IPAC2016 - List of Keywords (gun)

Paper	Title	Other Keywords	Page
MOXBA01	Beam Commissioning of PAL-XFEL	undulator, laser, linac, cathode	6
	J.H. Han PAL, Pohang, Kyungbuk, Republic of Korea
	The Pohang Accelerator Laboratory X-ray Free electron Laser (PAL-XFEL) project aims at the generation of X-ray FEL radiation for photon users. The machine consists of a 10 GeV normal-conducting S-band linear accelerator (linac) and two undulator beamlines initially. The hard X-ray beamline will provide FEL radiation between 0.6 and 0.1 nm or shorter. The soft X-ray line will provide FEL radiation between 4.5 and 1 nm. The linac and hard X-ray beamline construction was complete by the end of 2015. The installation of the soft X-ray line is ongoing. High power RF conditioning of the linac started in late autumn 2015. Beam commissioning of the linac started in April 2016. We report the beam commissioning status.
	Slides MOXBA01 [4.978 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOXBA01
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MOPMB005	Study of Short Bunches at the Free Electron Laser CLIO	radiation, cavity, electron, simulation	78
	V. Khodnevych, N. Delerue, S. Jenzer LAL, Orsay, France J.P. Berthet, F. Glotin, J.-M. Ortega, R. Prazeres CLIO/ELISE/LCP, Orsay, France V. Khodnevych National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
	Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01). CLIO is a Free Electron Laser based on a thermionic electron gun. In its normal operating mode it delivers electron 8 pulses but studies are ongoing to shorten the pulses to about 1 ps. We report on simulations showing how the pulse can be shortened and the expected signal yield from several bunch length diagnostics (Coherent Transition Radiation, Coherent Smith Purcell Radiation).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB005
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MOPMB009	Electron Beam Probe for the Bunch Length Measurements at BERLinPro	electron, diagnostics, simulation, operation	92
	D. Malyutin, A.N. Matveenko HZB, Berlin, Germany
	For the successful operation of various accelerator facilities a detailed bunch characterization is required. A complete description can be achieved using various diagnostic systems installed along an accelerator beamline. Ideally the diagnostic should be able to measure parameters of a single bunch in a non-destructive manner. For bunch length measurements this results in a complicated task especially for bunch duration below 1 ps. One of the possible solutions is a diagnostic based on the interaction of a low energy electron beam with electro-magnetic fields of the relativistic bunch. The bunch length can be readily deduced from the resulting scatter. In this paper bunch length measurement technique based on a low energy electron beam is introduced. Results of numerical simulations of measurements are presented. A possible setup of such diagnostic system for BERLinPro facility is proposed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB009
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MOPMB015	Technical Design Considerations About the SINBAD-ARES Linac	linac, laser, electron, acceleration	112
	B. Marchetti, R.W. Aßmann, U. Dorda, K. Flöttmann, M. Hachmann, I. Hartl, J. Herrmann, M. Hüning, G. Kube, F. Ludwig, F. Mayet, M. Pelzer, I. Peperkorn, S. Pfeiffer, H. Schlarb, M. Titberidze, G. Vashchenko, M.K. Weikum, L. Winkelmann, K. Wittenburg, J. Zhu DESY, Hamburg, Germany R. Rossmanith KIT, Karlsruhe, Germany
	The SINBAD facility (Short and INnovative Bunches and Accelerators at Desy) is foreseen to host various experiments in the field of production of ultra-short electron bunches and novel high gradient acceleration technique. The SINBAD linac, also called ARES (Accelerator Research experiment at SINBAD), will be a conventional S-band linear RF accelerator allowing the production of low charge (0.5 pC - few pC) ultra-short electron bunches (FWHM, length <= 1 fs - few fs) having 100 MeV energy. In this paper we present the current status of the technical design considerations, motivate the foreseen diagnostics for the RF gun commissioning and present examples of foreseen applications.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB015
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MOPMB027	Beam Parameter Measurement After Relocation of S-Band Linear Accelerator	electron, linac, simulation, laser	146
	I. Nozawa, M. Gohdo, K. Kan, T. Kondoh, J. Yang, Y. Yoshida ISIR, Osaka, Japan
