LINAC2018 - List of Keywords (cathode)

Paper	Title	Other Keywords	Page
MOPO006	Crosstalk Effect in the LEReC Booster Cavity	cavity, resonance, booster, HOM	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	cavity, electron, 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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MOPO010	JINR Photocathode Research: Status and Plans	electron, laser, gun, scattering	62
	M.A. Nozdrin, N. Balalykin, J. Huran, V.F. Minashkin, G. Shirkov JINR, Dubna, Moscow Region, Russia E. Gacheva, A. Poteomkin, V. Zelenogorsky IAP/RAS, Nizhny Novgorod, Russia J. Huran Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
	Photocathode research in the frame of the "transmission" photocathode conception (backside illuminated cathode based on a quartz/sapphire plate or a metal mesh which is a substrate for thin film made of a photomaterial) is being conducted in the Veksler and Baldin Laboratory of High Energy physics (LHEP) of the Joint Institute for Nuclear Research (JINR). Status of the 30-kev DC Photogun test bench and recent results of the extremely thin carbon film based cathodes research are described. Progress in the full-scale photoinjector prototype (max electron energy of 400 keV) is given. Startup of the photoinjector was performed, 70 keV electrons were extracted (650 pC).
	Poster MOPO010 [1.564 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO010
About •	paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO027	Photocathode Laser Pulse Shaping for Improved Emittance	laser, electron, gun, emittance	84
	M. Kotur, J. Andersson, J. Björklund Svensson, M. Brandin, F. Curbis, L. Isaksson, F. Lindau, R. Lindvall, E. Mansten, R. Svärd, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden
	We present a setup for producing and characterizing picosecond ultraviolet laser pulses for use in the MAX IV photocathode electron gun preinjector. Frequency-tripled laser pulses from a commercial laser system are shaped directly in the ultraviolet domain using a Fourier-domain pulse shaper. The pulses were characterized using a transitent grating FROG. We discuss a proposed upgrade of the pulse shaper, as well as its limitations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO027
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO029	Physics design and dynamic simulation of a C-band photocathode electron gun for UEM	electron, gun, emittance, solenoid	90
	T. Chen, W. Li, Y.J. Pei, Zh. X. Tang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	For discovering structure at atomic scale and getting more details of chemical material and biological tissue, an ultrafast electron microscopy (UEM) has been developed and applied in plenty of subjects and studies. This paper described a C-band photocathode electron gun which will be working at 5712MHz to produce ultrashort electron beams with better dynamic parameters. The RF gun is using coaxial coupler to decrease the size of the gun and keep better symmetry of the field in the photocathode gun so that the beam emittance and energy spread can be reduce a lot. The photocathode rf gun will be a important part of the ultrafast electron microscopy (UEM). Using CST MWS and superfish code to simulate design the gun. After dynamic simulation, the beam parameters as the following: Energy is of 3MeV, Normal emittance of 0.12mm-mrad in boin direction, energy spread is of 5.8·10^-4, which are better enough for an UEM.
	Poster MOPO029 [3.599 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO029
About •	paper received ※ 11 September 2018 paper accepted ※ 22 September 2018 issue date ※ 18 January 2019
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MOPO035	Status of CLARA Front End Commissioning	linac, laser, GUI, MMI	98
	D. Angal-Kalinin, A.D. Brynes, S.R. Buckley, P.A. Corlett, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P.C. Hornickel, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, A.J. Moss, T.C.Q. Noakes, M.D. Roper, D.J. Scott, B.J.A. Shepherd, E.W. Snedden, N. Thompson, C. Tollervey, D.A. Walsh, T.M. Weston, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.J. Cash, R.F. Clarke, G. Cox, C. Hodgkinson, R.J. Smith, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom K.D. Dumbell, B.J.A. Shepherd Cockcroft Institute, Warrington, Cheshire, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility under development at Daresbury Laboratory. The principal aim of CLARA is to test advanced FEL schemes which can later be implemented on existing and future short wavelength FELs. We report on the commissioning of the CLARA front end, consisting of a photoinjector and the first linac section, and merger into the existing VELA (Versatile Electron Linear Accelerator) beamline.
