IPAC2018 - List of Keywords (gun)

Paper	Title	Other Keywords	Page
MOZGBF3	40 Years of Electron Cooling at CERN	electron, proton, antiproton, experiment	69
	G. Tranquille CERN, Geneva, Switzerland
	For nearly 40 years electron cooling has been used extensively on the storage rings of the CERN accelerator complex for the accumulation of ions or for the improvement of beam quality for precision experiments. Since the first cooling experiments on ICE the coolers have evolved to incorporate the latest advances in electron cooling technology and many unique experiments have also been performed when the coolers are not used for everyday operation. The trapping of anti-hydrogen atoms and more recently lead-lead and proton-lead ion collisions in the LHC have been made possible thanks to cooling in the AD and cooling and accumulation of lead ions in the LEIR respectively. The next cooler to be built at CERN will be installed on ELENA and will operate at electron energies below 350 eV. Many challenges lie ahead in operating at such a low energy with minimum perturbation to the storage ring. The present AD cooler, which has already seen two re-incarnations, will also be replaced with a new state-of-the-art device operating at higher energies in order to improve the quality of the antiproton beam in this ring.
	Slides MOZGBF3 [14.902 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF3
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MOPMK011	VEPP-5 Injection Complex: New Possibilities for BINP Electron-Positron Colliders	positron, electron, injection, collider	371
	Yu. Maltseva, A.V. Andrianov, K.V. Astrelina, V.V. Balakin, A.M. Batrakov, O.V. Belikov, D.E. Berkaev, M.F. Blinov, D. Bolkhovityanov, A. Butakov, E.V. Bykov, N.S. Dikansky, F.A. Emanov, A.R. Frolov, V.V. Gambaryan, K. Gorchakov, Ye.A. Gusev, S.E. Karnaev, G.V. Karpov, A.S. Kasaev, E. Kenzhbulatov, V.A. Kiselev, S. Kluschev, A.A. Kondakov, I. Koop, I.E. Korenev, N.Kh. Kot, V.R. Kozak, A.A. Krasnov, S.A. Krutikhin, I.V. Kuptsov, G.Y. Kurkin, N.N. Lebedev, A.E. Levichev, P.V. Logatchov, A.A. Murasev, V. Muslivets, D.A. Nikiforov, An.A. Novikov, A.V. Ottmar, A.V. Pavlenko, I.L. Pivovarov, V.V. Rashchenko, Yu. A. Rogovsky, S.L. Samoylov, N. Sazonov, A.V. Semenov, D.B. Shwartz, A.N. Skrinsky, A.A. Starostenko, D.A. Starostenko, A.G. Tribendis, A.S. Tsyganov, S.P. Vasichev, S.V. Vasiliev, V.D. Yudin, I.M. Zemlyansky, A.N. Zhuravlev BINP SB RAS, Novosibirsk, Russia A.V. Andrianov, V.V. Balakin, F.A. Emanov, I. Koop, A.A. Krasnov, A.E. Levichev, D.A. Nikiforov, A.V. Pavlenko, Yu. A. Rogovsky, D.B. Shwartz, A.A. Starostenko NSU, Novosibirsk, Russia A.I. Mickailov Budker INP & NSU, Novosibirsk, Russia A.G. Tribendis NSTU, Novosibirsk, Russia
	VEPP-5 Injection Complex (IC) is designed to supply BINP RAS colliders with high energy electron and positron beams. Recently constructed K-500 beam transfer line connects IC to both VEPP-4M and VEPP-2000 colliders. IC two collider operation was successfully performed in 2016. Nowadays, research on improvement of IC productivity is carried out, in particular 10.94 MHz RF cavity instead of 700 MHz one was installed and a new electron gun installation is expected to be this summer. Moreover, longitudinal beam profile measurements in IC damping ring using a streak-camera were carried out. Operation experience of IC and results of longitudinal beam profile measurements are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK011
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MOPMK015	Development of a Bunched-Beam Electron Cooler for the Jefferson Lab Electron-Ion Collider	electron, linac, kicker, cathode	382
	S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, A. Hutton, R. Li, R.A. Rimmer, Y. Roblin, C. Tennant, H. Wang, H. Zhang, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177. Jefferson Lab is in the process of designing an electron-ion collider with unprecedented luminosity at a 65 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires novel use of bunched-beam cooling. We will present a new design for a Circulator Cooler Ring for bunched-beam electron cooling. This requires the generation and transport of very high-charge magnetized bunches, acceleration of the bunches in an energy recovery linac, and transfer of these bunches to a circulating ring that passes the bunches 11 times through the proton or ion beam inside cooling solenoids. This design requires the suppression of the effects of space charge and coherent synchrotron radiation using shielding and RF compensation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK015
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MOPML034	Development Status of Superconducting RF Transmission Electron Microscope	cavity, acceleration, LLRF, SRF	481
	N. Higashi, A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, F. Qiu, M. Yamamoto KEK, Ibaraki, Japan S. Yamashita University of Tokyo, Tokyo, Japan
	Now we are developing a new type of transmission electron microscope (TEM) employing the accelerator technologies. In place of a DC thermal gun generally used in conventional TEMs, we apply a photocathode gun and a special-shaped superconducting cavity, named two-mode cavity. The two-mode cavity has two resonant modes of TM010 (1.3 GHz) and TM020 (2.6 GHz). To superimpose these, we can suppress the increase of the energy spread, which is needed for the high-spatial-resolution TEMs. We have already developed some prototypes of the photocathode gun and two-mode cavity, and now in the middle of the performance tests. In this presentation, we will show the latest status of the development.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML034
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MOPML044	Start-to-End Beam Dynamic Simulations for PRAE	emittance, linac, laser, solenoid	495
	A. Vnuchenko IFIC, Valencia, Spain C. Bruni, M. El Khaldi, A. Faus-Golfe, P. Lepercq, C. Vallerand LAL, Orsay, France A. Latina CERN, Geneva, Switzerland
	The PRAE project (Platform for Research and Applications with Electrons) aims at creating a multidisciplinary R&D facility in the Orsay campus gathering various scientific communities involved in radiobiology, subatomic physics, instrumentation and particle accelerators around an electron accelerator delivering a high-performance beam with energy up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and future challenging R&D. In this paper we report the first start-to-end simulations from the RF gun, going through the linac and finally to the different experimental platforms. The beam dynamics simulations have been performed using a concatenation of codes. In particular for the linac the RF-Track code recently developed at CERN will be used and benchmarked. The different working points have been analysed in order to minimise the transverse emittance and the beam energy spread including space charge effects at low electron energies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML044
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MOPML055	Preliminary Physics Design of a Linac with the Variable Energy for Industrial Applications	linac, electron, beam-loading, simulation	530
	Zh. X. Tang USTC, Hefei, Anhui, People's Republic of China L. Wang, D.R. Xu USTC/NSRL, Hefei, Anhui, People's Republic of China
	This paper describes the physics design of a S-band (2856 MHz) linear accelerator (linac) with variable energy tuning. The system consists of a DC gun for generating electron, prebuncher for velocity modulation and two travelling wave (TW) accelerating sections for acceleration. The accelerating structure is a 2'Ð/3 mode constant gradient TW structure, which comprises TW buncher cells, followed by uniform cells. The structure is designed to accelerate 45 keV electron beam from the electron gun to 3.2 MeV, and then 10 MeV. An important feature of the TW linac is that the RF output power of the first linac is as the RF input power of the second linac. Three dimensional transient simulations of the accelerating structure along with the input and output couplers have been performed to explicitly demonstrate this feature. Beam dynamics is performed to calculate the beam parameter.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML055
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MOPML066	Ultrafast Mega-electron-volt Gas-Phase Electron Diffraction at SLAC National Accelerator Laboratory	electron, vacuum, laser, experiment	556
	X. Shen, R.K. Li, X.J. Wang, S.P. Weathersby, J. Yang SLAC, Menlo Park, California, USA
	Funding: This work was supported in part by the U.S. Department of Energy Contract No. DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund. Ultrashort mega-electron-volt (MeV) electron beams from radio-frequency (rf) photoinjectors have recently attracted strong interests for application in ultrafast gas-phase electron diffraction (UGED). Such high-brightness electron beams are capable of providing 100-fs level temporal resolution and sub-Angstrom level spatial resolution to capture the ultrafast structural dynamics from photoexcited gas molecules. To experimentally demonstrate such an ultrafast electron scattering instrument, a high performance UGED system has been commissioned at SLAC National Accelerator Laboratory. The UGED instrument produces 3.7 MeV electron beams with 2 fC beam charge at 180-Hz repetition rate. The temporal resolution is characterized to be 150 fs full-width-at-half-maximum (FWHM), while the spatial resolution is measured to be 0.76 Å FWHM. The UGED instrument also demonstrates outstanding performance in vacuum, rf, and electron beam pointing stability. Details of the performance of the SLAC MeV UGED system is reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML066
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MOPML067	9/6 MeV European S-band Linac Structure for Container Inspection System at RTX and KAERI	electron, coupling, linac, bunching	560
	P. Buaphad, H.D. Park, S. Song RTX, Daejeon, Republic of Korea P. Buaphad, Y. Joo University of Science and Technology of Korea (UST), Daejeon, Republic of Korea P. Buaphad, S.C. Cha, Y. Joo, Y. Kim, H.R. Lee KAERI, Jeongeup-si, Republic of Korea
	Recently, demands on low energy electron linear accelerators (linacs) for industrial applications are rapidly growing. Their beam energies are lower than 20 MeV, and they require a compact, cheap, and stable accelerator system. For the Container Inspection System (CIS), KAERI successfully developed a 9/6 MeV American S-band (= 2856 MHz) linac with a 5 MW klystron in 2013. To reduce the cost of the RF source, recently, KAERI and RTX also have been developing another 9/6 MeV European S-band (= 2998 MHz) linac by using a magnetron with a lower RF power of about 3.1 MW. Its accelerating structure is designed to be operated in π/2 mode by coupling 13 accelerating cells together through 12 side-coupling cells. The CST Microwave Studio is used for electromagnetic simulations and optimization of the accelerating structure. After various optimizations, a shunt impedance of 84 MΩ/m is obtained at π/2 mode frequency of 2998.31 MHz. In this paper, we describe design concept, optimization, and RF measurement of the new 9/6 MeV European S-band linac structure. Then, we compare it with our old American S-band linac structure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML067
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TUYGBE2	CBETA, the 4-Turn ERL with SRF and Single Return Loop	electron, linac, SRF, cryomodule	635
	G.H. Hoffstaetter, N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, S.J. Full, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, C.E. Mayes, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.S. Berg, S.J. Brooks, C. Liu, G.J. Mahler, F. Méot, R.J. Michnoff, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte BNL, Upton, Long Island, New York, USA D. Douglas JLab, Newport News, Virginia, USA J.K. Jones Cockcroft Institute, Warrington, Cheshire, United Kingdom D. Jusic Cornell University, Ithaca, New York, USA D.J. Kelliher STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom B.C. Kuske, M. McAteer, J. Völker HZB, Berlin, Germany
	Funding: Supported by NSF award DMR-0807731, DOE grant DE-AC02-76SF00515, and NYSERDA. A collaboration between Cornell University and Brookhaven National Laboratory has designed and is constructing CBETA, the Cornell-BNL ERL Test Accelerator on the Cornell campus. The ERL technology that has been prototyped at Cornell for many years is being used for this new accelerator, including a DC electron source and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current linac cryomodule optimized for ERLs, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. BNL has designed multi-turn ERLs for several purpose, dominantly for the electron beam of eRHIC, its Electron Ion Collider (EIC) project and for the associated fast electron cooling system. Also in JLEIC, the EIC designed at JLAB, an ERL is envisioned to be used for electron cooling. The number of transport lines in an ERL is minimized by using return arcs that are comprised of a Fixed Field Alternating-gradient (FFA) design. This technique will be tested in CBETA, which has a single return for the 4-beam energies with strongly-focusing permanent magnets of Halbach type. The high-brightness beam with 150~MeV and up to 40~mA will have applications beyond accelerator research, in industry, in nuclear physics, and in X-ray science. Low current electron beam has already been sent through the most relevant parts of CBETA, from the DC gun through both cryomodules, through one of the 8 similar separator lines, and through one of the 27 similar FFA structures. Further construction is envisioned to lead to a commissioning start for the full system early in 2019.
	Slides TUYGBE2 [17.343 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBE2
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TUYGBF4	Design and Simulation Tools for the High-Intensity Industrial Rhodotron Electron Accelerator	cavity, dipole, electron, cathode	651
	W.J.G.M. Kleeven, M. Abs, J. Brison, E. Forton, J. M. Hubert, J. Walle IBA, Louvain-la-Neuve, Belgium
	The Rhodotron is a compact industrial CW recirculating electron accelerator producing intense beams with energies in the range from about 1 to 10 MeV. RF-frequencies are in the range of 100 to 400 MHz. Average beam powers can range from 10 kW to almost 1 MW, depending of the specific type of Rhodotron. Main industrial applications are polymer cross-linking, sterilization, food treatment and container security scanning. Recently, RF pulsing was developed to reduce the average wall power dissipation, thus reducing drastically the energy consumption. Pulsing also permits smaller cavities and higher energies up to 40 MeV, opening the way to applications such as mobile irradiators, or isotopes production by photonuclear reactions, thus offering a compact and high beam duty alternative to linacs. This paper concentrates on some crucial design tools and methods for transverse and longitudinal optics studies, particle tracking with space charge, beam formation studies in the electron gun and dipole magnet design.
	Slides TUYGBF4 [11.952 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBF4
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TUPAF056	The CERN-ELENA Electron Cooler Magnetic System	solenoid, electron, alignment, proton	842
	G. Tranquille, L.V. Jørgensen CERN, Geneva, Switzerland D. Luckin, R.J. Warner Tesla Engineering Limited, West-Sussex, United Kingdom
	Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler the performance of which is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the efficient recuperation of the electrons in the collector and the quality of the guiding magnetic field ensure an optimal performance of the cooler. The ELENA cooler is a compact device incorporating an adiabatic expansion to reduce the electron beam temperature as well as electrostatic bending plates for efficient collection of the electron beam. The transverse components of the longitudinal field in the cooling section must be kept small (Bt/Bl ≤ 5x10-4) to ensure a minimal perturbation to the electron beam transverse temperature. The longitudinal field itself needs to be as low as possible such that the distortion to the closed orbit of the circulating ion beam due to the short 90° toroids is kept as small as possible. We present the solutions chosen to design and construct a magnetic system within the above constraints as well as the setup used to measure and optimise the magnetic field components.
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TUPMF002	A Cu Photocathode for the Superconducting RF Photoinjector of BERLinPro	cathode, SRF, cavity, laser	1247
	J. Kühn, M. Bürger, A. Frahm, A. Jankowiak, T. Kamps, G. Klemz, G. Kourkafas, A. Neumann, N. Ohm, M. Schmeißer, M. Schuster, J. Völker HZB, Berlin, Germany P. Murcek, J. Teichert HZDR, Dresden, Germany
	The initial commissioning of the Superconducting RF (SRF) photoinjector is done with a Cu photocathode due to its robustness with regard to interactions with the SRF cavity of the injector. Here we present the preparation and characterization of a Cu photocathode plug and the diagnostics to insert the photocathode in the back wall of the SRF cavity. A polycrystalline bulk Cu plug was polished, particle free cleaned and characterized by x-ray photoelectron spectroscopy. During the transfer of the photocathode insert into the gun module the whole process was controlled by several diagnostic tools monitoring the insert position as well as RF, vacuum and cryogenic signals. We discuss the challenges of the photocathode transfer into an SRF cavity and how they can be tackled.
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TUPMF020	Demonstration of Fast, Single-shot Photocathode QE Mapping Method Using MLA Pattern Beam	laser, cathode, electron, optics	1293
	E.E. Wisniewski, M.E. Conde, D.S. Doran, W. Gai, Q. Gao, W. Liu, J.G. Power, C. Whiteford ANL, Argonne, Illinois, USA Q. Gao TUB, Beijing, People's Republic of China G. Ha PAL, Pohang, Republic of Korea A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA
	Funding: UChicago Argonne, LLC, Operator of Argonne National Laboratory ("Argonne"). Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. Quantum efficiency (QE) is the chief figure of merit in the characterization of photocathodes. Semiconductor photocathodes, especially when used in high rep-rate photo-injectors, are known to show QE degradation over time and must be replaced. The total QE is the basic diagnostic which is used widely and is easy to obtain. However, a QE map indicating variations of QE across the cathode surface has greater utility. It can quickly diagnose problems of QE inhomogeneity. Most QE mapping techniques require hours to complete and are thus disruptive to a user facility schedule. A fast, single-shot method has been proposed (citation) using a micro-lens array (MLA) generated QE map. In this paper we report the implementation of the method at Argonne Wakefield Accelerator facility. A micro-lens array (MLA) is used to project an array of beamlets onto the photocathode. The resulting photoelectron beam in the form of an array of electron beamlets is imaged at a YAG screen. Four synchronized measurements are made and the results used to produce a QE map of the photocathode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF020
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TUPMF025	LEReC Photocathode DC Gun Beam Test Results	cathode, operation, laser, electron	1306
	D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, X. Gu, L.R. Hammons, P. Inacker, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, C. Liu, K. Mernick, T.A. Miller, M.G. Minty, V. Ptitsyn, T. Rao, J. Sandberg, S. Seletskiy, P. Thieberger, J.E. Tuozzolo, E. Wang, Z. Zhao BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Low Energy RHIC Electron cooler (LEReC) project is presently under commissioning at Brookhaven National Laboratory (BNL). LEReC requires high average current up to 85mA and high-quality electron beam. A 400 kV DC gun equipped with a photocathode and laser system has been chosen to provide a source of high-quality electron beams. We started testing the DC gun during the RHIC run 2017. First electron beam from LEReC DC gun was delivered in April 2017 . During the DC gun test critical elements of LEReC such as laser beam system, cathode exchange system, cathode QE lifetime, DC gun stability, beam instrumentation, the high-power beam dump system, machine protection system and controls have been tested. Average current of 10 mA for few hours of operation was reached in August 2017. In this paper we present experimental results and experience learned during the LEReC DC gun beam testing. D. Kayran et al., "First Results of Commissioning DC Photo-gun for RHIC Low Energy Electron Cooler (LEReC)", in Proc of ERL2017.
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TUPMF061	Physical Design of the 500 MeV Electron Linac for the High Energy Photon Source	linac, electron, bunching, emittance	1404
	S. Pei, D.Y. He, X. He, J.L. Li, J. Liu, X. Ma, C. Meng, X. Wang, O. Xiao, J.R. Zhang, Z.S. Zhou IHEP, Beijing, People's Republic of China S. Shu Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	Funding: Work supported by the HEPS project and the National Natural Science Foundation of China (11475201). peisl@ihep.ac.cn The High Energy Photon Source (HEPS) is a 6 GeV light source with ultra-low emittance, it is proposed to be built at Huairou district, northeast suburb of Beijing, China. A 500 MeV electron linac will be used to generate the electron beam for injection into the booster. Here the preliminary physical design of the electron linac is presented.
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TUPMF086	Status of the ARES RF Gun at SINBAD: From its Characterization and Installation towards Commissioning	cavity, linac, status, electron	1474
	B. Marchetti, R.W. Aßmann, S. Baark, F. Burkart, U. Dorda, K. Flöttmann, I. Hartl, J. Hauser, J. Herrmann, M. Hüning, K. Knebel, O. Krebs, G. Kube, W. Kuropka, S. Lederer, F. Lemery, F. Ludwig, D. Marx, F. Mayet, M. Pelzer, I. Peperkorn, F. Poblotzki, S. Pumpe, J. Rothenburg, H. Schlarb, M. Titberidze, G. Vashchenko, T. Vinatier, P.A. Walker, L. Winkelmann, K. Wittenburg, S. Yamin, J. Zhu DESY, Hamburg, Germany
