute for Basic Sciences (IBS) in Korea. The prototype Low-Level Radio Frequency (LLRF) operated at 81.25 MHz has been designed and fabricated for a prototype Radio Fre-quency Quadrupole (RFQ) cavity in RAON. Stabilities of ±1 % in amplitude and ±1 degree in phase are required for specifications of the RFQ system. The prototype LLRF controls the RF amplitude and phase in the cavity by PID feedback loop. The prototype LLRF has been tested with one RFQ cavity and stabilities have been measured. In this paper, we present the design and results of stability test.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO094

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

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MOPO101

LINAC-multitool - an Open Source Java-toolkit

linac, GUI, simulation, MMI

217

M. Schwarz, D. Bade, J. Corbet, H. Podlech
IAP, Frankfurt am Main, Germany

Funding: Work supported by BMBF contr. No. 05P15RFRBA and HIC for FAIR
Dedicating more precious time to advanced research instead of spending it towards timeconsuming routine tasks is a desirable goal in particle accelerator simulation and development. Requirements engineering was started at IAP in order to identify routine processes at our institute’s R&D that can be automated or simplified. Results indicated that there were several areas to consider: Bead pull measurements, data processing and visualization for the beam dynamics code LORASR, CST field map processing for the use with TraceWin, conversion between different particle distribution data formats and more. Subsequently development of the LINAC-Multitool started to rationalize these processes and replace preexisting scripts also to ensure consistency of results and increase transparency and reliability of computation. In order to guarantee maintainability, expandability and platform independence, LINAC-Multitool is programmed using Java and will be open source. This contribution presents the current state of development.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO101

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

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MOPO102

Progress of MicroTCA.4 based LLRF System of TARLA

LLRF, controls, hardware, operation

220

C. Gumus, M. Hierholzer, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
A.A. Aksoy, A. Aydin, C. Kaya
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
O.F. Elcim
Ankara University Institute of Accelerator Technologies, Golbasi, Turkey

The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is constructing a 40 MeV Free Electron Laser with continuous wave RF operation. DESY is responsible for delivering a turnkey LLRF system based on MicroTCA.4 standard that will be used to control four superconducting (SC) TESLA type cavities as well as the two normal conducting buncher cavities. This highly modular system is further used to control the mechanical tuning of the SC cavities by control of piezo actuators and mechanical motor tuners. With the usage of ChimeraTK framework, integration to EPICS control system is also implemented. This poster describes the system setup and integration to the existing accelerator environment with hardware and software components along with the latest updates from the facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO102

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

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MOPO104

LLRF R&D Towards CW Operation of the European XFEL

FEL, controls, LLRF, resonance

223

A. Bellandi, V. Ayvazyan, J. Branlard, C. Gumus, S. Pfeiffer, K.P. Przygoda, R. Rybaniec, H. Schlarb, Ch. Schmidt, J.K. Sekutowicz
DESY, Hamburg, Germany
W. Cichalewski
TUL-DMCS, Łódź, Poland

The ever growing request for machines with a higher average beam pulse rate and also with a relaxed (< 1 MHz) pulse separation calls for superconducting linacs that operate in Long Pulse (LP) or Continuous Wave (CW) mode. For this purpose the European X-ray Free Electron Laser (European XFEL) could be upgraded to add the ability to run in CW/LP mode. Cryo Module Test Bench (CMTB) is a facility used to perform tests on superconducting cavity cryomodules. Because of the interest in upgrading European XFEL to a CW machine, CMTB is now used to perform studies on XM-3, a 1.3 GHz European XFEL-like cryomodule with modified coupling that is able to run with very high quality factor (QL = 10E7…10E8) values. The RF power source allows running the cavities at gradients larger than 16 MV/m. Because of the QL and gradient values involved in these tests, detuning effects like mechanical resonances and microphonics became more challenging to regulate. The goal is then to determine the appropriate set of parameters for the LLRF control system to keep the error to be less than 0.01° in phase and 0.01% in amplitude.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO104

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

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MOPO106

New Digital LLRF System for HIT

controls, LLRF, linac, feedback

227

E. Feldmeier, Th. Haberer, A. Peters
HIT, Heidelberg, Germany

The Heidelberg Ion Therapy Center HIT is in clinical operation since 2009. The accelerator complex consists of a linear accelerator and a synchrotron to provide carbon ions and protons for clinical use as well as helium and oxygen ions. The analog LLRF system for the linac should be replaced after more than 10 years of continuous operation. In its life-time the LLRF caused no interruption of the clinical operation with a downtime of more than 15 minutes. In order to keep the reliability in the next 10 years at least as high, a new digital LLRF system is planned. Further difficulties for the installation of a new system are due to the clinical full time usage of the accelerator and the short maintenance slots of only two days in series.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO106

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

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MOPO118

Optimized Design for a Compact Linac with Collinear Absorbing Loads at the Hust FEL-THz

linac, FEL, radiation, electron

242

J. Jiang, G. Feng, T. Hu, Y. Lu, X.D. Tu, Y.Q. Xiong
HUST, Wuhan, People’s Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People’s Republic of China

To meet the requirement of miniaturization for high power THz radiation in the field of commercial and civil use, RF Linacs have been applied widely as beam injectors, and the Linac with collinear absorbing loads reveals the potential to achieve a tradeoff between performance and compactness. Under overall consideration of systematic conflicts, optimization choices for such Linacs involving power absorbing ability, accelerating efficiency, as well as beamline length were described in this context. Meanwhile, cold testing has been conducted to verify design parameters for the collinear absorbing loads. Furthermore, elaborated calculation of thermal power loss and integrated helical water channel cooling has been performed for the 14MeV Linac with collinear absorbing loads installed on the HUST FEL-THz, and online experiments demonstrated that both the accelerating efficiency and the water cooling performance fulfilled operation demands.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO118

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

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MOPO119

Design of a Fully Automated Test Bench for Measuring the Field Distribution in Standing Wave Cavity

simulation, coupling, controls, network

246

Y. Lu, G. Feng, T. Hu, J. Jiang, X.D. Tu, Y.Q. Xiong
HUST, Wuhan, People’s Republic of China

The resonant cavity plays a great role in the linear accelerator. An accurate measurement of the cavity field distribution is very important to design linear accelerators. A fully computer controlled bench for the electric field distribution has been developed in this context. Based on the perturbation theory, the acquisition of the resonant frequency shift is proportional to the square of E (electric field). In order to verify the reliability of the test bench, a standard cylindrical cavity has been tested in this measurement system. The simulation by HFSS (High Frequency Structure Simulator) and the practice will be both presented in this paper. And the result demonstrates that, because of its high concentricity, the automated test bench achieves high precision in measuring the distribution of electric field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO119

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

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MOPO120

Improvement of the Linear Part in the Tuner System of ADS 25 MeV Linac

linac, experiment, proton, superconducting-cavity

250

L. Zhang, Z. Gao, L.B. Liu, F.F. Wang, B. Zhang
IMP/CAS, Lanzhou, People’s Republic of China

Tuner system is the indispensable part of ADS high current proton superconducting linac. It influences the working frequency of superconducting cavity of particle accelerator. To completely understand the working situa-tion of the tuner system and analyses the problems existing in it, experiments of linear part were fully conducted.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO120

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paper received ※ 09 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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MOPO130

Magnetic Flux Generated by Thermal Current in CEBAF 5-Cell Cavity System

cryomodule, experiment, niobium, operation

273

R.L. Geng
JLab, Newport News, Virginia, USA
S.C. Huang
IMP/CAS, Lanzhou, People’s Republic of China

The unloaded quality factor Q0 of many 5-cell CEBAF cavities were lowered by a factor of ~2 from their vertical qualification testing to their beam operation in CEBAF tunnel. Causes of this Q0 degradation were studied previously, including a more recent one addressing static fluxes arising from magnetic components near a 5-cell cavity. This paper reports on a preliminary study of the dynamic fluxes generated by a thermal current. Such a thermal current arises from the Seebeck effect and flows in closed loops formed by a niobium cavity and its surrounding tuner rods and liquid helium vessel that are made of stainless-steel. The behaviors of magnetic fluxes in response to various thermal profiles on a 5-cell CEBAF cavity with integrated tuner rods were studied in a JLAB VTA dewar. An outcome of this study is a proposed cool-down procedure for eliminating the thermal current generated magnetic fluxes around 5-cell cavities placed in CEBAF tunnels. This procedure may be useful to improve cavity Q0 in a cost-effective manner, which in turn saves cryogenic expenditures for sustaining CEBAF operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO130

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paper received ※ 01 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TU1A01

Challenges in Superconducting Accelerating Module Design and Construction for High Power Proton Accelerators

cryomodule, linac, vacuum, alignment

280

C. Madec
CEA/DSM/IRFU, France

CEA is engaged in the construction of the IFMIF, SARAF and ESS superconducting linacs and in particular in the design and production of a their accelerating cryomodules: 1 low-beta half-wave 176 MHz resonators for IFMIF, 4 low-beta half-wave 176 MHz resonators for SARAF and 30 medium and high-beta elliptical cavity resonators for ESS. The developments of these RF cryomodules, although at various stages, are led in parallel by the cryomodule team at CEA-Saclay, including all RF, mechanical, thermal, cryogenic, integration and QA-QC aspects in a global approach which attempts to optimise synergies and lessons learnt between these projects. A status report will be presented describing the common approaches and methods, and the systemic particularities of each project.