	Slides MOPO035 [1.870 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO035
About •	paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO036	Status of the 10 MW MBKs during Commissioning of the European XFEL in DESY	FEL, klystron, operation, gun	102
	V. Vogel (Fogel), L. Butkowski, A. Cherepenko, S. Choroba, J. Hartung DESY, Hamburg, Germany
	At present 26 RF stations for European XFEL are in operation. Each of the RF stations consists of a HV modulator located in a separate building on the DESY campus, up to 1600 m long 10 kV HV cables that connect the modulator and the HV pulse transformer located in the underground tunnel, 120kV, 3 m long HV cable connecting the HV pulse transformer and the connection module of the horizontal multi-beam klystron. Two RF stations of the injector have already achieved about 20000 hours of operation, RF stations of the XFEL bunch compressor area have operated up to 11000 hours and in the XFEL main linac up to 8000 hours. To increase the lifetime of the klystrons, we use a fast protection system (KLM) that is based on the comparison of the actual RF shape and the expected RF shape. In the case of a difference exceeding a certain margin, for example, in the case of RF breakdown in a klystron or RF breakdown in a waveguide system, the KLM quickly, shorter than 500 ns, switches off the input RF signal. Thus, it does prevents the vacuum level in the klystron worsen too much or it minimizes the RF overvoltage time at the output windows of the klystron in case of breakdown in waveguides.
	Slides MOPO036 [5.241 MB]
	Poster MOPO036 [0.658 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO036
About •	paper received ※ 05 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO037	SRF Gun Development at DESY	gun, cavity, 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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TUPO002	Electron Gun for 100 MeV / 100 kW Linear Accelerator of Electrons as the Driver of Nuclear Subcritical Assembly Neutron Source	gun, electron, neutron, controls	323
	M. Moisieienko, O. Bezditko, A. Mytsykov, A.Y. Zelinsky NSC/KIPT, Kharkov, Ukraine
	100 MeV / 100 kW linear electron accelerator of The "neutron source" nuclear subcritical assembly uses the 120 KW triode electron gun as the primary source of electrons. The gun is designed, manufactured and tested at IHEP, Beijing, China. At present, the gun is installed, tested. The maximum impulse current of the gun equal to 2 A. Under design operation, the impulse current of the gun equal to 0.55 A.The report describes the construction of a 120 kV triode electron gun, the results of testing and test operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO002
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO050	Construction of Thin-film Coating System Toward the Realization of Superconducting Multilayered Structure	cavity, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO050
About •	paper received ※ 18 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO059	Latest Results of Salt Based Bipolar Electro-polishing R&D at Cornell	cavity, SRF, niobium, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO059
About •	paper received ※ 19 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO067	Study on New Removal Thickness Distribution Improvement Methods for Niobium 9-cell Cavity Vertical Electropolishing with Ninja Cathode	cavity, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO067
About •	paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO068	Vertical Electropolishing of 1.3 GHz Niobium Nine-cell SRF Cavity: Bulk Removal and RF Performance	cavity, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO068
About •	paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO069	Development of Vertical Electropolishing Facility for Nb 9-cell Cavity (2)	cavity, controls, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO069
About •	paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO074	Design and Fabrication of KEK Superconducting RF Gun #2	gun, SRF, cavity, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO074
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO076	An Innovative Nb3Sn Film Approach and Its Potential for SRF Applications	cavity, SRF, site, accelerating-gradient	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO076
About •	paper received ※ 21 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO078	Extension of Busch’s Theorem to Particle Beams	emittance, solenoid, experiment, electron	516
	L. Groening, C. Xiao GSI, Darmstadt, Germany M. Chung UNIST, Ulsan, Republic of Korea