	The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host multiple experiments relating to the production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD-ARES linac will be a conventional S-band linear RF accelerator allowing the production of low charge (0.5 pC - tens pC) ultra-short electron bunches (FWHM length =< 1 fs - few fs) with 100 MeV energy. The installation of the linac will proceed in stages. In this paper we report on the status of the characterization of the ARES RF gun and the installations of the related infrastructure.
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TUPML006	Updates of the Argonne Cathode Test-stand	cathode, laser, electron, experiment	1542
	J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng ANL, Argonne, Illinois, USA S.P. Antipov, G. Chen, E. Gomez, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Baryshev Michigan State University, East Lansing, Michigan, USA
	The Argonne Cathode Test-stand (ACT) is a unique testbed to develop cathodes and to conduct fundamental surface study under ultra-high rf field (up to 700 MV/m with pin-shaped cathodes). The test-stand consists of an L-band 1.3 GHz single-cell photocathode rf gun and a field emission (FE) imaging system to locate emitters with a resolution of ∼20 𝜇m. In the recent upgrade, UV laser has been introduced to improve the imaging system and to significantly expand the ACT towards photoemission and laser-assisted field emission research. In addition, a load-lock system has been added to the beam line to expedite the cathode switching period. The paper will present details of the upgrade as well as experiments planned in the near future.
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TUPML028	Photocathodes R&D for High Brightness and Highly Polarized Electron Beams at Cornell University	electron, cathode, emittance, simulation	1601
	L. Cultrera, J. Bae, A.C. Bartnik, I.V. Bazarov, R. Doane, A. Galdi, C.M. Gulliford, W. H. Li, J.M. Maxson, S.A. McBride, T.P. Moore, C. M. Pierce, C. Xu Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Cornell University is a leader in the development of photocathode materials for the production of high brightness electron beam sources for applications in large scale accelerators and small scale electron scattering experiments. During the last year we have also included Mott polarimetry to investigate long lifetime spin-polarized photocathodes materials. Another thrust of our laboratory is the exploration of ultra low emittance photocathodes at cryogenic temperatures, for which we are building a novel LHe cryogenic electron source. We will review updates from our lab across each of these areas.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML028
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TUPML064	Staged Two Beam Acceleration Beam Line Design for the AWA Facility	kicker, experiment, laser, acceleration	1688
	N.R. Neveu IIT, Chicago, Illinois, USA W. Gai, C.-J. Jing, J.G. Power ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357. Two beam acceleration is a candidate for future high energy physics machines and FEL user facilities. This scheme consists of two independent electron beam lines operating synchronously. High-charge, 70 MeV drive bunch trains are injected from the RF photo-injector into decelerating structures to generate a few hundred of MW of RF power. This RF power is transferred through an RF waveguide to accelerating structures that are used to accelerate the witness beam. Staging refers to the sequential acceleration (energy gain) in two or more structures on the witness beam line. A kicker was incorporated on the drive beam line to accomplish a modular design so that each accelerating structure can be independently powered by a separate drive beam. Simulations were performed in OPAL-T to model the two beam lines. Beam sizes at the center of the structures was minimized to ensure good charge transmission. The resulting design will be the basis for proof of principle experiments that will take place at the Argonne Wakefield Accelerator (AWA) facility.
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WEYGBE2	Applications of Caustic Methods to Longitudinal Phase Space Manipulation	FEL, electron, linac, optics	1790
	T.K. Charles The University of Melbourne, Melbourne, Victoria, Australia T.K. Charles CERN, Geneva, Switzerland D. Douglas JLab, Newport News, Virginia, USA P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Longitudinal phase space management is a key feature of recirculating machines. Careful consideration of the longitudinal matching is required not only in order to ensure a high peak current, low energy spread bunch is delivered to the FEL but also to support the deceleration and energy recovery of the spent beam. In a similar manner, longitudinal phase space manipulation can be utilised for pulse shaping in bunch compression, to minimise the influence of CSR-induced emittance growth. In this paper, we present a method for longitudinal phase space matching based upon the avoidance of electron trajectory caustics. Through considering the conditions under which caustics will form, we generate exclusion plots identifying the viable parameter space at numerous positions through beam acceleration and energy recovery. The result is a method for selecting the linear momentum compaction and the higher-order momentum compaction to satisfy the non-caustic condition whilst achieving the bunch compression or lengthening as required.
	Slides WEYGBE2 [6.292 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBE2
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WEPAF034	A Supersonic Gas Jet-Based Beam Profile Monitor Using Fluorescence for HL-LHC	electron, photon, luminosity, hadron	1891
	H.D. Zhang, A.S. Alexandrova, R. Schnuerer, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom M. Ady, E. Barrios Diaz, N. Chritin, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness CERN, Geneva, Switzerland A.S. Alexandrova, A. Salehilashkajani, R. Schnuerer, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom P. Forck, S. Udrea GSI, Darmstadt, Germany P. Smakulski WRUT, Wroclaw, Poland
	Funding: The HL-LHC project, the Helmholtz Association under contract VH-NG-328, the EU's 7th Framework Programme under grant agreement no 215080 and the STFC Cockcroft core grant No. ST/G008248/1. The High-Luminosity Large Hadron Collider (HL-LHC) project aims to increase the machine luminosity by a factor of 10 as compared to the LHC's design value. To achieve this goal, a special type of electron lens is being developed. It uses a hollow electron beam which co-propagates with the hadron beam to act on any halo particles without perturbing the core of the beam. The overlapping of both beams should be carefully monitored. This contribution presents the design principle and detailed characteristics of a new supersonic gas jet-based beam profile monitor. In contrast to earlier monitors, it relies on fluorescence light emitted by the gas molecules in the jet following interaction with the primary hadron beams. A dedicated prototype has been designed and built at the Cockcroft Institute and is being commissioned. Details about monitor integration, achievable resolution and dynamic range will be given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF034
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WEPAL002	Improvement of Personnel and Machine Protection System in Superkekb Injector Linac	linac, operation, PLC, controls	2140
	I. Satake, H. Honma, A. Shirakawa, N. Toge KEK, Ibaraki, Japan
	Since summer of 2010, the radiation control area for the KEK electron positron injector linac had been split at the around 3 GeV point by a concrete wall into upstream and downstream parts with independent beam sources. This was so as to allow operation of the downstream part for beam injection into photon factory rings while construction and development of new electron guns proceed in the upstream part. In summer of 2017, this arrangement was revised and the entire injector linac was reconsolidated into a single radiation control area. This was in conjunction with the introduction of the 1.1 GeV positron damping ring for Phase-II operation of SuperKEKB and successful development of new electron RF guns in the far upstream part of the linac. Along with this reconsolidation, the personnel and machine protection system was modified and improved. Interlock signal lines for the damping ring and RF guns were added. The operation panel of the main console was modified accordingly. In addition, the screen displays of the interlock status were updated. In this paper we report on the renewed system of KEK injector linac in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL002
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WEPAL039	LCLS-II Gun/Buncher LLRF System Design	LLRF, cavity, SRF, controls	2258
	G. Huang, K.S. Campbell, L.R. Doolittle, J.A. Jones, Q. Qiang, C. Serrano LBNL, Berkeley, California, USA S. Babel, A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, J.H. De Long, J.A. Diaz Cruz, B. Hong, A. McCollough, A. Ratti, C.H. Rivetta, D. Rogind, F. Zhou SLAC, Menlo Park, California, USA R. Bachimanchi, C. Hovater, D.J. Seidman JLab, Newport News, Virginia, USA B.E. Chase, E. Cullerton, J. Einstein-Curtis, D.W. Klepec Fermilab, Batavia, Illinois, USA J.A. Diaz Cruz CSU, Fort Collins, Colorado, USA
	Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-05CH11231. For a free electron laser, the stability of injector is critical to the final electron beam parameters, e.g., beam energy, beam arrival time, and eventually it determines the photon quality. The LCLS-II project's injector contains a VHF copper cavity as the gun and a two-cell L-band copper cavity as its buncher. The cavity designs are inherited from the APEX design, but requires more field stability than demonstrated in APEX operation. The gun LLRF system design uses a connectorized RF front end and low noise digitizer, together with the same general purpose FPGA carrier board used in the LCLS-II SRF LLRF system. The buncher LLRF system directly adopts the SRF LLRF chassis design, but programs the controller to run the normal conducting cavities. In this paper, we describe the gun/buncher LLRF system design, including the hardware design, the firmware design and bench test.
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WEPAL040	High Precision Synchronization Development for HiRES, the Ultrafast Electron Diffraction Beamline at LBNL	laser, controls, electron, LLRF	2262
	Y. Yang, K.M. Baptiste, M. Betz, L.R. Doolittle, Q. Du, D. Filippetto, G. Huang, F. Ji LBNL, Berkeley, California, USA
	Precise synchronization between the laser and electron is critical for the pump-probe experiments in the HiRES Ultrafast Electron Diffraction facility. We are upgrading the LLRF and laser control system, which ultimately aims at a synchronization below 50 fs RMS between the pump laser pulse and electron probe at the sample plane. Such target poses tight requirements on the RF field stability both in amplitude and phase, and on the synchronization between the RF field and the laser repetition rate. We are presently developing a new LLRF system that has the potential to decrease the overall noise, reaching the required stability of tens of ppm on RF amplitude and phase. For the laser control side, we are replacing the long coaxial cables with fibers for both control signal transmission and laser signal reception. The control transmission side has been implemented, and the timing jitter has been reduced.
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WEPMF051	Multipacting in an RF Window: Simulations and Measurements	multipactoring, electron, simulation, resonance	2483
	M. Bousonville, S. Choroba DESY, Hamburg, Germany
	Electron guns are used in the accelerators of the European XFEL and FLASH. They are operated at 1.3 GHz. The RF peak power is 5 MW at 650 us pulse width and 10 Hz repetition rate. In order to understand the multipacting that occurs during conditioning, it was simulated in the RF window type that is used for the electron gun in the XFEL. The reduction in secondary emission yield associated with conditioning was taken into account. Since the RF windows are tested with high power on a test stand before their use, without the electron gun, measurement results are available which are compared with the simulation results. The main advantage of the simulation compared to the measurement is that the locations of multipacting can be determined in the RF window. This could be helpful for the development of high-power RF components in the future, in order to detect pronounced multipacting resonances even before production and to avoid them by design changes.
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WEPMF055	The REGAE Accelerator Vacuum System	vacuum, cathode, operation, electron	2493
	S. Lederer, K. Flöttmann, L. Lilje, N. Plambeck DESY, Hamburg, Germany
	Since 2011 the Relativistic Electron Gun for Atomic Exploration (REGAE) is operated at DESY in Hamburg. The accelerator consists mainly of a high gradient S-band RF-gun, which generates ultra-low emittance electron bunches, and an S-band RF-buncher cavity for bunch compression. In this contribution we describe the vacuum system of the REGAE accelerator. We will cover design aspects, applied cleaning and installation procedures as well as operation experience over the last years.
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WEPMF056	Cs2Te Photocathode Lifetime at Flash and European XFEL	cathode, FEL, laser, operation	2496
	S. Lederer, S. Schreiber DESY, Hamburg, Germany
	The photo-injectors of FLASH and the European XFEL at DESY (Hamburg, Germany) use Cs2Te photocathodes. In this contribution we give an update on the lifetime and quantum efficiency of the cathodes operated in both facilities. Cathode #680.1 was operated at the European XFEL from the injector commissioning to the first user run for over 700 days. At FLASH cathode #73.3 has been operated with a record of more than 1000 days.
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WEPMF066	Fabrication of Split-Section X-band Structure Using Elastic Averaging	vacuum, alignment, coupling, electron	2521
	P. Borchard, S.A. Appert, J.S. Hoh Dymenso LLC, San Francisco, USA
	Conventional accelerator structures are manufactured using axial stacks of cylindrical components which, when brazed together, form the accelerator cell structure. Splitting the accelerator structure into two sections along the beam axis allows for a significant reduction in part count and vacuum joint length. The resultant single and coplanar vacuum joint between the two split sections allows for joining techniques such as electron beam welding or brazing of the parts to form the accelerator vacuum envelope. High precision alignment of the two sections is achieved through an elastic averaging interface coupling where improved accuracy is derived from the averaging of errors over a large number of relatively compliant contacting members. The monoblock split sections allow for highly optimized cooling configurations with enhanced heat removal in high heat flux regions, reducing vacuum wall thermal stresses and enabling higher power operation. This paper describes the engineering and manufacturing of four generations of brazed and electron beam welded X-band accelerator structures at both 9.3 GHz and 11.4 GHz frequencies.
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WEPMF068	Inexpensive Brazeless Accelerator Prototype	cavity, vacuum, operation, electron	2528
	S.P. Antipov, R.A. Kostin, S.V. Kuzikov Euclid TechLabs, LLC, Solon, Ohio, USA A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Funding: DOE SBIR A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. Here we report on manufacturing and testing of brazeless accelerator prototype.
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WEPML060	Yb/Nd Doped Hybrid Solid Laser of RF Gun and Beam Commissioning for Phase-II of SuperKEKB	laser, injection, electron, MMI	2836
	R. Zhang, T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou KEK, Ibaraki, Japan
	For SuperKEKB project schedule of the phase-II, low emittance 1 nC electron beams were required with good stability and reliability at end of the linac. In the injector linac, several instruments have been installed. An Nd/Yb hybrid laser system is development with two beam lines light source. The both side of quasi-traveling wave side coupled cavity S-band RF gun were injected by the two sub μJ UV picosecond laser pulses at same times. And beam commissioning with the RF gun is in progress.
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THPAF024	Understanding and Compensating Emittance Diluting Effects in Highly Optimized Ultrafast Electron Diffraction Beamlines	emittance, electron, space-charge, cathode	3004
	C. M. Pierce, I.V. Bazarov, C.M. Gulliford, J.M. Maxson Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S. Baturin Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA M.A. Gordon, Y.K. Kim University of Chicago, Chicago, Illinois, USA
	Funding: This work was supported by the Center for Bright Beams, NSF PHY-1549132 and Department of Energy grant DE-SC0014338. The application of Multiobjective Genetic Algorithm optimization (MOGA) to photoemission based ultrafast electron diffraction (UED) beamlines featuring extremely low cathode mean transverse energies has lead to designs with emittances as low as 1 nm for sub-picosecond bunches with 10⁵ electrons*. Analysis of these results shows significant emittance growth during transport: with emittance dilution as high as a factor of 200-4000% for various designs and optics settings. In this study we quantify and model the individual sources of emittance growth (slice mismatches and space charge), and explore the use of the core emittance as a strong invariant. C. Gulliford, A. Bartnik, and I. Bazarov. Multi- objective optimizations of a novel cryocooled dc gun based UED beam line. Phys. Rev. Ac- celerators and Beams, 19(9):093402, 2016.
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THPAF087	Multi-Objective Optimization of an SRF Photoinjector with Booster Section for High Brightness Beam Performance	booster, cavity, emittance, brightness	3193
	E. Panofski, A. Jankowiak, T. Kamps, A. Neumann HZB, Berlin, Germany
	Several future accelerator projects, light sources and user experiments require high brightness electron beams. SRF photoinjectors operating in continuous-wave (cw) mode hold the potential to serve as an electron source generating beams of high average brightness and short bunch lengths. Different operation and design parameters of the SRF photoinjector impact the beam dynamics and thus the beam brightness. A universal multi-objective optimization program based on a genetic algorithm was developed to extract optimum gun parameter settings from Pareto-optimum solutions. After getting the first optimum results, the photoinjector is supplemented with a booster section downstream. The new optimization results are presented. Further, the optimization program is applied to evaluate the impact of the field flatness of the gun cavity on the high brightness performance.
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THPAK071	Simulation Study of the Magnetized Electron Beam	solenoid, cathode, electron, simulation	3395
	S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft ODU, Norfolk, Virginia, USA J. F. Benesch, F.E. Hannon, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman JLab, Newport News, Virginia, USA
	Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177 Electron cooling of the ion beam plays an important role in electron ion colliders to obtain the required high luminosity. This cooling efficiency can be enhanced by using a magnetized electron beam, where the cooling process occurs inside a solenoid field. This paper compares the predictions of ASTRA and GPT simulations to measurements made using a DC high voltage photogun producing magnetized electron beam, related to beam size and rotation angles as a function of the photogun magnetizing solenoid and other parameters.
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THPAK086	A 2D Steady-State Space Charge Solver for Azimuthally Symmetric Problems of Arbitrary Degree	space-charge, cathode, electromagnetic-fields, distributed	3431
	A.R. Gold, A. R. Gold, S.G. Tantawi SLAC, Menlo Park, California, USA
	Correctly and rapidly simulating the steady-state interaction between particle beams and electromagnetic fields is crucial to the design and optimization of accelerator and radiofrequency (RF) source components. Iteratively solving for the self-consistent interaction between particles and fields can prove challenging and highly susceptible to numerical noise and mesh induced instabilities. We present herein two new approaches to solving the self-consistent trajectories of particles in the presence of external and self fields. The first method reformulates the integrated self field contribution as a path integral. The second method uses a hybrid Eulerian framework and produces an interpolated continuous current density, resulting in 1-2 orders of magnitude fewer particles required to obtain an accurate solution. We conclude with benchmarking results which show this method is as accurate as state of the art PIC solvers, while running 80-120X faster.
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THPAK154	Beam Parameter Optimization for UEM Facility with Photo-Emission S-band RF Gun	electron, space-charge, laser, emittance	3610
	H.R. Lee, P. Buaphad, Y. Joo University of Science and Technology of Korea (UST), Daejeon, Republic of Korea S.C. Cha, Y. Kim KAERI, Daejon, Republic of Korea B.L. Cho KRISS, Daejeon, Republic of Korea H. Suk GIST, Gwangju, Republic of Korea
	Ultrafast Electron Microscopy (UEM) can provide snapshot images of a dynamic process in samples with an ultrafast time resolution, which is shorter than picosecond. The Future Accelerator R&D Team at KAERI has been preparing a UEM facility with a photo-emission S-band (= 2856 MHz) RF gun by collaborating with GIST and KRISS. To achieve a higher spatial resolution as well as a higher time resolution, the transverse beam emittance, beam divergence, and energy spread should be smaller, and the bunch length should be shorter. Beam dynamics simulations with ASTRA code is used to optimize those beam parameters in the RF gun. In this paper, we describe ASTRA optimizations of the S-band RF gun to achieve high spatial-temporal resolutions for the UEM facility.
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THPAL009	A TM01 Mode Launcher With Quadrupole Field Components Cancellation for High Brightness Applications	network, GUI, quadrupole, brightness	3631