Slides TU1A01 [11.896 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1A01

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paper received ※ 14 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TU1A03

Status and Issues (Microphonics, LFD, MPS) with TRIUMF ARIEL e-Linac Commissioning

linac, TRIUMF, MMI, electron

286

S.R. Koscielniak, M. Alcorta, F. Ames, E. Chapman, K. Fong, B. Humphries, O.K. Kester, D. Kishi, R.E. Laxdal, Y. Ma, T. Planche, M. Rowe, S.D. Rädel, V.A. Verzilov, Z.Y. Yao
TRIUMF, Vancouver, Canada

The ARIEL electron linac (e-linac) is designed to generate cw beams of up to 30 MeV and 10 mA for delivery to a photo-convertor. Bremsstrahlung induced fission of a production target yields neutron-rich rare isotope beams to be supplied to the ISAC experimental facilities. The beam power will eventually reach 300 kW, and a machine protection system (MPS) with 10 μs rapidity is essential. The e-linac, which adopts 1.3 GHz, 2K SRF technology, is composed of a 10 MeV single-cavity injector cryomodule (EINJ) and a 20 MeV two-cavity accelerator cryomodule (EACA). The latter has vector-sum control of two cavities driven from a single klystron. Beam commissioning of these systems is ongoing since 2016. The magnetic optics and MPS commissioning to 10 MeV is reported herein. Beam has been accelerated up to 25 MeV, and thread-ed to the high energy dump (EHD). A campaign to investigate microphonics driving terms, LN2 disturb-ances, and a ponderomotive instability in the EACA, is underway.

Slides TU1A03 [9.683 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1A03

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

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TU1A05

Seamless Quarter Wave Resonators for HIE ISOLDE

ISOL, niobium, linac, cryomodule

292

W. Venturini Delsolaro, A. Miyazaki
CERN, Geneva, Switzerland

The HIE-ISOLDE post accelerator consists of 4 cryomodules with 5 niobium-coated Quarter Wave Reso-nators (QWR) each. The standard manufacturing tech-nique was to machine the inner and outer conductor sepa-rately, to shrink-fit the 2 pieces and to apply an electron beam welding at the interface. Due toμcracks, ob-served on some of the cavities around the welds, we took the decision to explore the possibility of a seamless de-sign. First cavities became available in late 2017 and were then cold-tested in the vertical cryostat. These seam-less coated quarter wave resonators have shown some of the highest Q-values of all HIE-ISOLDE cavities in the acceptance tests. Furthermore, we studied the cavity per-formance with different compensations of the earth mag-netic field and different temperature gradients upon cool down. These tests have demonstrated record-breaking RF surface fields for the Nb/Cu technology. This paper re-views the design and fabrication and reports on the cold tests results of seamless quarter wave resonators, and of possible future applications

Slides TU1A05 [30.518 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1A05

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

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TU2A01

First Acceleration of Heavy Ion Beams with a Superconducting Continuous Wave HIM/GSI CW-linac

linac, heavy-ion, acceleration, emittance

297

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

First acceleration of heavy ion beams with a superconducting continuous wave HIM/GSI CW-Linac After successful RF-testing of a new superconducting Linac RF-cavity at GSI Helmholtzzentrum für Schwerionenforschung and a short commissioning and ramp up time of some days, this 15-gaps Crossbar H-cavity accelerated first time heavy ion beams with full transmission up to the design beam energy. The design acceleration gain of 3.5 MV inside a length of less than 70 cm has been verified with heavy ion beam of up to 1.5 particle mkA. The measured beam parameters show a nice beam quality. The machine commissioning with beam is a milestone of the R&D work of Helmholtz Institute Mainz and GSI in collaboration with Goethe University Frankfurt in development of the superconducting heavy ion continuous wave linear accelerator CW-Linac.

Slides TU2A01 [3.385 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU2A01

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

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TU2A03

Layout of the New FAIR Post-stripper DTL for Intense Heavy Ion Beams

DTL, quadrupole, operation, emittance

303

S. Mickat, X. Du, P. Gerhard, L. Groening, M. Heilmann, M. Kaiser, A. Rubin, V. Srinivasan, W. Sturm
GSI, Darmstadt, Germany

The new post-stripper DTL at GSI shall accelerate uranium beams with space charge induced tune depressions of up to 37% to 11.4 MeV/u. Emittance dilution must be kept below few percent. However, the layout must also allow for delivery of lightest ions to just 3.0 MeV/u. This broad-banded range of requirements imposes huge challenges on the layout and fabrication especially of the cavities and drift tube magnets.

Slides TU2A03 [4.777 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU2A03

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

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TU2A04

Progress Report on LIPAC

rfq, MMI, linac, SRF

308

M. Sugimoto, T. Akagi, T. Ebisawa, Y. Hirata, R. Ichimiya, A. Kasugai, K. Kondo, S. Maebara, K. Sakamoto, T. Shinya
QST, Aomori, Japan
P. Abbon, N. Bazin, B. Bolzon, N. Chauvin, S. Chel, R. Gobin, J. Marroncle, B. Renard
CEA/IRFU, Gif-sur-Yvette, France
L. Antoniazzi, L. Bellan, D. Bortolato, M. Comunian, E. Fagotti, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo
INFN/LNL, Legnaro (PD), Italy
P.-Y. Beauvais, H. Dzitko, D. Gex, R. Heidinger, A. Jokinen, I. Moya, G. Phillips
Fusion for Energy, Garching, Germany
P. Cara
IFMIF/EVEDA, Rokkasho, Japan
D. Gavela, D. Jiménez-Rey, I. Kirpitchev, J. Mollá, P. Méndez, I. Podadera, D. Regidor, R. Varela, M. Weber
CIEMAT, Madrid, Spain
J. Knaster
F4E, Barcelona, Spain
G. Pruneri
Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy

International Fusion Materials Irradiation Facility (IFMIF) is the neutron source for simulating fusion reactor environment using two 40 MeV/125 mA CW D⁺ beams. LIPAc facility is under construction in Rokkasho for validating 9 MeV/125 mA CW linac technology as a prototype of the IFMIF accelerator. Commissioning of 5 MeV CW RFQ is underway after the completion of installation of RFQ, MEBT, diagnostic plate. low power beam dump, RF power system and their auxiliaries. As the first step, high power RF conditioning is planned to complete in early 2018 and beam commissioning will start with stepwise approach at the same time. The status of LIPAc construction for preparing 9 MeV acceleration and results of RFQ beam commissioning are presented.

Slides TU2A04 [9.651 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU2A04

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

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TU1P01

Extreme High Brightness Electron Beam Generation in a Space Charge Regime

emittance, electron, space-charge, bunching

314

A. Bacci
Istituto Nazionale di Fisica Nucleare, Milano, Italy
L. Faillace, M. Rossetti Conti
Universita’ degli Studi di Milano & INFN, Milano, Italy

The generation of ultra-short, low emittance and low energy spread electron bunches is nowadays a critical requirement for accelerators in plasma wave or for femto-second light sources. A new longitudinal compression scheme, based on velocity and ballistic bunching tech-niques in presence of space charge forces, allows to enter in a peculiar regime, so-called laminar bunching (LB). In this regime, the bunch is longitudinally compressed, at the expense of its transverse size, and the over-bunching is forbidden by the laminarity: going to the minimal longi-tudinal dimension the bunch is adiabatically frozen and transversally refocused. Furthermore this technique heats slightly the uncorrelated energy spread resulting in elec-tron distributions that, in case of bending paths, does not require Laser Heater devices.

Slides TU1P01 [1.720 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1P01

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paper received ※ 12 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019

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TUPO003

Development of CW Heavy Ion Linac at IMP

DTL, linac, MMI, rfq

326

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

DTL, linac, simulation, quadrupole

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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TUPO009

Heat Treatment for a Prototype Half-Wave Resonator Cavity

niobium, vacuum, SRF, lattice

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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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO009

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

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TUPO017

The New Light Ion Injector for NICA

linac, diagnostics, LLRF, rfq

362

B. Koubek, M. Basten, H. Höltermann, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO017

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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

cryomodule, cryogenics, controls, experiment

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

cryomodule, pick-up, damping, linac

370

Y. Ma, K. Fong, M. Keikha, J.J. Keir, D. Kishi, S.R. Koscielniak, D. Lang, R.E. Laxdal, 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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TUPO023

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

simulation, HOM, linac, software

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

GUI, cryomodule, FEL, LLRF

380

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

FEL, vacuum, SRF, linac

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

cryomodule, FEL, operation, feedback

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

superconducting-RF, radio-frequency, linac, SRF

391

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

SRF, niobium, electromagnetic-fields, pick-up

395

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

HOM, SRF, linac, operation

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

HOM, dipole, luminosity, ECR

402

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

experiment, electromagnetic-fields, SRF, superconducting-cavity

405

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

plasma, electron, experiment, SRF

408

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

experiment, SRF, HOM, niobium

412

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

multipactoring, linac, TRIUMF, simulation

417

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

TRIUMF, LLRF, controls, niobium

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

HOM, cryomodule, vacuum, target

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

SRF, site, superconductivity, lattice

427

M.C. Burton, A.D. Palczewski, H.L. Phillips, C.E. Reece, 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