	In 1926, H. Busch formulated a theorem for one single charged particle moving along a region with longitudinal magnetic field. The theorem relates particle angular momentum to the amount of field lines being enclosed by the particle cyclotron motion. Recently it has been extended to accelerated particle beams [Phys. Rev. Accel. Beams 21 014201 (2018)]. This contribution sketches this extension and applies the extended theorem to successfully performed emittance manipulations with electron and ion beams.
	Slides TUPO078 [0.999 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO078
About •	paper received ※ 24 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO093	Excitation of Millimeter Wavelength Cavity Structure	cavity, gun, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO093
About •	paper received ※ 10 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	cavity, gun, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-WE1A03
About •	paper received ※ 14 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO093	Status and Results Obtained on a RF Conditioning Test Bench for 704 MHz Couplers in the Frame of ESS Project	klystron, status, high-voltage, site	895
	S. Sierra, Y. Amal, Ch.L. Lievin, I. Yao Leclerc TED, Velizy-Villacoublay, France M.E. Chahbazian, J.G. De_Oliveira, A.G. Goeury, L.J. Nennig, S.P. Petitjean GERAC Thales, Le Barp, France
	Thales and Gerac are developing a test bench able to make the RF conditioning of the Fundamental Power Couplers at 704 MHz in the frame of the ESS project for CEA. The status of the developments of the test bench is described including the modulator, klystron and all relative equipments. The paper will also describes the results obtained at the date of presentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO093
About •	paper received ※ 10 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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THPO116	Space-Charge Dominated Photoemission in High Gradient Photocathode RF Guns	space-charge, laser, emittance, gun	941
	Y. Chen, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan DESY Zeuthen, Zeuthen, Germany H. Chen, Y. C. Du, W.-H. Huang, C.-X. Tang, Q.L. Tian, L.X. Yan TUB, Beijing, People’s Republic of China H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany M. Dohlus DESY, Hamburg, Germany S. A. Schmid Institut Theorie Elektromagnetischer Felder, TU Darmstadt, Darmstadt, Germany
	The cathode emission physics plays a crucial role in the overall beam dynamics in the gun. Interplays between intricate emission mechanisms in the cathode vicinity strongly influence the cathode quantum efficiency (QE) and the intrinsic emittance. The presence of strong space-charge effects in high gradient RF guns further complicates the emission process. A proper modeling of photoemission and a careful treatment of the space-charge contribution is thus of great necessity to understanding the formation of the beam slice emittance. In this article, emission measurements are carried out using the L-band cesium-telluride photocathode RF gun at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) and the S-band copper photocathode RF gun at Tsinghua University. Following the Dowell model a simple so-called space-charge iteration approach is developed and used to determine the QE through temporal and spatial-dependent electromagnetic fields. An impact of the space-charge cooling on the thermal emittance is presented. Measurement data are shown and discussed in comparisons to preliminary simulation results.
	Slides THPO116 [6.249 MB]
	Poster THPO116 [3.157 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO116
About •	paper received ※ 11 September 2018 paper accepted ※ 21 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, cavity	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO124
About •	paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO125	Runing Status of SRF Gun II at the ELBE Radiation Center	gun, SRF, laser, operation	952
	R. Xiang, A. Arnold, P.N. Lu, P. Murcek, J.S. Schaber, J. Teichert, H. Vennekate, P.Z. Zwartek HZDR, Dresden, Germany
	Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1 and the Deutsche Forschungsgemeinschaft (DFG) grant XI10⁶/2-1. As a new electron source with higher brilliance, the second version of the superconducting RF photoinjector (SRF Gun II) has been successfully commissioned at the ELBE Center for High-Power Radiation Sources since 2014. SRF Gun II features an improved 3.5-cell niobium cavity as well as a superconducting solenoid in the same cryomodule. For user operation the SRF Gun II with Mg photocathode successfully generated stable beam with bunch charges up to 200 pC in CW mode, and with sub-ps bunch length. In this presentation the gun’s status and beam parameters will be presented.
	Poster THPO125 [1.520 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO125
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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Paper