	G. Castorina INFN-Roma1, Rome, Italy A.D. Cahill, J.B. Rosenzweig UCLA, Los Angeles, California, USA F. Cardelli, G. Franzini, A. Marcelli, B. Spataro INFN/LNF, Frascati (Roma), Italy L. Celona, S. Gammino, G. Torrisi INFN/LNS, Catania, Italy V.A. Dolgashev SLAC, Menlo Park, California, USA L. Ficcadenti Rome University La Sapienza, Roma, Italy M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy G. Sorbello University of Catania, Catania, Italy
	The R&D of high gradient radiofrequency (RF) devices is aimed to develop innovative accelerating structures based on new manufacturing techniques and materials in order to construct devices operating with the highest accelerating gradient. Recent studies have shown a large increase in the maximum sustained RF surface electric fields in copper structures operating at cryogenic temperatures. These novel approaches allow significant performance improvements of RF photoinjectors. Indeed the operation at high surface fields results in considerable increase of electron beam brilliance. This increased brilliance requires high field quality in the RF photoinjector and specifically in its power coupler. In this work we present a novel power coupler for the RF photoinjector. The coupler is a compact X-band TM01 mode launcher with a fourfold symmetry which minimized both the dipole and the quadrupole RF components.
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THPAL095	Metal Photocathodes Preparation for Compact Linear Accelerator at Daresbury Laboratory	plasma, cathode, electron, laser	3865
	A.N. Hannah, J.A. Conlon, L.B. Jones, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V. R. Dhanak The University of Liverpool, Liverpool, United Kingdom L.B. Jones, B.L. Militsyn Cockcroft Institute, Warrington, Cheshire, United Kingdom S. Lederer DESY Zeuthen, Zeuthen, Germany S. Lederer DESY, Hamburg, Germany
	The photoinjector of the CLARA FEL test facility Front End at Daresbury Laboratory is based on a S-band 10 Hz photocathode RF-gun operating with a copper photocath-ode which is driven by the third harmonic of a Ti:Sapphire laser (266 nm). The main aim of this study was to establish a procedure to prepare the Cu surface prior to installation so a Quantum Efficiency (QE) of 10^-5 or higher can be achieved at laser power density below the ablation threshold of copper. The best results have been obtained by ex-situ chemical cleaning. This removed the surface oxide layer whilst at the same time producing a surface buffer layer. This inhibited the regrowth of native oxide for up to a week when exposed to normal ambient atmospheric conditions. With either chemical cleaning or Ar plasma cleaning after heating the sample in-situ to 150 °C for 90 minutes or 250 °C for 40 hours, almost all of the surface oxide was removed. For these surfaces a QE of 4.10-5 or better was measured. Oxygen plasma cleaning at 100% and 20% power produced CuO layer with surface carbon contaminant to 3 atomic %, however in-situ thermal cycling resulted in at best a QE of 3·10-6.
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THPAL149	RF System Based on Two Klystrons and Phase Modulation for Photo-Cathode Injector	klystron, linac, experiment, cathode	3996
	P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	We proposed an RF system with two klystrons, of which the powers are combined by a 3dB-hybrid. By managing the phases of the two klystrons respectively, the two pulses from the two output ports of the 3dB-hybrid can be of different powers, phases, and shapes. One of the two pulses can be set to an RF gun, while the other one can feed traveling accelerating structures. Two methods of phase modulation were proposed based on this scheme. Comparing with the state-of-art RF system, the new one can be of high efficiency or can generate electron beams with higher energy. The detailed analysis of the two methods and some experiments are described in this paper.
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THPMF001	Beam Dynamics Studies for Beam Focusing and Solenoid Alignment at SINBAD	solenoid, alignment, emittance, linac	4026
	S. Yamin, R.W. Aßmann, B. Marchetti, J. Zhu DESY, Hamburg, Germany
	SINBAD (Short INnovative Bunches and Accelerators at DESY) facility under construction at DESY plans to host several experiments for the production of ultra-short bunches and will be a test facility for high-gradient compact novel acceleration techniques. The ARES (Accelerator Research Experiment at SINBAD) linac is foreseen to produce ultra-short bunches to be injected e.g. into Novel Dielectric Laser Acceleration structures or Laser Wake-Field Acceleration experiments. The work presented in this paper is based on optimization of the focusing system consisting of solenoids for the ARES, which have been studied earlier in detail but is revisited for updated beamline. Moreover tolerances for the possible misalignment of solenoids are presented investigating the effect on the beam properties during the gun commissioning. * J. Zhu, R. Assmann, U. Dorda, B. Marchetti, "Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD", Nucl. Instrum. Methods Phys. Res., Sect. A 829, 229 (2016)
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THPMF029	Novel MCP-Based Electron Source Studies	electron, laser, cathode, controls	4107
	V.D. Shiltsev, G. Stancari Fermilab, Batavia, Illinois, USA M.J. Haughey Edinburgh University, Edinburgh, United Kingdom
	Microchannel plates were recently proposed as cathodes for electron guns, as part of a novel electron lens design to be tested in the IOTA facility at FNAL. We experimentally assessed the suitability of microchannel plate technology in this design and studied the microchannel plate based photomultiplier (MCP-PMT) system using different sources of light pulses. Here we present the results of the nanosecond time response tests and the maximum current density tests as well as the dependency on the magnetic field strength. Several ideas how to proceed beyond O(100 mA/cm²) density observed in the first tests.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF029
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THPMF032	Preparation and Testing of the BERLinPro Gun 1.1 Cavity	cavity, cathode, pick-up, niobium	4117
	H.-W. Glock, J. Knobloch, A. Neumann, Y. Tamashevich HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association For the BERLinPro energy recovery LINAC, HZB is developing a superconducting 1.4-cell electron gun, which, in its final version, is planned to be capable of CW 1.3 GHz operation with 77 pC/bunch. For this purpose a series of three superconducting cavities, denoted as Gun 1.0, Gun 1.1 (both designed for 6 mA) and Gun 2.0 (100 mA) is foreseen. Here the status of the Gun 1.1 cavity is described, including results of the recent vertical testing. Lessons learned from the production and preparation process are summarized, also in order to identify issues critical for the production of Gun 2.0.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF032
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THPMF034	Status Report of the Berlin Energy Recovery Linac Project BERLinPro	SRF, cathode, vacuum, cavity	4127
	M. Abo-Bakr, W. Anders, Y. Bergmann, K.B. Bürkmann-Gehrlein, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, F. Glöckner, F. Göbel, B.D.S. Hall, S. Heling, H.-G. Hoberg, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, G. Kourkafas, J. Kühn, B.C. Kuske, J. Kuszynski, A.N. Matveenko, M. McAteer, A. Meseck, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, L. Pichl, J. Rahn, M.A.H. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker HZB, Berlin, Germany A. Bundels Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
	Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the last year's progress, including the comissioning of the gun module as the first SRF component to be installed in BERLinPro.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF034
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THPMF039	Study of Magnesium Photocathodes for Superconducting RF Photoinjectors	laser, cathode, SRF, cavity	4142
	R. Xiang, A. Arnold, P.N. Lu, P. Murcek, J. Teichert, H. Vennekate HZDR, Dresden, Germany
	Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1. The superconducting RF photoinjector (SRF Gun II) has successfully served for the ELBE user facility at HZDR. Nevertheless, the quality of photocathodes is one of the most critical issues in improving the stability and reliability for its application. Magnesium has a comparably low work function (3.6 eV) and shows a quantum efficiency up to 0.3% after laser cleaning. However, the present cleaning process with a high intensity laser beam is time consuming and produces unwanted surface roughness, which leads to a higher thermal emittance. Thermal treatment and Excimer laser cleaning for Mg cathodes are investigated as alternative methods. In this work, the new cleaning procedures are tested and optimized, and the quantum efficiency of Mg samples with different microstructure, composition and suppliers are compared.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF039
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THPMF040	Experiences with the SRF Gun II for User Operation at the ELBE Radiation Source	radiation, SRF, undulator, electron	4145
	J. Teichert, A. Arnold, M. Bawatna, P.E. Evtushenko, M. Gensch, B.W. Green, S. Kovalev, U. Lehnert, P.N. Lu, P. Michel, P. Murcek, H. Vennekate, R. Xiang HZDR, Dresden, Germany
	Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1. The second version of the superconducting RF pho-toinjector (SRF Gun II) was successfully commissioned at the ELBE radiation source in 2014. The gun features an improved 3.5-cell niobium cavity combined with a super-conducting solenoid integrated in the cryostat. With a Mg photocathode the SRF Gun II is able to generate bunches with up to 200 pC and with sub-ps length in CW mode with 100 kHz pulse frequency for the THz radiation fa-cility at ELBE. In the ELBE linac, the beam is accelerat-ed, gets a proper correlated energy spread, and is com-pressed in a magnetic chicane. Sub-ps pulses are obtained producing coherent diffraction radiation and superradiant undulator radiation.
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THPMF048	Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation	experiment, simulation, laser, electron	4166
	N.R. Neveu IIT, Chicago, Illinois, USA S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Argonne, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357. In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF048
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THPMF049	Photoinjector Optimization Studies at the AWA	simulation, emittance, laser, experiment	4169
	N.R. Neveu IIT, Chicago, Illinois, USA J. Larson, J.G. Power ANL, Argonne, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357. With a variable charge range of 0.1 nC - 100 nC, the Argonne Wakefield Accelerator facility (AWA) has a unique and dynamic set of operating parameters. Adjustment of the optics and occasionally the rf phases is required each time the bunch charge is changed. Presently, these adjustments are done by the operator during each experiment. This is time consuming and inefficient, more so at high charge and for complex experimental set ups. In an attempt to reduce the amount of time spent adjusting parameters by hand, several optimization methods in simulation are being explored. This includes using the well-known Genetic Algorithm (NSGA-II), incorporated into OPAL-T. We have also investigated a model-based method and novel structure based algorithms developed at ANL. Ongoing efforts include using these optimization methods to improve operations at the AWA. Simulation results will be compared to measured beam parameters at the AWA, and one optimization method will be selected for use in guiding operations going forward.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF049
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THPMF056	Optimisation Study of the Fabry-Pérot Optical Cavity for the MARIX/BRIXS Compton X-Ray Source	laser, cavity, electron, photon	4192
	I. Drebot, A. Bacci, F. Broggi, S. Cialdi, C. Curatolo, D. Giannotti, D. Giove, A.R. Rossi, L. Serafini, M. Statera, V. Torri Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Bosotti, P. Michelato, L. Monaco, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy R. Calandrino, A. Delvecchio HSP, Milan, Italy P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi INFN-Ferrara, Ferrara, Italy A. Esposito, L. Faillace, A. Gallo, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy G. Galzerano, E. Puppin, A. Tagliaferri Politecnico/Milano, Milano, Italy G. Mettivier, P. Russo UniNa, Napoli, Italy V. Petrillo, F. Prelz, M. Rossetti Conti Universita' degli Studi di Milano & INFN, Milano, Italy M. Placidi, G. Turchetti Bologna University, Bologna, Italy A. Sarno INFN-Napoli, Napoli, Italy
	We present the study of the optimization of the optical cavity parameters, in order to maximise the flux of scattered photons in the Compton scattering process. In the optimisation, we compensate the losses of the photon number due to the elliptical shape of the laser pulse in optical cavity with a high focusing electron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF056
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THPMF058	The MariX source (Multidisciplinary Advanced Research Infrastructure with X-rays)	electron, FEL, cavity, radiation	4199
	V. Petrillo, N. Piovella Universita' degli Studi di Milano, Milano, Italy A. Bacci, F. Castelli, S. Cialdi, C. Curatolo, I. Drebot, D. Giannotti, D. Giove, C. Meroni, A.R. Rossi, L. Serafini, M. Statera, V. Torri Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Bosotti, F. Broggi, F. Groppi, P. Michelato, L. Monaco, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy R. Calandrino, A. Delvecchio HSP, Milan, Italy F. Camera, S. Coelli, G. Onida, B. Paroli, L. Perini, F. Prelz, M. Rossetti Conti, F. Tomasi Universita' degli Studi di Milano & INFN, Milano, Italy P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi INFN-Ferrara, Ferrara, Italy A. Castoldi, G. Ghiringhelli, C. Guazzoni, M. Moretti, E. Pinotti Polytechnic of Milan, Milano, Italy S. Di Mitri Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy A. Esposito, A. Gallo, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy L. Faillace RadiaBeam, Santa Monica, California, USA G. Galzerano, E. Puppin, A. Tagliaferri Politecnico/Milano, Milano, Italy G. Mettivier, P. Russo UniNa, Napoli, Italy M. Placidi LBNL, Berkeley, California, USA G. Rossi Università degli Studi di Milano, Milano, Italy R.I. Saban CERN, Geneva, Switzerland A. Sarno INFN-Napoli, Napoli, Italy F. Stellato INFN - Roma Tor Vergata, Roma, Italy G. Turchetti Bologna University, Bologna, Italy
	MariX (Multidisciplinary advanced research infra-structure with X-rays) is a joint project of INFN and University of Milan, aiming at developing a twin X-ray Source of advanced characteristics for the future Sci-entific Campus of the University of Milan. Presently in its design study phase, it will be built in the post Expo area located in north-west Milan district. The first component of the X-source MariX is BriXS (Bright and compact X-ray Source), a Compton X-ray source based on superconducting cavities technology for the electron beam with energy recirculation and on a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz, producing 20-180 keV radiation for medical applications. The BriXS accelerator is also serving as injector of a 3.8 GeV superconductive linac, driving a X-ray FEL at 1 MHz, for providing coherent, moderate flux radiation at 0.3-10 KeV at 1 MHz. Scientific case, layout and typical parameters of MariX will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF058
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THPMF068	Commissioning Status of FLUTE	electron, laser, experiment, MMI	4229
	A. Malygin, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, S. Marsching, W. Mexner, A. Mochihashi, A.-S. Müller, M.J. Nasse, G. Niehues, R. Ruprecht, T. Schmelzer, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan KIT, Karlsruhe, Germany I. Križnar Cosylab, Ljubljana, Slovenia M. Schwarz CERN, Geneva, Switzerland
	FLUTE (Ferninfrarot Linac- Und Test-Experiment) will be a new compact versatile linear accelerator at the KIT. Its primary goal is to serve as a platform for a variety of accelerator studies as well as to generate strong ultra-short THz pulses for photon science. The phase I of the project, which includes the RF photo injector providing electrons at beam energy of 7 MeV and a corresponding diagnostics section, is currently being commissioned. In this contribution, we report on the latest progress of the commissioning phase. The status of the gun conditioning will be given, followed by an overview of the RF system and the laser system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF068
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THPMF072	Implementation of Ultra-Low Frequency Non-Linear Raman Spectroscopy with the Gun Laser at FLUTE	experiment, scattering, laser, optics	4242
	S. Funkner, E. Bründermann, A.-S. Müller, M.J. Nasse, G. Niehues, T. Schmelzer, J.L. Steinmann, M. Yan KIT, Eggenstein-Leopoldshafen, Germany M. Tani University of Fukui, Fukui, Japan
	At the Karlsruhe Institute of Technology (KIT) the new compact versatile linear accelerator FLUTE is currently under commissioning. This accelerator will provide intense broadband THz pulses for spectroscopic experiments. Here, we demonstrate the implementation of a coherent Raman spectrometer using the RF gun laser of FLUTE. With our experiment, we can measure the Raman spectrum at ultra-low frequencies. The measurement principle, which was recently published, is based on coherent nonlinear excitation of the observed sample. The spectrometer consists of a stretcher and an interferometer, which can be simply built from standard optics. We will show that the accessible spectral range overlaps well with that from the THz pulses of the planned FLUTE experiment. Thus, the coherent Raman experiment can provide spectral information complementary to absorption spectral measurements using the THz radiation of FLUTE.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF072
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THPMF088	R&D Activity on Alkali-Antimonied Photocathodes at INFN-Lasa	cathode, laser, electron, operation	4284
	D. Sertore, P. Michelato, L. Monaco INFN/LASA, Segrate (MI), Italy C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	Based on the long-term experience on R&D and production of cesium telluride photocathodes for the high brightness photo-injectors and the past experience on green photocathodes developed in ‘90s , we have started a new R&D activity aiming to reach a reproducible and robust recipe for green photocathodes usable in RF gun. In this paper we present and discuss the first results so far obtained on K2CsSb photoemissive films deposited on polished Mo plugs and the plan for future studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF088
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THPMF089	Design of a Radial RF Electron Gun	cavity, electron, cathode, target	4287
	J.W. Lewellen, F.L. Krawczyk LANL, Los Alamos, New Mexico, USA J.R. Harris Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
	Funding: DOE Accelerator Stewardship Program Most electron beam sources generate beams that propagate away from the source in a single primary direction, with the overall envelope being either pencil-like or sheet-like. We present the design of a radial RF electron gun, intended to produce a radially propagating electron beam (either towards or away from an axis) with the overall envelope being that of an expanding or contracting annulus. Such a source has several potential advantages for materials processing, and may also be useful as the basis for unique optical elements for hadron machines.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF089
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THPMK001	Creating Two-Pulse Beams from a Photoinjector for Two Color FEL or Beam Driven PWFA Experiments	linac, emittance, simulation, cathode	4294
	J. Andersson, J. Björklund Svensson, M. Kotur, F. Lindau, S. Thorin MAX IV Laboratory, Lund University, Lund, Sweden
	The MAX IV linac is investigated as a FEL driver in the SXL project, but there is also an ongoing investigation in using the linac as a driver for beam driven plasma wakefield acceleration experiments. From both these applications, double pulses from the photoinjector within the same RF period is desired. In this paper we discuss the possibilities of using the current photoinjector at MAX IV as driver and show simulations results from the pre-injector, both for FEL applications and for PWFA applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK001
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THPMK002	The Pre-Injector Design for the MAX IV SXL	cathode, emittance, linac, laser	4297
	J. Andersson, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, D. Olsson, L.K. Roslund, S. Thorin MAX IV Laboratory, Lund University, Lund, Sweden
	In this paper we present the current status of the design for the pre-injector (photo-cathode gun, solenoid and first linac) for the SXL project at MAX IV. The SXL project requires a higher repetition rate and since improved beam quality compared to what the current photo-cathode gun can operate at is needed, a new photo-cathode gun will be manufactured. We briefly describe the components of the pre-injector, followed by the design of the new photo-cathode gun. The design is similar to the old gun but with a new RF cavity using elliptical irises and racetrack profile main cell. The current parameters for the next gun to be manufactured are discussed, and some simulations and expected beam quality from the injector are shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK002
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THPMK009	Study on Improving Durability of Bialkali Photocathode for an RF-Gun with the CsBr Protective Layer	cathode, electron, laser, ion-source	4310
	J. Miyamatsu, H. Ono, M. Washio Waseda University, Tokyo, Japan H. Iijima Tokyo University of Science, Tokyo, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