SRF, niobium, controls, operation

431

H. Tian, J. Carroll, C.E. Reece, 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

linac, HOM, coupling, SRF

435

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

laser, ECR, niobium, experiment

438

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

vacuum, accelerating-gradient, niobium, superconducting-cavity

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

cathode, experiment, SRF, site

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

simulation, electron, distributed, 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

simulation, pick-up, superconducting-cavity, resonance

451

J.Y. Yoon, J.B. Bhang, H.J. Cha, 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

vacuum, electromagnetic-fields, cryogenics, superconducting-cavity

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

niobium, SRF, radio-frequency, electron

458

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

operation, SRF, linac, site

462

R.D. Porter, D.L. Hall, M. Liepe, J.T. Maniscalco
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

SRF, collider, GUI, linear-collider

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

network, SRF, cryomodule, linac

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

SRF, niobium, cathode, radio-frequency

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

SRF, cryomodule, collider, electron

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

ECR, SRF, accelerating-gradient, solenoid

480

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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TUPO067

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

cathode, experiment, niobium, status

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

cathode, target, niobium, SRF

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)

controls, cathode, niobium, operation

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

vacuum, injection, MMI, operation

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

SRF, injection, background, vacuum

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

vacuum, controls, SRF, niobium

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

niobium, vacuum, injection, ECR

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

cathode, gun, SRF, niobium

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

SRF, site, accelerating-gradient, cathode

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. Hayano, 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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TUPO084

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

linac, heavy-ion, cryomodule, experiment

525

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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TUPO091

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

dipole, linac, polarization, focusing

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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TUPO093

Excitation of Millimeter Wavelength Cavity Structure

gun, cathode, simulation, emittance

543

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

simulation, controls, experiment, linac

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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TUPO101

Design of Practical HSC Type Injector for Cancer Therapy

rfq, linac, DTL, injection

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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TUPO116

Particle Dynamics Optimization in DTL

focusing, quadrupole, DTL, emittance

579

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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TUPO132

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

LLRF, controls, FEL, FPGA

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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WE1A03

Latest Results of CW 100 mA Electron RF Gun for Novosibirsk ERL Based FEL

gun, cathode, radiation, electron

598

V. Volkov, V.S. Arbuzov, E. Kenzhebulatov, E.I. Kolobanov, A.A. Kondakov, E.V. Kozyrev, S.A. Krutikhin, I.V. Kuptsov, G.Y. Kurkin, S.V. Motygin, A.A. Murasev, V.K. Ovchar, V.M. Petrov, A.M. Pilan, V.V. Repkov, M.A. Scheglov, I.K. Sedlyarov, S.S. Serednyakov, O.A. Shevchenko, S.V. Tararyshkin, A.G. Tribendis, N.A. Vinokurov
BINP SB RAS, Novosibirsk, Russia

Continuous wave (CW) 100 mA electron rf gun for injecting high-quality 300-400 keV electron beam to the Energy Recovery Linac (ERL) driving the Novosibirsk Free Electron Laser (FEL) was developed, built, and commissioned in a diagnostics beam line. The rf gun consists of normal conducting 90 MHz rf cavity with a gridded thermionic cathode unit. Tests of the rf gun confirmed its design performance in strict accordance with numerical simulations. The gun was tested up to the design specifications at a test bench that includes a diagnostics beam line. The design features of different components of the rf gun are presented. The commissioning experience is discussed. The latest beam results are reported.

Slides WE1A03 [2.829 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-WE1A03

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

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WE1A04

The High Power RF System for the European XFEL

klystron, FEL, GUI, gun

601

S. Choroba
DESY, Hamburg, Germany

The presentation will be on the design, construction and commissioning of the high power RF system for the European XFEL. The RF system consists of 26 high power RF stations each capable of 10MW RF pulse power. It will report on the overall system layout, cover RF system components e.g. klystrons, modulators and high power RF waveguide distribution. It will also cover system modifications during construction phase and report on commissioning results.

Slides WE1A04 [12.620 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-WE1A04

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

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WE2A03

Construction Status of the Superconducting Linac at RIKEN RIBF

vacuum, linac, cryomodule, DTL

620

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

An upgrade project of the RIKEN Heavy-Ion Linac, RILAC, is under going, which aims at the further investigation of the super-heavy elements and production of radioactive isotopes for medical applications. In this project, a new superconducting ECR ion source and superconducting RF (SRF) booster linac are being developed and constructed. The SRF linac consists of 10 quarter-wavelength resonator operated at 73 MHz, that are contained in three cryomodules. The construction status, including the first vertical test results, will be given in this paper.

Slides WE2A03 [23.169 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-WE2A03

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paper received ※ 14 September 2018 paper accepted ※ 17 October 2018 issue date ※ 18 January 2019

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TH2A01

Nitrogen Infusion R&D for CW Operation at DESY

FEL, operation, SRF, niobium

652

M. Wenskat, A.D. Dangwal Pandey, B. Foster, T.F. Keller, D. Reschke, J. Schaffran, S. Sievers, N. Walker, H. Weise
DESY, Hamburg, Germany
C. Bate, G.D.L. Semione, A. Stierle
University of Hamburg, Hamburg, Germany
B. Foster
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
B. Foster
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

The European XFEL cw upgrade requires cavities with reduced surface resistance (high Q-values) for high duty-cycle while maintaining high accelerating gradient for short-pulse operation. To improve on European XFEL performance, a recently discovered treatment is investigated: The so called Nitrogen-infusion. The recent test results of the cavity based R&D and the progress of the relevant infrastructure is presented. The aim of this approach is to establish a stable, reproducible recipe and to identify all key parameters for this process. In parallel, advanced surface analyses, such as SEM/EDX, TEM, XPS, XRR, GIXRD and TOF-SIMS, of samples after in-situ treatment, cut-outs of cavities and samples treated together with cavities are done. The aim of this approach is to understand the underlying processes of the material evolution, resulting in the improved performance. Results of these analyses, their implications for the cavity R&D, and next steps are presented.

Slides TH2A01 [4.597 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH2A01

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

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TH1P03

New Trends in Proton and Carbon Therapy Linacs

linac, DTL, rfq, proton

666

S. Benedetti
CERN, Geneva, Switzerland

In the last years, many developments have contributed to make feasible an all linac solution for proton and carbon ion therapy, with typical output energies of about 200 MeV and 400 MeV/u, respectively. The efficient beam matching of the source to the high-energy linacs, operating at 3 GHz, represents one of the major challenges. With the successful test of a 750 MHz RFQ at CERN, this possibility starts to be a reality. At the same time CERN is testing a high-gradient S-band cavity, successfully exceeding the accelerating gradient goal of 50 MV/m - more than twice what has been obtained before - and paving the way to more compact medical facilities. In this paper, some of the most significant projects involving linear accelerators for hadron therapy will be presented.

Slides TH1P03 [3.378 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH1P03

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

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THPO002

Investigation of SRF Elliptical Cavities Made by New Nb Materials in KEK

niobium, collider, superconducting-RF, SRF

676

T. Dohmae, K. Umemori, Y. Watanabe, M. Yamanaka
KEK, Ibaraki, Japan
T. Okada
Sokendai, Ibaraki, Japan

Cost reduction for cavity fabrication is currently main issue to realize international linear collider. Cavity fabrication facility (CFF) in KEK is approaching this issue from a point of view of materials for cavities. CFF had fabricated SRF elliptical cavities made by two types of niobium; one is high tantalum contained and low RRR (< 100) fine grain niobium, and the other is high tantalum contained and RRR < 300 large grain (LG) niobium. Former was melted two times (normally five times) which results RRR recovery up to around 300, and used for cell parts. Two 3-cell cavities were fabricated for each material respectively and vertical tested. One of these cavity made by LG achieved accelerator gradients of more than 40 MV/m. In this report, cavity materials and vertical test results are presented in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO002

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

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THPO004

Pulsed Operation of CEBAF for JLEIC Injection

injection, electron, linac, beam-loading

682

J. Guo, J.M. Grames, R. Kazimi, F. Lin, T. E. Plawski, R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
JLab Electron Ion Collider (JLEIC) is planning to use the recently upgraded 12 GeV CEBAF 1497 MHz SRF CW recirculating linac as a full-energy injector for the electron collider ring. The JLEIC electron injection requires 3-4µs long bunch trains with a 20-400ms spacing in between, resulting in uneven beam loading for the CW CEBAF. With the high beam current in JLEIC collider rings, the low duty factor of injection also requires to a very high pulsed beam current from CEBAF, exacerbating the transient beam loading issue. In this paper, we will present CEBAFs detailed pulsed operation scheme for JLEIC injection, as well as some experimental results at CEBAF.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO004

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

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THPO006

Status of 650 MHz SRF Cavity for eRHIC SRF Linac

SRF, HOM, linac, collider

688

W. Xu, I. Ben-Zvi, Y. Gao, D. Holmes, P. Kolb, G.T. McIntyre, R. Porqueddu, K.S. Smith, F.J. Willeke, Q. Wu, A. Zaltsman
BNL, Upton, Long Island, New York, USA

Funding: This work is supported by LDRD program of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
A 5-cell 650 MHz SRF cavity was designed for eRHIC SRF linac. One Cu cavity was fabricated for HOM damping study, and one Nb cavity was fabricated for SRF studies. Through various post-processing recipes and vertical tests, the SRF study includes high Q-value study for ERL SRF linac and high gradient study for recirculating linac. This paper reports the HOM damping measurement on the Cu cavity and preliminary vertical test results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO006

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paper received ※ 22 August 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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THPO007

MESA - Status of the Implementation of the MicroTCA.4-based LLRF Control System

controls, LLRF, experiment, simulation

691

J.N. Bai, K. Aulenbacher, J. Diefenbach, F. Fichtner
IKP, Mainz, Germany
P. Echevarria
HZB, Berlin, Germany
R.G. Heine
KPH, Mainz, Germany

MESA at the Institut für Kernphysik (KPH) at Johannes Gutenberg-Universität Mainz is a multi-turn energy recovery linac (ERL), aiming to serve as user facility for particle physics experiments. The RF-accelerating systems of MESA consist of four 9-cell TESLA superconducting cavities, four normal conducting (NC) pre-accelerator cavities, two NC buncher cavities and two NC chopper cavities. They operate in continuous wave (CW) mode. In order to control the radio frequency (RF) amplitude and phase within the 12 cavities with the required accuracy and stability in the range of better than 0.01% and 0.01°, the MicroTCA.4 based digital low-level RF (LLRF) control system based on the development at DESY, Hamburg will be well adapted for the MESA cavities. In this paper, we describe the theoretical modelling of superconducting cavity and PID controller in SIMULINK which is useful to find the suitable control parameter for the PID controller and to predict the system performance. The progress to date of the implementation and tests of the LLRF system at MESA will also be presented.