Title

Other Keywords

Page

MOPO006

Crosstalk Effect in the LEReC Booster Cavity

cavity, resonance, booster, HOM

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

cavity, electron, 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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MOPO010

JINR Photocathode Research: Status and Plans

electron, laser, gun, scattering

62

M.A. Nozdrin, N. Balalykin, J. Huran, V.F. Minashkin, G. Shirkov
JINR, Dubna, Moscow Region, Russia
E. Gacheva, A. Poteomkin, V. Zelenogorsky
IAP/RAS, Nizhny Novgorod, Russia
J. Huran
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic

Photocathode research in the frame of the "transmission" photocathode conception (backside illuminated cathode based on a quartz/sapphire plate or a metal mesh which is a substrate for thin film made of a photomaterial) is being conducted in the Veksler and Baldin Laboratory of High Energy physics (LHEP) of the Joint Institute for Nuclear Research (JINR). Status of the 30-kev DC Photogun test bench and recent results of the extremely thin carbon film based cathodes research are described. Progress in the full-scale photoinjector prototype (max electron energy of 400 keV) is given. Startup of the photoinjector was performed, 70 keV electrons were extracted (650 pC).

Poster MOPO010 [1.564 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO010

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

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MOPO027

Photocathode Laser Pulse Shaping for Improved Emittance

laser, electron, gun, emittance

84

M. Kotur, J. Andersson, J. Björklund Svensson, M. Brandin, F. Curbis, L. Isaksson, F. Lindau, R. Lindvall, E. Mansten, R. Svärd, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

We present a setup for producing and characterizing picosecond ultraviolet laser pulses for use in the MAX IV photocathode electron gun preinjector. Frequency-tripled laser pulses from a commercial laser system are shaped directly in the ultraviolet domain using a Fourier-domain pulse shaper. The pulses were characterized using a transitent grating FROG. We discuss a proposed upgrade of the pulse shaper, as well as its limitations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO027

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

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MOPO029

Physics design and dynamic simulation of a C-band photocathode electron gun for UEM

electron, gun, emittance, solenoid

90

T. Chen, W. Li, Y.J. Pei, Zh. X. Tang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

For discovering structure at atomic scale and getting more details of chemical material and biological tissue, an ultrafast electron microscopy (UEM) has been developed and applied in plenty of subjects and studies. This paper described a C-band photocathode electron gun which will be working at 5712MHz to produce ultrashort electron beams with better dynamic parameters. The RF gun is using coaxial coupler to decrease the size of the gun and keep better symmetry of the field in the photocathode gun so that the beam emittance and energy spread can be reduce a lot. The photocathode rf gun will be a important part of the ultrafast electron microscopy (UEM). Using CST MWS and superfish code to simulate design the gun. After dynamic simulation, the beam parameters as the following: Energy is of 3MeV, Normal emittance of 0.12mm-mrad in boin direction, energy spread is of 5.8·10^-4, which are better enough for an UEM.

Poster MOPO029 [3.599 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO029

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paper received ※ 11 September 2018 paper accepted ※ 22 September 2018 issue date ※ 18 January 2019

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MOPO035

Status of CLARA Front End Commissioning

linac, laser, GUI, MMI

98

D. Angal-Kalinin, A.D. Brynes, S.R. Buckley, P.A. Corlett, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P.C. Hornickel, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, A.J. Moss, T.C.Q. Noakes, M.D. Roper, D.J. Scott, B.J.A. Shepherd, E.W. Snedden, N. Thompson, C. Tollervey, D.A. Walsh, T.M. Weston, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.J. Cash, R.F. Clarke, G. Cox, C. Hodgkinson, R.J. Smith, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
K.D. Dumbell, B.J.A. Shepherd
Cockcroft Institute, Warrington, Cheshire, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility under development at Daresbury Laboratory. The principal aim of CLARA is to test advanced FEL schemes which can later be implemented on existing and future short wavelength FELs. We report on the commissioning of the CLARA front end, consisting of a photoinjector and the first linac section, and merger into the existing VELA (Versatile Electron Linear Accelerator) beamline.

Slides MOPO035 [1.870 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO035

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

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MOPO036

Status of the 10 MW MBKs during Commissioning of the European XFEL in DESY

FEL, klystron, operation, gun

102

V. Vogel (Fogel), L. Butkowski, A. Cherepenko, S. Choroba, J. Hartung
DESY, Hamburg, Germany

At present 26 RF stations for European XFEL are in operation. Each of the RF stations consists of a HV modulator located in a separate building on the DESY campus, up to 1600 m long 10 kV HV cables that connect the modulator and the HV pulse transformer located in the underground tunnel, 120kV, 3 m long HV cable connecting the HV pulse transformer and the connection module of the horizontal multi-beam klystron. Two RF stations of the injector have already achieved about 20000 hours of operation, RF stations of the XFEL bunch compressor area have operated up to 11000 hours and in the XFEL main linac up to 8000 hours. To increase the lifetime of the klystrons, we use a fast protection system (KLM) that is based on the comparison of the actual RF shape and the expected RF shape. In the case of a difference exceeding a certain margin, for example, in the case of RF breakdown in a klystron or RF breakdown in a waveguide system, the KLM quickly, shorter than 500 ns, switches off the input RF signal. Thus, it does prevents the vacuum level in the klystron worsen too much or it minimizes the RF overvoltage time at the output windows of the klystron in case of breakdown in waveguides.