	At Waseda University, we have been studying for high quality electron beam generation and developing variety of application experiments using 1.6 cells photocathode RF-gun. We are using photocathode as the electron source, which can generate high-performance electron beam such as low emittance, short pulse. The performance of photocathodes is evaluated mainly in terms of Quantum Efficiency (Q.E.) and the lifetime. Cs-Te photocathode used in the RF-Gun at Waseda University is known for high Q.E. with UV light and relatively longer lifetime among semiconducting photocathodes. For increasing the charge of electron beam and simplify the laser system, we started introducing CsK2Sb photocathode in the RF-gun which has light sensitivity in UV and visible range, and high Q.E. with green light. However, CsK2Sb photocathode has a difficulty in durability and we observed that it was not enough for long-term operation in the RF-gun. Then we plan to improve lifetime and durability of CsK2Sb photocathode by coating the cathode surface with CsBr thin film. In this conference, we report the result of lifetime measurement of CsK2Sb photocathode with CsBr thin film and future prospects.
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THPMK018	Design of a rotationally symmetric S-band photocathode RF gun	cathode, impedance, emittance, coupling	4336
	Zh. X. Tang USTC, Hefei, Anhui, People's Republic of China Z.G. He, W.W. Li, Y.J. Pei, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	The photocathode RF gun is one of the most critical components for high quality electron beam sources. The asymmetric multi-pole field contributes to the transverse emittance growth and degrades the beam quality. In order to overcome the problem, we propose a novel rotationally symmetric 1.6 cell RF gun to construct the symmetric field in this paper. The concrete proposal is that a coaxial cell with a symmetrical distribution of four grooves is concatenated to the first 0.6 cell at the photocathode end to form a new resonant cell (NRC) to mantain the symmetric multi-pole field in 1.6 cell. Our simulations indicate that 3D multi-pole fields of NRC are with the perfect symmetry. After that, the profile of the RF gun is optimized to improve the shunt impedance and mode separation and make the surface peak electric field at the photocathode end. Our simulations demonstrate promising outlook of using coaxial cell for photocathode RF guns with various applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK018
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THPMK059	Commissioning of Front End of CLARA Facility at Daresbury Laboratory	cathode, cavity, controls, MMI	4426
	D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.A. Griffiths, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, T.J. Price, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, T.M. Weston, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P. Goudket, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom R.J. Cash, R.F. Clarke, G. Cox, G.P. Diakun, A. Gallagher, K.D. Gleave, M.D. Hancock, J.P. Hindley, C. Hodgkinson, A. Oates, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility being developed at STFC 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. The installation of the Front End (FE) section of CLARA, a S-bend merging with existing VELA (Versatile Electron Linear Accelerator) beam line and installation of a high repetition rate RF gun on VELA was completed in 2017. First beam commissioning results and high level software developments are presented in this paper.
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THPMK085	Development of a Pre-Injector Test Bench for Future SLRI Light Source	electron, cavity, emittance, cathode	4499
	K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak SLRI, Nakhon Ratchasima, Thailand
	A pre-injector test bench at the Synchrotron Light Research Institute (SLRI) is under development as one of the preparations for the future SLRI light source and of choices for the possible upgrade of the current injector. The pre-injector test bench includes a pulsed thermionic gun, a fast pulse deflector, a buncher and a pre-buncher. The thermionic electron gun with a cathode made of a single crystal CeB6 is employed as an electron emitter providing small emittance and uniform electron density. The fast pulse deflector shorten the extracted electrons of a few microseconds to that of a few nanoseconds. The electron pulses are further bunched by both the 238 MHz pre-buncher and the 476 MHz buncher to allow the 1-MeV electron beam. The experimental setups for emittance and beam profile measurements are installed on a movable diagnostic stand which is, later on, replaced by the beam bunching devices. The designs of the test bench will be discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK085
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THPMK088	Low Emittance Thermionic Electron Gun at SLRI	electron, cathode, emittance, high-voltage	4509
	K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak SLRI, Nakhon Ratchasima, Thailand
	The Synchrotron Light Research Institute (SLRI) has developed a new thermionic electron gun producing low emittance electron beam for the future upgrade of the existing one. The thermionic cathode made of a CeB6 single crystal is selected due to its properties providing high electron beam current, uniform current density, and high resistance to contamination. In addition, the CeB6 cathode of 3 mm in diameter can produce up to a few Amperes of electron beam current. The electron gun is pulsed at 500 kV with a few microseconds wide to avoid high voltage breakdown as well as to reduce space charge effect resulting in the emittance growth of the extracted electron beam. The preliminary simulation and design of the electron gun together with the high voltage system are described in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK088
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THPMK095	Design of an RF Modulated Thermionic Electron Source at TRIUMF	GUI, electron, impedance, cathode	4524
	K. Fong, D.W. Storey TRIUMF, Vancouver, Canada
	The electron source in the TRIUMF ARIEL project is a gridded dispenser cathode. The cathode is biased at -300kV, and the grid requires a RF control signal of up to 150V at 650 MHz. The required RF power is approximately 20 W and is provided by an RF amplifier located outside the gun vessel. This RF power is coupled into the gun circuit through a ceramic transmission line. The design of this ceramic transmission line, as well as the impedance transformation circuit which provides both the impedance matching and the dc powers to the gun assembly are described.
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THPMK097	First Conceptual Design Studies of an Electron Source for Ultrafast Electron Diffraction at DELTA	electron, cavity, laser, space-charge	4530
	D. Krieg, S. Khan DELTA, Dortmund, Germany K. Sokolowski-Tinten Universität Duisburg-Essen, Duisburg, Germany
	Funding: MERCUR Pr-2017-0002 Ultrafast electron diffraction (UED) is a technique to study the structural dynamics of matter, combining diffraction of electrons with sub-angstrom De-Broglie wavelength with femtosecond time resolution. The method is complementary to X-ray scattering at free-electron lasers. UED pump-probe experiments require ultrashort laser pulses to pump a sample, electron bunches with small emittance and ultrashort length to analyze the state of the sample by diffraction, as well as excellent control of the delay between them. While most UED systems are based on electrostatic electron sources in the keV regime, electrons accelerated to a few MeV in a radiofrequency photocathode gun offer significant advantages regarding emittance and bunch length due to the reduction of space charge effects. Furthermore, the longer mean free path of MeV electrons allows for thicker samples and hence a broader range of possible materials. In this paper, a first conceptual design and simulation results for a university-based UED facility with ultrashort and low-emittance MeV electron bunches are presented.
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THPMK101	Inverted Geometry Photo-Electron Gun Research and Development at TU Darmstadt	cathode, electron, linac, operation	4545
	M. Herbert, J. Enders, Y. Fritzsche, N. Kurichiyanil, V. Wende TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by the Deutsche Forschungsgemeinschaft through GRK 2128 'AccelencE' The Institute for nuclear physics at TU Darmstadt houses the Superconducting Darmstadt Linear Accelerator S-DALINAC. A photo-electron gun using GaAs photocathodes to provide pulsed and/or polarized electron beams, the S-DALINAC Polarized Injector SPIn, has been installed * for future nuclear-structure investigations. In order to conduct research and development for this source, a test facility for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen (Photo-CATCH) has been constructed. This setup provides several chambers for photocathode handling and a 60 keV beamline for photo-gun design studies**. Currently, an upgraded inverted insulator geometry is under investigation for Photo-CATCH that is supposed to be implemented at SPIn. We will present the current developments at Photo-CATCH and future measurements. Y. Poltoratska et al., J. Phys.: Conf. Series 298 (2011) J. Enders, AIP Conf. Proc. 1563, 223 (2013) * M. Espig, Diss., TU Darmstadt (2016) **** N. Kurichiyanil, Diss., TU Darmstadt (2016)
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THPMK108	Production of Magnetized Electron Beam from a DC High Voltage Photogun	cathode, solenoid, electron, laser	4567
	M.A. Mamun, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.R. Delayen, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M. Poelker, R. Suleiman, M.G. Tiefenback, Y.W. Wang, S. Zhang JLab, Newport News, Virginia, USA S.A.K. Wijethunga ODU, Norfolk, Virginia, USA
	Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177 Bunched-beam electron cooling is a key feature of all proposed designs of the future electron-ion collider, and a requirement for achieving the highest promised collision luminosity. At the Jefferson Lab Electron Ion Collider (JLEIC), fast cooling of ion beams will be accomplished via so-called 'magnetized cooling' implemented using a recirculator ring that employs an energy recovery linac. In this contribution, we describe the production of magnetized electron beam using a compact 300 kV DC high voltage photogun with an inverted insulator geometry, and using alkali-antimonide photocathodes. Beam magnetization was assessed using a modest diagnostic beamline that includes YAG view screens used to measure the rotation of the electron beamlet passing through a narrow upstream aperture. Magnetization results are presented for different gun bias voltages and for different laser spot sizes at the photocathode, using 532 nm lasers with DC and RF time structure. Photocathode lifetime was measured at currents up to 4.5 mA, with and without beam magnetization.
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THPMK110	300 kV DC High Voltage Photogun with Inverted Insulator Geometry and CsK2sb Photocathode	cathode, high-voltage, emittance, laser	4571
	Y.W. Wang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, G.A. Krafft, M.A. Mamun, G.G. Palacios Serrano, M. Poelker, R. Suleiman, M.G. Tiefenback, S. Zhang JLab, Newport News, Virginia, USA G.A. Krafft, S.A.K. Wijethunga ODU, Norfolk, Virginia, USA
	Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177 A compact DC high voltage photogun with inverted-insulator geometry was designed, built and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This presentation describes key electrostatic design features of the photogun with accompanying emittance measurements obtained across the entire photocathode surface that speak to field non-uniformity within the cathode/anode gap. A summary of initial photocathode lifetime measurements at beam currents up to 4.5 mA is also presented.
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THPMK145	Evaluation of Coherent Terahertz Radiation Generated from Tilted Electron Beams Aiming for Higher Light Intensity	radiation, electron, target, controls	4642
	M. Brameld, K. Sakaue, Y. Tadenuma, M. Washio, R. Yanagisawa Waseda University, Tokyo, Japan R. Kuroda, Y. Taira AIST, Tsukuba, Japan
	Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083. When a target medium is irradiated by electron beams travelling at relativistic speed, terahertz(THz) radiation is produced by Cherenkov radiation. THz radiation is released at an angle to the direction of travel of the electron beams, and the coherence of the radiation can be improved by tilting the electron beams to match this angle, resulting in higher light intensity. The Cherenkov angle differs according to the refraction index of the target medium. At Waseda University, the generation of high-quality electron beams by a Cs-Te Photocathode RF-Gun and its applications are being researched. By utilizing the RF-Deflector, the tilt angle of the electron beam can be controlled to achieve coherent THz radiation. To gain higher light intensity, the use of Silicon and Aerogel as a target medium was challenged and compared to the conventional medium TOPAS. The THz radiation produced from the three target mediums were analyzed by use of the power meter and time domain spectroscopy(TDS). At this conference, the generation of THz Cherenkov radiation from different target mediums and the measurement results will be reported along with future perspectives.
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THPML010	Modeling of Diamond Field Emitter Arrays for Shaped Electron Beam Production	electron, simulation, emittance, experiment	4668
	K.E. Nichols, H.L. Andrews, D.Y. Shchegolkov, E.I. Simakov LANL, Los Alamos, New Mexico, USA
	We present simulations of shaped electron beam production from diamond field emitter array (DFEA) cathodes. DFEAs are arrays of diamond pyramids with bases of the order of 10 microns that produce high current densities. These arrays can be fabricated in arbitrary shapes such as a triangle or a double triangle, so that they produce an inherently shaped beam. These transversely shaped beams can be put through an emittance exchanger to produce a longitudinally shaped electron beam distribution for use with high-transformer ratio wakefield accelerators. Simulations are conducted with MICHELLE. We design cathodes and focusing systems that preserve the beam's shape while transporting it to the emittance exchanger.
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THPML017	Beam Dynamics Calculation of a New Injection System for LINAC II	electron, linac, injection, operation	4687
	J.X. Zhang, M. Hüning DESY, Hamburg, Germany
	The Linac II at DESY (Deutsches Elektronen Synchrotron) is an electron/positron linear accelerator with a 400 MeV primary electron linac, an 800 MW positron converter, and a 450 MeV secondary electron/positron linac. For reliability two injection systems can be switched, a 150 kV bombarder diode gun dating from 1969 and a 100 kV triode gun commissioned in 2014. The older bombarder gun shall be replaced with a triode gun optimized for injection into the synchrotron radiation facility PETRA III. In this paper, the parameters of the existing injectors and the design considerations for the new injector are presented. The preliminary beam dynamics calculation of the new injection system will be performed; the future plan of the replacement will be discussed.
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THPML020	The First Results of Trial Operation and Performance Improve of the 100 MeV/ 100 kW Electron Linear Accelerator of the NSC KIPT SCA Neutron Source	electron, neutron, MMI, operation	4693
	A.Y. Zelinsky, O.E. Andreev, V.P. Androsov, O. Bezditko, O.V. Bykhun, A.N. Gordienko, V.A. Grevtsev, A. Gvozd, V.E. Ivashchenko, I.I. Karnaukhov, I.M. Karnaukhov, V.P. Lyashchenko, M. Moisieienko, A.V. Reuzayev, D.V. Tarasov, V.I. Trotsenko NSC/KIPT, Kharkov, Ukraine Y.L. Chi IHEP, Beijing, People's Republic of China
	The NSC KIPT SCA Neutron Source uses 100 MeV/ 100 kW electron linear accelerator as a driver for the generation of the initial neutrons. The trial operation of the accelerator was started in 2018. To provide design electron beam parameters is the primary task of the first stage of the trial operation. During the first stage of the accelerator operation the following tasks were under consideration: minimization of the electron beam losses along accelerator, providing of the stable electron beam pulse current, adjustment of the electron beam position along accelerator and providing of the uniform electron beam distribution at the tungsten neutron generating target. The main results of the accelerator operation and methods of performance improve are described in the paper.
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THPML054	Design Studies of an S-Band Multipacting Electron Gun	electron, cavity, cathode, operation	4759
	C. Henkel, W. Hillert, V. Miltchev University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany K. Flöttmann DESY, Hamburg, Germany
	A multipacting electron gun (MEG) is a micro-pulse electron source based on secondary electron emission in a resonant microwave cavity structure for the generation of low emittance electron bunches with high repetition rate. By theoretical simulations a suitable radio-frequency gun design at 3 GHz is established, simultaneously meeting the demands of bunch production and amplification process as well as including the effects of space charge and beam loading for the evolution of a stable beam. In this contribution we show detailed simulation studies of the impact of important design parameters like mechanical dimensions and choice of material on the average output current, which is in the order of several mA. For the experimental investigation a test setup is under construction, which may demonstrate the application of MEG's as a serious alternative or addition to commonly used electron sources like thermionic and photocathodes.
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THPML055	Scaled Studies on Radio Frequency Sources for Megawatt-Class Ionospheric Heaters	electron, impedance, cathode, experiment	4763
	B.L. Beaudoin, T.M. Antonsen, J.A. Karakkad, A.H. Narayan, G.S. Nusinovich, K.J. Ruisard UMD, College Park, Maryland, USA R. Fischer Naval Research Laboratory (NRL), Washington, USA S.H. Gold, A. Ting NRL, Washington,, USA
	Funding: Funding for this project and travel is provided by the Air Force Office of Scientific Research under grant FA95501410019. The ionosphere plays a prominent role in the performance of critical civilian and military communication systems. The key instrument in Ionospheric Modification (IM) research is a powerful, ground-based, High Frequency (HF) source of electromagnetic waves known as a heater. With a mobile heater, investigators would be able to conduct IM research at different latitudes without building a costly permanent installation. A new highly efficient Megawatt class of Radio Frequency sources is required to reduce the overall power demands on a fully deployable system. Such a source has been described previously. Results of a scaled experiment, using the electron beam produced by a gridded gun to drive an external lumped element circuit for high efficiency radio frequency generation is presented. The IOT gun produces an electron beam bunched at the driving frequency that is then collected by an external circuit for impedance matching to the load. Results showed that effects such as the internal resistance of the inductor and deflection of beam electrons by the induced RF voltages on the beam collector are important considerations to be included in the design of a practical device. B.L. Beaudoin, G.S. Nusinovich, G. Milikh, A. Ting, S. Gold, J.A. Karakkad, A.H. Narayan, D.B. Matthew, D.K. Papadopoulos, T.M. Antonsen Jr., Journal of Elec. Waves and Appl.,31,17,pp.1786, 2017.
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THPML090	Optical Beam Loss Monitors Based on Fibres for the CLARA Phase 1 Beam-Line	electron, MMI, diagnostics, cathode	4869
	A.S. Alexandrova, L.J. Devlin, V. Tzoganis, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom A.D. Brynes, F. Jackson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.D. Brynes, F. Jackson, V. Tzoganis, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom E. Effinger, E.B. Holzer CERN, Geneva, Switzerland
	Funding: Work supported by STFC Cockcroft Institute core Grant No. ST/G008248/1 Fibre based Optical Beam Loss Monitors (oBLMs) are on-line devices used in-situ to measure losses along a beam-line. The technology is based on the detection of Cherenkov radiation, produced inside quartz fibres placed alongside the beampipe, from the interaction of secondary showers generated from losses hitting the vacuum pipe. This contribution presents ongoing developments of an oBLM system installed along the Compact Linear Accelerator for Research and Applications (CLARA). The oBLM system consists of 4 channels which allows for sub-metre loss resolution with two dimensional coverage along the entirety of the beam line, as opposed to conventional localised BLM systems. The system was first commissioned to measure dark current from the injector. The ability of the system to locate longitudinal positions of known beam loss locations has also been measured and has shown excellent agreement. We present measurements acquired from the detector during regular operation and during dedicated beam tests. We also discuss the incorporation of the monitor into the accelerator diagnostics system and its use in assisting accelerator characterisation and performance.
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THPML133	Design and Optimization of the Electron Gun	electron, cathode, software, simulation	4995
	K. Huang, T.L. He, Z.L. Ren, D.R. Xu, H. Xu USTC/NSRL, Hefei, Anhui, People's Republic of China Y. Chen Department of Information Engineering , Anhui Economic Management Cadres' Institute, Hefei, Anhui, People's Republic of China
	Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 and 10875118. Design of an energy-modified electron gun is of significance to do some research on the properties of Diamond-amplified cathode. Based on the design method of the Pierce electron gun, the optimum parameters of the electron gun have been obtained using the Opera-3D program. And the beam waist's position, the beam current, the beam size and the beam emittance related to the electron bean energy was investigated in this paper.
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Paper