Poster THPO007 [1.274 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO007

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paper received ※ 11 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019

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THPO008

Long-term 0peration with Beam and Cavity Performance Degradation in Compact-ERL Main Linac at KEK

operation, linac, vacuum, cryomodule

695

H. Sakai, T. Furuya, E. Kako, T. Konomi, T. Miura, F. Qiu, K. Umemori
KEK, Ibaraki, Japan

We developed ERL main linac cryomodule for Compact ERL (cERL) in KEK. The module consists of two 9-cell 1.3 GHz superconducting cavities. After construction of cERL recirculation loop, beam operation was started in 2013 Dec. First electron beam of 20 MeV successfully passed the main linac cavities. Beam current increased step by step and currently reached to 1mA (CW). Energy recovery has successfully achieved. However, field emission was one of the problems for long term operation. Therefore, the performance of the SRF cavities through long term beam operation has been investigated. In this paper, we express the measurement of the cavity performances and its degradation during long term beam operation. We also described the details of the cavity performance degradation and some trial for the cavity performance recovery.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO008

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

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THPO009

Evaluation of 60pC Beam Performance at cERL Injector for ERL Based EUV-FEL

emittance, optics, electromagnetic-fields, space-charge

699

T. Hotei
Sokendai, Ibaraki, Japan
R. Kato, T. Miyajima
KEK, Ibaraki, Japan

In order to compensate for the emittance which is increased by space charge in the low energy region, it is important to transport the beam as designed. Until now, we did not consider couplers in injector superdonducting cavities in optics design. But in this study, to improve optics matching and emittance compensation conditions for space charge dominated beam in cERL at KEK, we introduced a new 3D cavity model. We first investigated the influence of the couplers on electromagnetic field distribution. As a result, it was found that an asymmetric focusing force is generated by the influence of the couplers. It also became clear that the influence of the coupler kick on the optics significantly devastated the emittance compensation condition from the calculating including space charge. Furthermore, it was found that by optimizing the optics in consideration of the coupler kick, it is possible to improve the beam control accuracy and reduce the emittance in beam commissioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO009

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

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THPO010

Novel Straight Merger for Energy Recovery Linacs

dipole, experiment, simulation, electron

702

K.E. Deitrick, A. Hutton
JLab, Newport News, Virginia, USA
A.C. Bartnik, C.M. Gulliford
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.A. Overstreet
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One of the most critical design considerations for an energy recovery linac (ERL) is how to merge the injected bunch onto the linac axis with minimal beam degradation. All merger designs in established and upcoming machines involve significant bending of the injected beam ’ even using a so-called straight merger bends the injected beam several degrees. We propose a merger which reduces the bending of the injected beam by an order of magnitude. By passing both beams through a septum magnet followed by an rf separator cavity with a superimposed dipole magnetic field, the injected beam bends minimally within the cavity, while the recirculated beam bends to align with the linac axis. Here we describe the concept in detail and present simulation results to demonstrate the advantages of such a design, particularly for magnetized beams or minimal energy separation between the injected and recirculated beams. Measurements from an experiment at CBETA evaluating the beam dynamics of the rf separator are presented and compared with simulation results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO010

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

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THPO011

First Energy Recovery Operation at the S-DALINAC: RF Control Stability Measurements

controls, operation, linac, beam-loading

706

M. Steinhorst, M. Arnold, N. Pietralla
TU Darmstadt, Darmstadt, Germany
C. Burandt
HIM, Mainz, Germany

Funding: *Supported by the DFG through GRK 2128.
One of the main research instruments at the institute for nuclear physics at the TU Darmstadt is the recirculating superconducting linear accelerator S‑DALINAC. Many improvements were implemented since the first recirculated beam in 1991. One of the major enhancement is the upgrade from a twice to a thrice recirculating scheme in 2015/2016. With this upgrade the operation mode can be changed between a conventional accelerating operation and energy recovery linac (ERL) mode by an 180° rf phaseshift of the beam done via a path length variation of the arcs in the second recirculation. ERL operation was not possible when the rf control system for the superconducting structures was set up in 2010. Therefore the current rf control system is not optimized for this kind of operation and so it had to be tested during ERL operation in order to also demonstrate its capability of this operation mode. In August 2017 a first once recirculating ERL operation was achieved. During this operation measurements regarding the rf control stability and the demand of rf power were done. This contribution is discussing this measurements and possible improvements for future energy recovery beam times.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO011

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

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THPO018

Building a 12GHz Traveling Wave Accelerating Structure Brazed Through Irises

controls, linac, collider, electron

721

V.A. Dolgashev, G.B. Bowden, M. Dal Forno, A.A. Haase
SLAC, Menlo Park, California, USA
A. Grudiev
CERN, Geneva, Switzerland
H. Zha
TUB, Beijing, People’s Republic of China

Accelerating structures are usually manufactured by precision turning of individual cells combined with precision milling for complex parts such as rf power couplers. These multiple parts are staked and brazed into a complete structure. We consider an alternative approach: precision milling of multiple cells and couplers into metal blocks that comprise halves or quadrants of the complete structure. We successfully produced a 12~GHz Compact Linear Collider (CLIC) main linac accelerating structure prototype using this method. A previous prototype was designed as an open structure with a gap between cell irises. Here we describe a different approach, an accelerating structure which is brazed through irises. It is based on a multi-cell traveling wave structure designed at CERN for PSI, so called "T24 PSI 12 GHz". This brazed-through irises structure was built at SLAC for high power tests at CERN. Here we describe the details of this process.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO018

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paper received ※ 19 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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THPO026

The Multi-physics Analysis of Dual-beam Drift Tube Linac

DTL, simulation, operation, linac

735

T. He, L. Lu, W. Ma, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang
IMP/CAS, Lanzhou, People’s Republic of China

The DB-DTL prototype is proposed to validate the fea-sibility of multi-beam accelerator in middle energy region. The main parameters are listed in Table.1. The DB-DTL will operate as pulse injector with the capacity of accelerating proton from 0.56 MeV to 2.5 MeV. The 35.83 kW normalized power dissipation of DB-DTL dis-sipated on the cavity internal surface will heat the cavity and cause cavity temperature rise and structural defor-mation, which will lead to resonant frequency shifting. The cooling water takes away the power to resolve this problem. In this paper, detailed multi-physics field simu-lation of DB-DTL is performed by using ANSYS multi-physics, which is a coupled electromagnetic, thermal and structural analysis.

Poster THPO026 [0.759 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO026

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

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THPO028

Magnetic Field Measurement and Analysis for Drift Tube Linac of CSNS

DTL, quadrupole, linac, drift-tube-linac

738

B. Li, M.X. Fan, A.H. Li, P.H. Qu, Y. Wang, X.L. Wu
CSNS, Guangdong Province, People’s Republic of China
Q. Chen, K.Y. Gong, W. Kang, H.C. Liu, J.X. Zhou
IHEP, Beijing, People’s Republic of China

Funding: The National Natural Science Foundation of China(11105166)； Youth Innovation Promotion Association（2015011）
A 324MHz Alvarez-type Drift Tube Linac (DTL) is used to accelerate the H⁻ ion beam from 3 to 80 MeV with peak current 15mA for China Spallation Neutron Source (CSNS). DTL is composed by 36 meters cavity and 161 DTs, the DT magnet coil adopted SAKAE structure with compact, smaller aperture. Magnetic field is measured by self-developed high precision rotating coil measurement system. This paper introduces the rotating coil measure-ment system simply and presents the 161 DTs magnetic field measurement results comprehensively, include mag-netic field center offset, integral magnetic field, higher-order harmonics. In addition, cooling test result of magnet coil is also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO028

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paper received ※ 31 August 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO029

Quality Factor and Power Loss of the CSNS DTL

DTL, operation, simulation, linac

741

P.H. Qu, M.X. Fan, A.H. Li, B. Li, J. Peng, Y. Wang, X.L. Wu
CSNS, Guangdong Province, People’s Republic of China
Q. Chen, K.Y. Gong, H.C. Liu
IHEP, Beijing, People’s Republic of China

An Alvarez-type Drift tube linac (DTL) was utilized to accelerate the H⁻ ion beam of up to 15mA peak current from 3 to 80MeV of China Spallation neutron source (CSNS). For ease of manufacturing and measurement, the CSNS DTL was divided into four independent cavities. The Q factor of four cavities were given, including the measurement results of low-power[1] and high-power[2], and several reasons for the low Q factor of the cavity in the measurement process were analysed. During the op-eration of the DTL, the frequent alarm of the water flow switch causes the power of the cavity to fall to 0. Esti-mate the power loss of each component, under the cir-cumstances of ensuring adequate water flow, reduce the alarm threshold of the water flow switch of some compo-nents to improve the stability of the system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO029