Slides MOPO036 [5.241 MB]

Poster MOPO036 [0.658 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO036

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paper received ※ 05 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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MOPO037

SRF Gun Development at DESY

gun, cavity, 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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TUPO002

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

gun, electron, neutron, controls

323

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

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

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO002

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paper received ※ 12 September 2018 paper accepted ※ 21 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

cavity, 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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TUPO059

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

cavity, SRF, niobium, 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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TUPO067

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

cavity, 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

cavity, 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)

cavity, controls, 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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TUPO074

Design and Fabrication of KEK Superconducting RF Gun #2

gun, SRF, cavity, 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

cavity, SRF, site, accelerating-gradient

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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TUPO078

Extension of Busch’s Theorem to Particle Beams

emittance, solenoid, experiment, electron

516

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

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

Slides TUPO078 [0.999 MB]

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

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

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TUPO093

Excitation of Millimeter Wavelength Cavity Structure

cavity, gun, 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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WE1A03

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

cavity, gun, 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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THPO093

Status and Results Obtained on a RF Conditioning Test Bench for 704 MHz Couplers in the Frame of ESS Project

klystron, status, high-voltage, site

895

S. Sierra, Y. Amal, Ch.L. Lievin, I. Yao Leclerc
TED, Velizy-Villacoublay, France
M.E. Chahbazian, J.G. De_Oliveira, A.G. Goeury, L.J. Nennig, S.P. Petitjean
GERAC Thales, Le Barp, France

Thales and Gerac are developing a test bench able to make the RF conditioning of the Fundamental Power Couplers at 704 MHz in the frame of the ESS project for CEA. The status of the developments of the test bench is described including the modulator, klystron and all relative equipments. The paper will also describes the results obtained at the date of presentation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO093

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paper received ※ 10 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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THPO116

Space-Charge Dominated Photoemission in High Gradient Photocathode RF Guns

space-charge, laser, emittance, gun

941

Y. Chen, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan
DESY Zeuthen, Zeuthen, Germany
H. Chen, Y. C. Du, W.-H. Huang, C.-X. Tang, Q.L. Tian, L.X. Yan
TUB, Beijing, People’s Republic of China
H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany
M. Dohlus
DESY, Hamburg, Germany
S. A. Schmid
Institut Theorie Elektromagnetischer Felder, TU Darmstadt, Darmstadt, Germany

The cathode emission physics plays a crucial role in the overall beam dynamics in the gun. Interplays between intricate emission mechanisms in the cathode vicinity strongly influence the cathode quantum efficiency (QE) and the intrinsic emittance. The presence of strong space-charge effects in high gradient RF guns further complicates the emission process. A proper modeling of photoemission and a careful treatment of the space-charge contribution is thus of great necessity to understanding the formation of the beam slice emittance. In this article, emission measurements are carried out using the L-band cesium-telluride photocathode RF gun at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) and the S-band copper photocathode RF gun at Tsinghua University. Following the Dowell model a simple so-called space-charge iteration approach is developed and used to determine the QE through temporal and spatial-dependent electromagnetic fields. An impact of the space-charge cooling on the thermal emittance is presented. Measurement data are shown and discussed in comparisons to preliminary simulation results.

Slides THPO116 [6.249 MB]

Poster THPO116 [3.157 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO116

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paper received ※ 11 September 2018 paper accepted ※ 21 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, cavity

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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THPO125

Runing Status of SRF Gun II at the ELBE Radiation Center

gun, SRF, laser, operation

952

R. Xiang, A. Arnold, P.N. Lu, P. Murcek, J.S. Schaber, J. Teichert, H. Vennekate, P.Z. Zwartek
HZDR, Dresden, Germany

Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1 and the Deutsche Forschungsgemeinschaft (DFG) grant XI10⁶/2-1.
As a new electron source with higher brilliance, the second version of the superconducting RF photoinjector (SRF Gun II) has been successfully commissioned at the ELBE Center for High-Power Radiation Sources since 2014. SRF Gun II features an improved 3.5-cell niobium cavity as well as a superconducting solenoid in the same cryomodule. For user operation the SRF Gun II with Mg photocathode successfully generated stable beam with bunch charges up to 200 pC in CW mode, and with sub-ps bunch length. In this presentation the gun’s status and beam parameters will be presented.

Poster THPO125 [1.520 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO125

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

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