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MOZGBF3

40 Years of Electron Cooling at CERN

electron, proton, antiproton, experiment

69

G. Tranquille
CERN, Geneva, Switzerland

For nearly 40 years electron cooling has been used extensively on the storage rings of the CERN accelerator complex for the accumulation of ions or for the improvement of beam quality for precision experiments. Since the first cooling experiments on ICE the coolers have evolved to incorporate the latest advances in electron cooling technology and many unique experiments have also been performed when the coolers are not used for everyday operation. The trapping of anti-hydrogen atoms and more recently lead-lead and proton-lead ion collisions in the LHC have been made possible thanks to cooling in the AD and cooling and accumulation of lead ions in the LEIR respectively. The next cooler to be built at CERN will be installed on ELENA and will operate at electron energies below 350 eV. Many challenges lie ahead in operating at such a low energy with minimum perturbation to the storage ring. The present AD cooler, which has already seen two re-incarnations, will also be replaced with a new state-of-the-art device operating at higher energies in order to improve the quality of the antiproton beam in this ring.

Slides MOZGBF3 [14.902 MB]

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MOPMK011

VEPP-5 Injection Complex: New Possibilities for BINP Electron-Positron Colliders

positron, electron, injection, collider

371

Yu. Maltseva, A.V. Andrianov, K.V. Astrelina, V.V. Balakin, A.M. Batrakov, O.V. Belikov, D.E. Berkaev, M.F. Blinov, D. Bolkhovityanov, A. Butakov, E.V. Bykov, N.S. Dikansky, F.A. Emanov, A.R. Frolov, V.V. Gambaryan, K. Gorchakov, Ye.A. Gusev, S.E. Karnaev, G.V. Karpov, A.S. Kasaev, E. Kenzhbulatov, V.A. Kiselev, S. Kluschev, A.A. Kondakov, I. Koop, I.E. Korenev, N.Kh. Kot, V.R. Kozak, A.A. Krasnov, S.A. Krutikhin, I.V. Kuptsov, G.Y. Kurkin, N.N. Lebedev, A.E. Levichev, P.V. Logatchov, A.A. Murasev, V. Muslivets, D.A. Nikiforov, An.A. Novikov, A.V. Ottmar, A.V. Pavlenko, I.L. Pivovarov, V.V. Rashchenko, Yu. A. Rogovsky, S.L. Samoylov, N. Sazonov, A.V. Semenov, D.B. Shwartz, A.N. Skrinsky, A.A. Starostenko, D.A. Starostenko, A.G. Tribendis, A.S. Tsyganov, S.P. Vasichev, S.V. Vasiliev, V.D. Yudin, I.M. Zemlyansky, A.N. Zhuravlev
BINP SB RAS, Novosibirsk, Russia
A.V. Andrianov, V.V. Balakin, F.A. Emanov, I. Koop, A.A. Krasnov, A.E. Levichev, D.A. Nikiforov, A.V. Pavlenko, Yu. A. Rogovsky, D.B. Shwartz, A.A. Starostenko
NSU, Novosibirsk, Russia
A.I. Mickailov
Budker INP & NSU, Novosibirsk, Russia
A.G. Tribendis
NSTU, Novosibirsk, Russia

VEPP-5 Injection Complex (IC) is designed to supply BINP RAS colliders with high energy electron and positron beams. Recently constructed K-500 beam transfer line connects IC to both VEPP-4M and VEPP-2000 colliders. IC two collider operation was successfully performed in 2016. Nowadays, research on improvement of IC productivity is carried out, in particular 10.94 MHz RF cavity instead of 700 MHz one was installed and a new electron gun installation is expected to be this summer. Moreover, longitudinal beam profile measurements in IC damping ring using a streak-camera were carried out. Operation experience of IC and results of longitudinal beam profile measurements are reported.

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MOPMK015

Development of a Bunched-Beam Electron Cooler for the Jefferson Lab Electron-Ion Collider

electron, linac, kicker, cathode

382

S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, A. Hutton, R. Li, R.A. Rimmer, Y. Roblin, C. Tennant, H. Wang, H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177.
Jefferson Lab is in the process of designing an electron-ion collider with unprecedented luminosity at a 65 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires novel use of bunched-beam cooling. We will present a new design for a Circulator Cooler Ring for bunched-beam electron cooling. This requires the generation and transport of very high-charge magnetized bunches, acceleration of the bunches in an energy recovery linac, and transfer of these bunches to a circulating ring that passes the bunches 11 times through the proton or ion beam inside cooling solenoids. This design requires the suppression of the effects of space charge and coherent synchrotron radiation using shielding and RF compensation.

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MOPML034

Development Status of Superconducting RF Transmission Electron Microscope

cavity, acceleration, LLRF, SRF

481

N. Higashi, A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, F. Qiu, M. Yamamoto
KEK, Ibaraki, Japan
S. Yamashita
University of Tokyo, Tokyo, Japan

Now we are developing a new type of transmission electron microscope (TEM) employing the accelerator technologies. In place of a DC thermal gun generally used in conventional TEMs, we apply a photocathode gun and a special-shaped superconducting cavity, named two-mode cavity. The two-mode cavity has two resonant modes of TM010 (1.3 GHz) and TM020 (2.6 GHz). To superimpose these, we can suppress the increase of the energy spread, which is needed for the high-spatial-resolution TEMs. We have already developed some prototypes of the photocathode gun and two-mode cavity, and now in the middle of the performance tests. In this presentation, we will show the latest status of the development.

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MOPML044

Start-to-End Beam Dynamic Simulations for PRAE

emittance, linac, laser, solenoid

495

A. Vnuchenko
IFIC, Valencia, Spain
C. Bruni, M. El Khaldi, A. Faus-Golfe, P. Lepercq, C. Vallerand
LAL, Orsay, France
A. Latina
CERN, Geneva, Switzerland

The PRAE project (Platform for Research and Applications with Electrons) aims at creating a multidisciplinary R&D facility in the Orsay campus gathering various scientific communities involved in radiobiology, subatomic physics, instrumentation and particle accelerators around an electron accelerator delivering a high-performance beam with energy up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and future challenging R&D. In this paper we report the first start-to-end simulations from the RF gun, going through the linac and finally to the different experimental platforms. The beam dynamics simulations have been performed using a concatenation of codes. In particular for the linac the RF-Track code recently developed at CERN will be used and benchmarked. The different working points have been analysed in order to minimise the transverse emittance and the beam energy spread including space charge effects at low electron energies.

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MOPML055

Preliminary Physics Design of a Linac with the Variable Energy for Industrial Applications

linac, electron, beam-loading, simulation

530

Zh. X. Tang
USTC, Hefei, Anhui, People's Republic of China
L. Wang, D.R. Xu
USTC/NSRL, Hefei, Anhui, People's Republic of China

This paper describes the physics design of a S-band (2856 MHz) linear accelerator (linac) with variable energy tuning. The system consists of a DC gun for generating electron, prebuncher for velocity modulation and two travelling wave (TW) accelerating sections for acceleration. The accelerating structure is a 2'Ð/3 mode constant gradient TW structure, which comprises TW buncher cells, followed by uniform cells. The structure is designed to accelerate 45 keV electron beam from the electron gun to 3.2 MeV, and then 10 MeV. An important feature of the TW linac is that the RF output power of the first linac is as the RF input power of the second linac. Three dimensional transient simulations of the accelerating structure along with the input and output couplers have been performed to explicitly demonstrate this feature. Beam dynamics is performed to calculate the beam parameter.

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MOPML066

Ultrafast Mega-electron-volt Gas-Phase Electron Diffraction at SLAC National Accelerator Laboratory

electron, vacuum, laser, experiment

556

X. Shen, R.K. Li, X.J. Wang, S.P. Weathersby, J. Yang
SLAC, Menlo Park, California, USA

Funding: This work was supported in part by the U.S. Department of Energy Contract No. DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund.
Ultrashort mega-electron-volt (MeV) electron beams from radio-frequency (rf) photoinjectors have recently attracted strong interests for application in ultrafast gas-phase electron diffraction (UGED). Such high-brightness electron beams are capable of providing 100-fs level temporal resolution and sub-Angstrom level spatial resolution to capture the ultrafast structural dynamics from photoexcited gas molecules. To experimentally demonstrate such an ultrafast electron scattering instrument, a high performance UGED system has been commissioned at SLAC National Accelerator Laboratory. The UGED instrument produces 3.7 MeV electron beams with 2 fC beam charge at 180-Hz repetition rate. The temporal resolution is characterized to be 150 fs full-width-at-half-maximum (FWHM), while the spatial resolution is measured to be 0.76 Å FWHM. The UGED instrument also demonstrates outstanding performance in vacuum, rf, and electron beam pointing stability. Details of the performance of the SLAC MeV UGED system is reported in this paper.

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MOPML067

9/6 MeV European S-band Linac Structure for Container Inspection System at RTX and KAERI

electron, coupling, linac, bunching

560

P. Buaphad, H.D. Park, S. Song
RTX, Daejeon, Republic of Korea
P. Buaphad, Y. Joo
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
P. Buaphad, S.C. Cha, Y. Joo, Y. Kim, H.R. Lee
KAERI, Jeongeup-si, Republic of Korea

Recently, demands on low energy electron linear accelerators (linacs) for industrial applications are rapidly growing. Their beam energies are lower than 20 MeV, and they require a compact, cheap, and stable accelerator system. For the Container Inspection System (CIS), KAERI successfully developed a 9/6 MeV American S-band (= 2856 MHz) linac with a 5 MW klystron in 2013. To reduce the cost of the RF source, recently, KAERI and RTX also have been developing another 9/6 MeV European S-band (= 2998 MHz) linac by using a magnetron with a lower RF power of about 3.1 MW. Its accelerating structure is designed to be operated in π/2 mode by coupling 13 accelerating cells together through 12 side-coupling cells. The CST Microwave Studio is used for electromagnetic simulations and optimization of the accelerating structure. After various optimizations, a shunt impedance of 84 MΩ/m is obtained at π/2 mode frequency of 2998.31 MHz. In this paper, we describe design concept, optimization, and RF measurement of the new 9/6 MeV European S-band linac structure. Then, we compare it with our old American S-band linac structure.

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TUYGBE2

CBETA, the 4-Turn ERL with SRF and Single Return Loop

electron, linac, SRF, cryomodule

635

G.H. Hoffstaetter, N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, S.J. Full, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, C.E. Mayes, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.S. Berg, S.J. Brooks, C. Liu, G.J. Mahler, F. Méot, R.J. Michnoff, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
BNL, Upton, Long Island, New York, USA
D. Douglas
JLab, Newport News, Virginia, USA
J.K. Jones
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D. Jusic
Cornell University, Ithaca, New York, USA
D.J. Kelliher
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
B.C. Kuske, M. McAteer, J. Völker
HZB, Berlin, Germany

Funding: Supported by NSF award DMR-0807731, DOE grant DE-AC02-76SF00515, and NYSERDA.
A collaboration between Cornell University and Brookhaven National Laboratory has designed and is constructing CBETA, the Cornell-BNL ERL Test Accelerator on the Cornell campus. The ERL technology that has been prototyped at Cornell for many years is being used for this new accelerator, including a DC electron source and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current linac cryomodule optimized for ERLs, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. BNL has designed multi-turn ERLs for several purpose, dominantly for the electron beam of eRHIC, its Electron Ion Collider (EIC) project and for the associated fast electron cooling system. Also in JLEIC, the EIC designed at JLAB, an ERL is envisioned to be used for electron cooling. The number of transport lines in an ERL is minimized by using return arcs that are comprised of a Fixed Field Alternating-gradient (FFA) design. This technique will be tested in CBETA, which has a single return for the 4-beam energies with strongly-focusing permanent magnets of Halbach type. The high-brightness beam with 150~MeV and up to 40~mA will have applications beyond accelerator research, in industry, in nuclear physics, and in X-ray science. Low current electron beam has already been sent through the most relevant parts of CBETA, from the DC gun through both cryomodules, through one of the 8 similar separator lines, and through one of the 27 similar FFA structures. Further construction is envisioned to lead to a commissioning start for the full system early in 2019.

Slides TUYGBE2 [17.343 MB]

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TUYGBF4

Design and Simulation Tools for the High-Intensity Industrial Rhodotron Electron Accelerator

cavity, dipole, electron, cathode

651

W.J.G.M. Kleeven, M. Abs, J. Brison, E. Forton, J. M. Hubert, J. Walle
IBA, Louvain-la-Neuve, Belgium

The Rhodotron is a compact industrial CW recirculating electron accelerator producing intense beams with energies in the range from about 1 to 10 MeV. RF-frequencies are in the range of 100 to 400 MHz. Average beam powers can range from 10 kW to almost 1 MW, depending of the specific type of Rhodotron. Main industrial applications are polymer cross-linking, sterilization, food treatment and container security scanning. Recently, RF pulsing was developed to reduce the average wall power dissipation, thus reducing drastically the energy consumption. Pulsing also permits smaller cavities and higher energies up to 40 MeV, opening the way to applications such as mobile irradiators, or isotopes production by photonuclear reactions, thus offering a compact and high beam duty alternative to linacs. This paper concentrates on some crucial design tools and methods for transverse and longitudinal optics studies, particle tracking with space charge, beam formation studies in the electron gun and dipole magnet design.

Slides TUYGBF4 [11.952 MB]

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TUPAF056

The CERN-ELENA Electron Cooler Magnetic System

solenoid, electron, alignment, proton

842

G. Tranquille, L.V. Jørgensen
CERN, Geneva, Switzerland
D. Luckin, R.J. Warner
Tesla Engineering Limited, West-Sussex, United Kingdom

Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler the performance of which is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the efficient recuperation of the electrons in the collector and the quality of the guiding magnetic field ensure an optimal performance of the cooler. The ELENA cooler is a compact device incorporating an adiabatic expansion to reduce the electron beam temperature as well as electrostatic bending plates for efficient collection of the electron beam. The transverse components of the longitudinal field in the cooling section must be kept small (Bt/Bl ≤ 5x10-4) to ensure a minimal perturbation to the electron beam transverse temperature. The longitudinal field itself needs to be as low as possible such that the distortion to the closed orbit of the circulating ion beam due to the short 90° toroids is kept as small as possible. We present the solutions chosen to design and construct a magnetic system within the above constraints as well as the setup used to measure and optimise the magnetic field components.

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TUPMF002

A Cu Photocathode for the Superconducting RF Photoinjector of BERLinPro

cathode, SRF, cavity, laser

1247

J. Kühn, M. Bürger, A. Frahm, A. Jankowiak, T. Kamps, G. Klemz, G. Kourkafas, A. Neumann, N. Ohm, M. Schmeißer, M. Schuster, J. Völker
HZB, Berlin, Germany
P. Murcek, J. Teichert
HZDR, Dresden, Germany

The initial commissioning of the Superconducting RF (SRF) photoinjector is done with a Cu photocathode due to its robustness with regard to interactions with the SRF cavity of the injector. Here we present the preparation and characterization of a Cu photocathode plug and the diagnostics to insert the photocathode in the back wall of the SRF cavity. A polycrystalline bulk Cu plug was polished, particle free cleaned and characterized by x-ray photoelectron spectroscopy. During the transfer of the photocathode insert into the gun module the whole process was controlled by several diagnostic tools monitoring the insert position as well as RF, vacuum and cryogenic signals. We discuss the challenges of the photocathode transfer into an SRF cavity and how they can be tackled.

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TUPMF020

Demonstration of Fast, Single-shot Photocathode QE Mapping Method Using MLA Pattern Beam

laser, cathode, electron, optics

1293

E.E. Wisniewski, M.E. Conde, D.S. Doran, W. Gai, Q. Gao, W. Liu, J.G. Power, C. Whiteford
ANL, Argonne, Illinois, USA
Q. Gao
TUB, Beijing, People's Republic of China
G. Ha
PAL, Pohang, Republic of Korea
A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Funding: UChicago Argonne, LLC, Operator of Argonne National Laboratory ("Argonne"). Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
Quantum efficiency (QE) is the chief figure of merit in the characterization of photocathodes. Semiconductor photocathodes, especially when used in high rep-rate photo-injectors, are known to show QE degradation over time and must be replaced. The total QE is the basic diagnostic which is used widely and is easy to obtain. However, a QE map indicating variations of QE across the cathode surface has greater utility. It can quickly diagnose problems of QE inhomogeneity. Most QE mapping techniques require hours to complete and are thus disruptive to a user facility schedule. A fast, single-shot method has been proposed (citation) using a micro-lens array (MLA) generated QE map. In this paper we report the implementation of the method at Argonne Wakefield Accelerator facility. A micro-lens array (MLA) is used to project an array of beamlets onto the photocathode. The resulting photoelectron beam in the form of an array of electron beamlets is imaged at a YAG screen. Four synchronized measurements are made and the results used to produce a QE map of the photocathode.

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TUPMF025

LEReC Photocathode DC Gun Beam Test Results

cathode, operation, laser, electron

1306

D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, X. Gu, L.R. Hammons, P. Inacker, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, C. Liu, K. Mernick, T.A. Miller, M.G. Minty, V. Ptitsyn, T. Rao, J. Sandberg, S. Seletskiy, P. Thieberger, J.E. Tuozzolo, E. Wang, Z. Zhao
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Low Energy RHIC Electron cooler (LEReC) project is presently under commissioning at Brookhaven National Laboratory (BNL). LEReC requires high average current up to 85mA and high-quality electron beam. A 400 kV DC gun equipped with a photocathode and laser system has been chosen to provide a source of high-quality electron beams. We started testing the DC gun during the RHIC run 2017. First electron beam from LEReC DC gun was delivered in April 2017 *. During the DC gun test critical elements of LEReC such as laser beam system, cathode exchange system, cathode QE lifetime, DC gun stability, beam instrumentation, the high-power beam dump system, machine protection system and controls have been tested. Average current of 10 mA for few hours of operation was reached in August 2017. In this paper we present experimental results and experience learned during the LEReC DC gun beam testing.
* D. Kayran et al., "First Results of Commissioning DC Photo-gun for RHIC Low Energy Electron Cooler (LEReC)", in Proc of ERL2017.