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paper received ※ 22 August 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO031

RF Conditioning and Beam Commissioning Status of CSNS DTL

DTL, vacuum, operation, MMI

747

Y. Wang, M.X. Fan, A.H. Li, B. Li, J. Peng, P.H. Qu, X.L. Wu
CSNS, Guangdong Province, People’s Republic of China
Q. Chen, K.Y. Gong, H.C. Liu
IHEP, Beijing, People’s Republic of China

The high power RF conditioning of CSNS DTL was finished in April 2017 with peak input power 1.6MW, 650us pulse width, 25Hz repetition frequency. With careful tuning of RF amplitude and phase, beam was accelerated to 80MeV successfully with maximum peak beam current 12mA and about 98% transmission efficiency. DTL operate stably at full power level with several trips per day without beam interruption after six months commissioning. The whole RF conditioning process was presented and some details of beam commissioning were described in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO031

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paper received ※ 05 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO034

Experimental Study of Tuning Method on a Model Alvarez DTL Cavity for CPHS Project

experiment, DTL, linac, drift-tube-linac

756

Y. Lei, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, S.X. Zheng
TUB, Beijing, People’s Republic of China

This article is devoted to the experimental study of tun-ing method for an Alvarez-type drift tube linac (DTL) of the Compact Pulse Hadron Source (CPHS) project at Tsinghua University. The biperiodic structure based on the post couplers are introduced to overcome the instability of the Alvarez DTL tank which is used to operate in 0 (or 2π) mode. The experimental method and results are pre-sented, and the tuning scheme for the formal CPHS DTL is summarized from the tuning experiment.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO034

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

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THPO035

Tuning and Low Power Test of the 325 MHz IH-DTL at Tsinghua University

DTL, proton, simulation, linac

759

R. Tang, C.T. Du, X. Guan, Y. Lei, P.F. Ma, K.D. Man, C.-X. Tang, X.W. Wang, Q.Z. Xing, W.B. Ye, H.Y. Zhang, S.X. Zheng
TUB, Beijing, People’s Republic of China
J. Li
NUCTECH, Beijing, People’s Republic of China

An interdigital H-mode drift tube linac (IH-DTL), which accelerates proton beam from 3 MeV to 7 MeV has been designed and assembled at Tsinghua University. There are 8 plungers in the 1 m tank and one co-axial coupler is used to feed the power. The frequency is tuned to 325 MHz. The field distribution is measured by the bead perturbation method. Finally, the gap voltage error has been tuned to be smaller than ±3.0%, which satisfies the design requirement. The Q factor of the tank is 7000 while the power dissipation is 244 kW. Details of the low power test is presented.

Poster THPO035 [1.268 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO035

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

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THPO038

Status of the Power Couplers for the CSNS DTL

DTL, coupling, vacuum, operation

767

M.X. Fan, A.H. Li, B. Li, P.H. Qu, Y. Wang, X.L. Wu
CSNS, Guangdong Province, People’s Republic of China
Q. Chen, K.Y. Gong, H.C. Liu
IHEP, Beijing, People’s Republic of China

There are four Drift Tube Linac (DTL) tanks in China Spallation Neutron Source (CSNS) Project. Each DTL tank requires a power coupler with a peak power of 2 MW and a duty cycle of 1.5% for beam operation. After approximately two years machining, all four couplers were already installed in the tunnel before year 2017. Up to now, the first phase of beam tuning has been completed, the maximum transmission power of the coupler exceeds 1.7 MW with a pulse width of 650 μs and a repetition rate of 25 Hz, meanwhile, the vacuum is maintained on the order of 10^-6 Pa during the operation and no breakdown was observed. This paper describes the architecture, the fabrication, the low power test results and the high power conditioning process of the coupler. Some problems encountered are also presented.
This work was supported by Youth Innovation Promotion Association of CAS (2015011)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO038

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paper received ※ 30 August 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO040

Operation Experiences of the J-PARC Linac

linac, operation, DTL, target

774

K. Hasegawa
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The J-PARC linac has delivered beam to users since 2008. As of 2018, the linac provides a 40 mA beam at an energy of 400 MeV to the following Rapid Cycling Synchrotron. We have had many issues to impede high availability during the operation. One of them was troubles of high voltage power supply of klystrons. The other category is related to vacuum property in accelerating cavities. The vacuum pumps were reinforced at the RFQ#1 in 2009. The cleaning of the inside surface of some acceleration cavities were performed after the big earthquake in 2011. The cooling water flow rate drop had been a long-time issue. We modified a cooling system to take better flow balances. As a result of these improvement, the availability is approximately 92% or more in these days. However, we have encountered another issue due to some aging components. The operation experiences and availability improvement at the J-PARC linac will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO040

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paper received ※ 19 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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THPO042

An Optimization Method of the Nose-cone Buncher Cavity

simulation, proton, radiation, bunching

778

W.L. Liu, P.T. Cong, Z.M. Wang
NINT, Shannxi, People’s Republic of China
H. Jiang, S.X. Zheng
TUB, Beijing, People’s Republic of China

The nose-cone buncher cavity is widely used on proton accelerators. It’s important to properly optimize the cavity geometry for fine RF performance. Howev-er, currently the optimization is usually carried out manually and the criteria are not objective enough. In this paper, an optimization method using the multi-objective, multi-variable optimization approach is presented. The geometry and RF parameters are con-sidered as the variables and objectives respectively. The goal function is defined as the weighted sum of multiple RF parameters. The multi-variable functions are approximately derived from the single-variable functions based on electromagnetic simulation. And an optimization code is developed accordingly which has been applied to the XiPAF debuncher optimization.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO042

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

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THPO045

Tuning Esperience on the ESS DTL Cold Model

DTL, interface, alignment, linac

784

F. Grespan, A. Baldo, P. Bottin, G.S. Mauro, A. Palmieri, A. Pisent
INFN/LNL, Legnaro (PD), Italy
P. Mereu, M. Mezzano
INFN-Torino, Torino, Italy

An aluminum model of the ESS DTL tank 2 has been delivered to INFN-LNL in december 2017. The tank is 7.1 m long, equipped with movable tuners and movable post couplers. The purpose of this DTL model is to verify the RF design choices (in particular on the first 2 tanks where the Post coupler distribution is irregular) as well as implement and debug algorithms and procedure for stabilization and tuning. The preparatory simulation work and the results of measurements campaign are here presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO045

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

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THPO047

SPIRAL2 Injector Commissioning

rfq, linac, emittance, diagnostics

790

R. Ferdinand, M. Di Giacomo, H. Franberg, O. Kamalou, J.-M. Lagniel, G. Normand, A. Savalle, F. Varenne
GANIL, Caen, France
D. Uriot
CEA/DRF/IRFU, Gif-sur-Yvette, France

The SPIRAL2 injector is composed of two ion sources (p/d and heavy ions up to A/Q=3) followed by a 730 keV/u RFQ. Beam commissioning has started in 2014 in parallel with the superconducting linac and HEBT installations. The RFQ beam commissioning started soon after the first RF conditioning done in October 2015. This paper describes the RFQ beam measurements done on the diagnostic plate for the reference particles (H⁺, 4He2+ and recently 18O6+) and the difficulties encountered for the RFQ commissioning at the A/Q=3 field level.

Slides THPO047 [7.846 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO047

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

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THPO049

Field Tuning of a Radio-frequency Quadrupole Using Full 3D Modeling

rfq, insertion, simulation, linac

798

T. Morishita, K. Hasegawa, Y. Kondo, H. Oguri
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Otani
KEK, Ibaraki, Japan

The radio-frequency quadrupole linac (RFQ) is operating in the frontend of the J-PARC linac to accelerates 50 mA negative hydrogen beams from 0.05 MeV to 3 MeV. As a backup, the spare RFQ has been fabricated in 2018. The vane-voltage ramping is adopted to improve the acceleration efficiency so that the cross-sectional shape is adjusted longitudinally to produce the designed voltage distribution. Then, the three-dimensional cavity models including modulations and cutbacks were created in CST Micro-Wave Studio. The vane-base widths and cutback depths were optimized to produce the desired vane-voltage distribution. In the final tuning, the heights of the stub turners were also determined based on the tuner responses obtained from the full 3D models. In this paper, the detailed design process of the cavity dimensions and the result of the low-power measurements are described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO049

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

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THPO050

Research on the New Cavity Structure of RFQ Accelerator With Bent Vanes at IMP

rfq, simulation, impedance, ECR

802

L. Yang, T. He, Y. He, C.X. Li, L. Lu, L.P. Sun, C.C. Xing
IMP/CAS, Lanzhou, People’s Republic of China
L. Yang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

A new cavity structure of RFQ accelerator with bent vanes is proposed to meet the miniaturization requirement of low frequency heavy ion accelerators at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The new structure has a downsized cross section by bending vanes while keeping a certain vane lengths. It also possesses the advantages of simple cooling structure and high power efficient when used in low frequency. The new structure has obvious advantages in reducing manufacturing difficulty of cavity, cutting down project cost, enhancing facility reliability and stability.