	Ultrashort electron bunches have been applied in many scientific fields including accelerator physics and radiation chemistry. Pulse radiolysis is application in radiation chemistry, which is a pump-probe measurement using an electron bunch and a laser pulse. Our laboratory aims to generate the electron bunches with durations of less-than femtoseconds using an S-band linear accelerator (linac) at Osaka University in order to improve the time resolution of the pulse radiolysis system. Recently, the linac system was relocated for expanding application using ultrashort electron bunches. The parameters of generated electron bunches including the bunch lengths will be reported.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB027
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MOPMB054	A High Sensitivity Faraday Cup for Ultrashort Electron Bunches	electron, simulation, laser, experiment	214
	S. Setiniyaz, I.H. Baek, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, S.V. Miginsky, J.H. Nam, S. Park, N. Vinokurov KAERI, Daejon, Republic of Korea S.V. Miginsky, N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	The UED (Ultrafast Electron Diffraction) beamline of KAERI (Korea Atomic Energy Research Institute) WCI (World Class Institute) Center has been successfully commissioned. A S-band co-axial RF photogun with 1.5 cylindrically symmetric cells was used to remove multiple modes of the electric filed inside the cavity. It is designed to generate sub-picosecond electron bunches with energy up to 3.3~MeV. We have developed a system consists of an in-air Faraday cup (FC) and a preamplifier for charge measurement. Tests performed utilizing 3.3~MeV electrons show the system were able to measure ultrashort bunches with tens of femtosecond pulse duration at 10 fC sensitivity. In this paper, we shall present the design, calibration and test results of this system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB054
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MOPMR001	Micro-mover Development and Test in the PAL-XFEL	solenoid, electron, cavity, controls	229
	B.G. Oh, J.H. Han, H. Heo, J.H. Hong, H.-S. Kang, C. Kim, D.E. Kim, K.-H. Park, Y.J. Suh PAL, Pohang, Kyungbuk, Republic of Korea
	Two micro-movers, which are able to control the horizontal, vertical and longitudinal positions as well as the yaw and pitch angles remotely, were developed and installed in the PAL-XFEL linac. The solenoid micro-mover in the gun section allows beam-based alignment of an electron beam to the solenoid field and the gun RF field. The X-band cavity micro-mover minimizes the transverse wake field effect caused by transverse misalignment between the beam and X-band cavity. Two micro-movers has similar specifications and the same mechanism, but the sizes are different from each other. In this paper, we present the design, manufacture and test results of the micro-movers.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR001
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MOPMR035	Bunch Length Measurements using a Transverse Deflecting Cavity on VELA	cavity, laser, electron, simulation	323
	J.W. McKenzie, S.R. Buckley, L.S. Cowie, P. Goudket, M. Jenkins, B.L. Militsyn, A.J. Moss, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A. Wolski The University of Liverpool, Liverpool, United Kingdom
	The VELA facility at Daresbury Laboratory in the UK includes a 5 MeV/c 2.5 cell S-band photoinjector gun. This gun operates in the "blow-out" regime with a sub-200 fs length drive laser: the resulting bunch length is determined by space-charge effects. We present measurements made with an S-band transverse deflecting cavity to characterise the bunch length as a function of charge, and as a function of the gun operating phase.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR035
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MOPMW001	A New Buncher for the ESRF Linac Injector	linac, electron, beam-loading, cavity	389
	A.S. Setty, A.S. Chauchat, D. Jousse Thales Communications & Security (TCS), Gennevilliers Cedex, France H. Delamare, J. Jacob, B. Ogier, T.P. Perron, E. Rabeuf, C. Richard, V. Serrière, R. Versteegen ESRF, Grenoble, France