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TUPMF061

Physical Design of the 500 MeV Electron Linac for the High Energy Photon Source

linac, electron, bunching, emittance

1404

S. Pei, D.Y. He, X. He, J.L. Li, J. Liu, X. Ma, C. Meng, X. Wang, O. Xiao, J.R. Zhang, Z.S. Zhou
IHEP, Beijing, People's Republic of China
S. Shu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

Funding: Work supported by the HEPS project and the National Natural Science Foundation of China (11475201). peisl@ihep.ac.cn
The High Energy Photon Source (HEPS) is a 6 GeV light source with ultra-low emittance, it is proposed to be built at Huairou district, northeast suburb of Beijing, China. A 500 MeV electron linac will be used to generate the electron beam for injection into the booster. Here the preliminary physical design of the electron linac is presented.

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TUPMF086

Status of the ARES RF Gun at SINBAD: From its Characterization and Installation towards Commissioning

cavity, linac, status, electron

1474

B. Marchetti, R.W. Aßmann, S. Baark, F. Burkart, U. Dorda, K. Flöttmann, I. Hartl, J. Hauser, J. Herrmann, M. Hüning, K. Knebel, O. Krebs, G. Kube, W. Kuropka, S. Lederer, F. Lemery, F. Ludwig, D. Marx, F. Mayet, M. Pelzer, I. Peperkorn, F. Poblotzki, S. Pumpe, J. Rothenburg, H. Schlarb, M. Titberidze, G. Vashchenko, T. Vinatier, P.A. Walker, L. Winkelmann, K. Wittenburg, S. Yamin, J. Zhu
DESY, Hamburg, Germany

The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host multiple experiments relating to the production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD-ARES linac will be a conventional S-band linear RF accelerator allowing the production of low charge (0.5 pC - tens pC) ultra-short electron bunches (FWHM length =< 1 fs - few fs) with 100 MeV energy. The installation of the linac will proceed in stages. In this paper we report on the status of the characterization of the ARES RF gun and the installations of the related infrastructure.

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TUPML006

Updates of the Argonne Cathode Test-stand

cathode, laser, electron, experiment

1542

J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng
ANL, Argonne, Illinois, USA
S.P. Antipov, G. Chen, E. Gomez, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Baryshev
Michigan State University, East Lansing, Michigan, USA

The Argonne Cathode Test-stand (ACT) is a unique testbed to develop cathodes and to conduct fundamental surface study under ultra-high rf field (up to 700 MV/m with pin-shaped cathodes). The test-stand consists of an L-band 1.3 GHz single-cell photocathode rf gun and a field emission (FE) imaging system to locate emitters with a resolution of ∼20 𝜇m. In the recent upgrade, UV laser has been introduced to improve the imaging system and to significantly expand the ACT towards photoemission and laser-assisted field emission research. In addition, a load-lock system has been added to the beam line to expedite the cathode switching period. The paper will present details of the upgrade as well as experiments planned in the near future.

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TUPML028

Photocathodes R&D for High Brightness and Highly Polarized Electron Beams at Cornell University

electron, cathode, emittance, simulation

1601

L. Cultrera, J. Bae, A.C. Bartnik, I.V. Bazarov, R. Doane, A. Galdi, C.M. Gulliford, W. H. Li, J.M. Maxson, S.A. McBride, T.P. Moore, C. M. Pierce, C. Xu
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell University is a leader in the development of photocathode materials for the production of high brightness electron beam sources for applications in large scale accelerators and small scale electron scattering experiments. During the last year we have also included Mott polarimetry to investigate long lifetime spin-polarized photocathodes materials. Another thrust of our laboratory is the exploration of ultra low emittance photocathodes at cryogenic temperatures, for which we are building a novel LHe cryogenic electron source. We will review updates from our lab across each of these areas.

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TUPML064

Staged Two Beam Acceleration Beam Line Design for the AWA Facility

kicker, experiment, laser, acceleration

1688

N.R. Neveu
IIT, Chicago, Illinois, USA
W. Gai, C.-J. Jing, J.G. Power
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
Two beam acceleration is a candidate for future high energy physics machines and FEL user facilities. This scheme consists of two independent electron beam lines operating synchronously. High-charge, 70 MeV drive bunch trains are injected from the RF photo-injector into decelerating structures to generate a few hundred of MW of RF power. This RF power is transferred through an RF waveguide to accelerating structures that are used to accelerate the witness beam. Staging refers to the sequential acceleration (energy gain) in two or more structures on the witness beam line. A kicker was incorporated on the drive beam line to accomplish a modular design so that each accelerating structure can be independently powered by a separate drive beam. Simulations were performed in OPAL-T to model the two beam lines. Beam sizes at the center of the structures was minimized to ensure good charge transmission. The resulting design will be the basis for proof of principle experiments that will take place at the Argonne Wakefield Accelerator (AWA) facility.

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WEYGBE2

Applications of Caustic Methods to Longitudinal Phase Space Manipulation

FEL, electron, linac, optics

1790

T.K. Charles
The University of Melbourne, Melbourne, Victoria, Australia
T.K. Charles
CERN, Geneva, Switzerland
D. Douglas
JLab, Newport News, Virginia, USA
P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Longitudinal phase space management is a key feature of recirculating machines. Careful consideration of the longitudinal matching is required not only in order to ensure a high peak current, low energy spread bunch is delivered to the FEL but also to support the deceleration and energy recovery of the spent beam. In a similar manner, longitudinal phase space manipulation can be utilised for pulse shaping in bunch compression, to minimise the influence of CSR-induced emittance growth. In this paper, we present a method for longitudinal phase space matching based upon the avoidance of electron trajectory caustics. Through considering the conditions under which caustics will form, we generate exclusion plots identifying the viable parameter space at numerous positions through beam acceleration and energy recovery. The result is a method for selecting the linear momentum compaction and the higher-order momentum compaction to satisfy the non-caustic condition whilst achieving the bunch compression or lengthening as required.

Slides WEYGBE2 [6.292 MB]

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WEPAF034

A Supersonic Gas Jet-Based Beam Profile Monitor Using Fluorescence for HL-LHC

electron, photon, luminosity, hadron

1891

H.D. Zhang, A.S. Alexandrova, R. Schnuerer, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Ady, E. Barrios Diaz, N. Chritin, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
CERN, Geneva, Switzerland
A.S. Alexandrova, A. Salehilashkajani, R. Schnuerer, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
P. Forck, S. Udrea
GSI, Darmstadt, Germany
P. Smakulski
WRUT, Wroclaw, Poland

Funding: The HL-LHC project, the Helmholtz Association under contract VH-NG-328, the EU's 7th Framework Programme under grant agreement no 215080 and the STFC Cockcroft core grant No. ST/G008248/1.
The High-Luminosity Large Hadron Collider (HL-LHC) project aims to increase the machine luminosity by a factor of 10 as compared to the LHC's design value. To achieve this goal, a special type of electron lens is being developed. It uses a hollow electron beam which co-propagates with the hadron beam to act on any halo particles without perturbing the core of the beam. The overlapping of both beams should be carefully monitored. This contribution presents the design principle and detailed characteristics of a new supersonic gas jet-based beam profile monitor. In contrast to earlier monitors, it relies on fluorescence light emitted by the gas molecules in the jet following interaction with the primary hadron beams. A dedicated prototype has been designed and built at the Cockcroft Institute and is being commissioned. Details about monitor integration, achievable resolution and dynamic range will be given.

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WEPAL002

Improvement of Personnel and Machine Protection System in Superkekb Injector Linac

linac, operation, PLC, controls

2140

I. Satake, H. Honma, A. Shirakawa, N. Toge
KEK, Ibaraki, Japan

Since summer of 2010, the radiation control area for the KEK electron positron injector linac had been split at the around 3 GeV point by a concrete wall into upstream and downstream parts with independent beam sources. This was so as to allow operation of the downstream part for beam injection into photon factory rings while construction and development of new electron guns proceed in the upstream part. In summer of 2017, this arrangement was revised and the entire injector linac was reconsolidated into a single radiation control area. This was in conjunction with the introduction of the 1.1 GeV positron damping ring for Phase-II operation of SuperKEKB and successful development of new electron RF guns in the far upstream part of the linac. Along with this reconsolidation, the personnel and machine protection system was modified and improved. Interlock signal lines for the damping ring and RF guns were added. The operation panel of the main console was modified accordingly. In addition, the screen displays of the interlock status were updated. In this paper we report on the renewed system of KEK injector linac in detail.

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WEPAL039

LCLS-II Gun/Buncher LLRF System Design

LLRF, cavity, SRF, controls

2258

G. Huang, K.S. Campbell, L.R. Doolittle, J.A. Jones, Q. Qiang, C. Serrano
LBNL, Berkeley, California, USA
S. Babel, A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, J.H. De Long, J.A. Diaz Cruz, B. Hong, A. McCollough, A. Ratti, C.H. Rivetta, D. Rogind, F. Zhou
SLAC, Menlo Park, California, USA
R. Bachimanchi, C. Hovater, D.J. Seidman
JLab, Newport News, Virginia, USA
B.E. Chase, E. Cullerton, J. Einstein-Curtis, D.W. Klepec
Fermilab, Batavia, Illinois, USA
J.A. Diaz Cruz
CSU, Fort Collins, Colorado, USA

Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-05CH11231.
For a free electron laser, the stability of injector is critical to the final electron beam parameters, e.g., beam energy, beam arrival time, and eventually it determines the photon quality. The LCLS-II project's injector contains a VHF copper cavity as the gun and a two-cell L-band copper cavity as its buncher. The cavity designs are inherited from the APEX design, but requires more field stability than demonstrated in APEX operation. The gun LLRF system design uses a connectorized RF front end and low noise digitizer, together with the same general purpose FPGA carrier board used in the LCLS-II SRF LLRF system. The buncher LLRF system directly adopts the SRF LLRF chassis design, but programs the controller to run the normal conducting cavities. In this paper, we describe the gun/buncher LLRF system design, including the hardware design, the firmware design and bench test.

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WEPAL040

High Precision Synchronization Development for HiRES, the Ultrafast Electron Diffraction Beamline at LBNL

laser, controls, electron, LLRF

2262

Y. Yang, K.M. Baptiste, M. Betz, L.R. Doolittle, Q. Du, D. Filippetto, G. Huang, F. Ji
LBNL, Berkeley, California, USA

Precise synchronization between the laser and electron is critical for the pump-probe experiments in the HiRES Ultrafast Electron Diffraction facility. We are upgrading the LLRF and laser control system, which ultimately aims at a synchronization below 50 fs RMS between the pump laser pulse and electron probe at the sample plane. Such target poses tight requirements on the RF field stability both in amplitude and phase, and on the synchronization between the RF field and the laser repetition rate. We are presently developing a new LLRF system that has the potential to decrease the overall noise, reaching the required stability of tens of ppm on RF amplitude and phase. For the laser control side, we are replacing the long coaxial cables with fibers for both control signal transmission and laser signal reception. The control transmission side has been implemented, and the timing jitter has been reduced.

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WEPMF051

Multipacting in an RF Window: Simulations and Measurements

multipactoring, electron, simulation, resonance

2483

M. Bousonville, S. Choroba
DESY, Hamburg, Germany

Electron guns are used in the accelerators of the European XFEL and FLASH. They are operated at 1.3 GHz. The RF peak power is 5 MW at 650 us pulse width and 10 Hz repetition rate. In order to understand the multipacting that occurs during conditioning, it was simulated in the RF window type that is used for the electron gun in the XFEL. The reduction in secondary emission yield associated with conditioning was taken into account. Since the RF windows are tested with high power on a test stand before their use, without the electron gun, measurement results are available which are compared with the simulation results. The main advantage of the simulation compared to the measurement is that the locations of multipacting can be determined in the RF window. This could be helpful for the development of high-power RF components in the future, in order to detect pronounced multipacting resonances even before production and to avoid them by design changes.

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WEPMF055

The REGAE Accelerator Vacuum System

vacuum, cathode, operation, electron

2493

S. Lederer, K. Flöttmann, L. Lilje, N. Plambeck
DESY, Hamburg, Germany

Since 2011 the Relativistic Electron Gun for Atomic Exploration (REGAE) is operated at DESY in Hamburg. The accelerator consists mainly of a high gradient S-band RF-gun, which generates ultra-low emittance electron bunches, and an S-band RF-buncher cavity for bunch compression. In this contribution we describe the vacuum system of the REGAE accelerator. We will cover design aspects, applied cleaning and installation procedures as well as operation experience over the last years.

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WEPMF056

Cs2Te Photocathode Lifetime at Flash and European XFEL

cathode, FEL, laser, operation

2496

S. Lederer, S. Schreiber
DESY, Hamburg, Germany

The photo-injectors of FLASH and the European XFEL at DESY (Hamburg, Germany) use Cs2Te photocathodes. In this contribution we give an update on the lifetime and quantum efficiency of the cathodes operated in both facilities. Cathode #680.1 was operated at the European XFEL from the injector commissioning to the first user run for over 700 days. At FLASH cathode #73.3 has been operated with a record of more than 1000 days.

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WEPMF066

Fabrication of Split-Section X-band Structure Using Elastic Averaging

vacuum, alignment, coupling, electron

2521

P. Borchard, S.A. Appert, J.S. Hoh
Dymenso LLC, San Francisco, USA

Conventional accelerator structures are manufactured using axial stacks of cylindrical components which, when brazed together, form the accelerator cell structure. Splitting the accelerator structure into two sections along the beam axis allows for a significant reduction in part count and vacuum joint length. The resultant single and coplanar vacuum joint between the two split sections allows for joining techniques such as electron beam welding or brazing of the parts to form the accelerator vacuum envelope. High precision alignment of the two sections is achieved through an elastic averaging interface coupling where improved accuracy is derived from the averaging of errors over a large number of relatively compliant contacting members. The monoblock split sections allow for highly optimized cooling configurations with enhanced heat removal in high heat flux regions, reducing vacuum wall thermal stresses and enabling higher power operation. This paper describes the engineering and manufacturing of four generations of brazed and electron beam welded X-band accelerator structures at both 9.3 GHz and 11.4 GHz frequencies.

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WEPMF068

Inexpensive Brazeless Accelerator Prototype

cavity, vacuum, operation, electron

2528

S.P. Antipov, R.A. Kostin, S.V. Kuzikov
Euclid TechLabs, LLC, Solon, Ohio, USA
A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Funding: DOE SBIR
A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. Here we report on manufacturing and testing of brazeless accelerator prototype.

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WEPML060

Yb/Nd Doped Hybrid Solid Laser of RF Gun and Beam Commissioning for Phase-II of SuperKEKB

laser, injection, electron, MMI

2836

R. Zhang, T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
KEK, Ibaraki, Japan

For SuperKEKB project schedule of the phase-II, low emittance 1 nC electron beams were required with good stability and reliability at end of the linac. In the injector linac, several instruments have been installed. An Nd/Yb hybrid laser system is development with two beam lines light source. The both side of quasi-traveling wave side coupled cavity S-band RF gun were injected by the two sub μJ UV picosecond laser pulses at same times. And beam commissioning with the RF gun is in progress.

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THPAF024

Understanding and Compensating Emittance Diluting Effects in Highly Optimized Ultrafast Electron Diffraction Beamlines

emittance, electron, space-charge, cathode

3004

C. M. Pierce, I.V. Bazarov, C.M. Gulliford, J.M. Maxson
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S. Baturin
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
M.A. Gordon, Y.K. Kim
University of Chicago, Chicago, Illinois, USA

Funding: This work was supported by the Center for Bright Beams, NSF PHY-1549132 and Department of Energy grant DE-SC0014338.
The application of Multiobjective Genetic Algorithm optimization (MOGA) to photoemission based ultrafast electron diffraction (UED) beamlines featuring extremely low cathode mean transverse energies has lead to designs with emittances as low as 1 nm for sub-picosecond bunches with 10⁵ electrons*. Analysis of these results shows significant emittance growth during transport: with emittance dilution as high as a factor of 200-4000% for various designs and optics settings. In this study we quantify and model the individual sources of emittance growth (slice mismatches and space charge), and explore the use of the core emittance as a strong invariant.
C. Gulliford, A. Bartnik, and I. Bazarov. Multi-
objective optimizations of a novel cryocooled dc gun based
UED beam line. Phys. Rev. Ac-
celerators and Beams, 19(9):093402, 2016.

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THPAF087

Multi-Objective Optimization of an SRF Photoinjector with Booster Section for High Brightness Beam Performance

booster, cavity, emittance, brightness

3193

E. Panofski, A. Jankowiak, T. Kamps, A. Neumann
HZB, Berlin, Germany

Several future accelerator projects, light sources and user experiments require high brightness electron beams. SRF photoinjectors operating in continuous-wave (cw) mode hold the potential to serve as an electron source generating beams of high average brightness and short bunch lengths. Different operation and design parameters of the SRF photoinjector impact the beam dynamics and thus the beam brightness. A universal multi-objective optimization program based on a genetic algorithm was developed to extract optimum gun parameter settings from Pareto-optimum solutions. After getting the first optimum results, the photoinjector is supplemented with a booster section downstream. The new optimization results are presented. Further, the optimization program is applied to evaluate the impact of the field flatness of the gun cavity on the high brightness performance.

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THPAK071

Simulation Study of the Magnetized Electron Beam

solenoid, cathode, electron, simulation

3395

S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft
ODU, Norfolk, Virginia, USA
J. F. Benesch, F.E. Hannon, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman
JLab, Newport News, Virginia, USA

Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177
Electron cooling of the ion beam plays an important role in electron ion colliders to obtain the required high luminosity. This cooling efficiency can be enhanced by using a magnetized electron beam, where the cooling process occurs inside a solenoid field. This paper compares the predictions of ASTRA and GPT simulations to measurements made using a DC high voltage photogun producing magnetized electron beam, related to beam size and rotation angles as a function of the photogun magnetizing solenoid and other parameters.

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THPAK086

A 2D Steady-State Space Charge Solver for Azimuthally Symmetric Problems of Arbitrary Degree

space-charge, cathode, electromagnetic-fields, distributed

3431

A.R. Gold, A. R. Gold, S.G. Tantawi
SLAC, Menlo Park, California, USA

Correctly and rapidly simulating the steady-state interaction between particle beams and electromagnetic fields is crucial to the design and optimization of accelerator and radiofrequency (RF) source components. Iteratively solving for the self-consistent interaction between particles and fields can prove challenging and highly susceptible to numerical noise and mesh induced instabilities. We present herein two new approaches to solving the self-consistent trajectories of particles in the presence of external and self fields. The first method reformulates the integrated self field contribution as a path integral. The second method uses a hybrid Eulerian framework and produces an interpolated continuous current density, resulting in 1-2 orders of magnitude fewer particles required to obtain an accurate solution. We conclude with benchmarking results which show this method is as accurate as state of the art PIC solvers, while running 80-120X faster.