Slides THPO050 [1.407 MB]

Poster THPO050 [0.398 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO050

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

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THPO051

The Multi-physics Analysis of LEAF RFQ

rfq, simulation, radio-frequency, quadrupole

805

X.B. Xu, T. He, Y. He, C.X. Li, L. Lu, W. Ma, A. Shi, L.B. Shi, L.P. Sun, C.C. Xing, L. Yang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

The 81.25 MHz CW RFQ is designed to accelerate heavy ions with Q/A from 1/7 to 1/2 at 0.5 MeV/u for the Low Energy Accelerator Facility (LEAF) at the Institute of Modern Physics (IMP) of the Chinese Academy of Science (CAS). The four-vane RFQ consists of six mod-ules with a total length of 5.95 meters, For the CW oper-ating mode, thermal management will be a very important issue, Therefore a multi-physics analysis is necessary to ensure that the cavity can stably operate at the high RF power . The multi-physics analysis process includes RF electromagnetic analysis, thermal analysis, mechanical analysis, and the frequency shift, the cooling water system is used for frequency tunning by the temperature adjustment, and also analyze RFQ undercuts, fixed tuners, and pi-mode rods, the results show that the thermal and structural design of this RFQ is reasonable.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO051

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

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THPO052

High Power Test of the LEAF-RFQ

rfq, acceleration, quadrupole, operation

808

L. Lu, Y. He, W. Ma, L.B. Shi, L.T. Sun, L.P. Sun, L. Yang, Y. Yang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

High power heavy ion drivers require a CW low-frequency accelerator for initial acceleration. A CW four-vane radio frequency quadrupole (RFQ) accelerator is designed to accelerate heavy ions A/q up to 7 from 14 keV/u to 500 keV/u, as a new injector for the Low Energy Accelerator Facility (LEAF) at Institute of Modern Physics (IMP). The measurements of low power test were reported previously. In this paper, the results of high power test of the RFQ, including the test of the acceleration systems and beam profiles, will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO052

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paper received ※ 07 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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THPO053

Status of the China Material Irradiation Facility RFQ

rfq, radiation, diagnostics, radio-frequency

811

C.X. Li, W.L. Chen, W.P. Dou, Z. Gao, Y. He, G. Huang, C.L. Li, L. Lu, W. Ma, A. Shi, L.B. Shi, L.P. Sun, F.F. Wang, W.B. Wang, Z.J. Wang, Q. Wu, X.B. Xu, L. Yang, P.Y. Yu, B. Zhang, J.H. Zhang, P. Zhang, T.M. Zhu
IMP/CAS, Lanzhou, People’s Republic of China

Funding: Supported by the National Magnetic Confinement Fusion Science Program of China (Grant No.2014GB104001) and the National Natural Science Foundation of China (Grant No.91426303).
The pulsed high power test and beam test of the China Material Irradiation Facility RFQ have been implemented. Before this, the radio frequency measurements and tuning are performed. In this paper, the processes and results of the radio frequency measurements, tuning, pulsed high power test and beam test will be presented. The results of tests are in good agreement with the design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO053

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

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THPO057

Redesign of CERN Linac3 RFQ for Lead 29+

rfq, linac, emittance, simulation

818

S. Benedetti, G. Bellodi, J.-B. Lallement, A.M. Lombardi
CERN, Geneva, Switzerland

CERN Linac3 is at the start of the CERN Heavy Ion Facility, providing 4.2 MeV/u ion beams to the Low Energy Ion Ring (LEIR). It mostly accelerates 208Pb²⁹⁺, though in recent years runs were performed with 40Ar¹¹⁺ and 129Xe²²⁺, in view of the increasing interest of the physics community towards lighter ions experiments. In the framework of the LHC Injectors Upgrade (LIU) project, measurements and beam dynamics simulations showed that a transmission bottleneck of Linac3 is represented by the RFQ. As this accelerator was originally designed for 208Pb²⁵⁺, the lower beam rigidity of the heavy ions currently in use and planned for the future permits a redesign of the RFQ optics aimed at increasing its transverse acceptance, and thus the transmitted beam current. A study of this has been performed, and the methodology adopted and the results are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO057

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

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THPO058

RF Design of a High-frequency RFQ Linac for PIXE Analysis

rfq, simulation, linac, proton

822

H.W. Pommerenke, A. Bilton, A. Grudiev, A.M. Lombardi, S.J. Mathot, E. Montesinos, M.A. Timmins, M. Vretenar
CERN, Geneva, Switzerland
H.W. Pommerenke, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: This work has been sponsored by the Wolfgang Gentner Program of the German Federal Ministry of Education and Research (grant no. 05E12CHA).
Protons with an energy of few MeV are commonly used for Ion Beam Analysis of materials, in particular with the Proton Induced X-ray Emission technique (PIXE). Because of its non-damaging character, PIXE is used in a variety of fields, in particular for the diagnosis of cultural heritage artwork. A compact accelerator based on a high frequency RFQ (Radio Frequency Quadrupole) linac has been designed and is being built at CERN. The length of the RFQ is only one meter and it allows the acceleration of a proton beam up to an energy of 2 MeV. The complete system is conceived to be transportable, allowing PIXE analysis almost anywhere. This paper covers the RF design of the compact RFQ operating at 750 MHz. We present general accelerator parameters and the current state of the RF design, which includes RFQ geometry and coupler design, thermal simulation and first particle tracking results.

Slides THPO058 [2.404 MB]

Poster THPO058 [2.192 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO058

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

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THPO064

Tuning of a Four-vane RFQ for Xi’an 200 MeV Proton Application Facility

rfq, dipole, quadrupole, coupling

838

X.D. Yu, X. Guan, Q.K. Guo, Y. Lei, P.F. Ma, X.W. Wang, Q.Z. Xing, S.X. Zheng
TUB, Beijing, People’s Republic of China
B.C. Wang, Z.M. Wang, C. Zhao
NINT, Shannxi, People’s Republic of China

This paper mainly describes the procedures and results of tuning a four-vane Radio Frequency Quadrupole (RFQ) accelerator for the Xi’an 200 MeV Proton Application Facility (XiPAF) project. The 3-meter-long RFQ will accelerate a 50 keV H⁻ beam from the ECR source to 3 MeV, and deliver it to the downstream drift tube linac (DTL) with a peak current of 5 mA, pulse length of 10-40 μs and maximum repetition rate of 0.5. The machining, assembly, and RF tuning of the RFQ cavity has been completed successfully. After tuning, the relative error of the operating quadrupole mode field is within ±2.7%, and the dipole mode com-ponent is within ±1.9% of the quadrupole mode. The RFQ now is ready for high-power RF conditioning.

Poster THPO064 [1.413 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO064

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

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THPO066

First High Power Test of the ESS High Beta Elliptical Cavity

SRF, linac, accelerating-gradient, flattop

841

H. Li, L. Hermansson, M. Jobs, R.J.M.Y. Ruber, R. Santiago Kern
Uppsala University, Uppsala, Sweden
G. Devanz, T. Hamelin
CEA/DSM/IRFU, France

ESS, the European Spallation Source, will adopt elliptical multi-cell superconducting cavities with a beta value of 0.86 to accelerate the proton beam up to 2 GeV at the last section of the linac. A 5-cell high-beta cavity for ESS project was tested with high power at FREIA Laboratory. A pulse mode test stand based on a self-excited loop was used in this test. The qualification of the cavity package involved a 5-cell elliptical cavity, a fundamental power coupler, a cold tuning system, LLRF system and a RF station. These tests represented an important verification before the series production. This paper presents the test configuration, RF conditioning history, first high power performance and experience of this cavity package.

Slides THPO066 [1.437 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO066

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paper received ※ 14 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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THPO067

Control System and Experiment for RAON HWR Cryomodules

cryomodule, controls, PLC, cryogenics

845

H. Kim, J.W. Choi, C.O. Choi, H. Jang, Y.W. Jo, H.C. Jung, Y. Jung, J.W. Kim, M.S. Kim, Y. Kim, D.Y. Lee, M. Lee, S. Lee, K.T. Seol, K.T. Son
IBS, Daejeon, Republic of Korea

A prototype of half-wave resonator (HWR) cryomodules is fabricated and tested. Cables and tray are installed for horizontal test. The design and the piping and instrumentation diagram (P&ID) of the HWR cryomodule are presented. The HWR cryomodule is tested with developed programmable logic controller (PLC) and experimental physics and industrial control system (EPICS) control systems. The heat loads of the HWR cryomodule for static and dynamic are measured.

Poster THPO067 [0.631 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO067

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

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THPO068

AN Effect of Field Emission on Low Beta Superconducting Cavities

pick-up, SRF, linac, simulation

849

X. Liu, Z. Gao, Y. He, G. Huang
IMP/CAS, Lanzhou, People’s Republic of China

Superconducting RF (SRF) technology is widely ap-plied in particle accelerators to shorten the accelerator length and lower the construction price due to its high acceleration gradients with low rf losses. Field emission is the chief limitation associated with the surface electric field which will finally determine the cavity performance during the operation. The pickup-drop signal caused by field emission seriously affect the stable operation of the superconducting linac in the Chinese initiative Accelera-tor-Driven Sub-critical System (CiADS) demon facility. Simulations of the field emission effect and experimental measurements of the pickup-drop signal have been per-formed on the half wavelength resonator (HWR) cavity. And a modified design of the pickup antenna will be discussed to solve the pickup-drop problem.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO068

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paper received ※ 12 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019

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THPO069

The Electromagnetic Optimization of TE-sample Host Cavity at IMP

SRF, niobium, linac, electron

852

S.C. Huang, Y. He, T. Tan, S.X. Zhang
IMP/CAS, Lanzhou, People’s Republic of China

As a part of the research and development work of thin-film materials for superconducting radio frequency(SRF) application in future accelerators at IMP, a 3.9GHz TE sample host cavity is being developed for the purpose of characterizing the RF Property and the loss mechanism of thin-film materials, which operates in the TE011 mode and accommodates disk sample with 110mm diameter, theoretically, the maximum magnetic field on sample surface will go up to 100mT, the resolution of surface resistance on sample will below nOhm by using thermometry technique( T-Mapping). In this paper, the electromagnetic optimization result of TE-sample host cavity will be presented, and the design consideration of hook tip style coupler and T-mapping system are also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO069

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

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THPO072

Cryogenic Tests of the Superconducting β=0.069 CH-cavities for the HELIAC-project

linac, heavy-ion, cryogenics, accelerating-gradient

855

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

In the future the existing UNILAC (UNIversal Linear Accelerator) at GSI will be most exclusively used as an injector for FAIR to provide short pulse high intensity heavy ion beams at low repetition rates [Barth3]. A new superconducting (sc) continuous wave (cw) high intensity heavy ion Linac should provide ion beams with max. duty factor above the coulomb barrier for the Super Heavy Element (SHE) program at GSI. The fundamental Linac design comprises a low energy beam transport (LEBT)-section followed by a sc Drift Tube Linac (DTL) consisting of sc Crossbar-H-mode (CH) structures for acceleration up to 7.3 MeV/u [*]. After the successful test and commissioning of the first demonstrator section with heavy ion beam from the HLI in 2017 [**], the next two sc CH-structures have been constructed and the first one has been extensively tested at cryogenic temperatures at the Institute for Applied Physics (IAP) at Goethe University Frankfurt (GUF). The results of the final cold test of the first CH-structure as well as the next steps realizing a new sc cw heavy ion LINAC at GSI will be presented.
[*]W. Barth et al., "Further investigations for a superconducting cw-Linac at GSI"
[**]W. Barth et al., "First high intensity heavy ion beam tests with a superconducting multi gap CH-cavity"

Poster THPO072 [1.150 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO072

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

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THPO073

RF Commissioning of the Superconducting 217 MHz CH Cavity for Heavy Ions and First Beam Operation

linac, heavy-ion, SRF, MMI

859

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

Future research programs at GSI in the field super heavy element (SHE) synthesis require high intense heavy ion beams above the coulomb barrier and high average particle currents. The upcoming demands exceed the technical opportunities of the existing UNIversal Linear ACcelerator (UNILAC). Consequently, a new dedicated superconducting (sc) continuous wave (cw) linac is crucial to keep the SHE research program at GSI competitive on a high level. Recently the first linac section, serving as a prototype to demonstrate the reliable operability of 217 MHz multi gap crossbar-H-mode (CH) cavities under a realistic accelerator environment, has been extensively tested with a heavy ion beam delivered from the GSI High Charge State Injector (HLI). Fulfilling its role as a key component of the whole demonstrator setup. The first sc 217 MHz CH cavity (CH⁰) successfully accelerated heavy ions up to the design beam energy and even beyond at high beam intensities and full transmission. In this contribution the rf commissioning and the first beam operation of the cavity is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO073

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

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THPO076

Multiphysics Design Studies of a Superconducting Quarter-wave Resonator at Peking University

multipactoring, simulation, SRF, accelerating-gradient

863

M. Chen, S. Chen, A.Q. Cheng, W. Cheng, J.K. Hao, S.W. Quan, F. Zhu
PKU, Beijing, People’s Republic of China

Funding: This work is supported by National Basic Research Program (2014CB845504)
A 81.25MHz, geometric β=0.046 quarter-wave resonator has been designed and analysed at Peking University. This paper mainly presents the multi-physics studies of this cavity, include electromagnetic design, mechanical analysis and multipacting simulation, to predict its behaviour under practical operating process. Various transverse vibration modes of inner conductor were found under different fixed conditions and an asymmetric shorting plate was adopted to avoid high possibility of multipacting
"quarter-wave resonator"
"multiphysics"
"multipacting"
"frequency detuning"
"stiffening design"

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO076

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

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THPO079

RF Test of Standing Wave Deflecting Cavity with Minimized Level of Aberrations

diagnostics, emittance, operation, electron

866

V.V. Paramonov
RAS/INR, Moscow, Russia
K. Flöttmann
DESY, Hamburg, Germany

For diagnostic of longitudinal distribution of electrons in unique REGAE bunches is applied a specially developed deflecting structure with minimized level of aberrations in the field distribution and improved RF efficiency. Short deflecting cavity was constructed and installed now in REGAE beam line. The cavity is tested at operational level of RF power. The main distinctive features of the cavity are mentioned and obtained results are reported.

Slides THPO079 [1.803 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO079

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

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THPO082

Physical Design of a Rectangular RF Deflector for Ultrashort Bunch Length Measurement

electron, simulation, FEL, coupling

872

J. Bai, Q.S. Chen, K. Fan
HUST, Wuhan, People’s Republic of China

Cylindrical deflectors which are now widely used for bunch length measurement suffer from the degeneration of polarization, while rectangular deflectors can separate polarization mode easily. This paper is focused on the study of a one-cell rectangular deflector, which is considerably different from cylindrical structure or multi-cell structure. A one-cell structure is free of π mode restriction and can achieve higher deflection efficiency per unit length. The proposed scheme is expected to achieve time resolution better than 200fs with the driving power less than 1MW. Cavity optimization and beam dynamic simulation are introduced in this paper.

Poster THPO082 [0.484 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO082

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

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THPO083

Transverse Deflecting Cavity for Longitudinal Beam Diagnostics at BERLinPro

diagnostics, emittance, vacuum, impedance

875

G. Kourkafas, T. Kamps, A. Neumann
HZB, Berlin, Germany
B. Keune
RI Research Instruments GmbH, Bergisch Gladbach, Germany

The Berlin Energy Recovery Linac Prototype (BERLinPro) at Helmholtz Zentrum Berlin (HZB) aims to deliver a continuous-wave electron beam of high average current (100 mA) and brilliance (normalized emittance below 1 mm mrad). The achievement of these ambitious goals necessitates a thorough determination of the bunch parameters after the first acceleration stages, namely the photoinjector and the succeeding booster module. For the measurement of primarily the bunch duration and subsequently the longitudinal phase space and transverse slice emittance, a single-cell 1.3-GHz TM110-like mode vertically deflecting cavity was manufactured by RI Research Instruments GmbH, following the respective design developed for the Cornell ERL injector. This article summarizes the design parameters, manufacturing procedure and testing of this pulsed RF resonator, together with the expected temporal measurement resolution for the nominal beam energies at the initial acceleration stages of BERLinPro.

Poster THPO083 [1.396 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO083

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

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THPO084

BPM Time of Flight Measurements for Setting-up the RF Cavities of the CERN Linac4

linac, DTL, simulation, electron

879

M. Bozzolan
CERN, Geneva, Switzerland

The newly constructed H⁻ LINAC4 at CERN has recently completed its first extended reliability run. It is equipped with Beam Position Monitors (BPMs) based on shorted-stripline pick-up electrodes to measure both position and Time of Flight (ToF). The ToF, in turn used to calculate the kinetic energy of the beam, is determined through signal phase shift measurements between pairs of BPMs. ToF measurements are performed by scanning of the phase of the RF injected into the cavities to find the nominal RF settings for optimal beam acceleration. This paper focuses on the technical aspects of the ToF measurement as well as on the results obtained during beam commissioning and their comparison with beam dynamics simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO084

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

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THPO090

The Analysis of Module Failure in High Solid-state Amplifier for High Current RFQ

scattering, simulation, experiment, rfq

886

L.P. Sun, Y. He, G. Huang, C.X. Li, L. Lu, A. Shi, L.B. Shi, X.B. Xu, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

New accelerator RF system was upgraded to the solid-state amplifier in ADS project due to its stable, sustainable and reliable. Until now, newest 80kW SSA was adopted in IMP, operating in 162.5MHz, and over 120 power modules were combined through several synthesizers for 80kW output. but since too many modules were optimized for amplitude and phase in the same time, one or some failure of circulator will lead to injure of whole RF system, when wavelength meets a specific condition, injure would turn out severe accident and heavy loss. In this paper, analyzing and simulating the multi-level synthetic matrix was the important method for ADS accident happened in June 20. 2017, the failure simulated results for RF amplify links under the specific circumstances also was presented simultaneously.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO090

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paper received ※ 17 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019

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THPO091

90 kW Solid-state RF Amplifier with a TE011-mode Cavity Power-combiner at 476 MHz

controls, FEL, power-supply, electron

889

Y. Otake, T. Asaka, T. Inagaki
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
S. Aizawa, K. Nagatsuka, T. Okuyama, K. Sato, H. Yamada
Nihon Koshuha Co. Ltd, Yokohama, Japan

Solid-state RF amplifiers, which have long lifetimes and small failures, are the recent trend of reliable and stable high-power rf sources for particle accelerators. Hence, we designed a 90kW solid-state amplifier with an extreme low-loss TE011 mode cavity (Q0=100, 000) power-combiner operated at 476 MHz and a 6 us pulse width. Developing this amplifier is for replacement of an IOT rf amplifier, at the X-ray free-electron laser, SACLA. In SACLA, highly RF phase and amplitude stabilities of less than 0.02 deg. and 10^-4 in rms are necessary to stable lasing within a 10 % intensity fluctuation. The amplifier comprises a drive amplifier, a reentrant cavity rf power divider, 100 final amplifiers with a 1 kW output each and a TE011 mode cavity combiner. Water-cooling within 10 mK and a DC power supply with a noise of less than -100 dBV at 10 Hz for the amplifier is necessary to realize the previously mentioned stabilities. Based on the test results of the amplifier, the above-mentioned specifications with the extreme low-loss are promising. The amplifier also allows us to operate in pulsed and CW rfs for linacs and ring accelerators. We report the performance of the 90kW amplifier.