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THPAK154

Beam Parameter Optimization for UEM Facility with Photo-Emission S-band RF Gun

electron, space-charge, laser, emittance

3610

H.R. Lee, P. Buaphad, Y. Joo
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
S.C. Cha, Y. Kim
KAERI, Daejon, Republic of Korea
B.L. Cho
KRISS, Daejeon, Republic of Korea
H. Suk
GIST, Gwangju, Republic of Korea

Ultrafast Electron Microscopy (UEM) can provide snapshot images of a dynamic process in samples with an ultrafast time resolution, which is shorter than picosecond. The Future Accelerator R&D Team at KAERI has been preparing a UEM facility with a photo-emission S-band (= 2856 MHz) RF gun by collaborating with GIST and KRISS. To achieve a higher spatial resolution as well as a higher time resolution, the transverse beam emittance, beam divergence, and energy spread should be smaller, and the bunch length should be shorter. Beam dynamics simulations with ASTRA code is used to optimize those beam parameters in the RF gun. In this paper, we describe ASTRA optimizations of the S-band RF gun to achieve high spatial-temporal resolutions for the UEM facility.

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THPAL009

A TM01 Mode Launcher With Quadrupole Field Components Cancellation for High Brightness Applications

network, GUI, quadrupole, brightness

3631

G. Castorina
INFN-Roma1, Rome, Italy
A.D. Cahill, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
F. Cardelli, G. Franzini, A. Marcelli, B. Spataro
INFN/LNF, Frascati (Roma), Italy
L. Celona, S. Gammino, G. Torrisi
INFN/LNS, Catania, Italy
V.A. Dolgashev
SLAC, Menlo Park, California, USA
L. Ficcadenti
Rome University La Sapienza, Roma, Italy
M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
G. Sorbello
University of Catania, Catania, Italy

The R&D of high gradient radiofrequency (RF) devices is aimed to develop innovative accelerating structures based on new manufacturing techniques and materials in order to construct devices operating with the highest accelerating gradient. Recent studies have shown a large increase in the maximum sustained RF surface electric fields in copper structures operating at cryogenic temperatures. These novel approaches allow significant performance improvements of RF photoinjectors. Indeed the operation at high surface fields results in considerable increase of electron beam brilliance. This increased brilliance requires high field quality in the RF photoinjector and specifically in its power coupler. In this work we present a novel power coupler for the RF photoinjector. The coupler is a compact X-band TM01 mode launcher with a fourfold symmetry which minimized both the dipole and the quadrupole RF components.

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THPAL095

Metal Photocathodes Preparation for Compact Linear Accelerator at Daresbury Laboratory

plasma, cathode, electron, laser

3865

A.N. Hannah, J.A. Conlon, L.B. Jones, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V. R. Dhanak
The University of Liverpool, Liverpool, United Kingdom
L.B. Jones, B.L. Militsyn
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S. Lederer
DESY Zeuthen, Zeuthen, Germany
S. Lederer
DESY, Hamburg, Germany

The photoinjector of the CLARA FEL test facility Front End at Daresbury Laboratory is based on a S-band 10 Hz photocathode RF-gun operating with a copper photocath-ode which is driven by the third harmonic of a Ti:Sapphire laser (266 nm). The main aim of this study was to establish a procedure to prepare the Cu surface prior to installation so a Quantum Efficiency (QE) of 10^-5 or higher can be achieved at laser power density below the ablation threshold of copper. The best results have been obtained by ex-situ chemical cleaning. This removed the surface oxide layer whilst at the same time producing a surface buffer layer. This inhibited the regrowth of native oxide for up to a week when exposed to normal ambient atmospheric conditions. With either chemical cleaning or Ar plasma cleaning after heating the sample in-situ to 150 °C for 90 minutes or 250 °C for 40 hours, almost all of the surface oxide was removed. For these surfaces a QE of 4.10-5 or better was measured. Oxygen plasma cleaning at 100% and 20% power produced CuO layer with surface carbon contaminant to 3 atomic %, however in-situ thermal cycling resulted in at best a QE of 3·10-6.

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THPAL149

RF System Based on Two Klystrons and Phase Modulation for Photo-Cathode Injector

klystron, linac, experiment, cathode

3996

P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

We proposed an RF system with two klystrons, of which the powers are combined by a 3dB-hybrid. By managing the phases of the two klystrons respectively, the two pulses from the two output ports of the 3dB-hybrid can be of different powers, phases, and shapes. One of the two pulses can be set to an RF gun, while the other one can feed traveling accelerating structures. Two methods of phase modulation were proposed based on this scheme. Comparing with the state-of-art RF system, the new one can be of high efficiency or can generate electron beams with higher energy. The detailed analysis of the two methods and some experiments are described in this paper.

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THPMF001

Beam Dynamics Studies for Beam Focusing and Solenoid Alignment at SINBAD

solenoid, alignment, emittance, linac

4026

S. Yamin, R.W. Aßmann, B. Marchetti, J. Zhu
DESY, Hamburg, Germany

SINBAD (Short INnovative Bunches and Accelerators at DESY) facility under construction at DESY plans to host several experiments for the production of ultra-short bunches and will be a test facility for high-gradient compact novel acceleration techniques. The ARES (Accelerator Research Experiment at SINBAD) linac is foreseen to produce ultra-short bunches to be injected e.g. into Novel Dielectric Laser Acceleration structures or Laser Wake-Field Acceleration experiments. The work presented in this paper is based on optimization of the focusing system consisting of solenoids for the ARES, which have been studied earlier in detail but is revisited for updated beamline. Moreover tolerances for the possible misalignment of solenoids are presented investigating the effect on the beam properties during the gun commissioning.
* J. Zhu, R. Assmann, U. Dorda, B. Marchetti, "Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD", Nucl. Instrum. Methods Phys. Res., Sect. A 829, 229 (2016)

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THPMF029

Novel MCP-Based Electron Source Studies

electron, laser, cathode, controls

4107

V.D. Shiltsev, G. Stancari
Fermilab, Batavia, Illinois, USA
M.J. Haughey
Edinburgh University, Edinburgh, United Kingdom

Microchannel plates were recently proposed as cathodes for electron guns, as part of a novel electron lens design to be tested in the IOTA facility at FNAL. We experimentally assessed the suitability of microchannel plate technology in this design and studied the microchannel plate based photomultiplier (MCP-PMT) system using different sources of light pulses. Here we present the results of the nanosecond time response tests and the maximum current density tests as well as the dependency on the magnetic field strength. Several ideas how to proceed beyond O(100 mA/cm²) density observed in the first tests.

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THPMF032

Preparation and Testing of the BERLinPro Gun 1.1 Cavity

cavity, cathode, pick-up, niobium

4117

H.-W. Glock, J. Knobloch, A. Neumann, Y. Tamashevich
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
For the BERLinPro energy recovery LINAC, HZB is developing a superconducting 1.4-cell electron gun, which, in its final version, is planned to be capable of CW 1.3 GHz operation with 77 pC/bunch. For this purpose a series of three superconducting cavities, denoted as Gun 1.0, Gun 1.1 (both designed for 6 mA) and Gun 2.0 (100 mA) is foreseen. Here the status of the Gun 1.1 cavity is described, including results of the recent vertical testing. Lessons learned from the production and preparation process are summarized, also in order to identify issues critical for the production of Gun 2.0.

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THPMF034

Status Report of the Berlin Energy Recovery Linac Project BERLinPro

SRF, cathode, vacuum, cavity

4127

M. Abo-Bakr, W. Anders, Y. Bergmann, K.B. Bürkmann-Gehrlein, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, F. Glöckner, F. Göbel, B.D.S. Hall, S. Heling, H.-G. Hoberg, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, G. Kourkafas, J. Kühn, B.C. Kuske, J. Kuszynski, A.N. Matveenko, M. McAteer, A. Meseck, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, L. Pichl, J. Rahn, M.A.H. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker
HZB, Berlin, Germany
A. Bundels
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany

Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the last year's progress, including the comissioning of the gun module as the first SRF component to be installed in BERLinPro.

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THPMF039

Study of Magnesium Photocathodes for Superconducting RF Photoinjectors

laser, cathode, SRF, cavity

4142

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

Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
The superconducting RF photoinjector (SRF Gun II) has successfully served for the ELBE user facility at HZDR. Nevertheless, the quality of photocathodes is one of the most critical issues in improving the stability and reliability for its application. Magnesium has a comparably low work function (3.6 eV) and shows a quantum efficiency up to 0.3% after laser cleaning. However, the present cleaning process with a high intensity laser beam is time consuming and produces unwanted surface roughness, which leads to a higher thermal emittance. Thermal treatment and Excimer laser cleaning for Mg cathodes are investigated as alternative methods. In this work, the new cleaning procedures are tested and optimized, and the quantum efficiency of Mg samples with different microstructure, composition and suppliers are compared.

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THPMF040

Experiences with the SRF Gun II for User Operation at the ELBE Radiation Source

radiation, SRF, undulator, electron

4145

J. Teichert, A. Arnold, M. Bawatna, P.E. Evtushenko, M. Gensch, B.W. Green, S. Kovalev, U. Lehnert, P.N. Lu, P. Michel, P. Murcek, H. Vennekate, R. Xiang
HZDR, Dresden, Germany

Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
The second version of the superconducting RF pho-toinjector (SRF Gun II) was successfully commissioned at the ELBE radiation source in 2014. The gun features an improved 3.5-cell niobium cavity combined with a super-conducting solenoid integrated in the cryostat. With a Mg photocathode the SRF Gun II is able to generate bunches with up to 200 pC and with sub-ps length in CW mode with 100 kHz pulse frequency for the THz radiation fa-cility at ELBE. In the ELBE linac, the beam is accelerat-ed, gets a proper correlated energy spread, and is com-pressed in a magnetic chicane. Sub-ps pulses are obtained producing coherent diffraction radiation and superradiant undulator radiation.

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THPMF048

Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation

experiment, simulation, laser, electron

4166

N.R. Neveu
IIT, Chicago, Illinois, USA
S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA
J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations.

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THPMF049

Photoinjector Optimization Studies at the AWA

simulation, emittance, laser, experiment

4169

N.R. Neveu
IIT, Chicago, Illinois, USA
J. Larson, J.G. Power
ANL, Argonne, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
With a variable charge range of 0.1 nC - 100 nC, the Argonne Wakefield Accelerator facility (AWA) has a unique and dynamic set of operating parameters. Adjustment of the optics and occasionally the rf phases is required each time the bunch charge is changed. Presently, these adjustments are done by the operator during each experiment. This is time consuming and inefficient, more so at high charge and for complex experimental set ups. In an attempt to reduce the amount of time spent adjusting parameters by hand, several optimization methods in simulation are being explored. This includes using the well-known Genetic Algorithm (NSGA-II), incorporated into OPAL-T. We have also investigated a model-based method and novel structure based algorithms developed at ANL. Ongoing efforts include using these optimization methods to improve operations at the AWA. Simulation results will be compared to measured beam parameters at the AWA, and one optimization method will be selected for use in guiding operations going forward.

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THPMF056

Optimisation Study of the Fabry-Pérot Optical Cavity for the MARIX/BRIXS Compton X-Ray Source

laser, cavity, electron, photon

4192

I. Drebot, A. Bacci, F. Broggi, S. Cialdi, C. Curatolo, D. Giannotti, D. Giove, A.R. Rossi, L. Serafini, M. Statera, V. Torri
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Bosotti, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
R. Calandrino, A. Delvecchio
HSP, Milan, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
A. Esposito, L. Faillace, A. Gallo, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
G. Galzerano, E. Puppin, A. Tagliaferri
Politecnico/Milano, Milano, Italy
G. Mettivier, P. Russo
UniNa, Napoli, Italy
V. Petrillo, F. Prelz, M. Rossetti Conti
Universita' degli Studi di Milano & INFN, Milano, Italy
M. Placidi, G. Turchetti
Bologna University, Bologna, Italy
A. Sarno
INFN-Napoli, Napoli, Italy

We present the study of the optimization of the optical cavity parameters, in order to maximise the flux of scattered photons in the Compton scattering process. In the optimisation, we compensate the losses of the photon number due to the elliptical shape of the laser pulse in optical cavity with a high focusing electron beam.

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THPMF058

The MariX source (Multidisciplinary Advanced Research Infrastructure with X-rays)

electron, FEL, cavity, radiation

4199

V. Petrillo, N. Piovella
Universita' degli Studi di Milano, Milano, Italy
A. Bacci, F. Castelli, S. Cialdi, C. Curatolo, I. Drebot, D. Giannotti, D. Giove, C. Meroni, A.R. Rossi, L. Serafini, M. Statera, V. Torri
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Bosotti, F. Broggi, F. Groppi, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
R. Calandrino, A. Delvecchio
HSP, Milan, Italy
F. Camera, S. Coelli, G. Onida, B. Paroli, L. Perini, F. Prelz, M. Rossetti Conti, F. Tomasi
Universita' degli Studi di Milano & INFN, Milano, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
A. Castoldi, G. Ghiringhelli, C. Guazzoni, M. Moretti, E. Pinotti
Polytechnic of Milan, Milano, Italy
S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Esposito, A. Gallo, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
L. Faillace
RadiaBeam, Santa Monica, California, USA
G. Galzerano, E. Puppin, A. Tagliaferri
Politecnico/Milano, Milano, Italy
G. Mettivier, P. Russo
UniNa, Napoli, Italy
M. Placidi
LBNL, Berkeley, California, USA
G. Rossi
Università degli Studi di Milano, Milano, Italy
R.I. Saban
CERN, Geneva, Switzerland
A. Sarno
INFN-Napoli, Napoli, Italy
F. Stellato
INFN - Roma Tor Vergata, Roma, Italy
G. Turchetti
Bologna University, Bologna, Italy

MariX (Multidisciplinary advanced research infra-structure with X-rays) is a joint project of INFN and University of Milan, aiming at developing a twin X-ray Source of advanced characteristics for the future Sci-entific Campus of the University of Milan. Presently in its design study phase, it will be built in the post Expo area located in north-west Milan district. The first component of the X-source MariX is BriXS (Bright and compact X-ray Source), a Compton X-ray source based on superconducting cavities technology for the electron beam with energy recirculation and on a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz, producing 20-180 keV radiation for medical applications. The BriXS accelerator is also serving as injector of a 3.8 GeV superconductive linac, driving a X-ray FEL at 1 MHz, for providing coherent, moderate flux radiation at 0.3-10 KeV at 1 MHz. Scientific case, layout and typical parameters of MariX will be discussed.

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THPMF068

Commissioning Status of FLUTE

electron, laser, experiment, MMI

4229

A. Malygin, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, S. Marsching, W. Mexner, A. Mochihashi, A.-S. Müller, M.J. Nasse, G. Niehues, R. Ruprecht, T. Schmelzer, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan
KIT, Karlsruhe, Germany
I. Križnar
Cosylab, Ljubljana, Slovenia
M. Schwarz
CERN, Geneva, Switzerland

FLUTE (Ferninfrarot Linac- Und Test-Experiment) will be a new compact versatile linear accelerator at the KIT. Its primary goal is to serve as a platform for a variety of accelerator studies as well as to generate strong ultra-short THz pulses for photon science. The phase I of the project, which includes the RF photo injector providing electrons at beam energy of 7 MeV and a corresponding diagnostics section, is currently being commissioned. In this contribution, we report on the latest progress of the commissioning phase. The status of the gun conditioning will be given, followed by an overview of the RF system and the laser system.

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THPMF072

Implementation of Ultra-Low Frequency Non-Linear Raman Spectroscopy with the Gun Laser at FLUTE

experiment, scattering, laser, optics

4242

S. Funkner, E. Bründermann, A.-S. Müller, M.J. Nasse, G. Niehues, T. Schmelzer, J.L. Steinmann, M. Yan
KIT, Eggenstein-Leopoldshafen, Germany
M. Tani
University of Fukui, Fukui, Japan

At the Karlsruhe Institute of Technology (KIT) the new compact versatile linear accelerator FLUTE is currently under commissioning. This accelerator will provide intense broadband THz pulses for spectroscopic experiments. Here, we demonstrate the implementation of a coherent Raman spectrometer using the RF gun laser of FLUTE. With our experiment, we can measure the Raman spectrum at ultra-low frequencies. The measurement principle, which was recently published, is based on coherent nonlinear excitation of the observed sample. The spectrometer consists of a stretcher and an interferometer, which can be simply built from standard optics. We will show that the accessible spectral range overlaps well with that from the THz pulses of the planned FLUTE experiment. Thus, the coherent Raman experiment can provide spectral information complementary to absorption spectral measurements using the THz radiation of FLUTE.

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THPMF088

R&D Activity on Alkali-Antimonied Photocathodes at INFN-Lasa

cathode, laser, electron, operation

4284

D. Sertore, P. Michelato, L. Monaco
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

Based on the long-term experience on R&D and production of cesium telluride photocathodes for the high brightness photo-injectors and the past experience on green photocathodes developed in ‘90s , we have started a new R&D activity aiming to reach a reproducible and robust recipe for green photocathodes usable in RF gun. In this paper we present and discuss the first results so far obtained on K2CsSb photoemissive films deposited on polished Mo plugs and the plan for future studies.

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THPMF089

Design of a Radial RF Electron Gun

cavity, electron, cathode, target

4287

J.W. Lewellen, F.L. Krawczyk
LANL, Los Alamos, New Mexico, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA

Funding: DOE Accelerator Stewardship Program
Most electron beam sources generate beams that propagate away from the source in a single primary direction, with the overall envelope being either pencil-like or sheet-like. We present the design of a radial RF electron gun, intended to produce a radially propagating electron beam (either towards or away from an axis) with the overall envelope being that of an expanding or contracting annulus. Such a source has several potential advantages for materials processing, and may also be useful as the basis for unique optical elements for hadron machines.

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THPMK001

Creating Two-Pulse Beams from a Photoinjector for Two Color FEL or Beam Driven PWFA Experiments

linac, emittance, simulation, cathode

4294

J. Andersson, J. Björklund Svensson, M. Kotur, F. Lindau, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV linac is investigated as a FEL driver in the SXL project, but there is also an ongoing investigation in using the linac as a driver for beam driven plasma wakefield acceleration experiments. From both these applications, double pulses from the photoinjector within the same RF period is desired. In this paper we discuss the possibilities of using the current photoinjector at MAX IV as driver and show simulations results from the pre-injector, both for FEL applications and for PWFA applications.

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THPMK002

The Pre-Injector Design for the MAX IV SXL

cathode, emittance, linac, laser

4297

J. Andersson, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, D. Olsson, L.K. Roslund, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden

In this paper we present the current status of the design for the pre-injector (photo-cathode gun, solenoid and first linac) for the SXL project at MAX IV. The SXL project requires a higher repetition rate and since improved beam quality compared to what the current photo-cathode gun can operate at is needed, a new photo-cathode gun will be manufactured. We briefly describe the components of the pre-injector, followed by the design of the new photo-cathode gun. The design is similar to the old gun but with a new RF cavity using elliptical irises and racetrack profile main cell. The current parameters for the next gun to be manufactured are discussed, and some simulations and expected beam quality from the injector are shown.

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THPMK009

Study on Improving Durability of Bialkali Photocathode for an RF-Gun with the CsBr Protective Layer

cathode, electron, laser, ion-source

4310

J. Miyamatsu, H. Ono, M. Washio
Waseda University, Tokyo, Japan
H. Iijima
Tokyo University of Science, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan

At Waseda University, we have been studying for high quality electron beam generation and developing variety of application experiments using 1.6 cells photocathode RF-gun. We are using photocathode as the electron source, which can generate high-performance electron beam such as low emittance, short pulse. The performance of photocathodes is evaluated mainly in terms of Quantum Efficiency (Q.E.) and the lifetime. Cs-Te photocathode used in the RF-Gun at Waseda University is known for high Q.E. with UV light and relatively longer lifetime among semiconducting photocathodes. For increasing the charge of electron beam and simplify the laser system, we started introducing CsK2Sb photocathode in the RF-gun which has light sensitivity in UV and visible range, and high Q.E. with green light. However, CsK2Sb photocathode has a difficulty in durability and we observed that it was not enough for long-term operation in the RF-gun. Then we plan to improve lifetime and durability of CsK2Sb photocathode by coating the cathode surface with CsBr thin film. In this conference, we report the result of lifetime measurement of CsK2Sb photocathode with CsBr thin film and future prospects.

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THPMK018

Design of a rotationally symmetric S-band photocathode RF gun

cathode, impedance, emittance, coupling

4336

Zh. X. Tang
USTC, Hefei, Anhui, People's Republic of China
Z.G. He, W.W. Li, Y.J. Pei, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The photocathode RF gun is one of the most critical components for high quality electron beam sources. The asymmetric multi-pole field contributes to the transverse emittance growth and degrades the beam quality. In order to overcome the problem, we propose a novel rotationally symmetric 1.6 cell RF gun to construct the symmetric field in this paper. The concrete proposal is that a coaxial cell with a symmetrical distribution of four grooves is concatenated to the first 0.6 cell at the photocathode end to form a new resonant cell (NRC) to mantain the symmetric multi-pole field in 1.6 cell. Our simulations indicate that 3D multi-pole fields of NRC are with the perfect symmetry. After that, the profile of the RF gun is optimized to improve the shunt impedance and mode separation and make the surface peak electric field at the photocathode end. Our simulations demonstrate promising outlook of using coaxial cell for photocathode RF guns with various applications.

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THPMK059

Commissioning of Front End of CLARA Facility at Daresbury Laboratory

cathode, cavity, controls, MMI

4426

D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.A. Griffiths, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, T.J. Price, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, T.M. Weston, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P. Goudket, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R.J. Cash, R.F. Clarke, G. Cox, G.P. Diakun, A. Gallagher, K.D. Gleave, M.D. Hancock, J.P. Hindley, C. Hodgkinson, A. Oates, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility being developed at STFC 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. The installation of the Front End (FE) section of CLARA, a S-bend merging with existing VELA (Versatile Electron Linear Accelerator) beam line and installation of a high repetition rate RF gun on VELA was completed in 2017. First beam commissioning results and high level software developments are presented in this paper.

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THPMK085

Development of a Pre-Injector Test Bench for Future SLRI Light Source

electron, cavity, emittance, cathode

4499

K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak
SLRI, Nakhon Ratchasima, Thailand

A pre-injector test bench at the Synchrotron Light Research Institute (SLRI) is under development as one of the preparations for the future SLRI light source and of choices for the possible upgrade of the current injector. The pre-injector test bench includes a pulsed thermionic gun, a fast pulse deflector, a buncher and a pre-buncher. The thermionic electron gun with a cathode made of a single crystal CeB6 is employed as an electron emitter providing small emittance and uniform electron density. The fast pulse deflector shorten the extracted electrons of a few microseconds to that of a few nanoseconds. The electron pulses are further bunched by both the 238 MHz pre-buncher and the 476 MHz buncher to allow the 1-MeV electron beam. The experimental setups for emittance and beam profile measurements are installed on a movable diagnostic stand which is, later on, replaced by the beam bunching devices. The designs of the test bench will be discussed in this paper.

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THPMK088

Low Emittance Thermionic Electron Gun at SLRI

electron, cathode, emittance, high-voltage

4509

K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak
SLRI, Nakhon Ratchasima, Thailand

The Synchrotron Light Research Institute (SLRI) has developed a new thermionic electron gun producing low emittance electron beam for the future upgrade of the existing one. The thermionic cathode made of a CeB6 single crystal is selected due to its properties providing high electron beam current, uniform current density, and high resistance to contamination. In addition, the CeB6 cathode of 3 mm in diameter can produce up to a few Amperes of electron beam current. The electron gun is pulsed at 500 kV with a few microseconds wide to avoid high voltage breakdown as well as to reduce space charge effect resulting in the emittance growth of the extracted electron beam. The preliminary simulation and design of the electron gun together with the high voltage system are described in the paper.

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THPMK095

Design of an RF Modulated Thermionic Electron Source at TRIUMF

GUI, electron, impedance, cathode

4524

K. Fong, D.W. Storey
TRIUMF, Vancouver, Canada

The electron source in the TRIUMF ARIEL project is a gridded dispenser cathode. The cathode is biased at -300kV, and the grid requires a RF control signal of up to 150V at 650 MHz. The required RF power is approximately 20 W and is provided by an RF amplifier located outside the gun vessel. This RF power is coupled into the gun circuit through a ceramic transmission line. The design of this ceramic transmission line, as well as the impedance transformation circuit which provides both the impedance matching and the dc powers to the gun assembly are described.

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THPMK097

First Conceptual Design Studies of an Electron Source for Ultrafast Electron Diffraction at DELTA

electron, cavity, laser, space-charge

4530

D. Krieg, S. Khan
DELTA, Dortmund, Germany
K. Sokolowski-Tinten
Universität Duisburg-Essen, Duisburg, Germany

Funding: MERCUR Pr-2017-0002
Ultrafast electron diffraction (UED) is a technique to study the structural dynamics of matter, combining diffraction of electrons with sub-angstrom De-Broglie wavelength with femtosecond time resolution. The method is complementary to X-ray scattering at free-electron lasers. UED pump-probe experiments require ultrashort laser pulses to pump a sample, electron bunches with small emittance and ultrashort length to analyze the state of the sample by diffraction, as well as excellent control of the delay between them. While most UED systems are based on electrostatic electron sources in the keV regime, electrons accelerated to a few MeV in a radiofrequency photocathode gun offer significant advantages regarding emittance and bunch length due to the reduction of space charge effects. Furthermore, the longer mean free path of MeV electrons allows for thicker samples and hence a broader range of possible materials. In this paper, a first conceptual design and simulation results for a university-based UED facility with ultrashort and low-emittance MeV electron bunches are presented.

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THPMK101

Inverted Geometry Photo-Electron Gun Research and Development at TU Darmstadt

cathode, electron, linac, operation

4545

M. Herbert, J. Enders, Y. Fritzsche, N. Kurichiyanil, V. Wende
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by the Deutsche Forschungsgemeinschaft through GRK 2128 'AccelencE'
The Institute for nuclear physics at TU Darmstadt houses the Superconducting Darmstadt Linear Accelerator S-DALINAC. A photo-electron gun using GaAs photocathodes to provide pulsed and/or polarized electron beams, the S-DALINAC Polarized Injector SPIn, has been installed * for future nuclear-structure investigations**. In order to conduct research and development for this source, a test facility for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen (Photo-CATCH) has been constructed***. This setup provides several chambers for photocathode handling and a 60 keV beamline for photo-gun design studies****. Currently, an upgraded inverted insulator geometry is under investigation for Photo-CATCH that is supposed to be implemented at SPIn. We will present the current developments at Photo-CATCH and future measurements.
* Y. Poltoratska et al., J. Phys.: Conf. Series 298 (2011)
** J. Enders, AIP Conf. Proc. 1563, 223 (2013)
*** M. Espig, Diss., TU Darmstadt (2016)
**** N. Kurichiyanil, Diss., TU Darmstadt (2016)

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THPMK108

Production of Magnetized Electron Beam from a DC High Voltage Photogun

cathode, solenoid, electron, laser

4567

M.A. Mamun, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.R. Delayen, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M. Poelker, R. Suleiman, M.G. Tiefenback, Y.W. Wang, S. Zhang
JLab, Newport News, Virginia, USA
S.A.K. Wijethunga
ODU, Norfolk, Virginia, USA

Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177
Bunched-beam electron cooling is a key feature of all proposed designs of the future electron-ion collider, and a requirement for achieving the highest promised collision luminosity. At the Jefferson Lab Electron Ion Collider (JLEIC), fast cooling of ion beams will be accomplished via so-called 'magnetized cooling' implemented using a recirculator ring that employs an energy recovery linac. In this contribution, we describe the production of magnetized electron beam using a compact 300 kV DC high voltage photogun with an inverted insulator geometry, and using alkali-antimonide photocathodes. Beam magnetization was assessed using a modest diagnostic beamline that includes YAG view screens used to measure the rotation of the electron beamlet passing through a narrow upstream aperture. Magnetization results are presented for different gun bias voltages and for different laser spot sizes at the photocathode, using 532 nm lasers with DC and RF time structure. Photocathode lifetime was measured at currents up to 4.5 mA, with and without beam magnetization.

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THPMK110

300 kV DC High Voltage Photogun with Inverted Insulator Geometry and CsK2sb Photocathode

cathode, high-voltage, emittance, laser

4571

Y.W. Wang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, G.A. Krafft, M.A. Mamun, G.G. Palacios Serrano, M. Poelker, R. Suleiman, M.G. Tiefenback, S. Zhang
JLab, Newport News, Virginia, USA
G.A. Krafft, S.A.K. Wijethunga
ODU, Norfolk, Virginia, USA

Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177
A compact DC high voltage photogun with inverted-insulator geometry was designed, built and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This presentation describes key electrostatic design features of the photogun with accompanying emittance measurements obtained across the entire photocathode surface that speak to field non-uniformity within the cathode/anode gap. A summary of initial photocathode lifetime measurements at beam currents up to 4.5 mA is also presented.

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THPMK145

Evaluation of Coherent Terahertz Radiation Generated from Tilted Electron Beams Aiming for Higher Light Intensity

radiation, electron, target, controls

4642

M. Brameld, K. Sakaue, Y. Tadenuma, M. Washio, R. Yanagisawa
Waseda University, Tokyo, Japan
R. Kuroda, Y. Taira
AIST, Tsukuba, Japan

Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083.
When a target medium is irradiated by electron beams travelling at relativistic speed, terahertz(THz) radiation is produced by Cherenkov radiation. THz radiation is released at an angle to the direction of travel of the electron beams, and the coherence of the radiation can be improved by tilting the electron beams to match this angle, resulting in higher light intensity. The Cherenkov angle differs according to the refraction index of the target medium. At Waseda University, the generation of high-quality electron beams by a Cs-Te Photocathode RF-Gun and its applications are being researched. By utilizing the RF-Deflector, the tilt angle of the electron beam can be controlled to achieve coherent THz radiation. To gain higher light intensity, the use of Silicon and Aerogel as a target medium was challenged and compared to the conventional medium TOPAS. The THz radiation produced from the three target mediums were analyzed by use of the power meter and time domain spectroscopy(TDS). At this conference, the generation of THz Cherenkov radiation from different target mediums and the measurement results will be reported along with future perspectives.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK145

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THPML010

Modeling of Diamond Field Emitter Arrays for Shaped Electron Beam Production

electron, simulation, emittance, experiment

4668

K.E. Nichols, H.L. Andrews, D.Y. Shchegolkov, E.I. Simakov
LANL, Los Alamos, New Mexico, USA

We present simulations of shaped electron beam production from diamond field emitter array (DFEA) cathodes. DFEAs are arrays of diamond pyramids with bases of the order of 10 microns that produce high current densities. These arrays can be fabricated in arbitrary shapes such as a triangle or a double triangle, so that they produce an inherently shaped beam. These transversely shaped beams can be put through an emittance exchanger to produce a longitudinally shaped electron beam distribution for use with high-transformer ratio wakefield accelerators. Simulations are conducted with MICHELLE. We design cathodes and focusing systems that preserve the beam's shape while transporting it to the emittance exchanger.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML010

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THPML017

Beam Dynamics Calculation of a New Injection System for LINAC II

electron, linac, injection, operation

4687

J.X. Zhang, M. Hüning
DESY, Hamburg, Germany

The Linac II at DESY (Deutsches Elektronen Synchrotron) is an electron/positron linear accelerator with a 400 MeV primary electron linac, an 800 MW positron converter, and a 450 MeV secondary electron/positron linac. For reliability two injection systems can be switched, a 150 kV bombarder diode gun dating from 1969 and a 100 kV triode gun commissioned in 2014. The older bombarder gun shall be replaced with a triode gun optimized for injection into the synchrotron radiation facility PETRA III. In this paper, the parameters of the existing injectors and the design considerations for the new injector are presented. The preliminary beam dynamics calculation of the new injection system will be performed; the future plan of the replacement will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML017

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THPML020

The First Results of Trial Operation and Performance Improve of the 100 MeV/ 100 kW Electron Linear Accelerator of the NSC KIPT SCA Neutron Source

electron, neutron, MMI, operation

4693

A.Y. Zelinsky, O.E. Andreev, V.P. Androsov, O. Bezditko, O.V. Bykhun, A.N. Gordienko, V.A. Grevtsev, A. Gvozd, V.E. Ivashchenko, I.I. Karnaukhov, I.M. Karnaukhov, V.P. Lyashchenko, M. Moisieienko, A.V. Reuzayev, D.V. Tarasov, V.I. Trotsenko
NSC/KIPT, Kharkov, Ukraine
Y.L. Chi
IHEP, Beijing, People's Republic of China

The NSC KIPT SCA Neutron Source uses 100 MeV/ 100 kW electron linear accelerator as a driver for the generation of the initial neutrons. The trial operation of the accelerator was started in 2018. To provide design electron beam parameters is the primary task of the first stage of the trial operation. During the first stage of the accelerator operation the following tasks were under consideration: minimization of the electron beam losses along accelerator, providing of the stable electron beam pulse current, adjustment of the electron beam position along accelerator and providing of the uniform electron beam distribution at the tungsten neutron generating target. The main results of the accelerator operation and methods of performance improve are described in the paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML020

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THPML054

Design Studies of an S-Band Multipacting Electron Gun

electron, cavity, cathode, operation

4759

C. Henkel, W. Hillert, V. Miltchev
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
K. Flöttmann
DESY, Hamburg, Germany

A multipacting electron gun (MEG) is a micro-pulse electron source based on secondary electron emission in a resonant microwave cavity structure for the generation of low emittance electron bunches with high repetition rate. By theoretical simulations a suitable radio-frequency gun design at 3 GHz is established, simultaneously meeting the demands of bunch production and amplification process as well as including the effects of space charge and beam loading for the evolution of a stable beam. In this contribution we show detailed simulation studies of the impact of important design parameters like mechanical dimensions and choice of material on the average output current, which is in the order of several mA. For the experimental investigation a test setup is under construction, which may demonstrate the application of MEG's as a serious alternative or addition to commonly used electron sources like thermionic and photocathodes.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML054

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THPML055

Scaled Studies on Radio Frequency Sources for Megawatt-Class Ionospheric Heaters

electron, impedance, cathode, experiment

4763

B.L. Beaudoin, T.M. Antonsen, J.A. Karakkad, A.H. Narayan, G.S. Nusinovich, K.J. Ruisard
UMD, College Park, Maryland, USA
R. Fischer
Naval Research Laboratory (NRL), Washington, USA
S.H. Gold, A. Ting
NRL, Washington,, USA

Funding: Funding for this project and travel is provided by the Air Force Office of Scientific Research under grant FA95501410019.
The ionosphere plays a prominent role in the performance of critical civilian and military communication systems. The key instrument in Ionospheric Modification (IM) research is a powerful, ground-based, High Frequency (HF) source of electromagnetic waves known as a heater. With a mobile heater, investigators would be able to conduct IM research at different latitudes without building a costly permanent installation. A new highly efficient Megawatt class of Radio Frequency sources is required to reduce the overall power demands on a fully deployable system. Such a source has been described previously*. Results of a scaled experiment, using the electron beam produced by a gridded gun to drive an external lumped element circuit for high efficiency radio frequency generation is presented. The IOT gun produces an electron beam bunched at the driving frequency that is then collected by an external circuit for impedance matching to the load. Results showed that effects such as the internal resistance of the inductor and deflection of beam electrons by the induced RF voltages on the beam collector are important considerations to be included in the design of a practical device.
* B.L. Beaudoin, G.S. Nusinovich, G. Milikh, A. Ting, S. Gold, J.A. Karakkad, A.H. Narayan, D.B. Matthew, D.K. Papadopoulos, T.M. Antonsen Jr., Journal of Elec. Waves and Appl.,31,17,pp.1786, 2017.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML055

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THPML090

Optical Beam Loss Monitors Based on Fibres for the CLARA Phase 1 Beam-Line

electron, MMI, diagnostics, cathode

4869

A.S. Alexandrova, L.J. Devlin, V. Tzoganis, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
A.D. Brynes, F. Jackson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.D. Brynes, F. Jackson, V. Tzoganis, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
E. Effinger, E.B. Holzer
CERN, Geneva, Switzerland

Funding: Work supported by STFC Cockcroft Institute core Grant No. ST/G008248/1
Fibre based Optical Beam Loss Monitors (oBLMs) are on-line devices used in-situ to measure losses along a beam-line. The technology is based on the detection of Cherenkov radiation, produced inside quartz fibres placed alongside the beampipe, from the interaction of secondary showers generated from losses hitting the vacuum pipe. This contribution presents ongoing developments of an oBLM system installed along the Compact Linear Accelerator for Research and Applications (CLARA). The oBLM system consists of 4 channels which allows for sub-metre loss resolution with two dimensional coverage along the entirety of the beam line, as opposed to conventional localised BLM systems. The system was first commissioned to measure dark current from the injector. The ability of the system to locate longitudinal positions of known beam loss locations has also been measured and has shown excellent agreement. We present measurements acquired from the detector during regular operation and during dedicated beam tests. We also discuss the incorporation of the monitor into the accelerator diagnostics system and its use in assisting accelerator characterisation and performance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML090

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THPML133

Design and Optimization of the Electron Gun

electron, cathode, software, simulation

4995

K. Huang, T.L. He, Z.L. Ren, D.R. Xu, H. Xu
USTC/NSRL, Hefei, Anhui, People's Republic of China
Y. Chen
Department of Information Engineering , Anhui Economic Management Cadres' Institute, Hefei, Anhui, People's Republic of China

Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 and 10875118.
Design of an energy-modified electron gun is of significance to do some research on the properties of Diamond-amplified cathode. Based on the design method of the Pierce electron gun, the optimum parameters of the electron gun have been obtained using the Opera-3D program. And the beam waist's position, the beam current, the beam size and the beam emittance related to the electron bean energy was investigated in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML133

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