Slides THPO091 [1.750 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO091

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paper received ※ 06 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019

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THPO096

Design Study of a High Efficiency Klystron for SuperKEKB Linac

klystron, gun, simulation, linac

901

F. Qiu, S. Fukuda, S. Matsumoto, T. Matsumoto, T. Miura, T. Natsui
KEK, Ibaraki, Japan

The injector linear accelerator (linac) for the SuperKEKB particle accelerator requires a higher efficiency klystron than the currently used 50 MW, S-band, pulsed unit (PV3050/E3730), which operates at the same voltage, to increase the power redundancy. The efficiency is expected to improve from the currently observed 45% to more than 60%. We propose a type of high efficiency klystron using novel bunching mechanisms. The 1-D disk model based code is used for preliminary optimization of the tube parameters; these parameters are further checked by 2-D codes known as field charge interaction (FCI) and MAGIC. In this paper, the design consideration of the high efficiency klystron is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO096

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

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THPO100

Development of a 1.5 GHz High-power CW Magnetron for SRF Accelerator

simulation, electron, SRF, coupling

908

L. Wenliang
College of Engineering and Applied Sciences for Nanjing University, Nanjing, People’s Republic of China
S. An, Y.J. Ke, S. Lingbin, Z. Pengjiao, L. Youchun, L. Zhao, B.Z. Zhou
PLAI, Nanjing, People’s Republic of China
J.Z. Li, L.P. Zhang, Hou, R. Rui
ADS, Jiangsu Province, People’s Republic of China

An 1.5 GHz, 13.5 kW CW high-power magnetron for a superconducting RF accelerator has been developed by Andesun Technology Group Co., Ltd. with Nanjing Sanle Electronic Information Industry Group Co., Ltd., in order to replace the klystron, that could reduce the power source cost to about one-third. The cavity, output power antenna and coupling door-nob have been optimized by using CST Studio. Testing results have shown that the resonance frequency and output power have met the requirements, and the efficiency of the magnetron is higher that 78.45%.

Poster THPO100 [0.574 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO100

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

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THPO103

Application of Solid State Amplifiers in ADS Project at IHEP

power-supply, controls, MMI, LLRF

914

O. Xiao
Institute of High Energy Physics (IHEP), People’s Republic of China
Y.L. Chi, N. Gan, X. Ma, Z.S. Zhou
IHEP, Beijing, People’s Republic of China

The solid state amplifier is an important part of the RF power source system of ADS project at IHEP. Three kinds of solid state amplifier with different power and frequency have been applied. In this paper, the specifications of solid state amplifier are presented. In addition, the principle of breakdown of power modules during the high power test of coupler are analyzed.

Poster THPO103 [0.195 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO103

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

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THPO107

High Power Coupler R&D for Superconducting CH-cavities

linac, simulation, Windows, heavy-ion

920

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

The upcoming demands of the future research programs at GSI exceed the technical opportunities of the existing UNIversal Linear ACcelerator (UNILAC). Besides, the machine will be exclusively used as an injector for FAIR (Facility for Antiproton and Ion Research) providing high power heavy ion beams at a low repetition rate for injection into the synchrotron. A new dedicated superconducting (sc) continuous wave (cw) Linac is crucial to keep the research program competitive. The first part of the cw-linac, comprising a 217 MHz multi gap Crossbar-H-mode (CH) cavity surrounded by two sc solenoids inside a cryostat, already served as a prototype demonstrating reliable operability in a realistic accelerator environment. A sufficient high power RF-coupling concept is needed to feed this newly developed cw-RF cavity with up to 5 kW of RF-power. A high power coupler test stand was recently built to provide for a testing environment; further upgrade measures of this test area are foreseen. This contribution deals with the recent coupler R&D for the demonstrator set up. Besides simulations of thermal losses at the coupler (inside the RF-cavity) will be shown as well.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO107

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

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THPO108

Development of an High Gradient Side Coupled Cavity for PROBE

proton, linac, coupling, target

924

S. Pitman, R. Apsimon, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
N. Catalán Lasheras, A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland
H.L. Owen
UMAN, Manchester, United Kingdom

The PROBE project aims to develop a high gradient proton accelerator for protons with energy around 250-350 MeV for proton radiography. Detailed studies have shown that the optimum design is a side coupled cavity at S-band. With an aperture of 8 mm a gradient of 54 MV/m can be obtained with 13 MW of RF power in a 30 cm structure. A prototype cavity has been machined by VDL and diffusion bonded by Bodycote. We present initial measurements of the prototype.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO108

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

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THPO109

A New Spherical Pulse Compressor Working with Degenerated "Whispering Gallery" Mode

coupling, GUI, simulation, collider

928

Z.B. Li, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People’s Republic of China
A. Grudiev
CERN, Geneva, Switzerland

CLIC is focusing on the Compact Linear Collider. To obtain a relatively high accelerating gradient, CLIC utilizes Pulse Compressors to increase the input power of accelerators. This work is to make an alternative design for CLIC pulse compression scheme. There are several kinds of pulse compressor: SLED, BOC, SLED-Ⅱ, spherical pulse compressor and so on. Usually, a spherical cavity, including BOC, can offer a higher Q factor compared with a cylindrical cavity. This design utilizes a spherical cavity working with degenerated Whispering Gallery mode.

Slides THPO109 [1.738 MB]

Poster THPO109 [1.913 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO109

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

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THPO115

Consolidation and Extension of the High-gradient LINAC RF Technology at PSI

FEL, linac, accelerating-gradient, polarization

937

P. Craievich, M. Bopp, H.-H. Braun, A. Citterio, H. Fitze, T. Garvey, T. Kleeb, F. Löhl, F. Marcellini, M. Pedrozzi, J.-Y. Raguin, L. Rivkin, K. Rolli, R. Zennaro
PSI, Villigen PSI, Switzerland

For SwissFEL a novel production process for high-gradient, high-precision C-band accelerating structures had been developed at PSI and was implemented for series production in collaboration with industry. The copper parts of the structures are machined and brazed relying on a ultra-high precision manufacturing process and tight mechanical tolerances; no RF tuning methods are applied during or after production. So far none of the structures of the series production failed during RF power conditioning and operation in the SwissFEL facility. After completing the series production for SwissFEL PSI started collaborations with CERN, ELETTRA and DESY for applying the production process and related know-how to other frequencies, namely S-band (3 GHz) and X-band (12 GHz). This paper gives an overview on the ongoing and planned R\&D activities and results obtained so far.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO115

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

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THPO124

Design of Pulsed HV and RF Combined Gun System Using Gridded Thermionic-Cathode

gun, emittance, electron, cathode

949

T. Asaka, H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
Y. Otake
JASRI, Hyogo, Japan
T. Taniuchi
JASRI/SPring-8, Hyogo-ken, Japan

In recent state-of -arts accelerators like an X-ray free electron laser, the electron beam performance of a linear accelerator demands a low emittance of ~ 2mm mrad. To obtain the low-emittance, such a 500kV thermionic-gun at SACLA and a photocathode rf gun generating 0.5~1MeV electron beams had been developed. Although the photocathode rf gun is compact, it is necessary to prepare a highly stabilized, large and complicated laser system. The 500-kV thermionic-gun of SACLA injector has also to prepare a technically difficult and large high voltage system. Hence, we propose a low-emittance gun system with a low-voltage and grid-loaded 50kV thermionic gun and a 238MHz rf cavity to overcome the complicated difficulty, as extension of the established technology. This system quickly accelerates the electron up to 500keV to preserve the low emittance and to cancel a grid focusing effect by the space charge force of the beam. By using a particle tracking code, we obtained the optimum voltage parameters of the grid and the 238MHz rf for obtaining the above-mentioned low emittance. In this paper, we present a numerical feasibility study to realize the low-emittance gun system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO124

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

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THPO127

The Effect of Energy Fluctuation on the Multi-bunch Acceleration in E-driven ILC Positron Source

positron, acceleration, beam-loading, booster

958

M. Kuriki, H. Nagoshi
HU/AdSM, Higashi-Hiroshima, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
K. Negishi
Iwate University, Morioka, Iwate, Japan
T. Okugi, T. Omori, M. Satoh, Y. Seimiya, J. Urakawa, K. Yokoya
KEK, Ibaraki, Japan
Y. Sumitomo
LEBRA, Funabashi, Japan
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

E-Driven method is a technical backup for positron source for ILC. In the positron source, the positron is generated and accelerated in a multi-bunch format with gaps in a macro-pulse. We employ AM (Amplitude Modulation) to suppress the transient beam-loading, but a small fluctuation is still expected, depending on the compensation accuracy. In this article, the positron yield which is ratio of numbers of positrons over electrons, is evaluated as a function of the compensation accuracy. With this result and the detail investigation of the beam loading compensation accuracy by AM, the positron yield of E-Driven Positron source for ILC is evaluated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO127

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

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