	The electron linac was designed to be able to deliver more than 2.5 A in less than 2 ns at 200 MeV within an energy spread of 1% for positrons production at ESRF . The 200 MeV electron linac was commissioned in 1991. A new gun, a cleaner, a pre-buncher cavity and 4 shielded lenses were tested and installed on the injector in 2008 . Then, a new Buncher for the ESRF electron linac injector was manufactured and commissioned in 2015. Meanwhile, some new settings were performed to reduce the energy spread for both cases: the long pulse mode and the short pulse mode. The simulations and measurements will be presented. D. Tronc et Al. "Electron injector for light source", Proc. EPAC88, Italy, Rome, June 1988. ** T. Perron et Al. "New preinjector for the ESRF booster", Proc. EPAC08, Italy, Genoa, June 2008.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW001
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MOPMW005	Design of Linac with the New Gaskets Clamping Fabrication Technique	vacuum, coupling, impedance, linac	403
	F. Cardelli INFN-Roma1, Rome, Italy D. Alesini INFN/LNF, Frascati (Roma), Italy M. Magi, L. Palumbo University of Rome La Sapienza, Rome, Italy F. Pellegrino, V. Pettinacci INFN-Roma, Roma, Italy
	Recently, a new technique for the realization of high gradient accelerating structures based on the use of gaskets without brazing processes, has been successfully tested at high power on a 1.6 cells RF gun (D. Alesini, et al, PRST 18, 02001, 2015). The new technique developed at the Laboratories of Frascati of the INFN (Italy) in the framework of the SPARC_LAB project has been also adopted for the ELI-NP RF gun. The use of the special gaskets that simultaneously guarantee the vacuum seal and a perfect RF contact allow to avoid the brazing process, strongly reducing the cost, the realization time and the risk of failure. Moreover, without copper annealing due to the brazing process, it is possible, in principle, to decrease the breakdown rate increasing, at the same time, the maximum achievable gradient. The extension of this new fabrication process to complex LINAC structures is the next step on the application of this new technique on particle accelerator. In the paper, we discuss how to extend this process to S-band and C-band Travelling Wave accelerating structures illustrating their electromagnetic design and their mechanical realization.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW005
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MOPMW039	TM01 Mode Launcher for Use in High Brightness Photoguns	quadrupole, electron, impedance, cavity	491
	A.D. Cahill UCLA, Los Angeles, California, USA M. Dal Forno, V.A. Dolgashev SLAC, Menlo Park, California, USA
	Funding: DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515 Photo rf guns are a source of electron beams for X-ray FELs such as LCLS and European XFEL. In existing photoguns power is coupled into the cavity by waveguides through the cell walls, like LCLS, or through coaxial coupling, at the European XFEL. We are considering feeding a gun using a circular waveguide with the TM01 mode. To do that we need a mode launcher, a matched device that couples the rectangular TE01 mode waveguide to a TM01 mode in a circular waveguide. Use of the mode launcher reduces complexity of the gun cavity and increases flexibility of positioning the input waveguide relative to the gun body. Mode launchers have been successfully used at SLAC and elsewhere for X-band high gradient tests. Because the existing mode launchers were not built for high brightness guns, they have a significant quadrupole field component. High brightness rf guns have tight requirements on output beam properties, and this quadrupole component adversely affects the beam. We have designed a mode launcher free of this disadvantage. We present design considerations, methodology, and an example S-band mode launcher.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW039
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MOPMW042	Multi-Dimensional RF Sources Design	klystron, electron, cavity, space-charge	501
	M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: Work supported by the US DOE under contract DE-AC02-76SF00515. Vacuum electronic devices, such as rf sources for accelerator applications, must provide high rf power with high efficiency. To achieve these requirements, multi-beam klystron and sheet-beam klystron devices have been developed. Multi-beam klystrons, at high frequency employ separate output cavities; hence they have the disadvantage that combining all the rf pulses, generated by all the beams, is challenging. Sheet-beam klystrons have problems with instabilities and with space charge forces that makes the beam not naturally confined. We are proposing an alternative approach that reduces space charge problems, by adopting geometries in which the space charge forces are naturally balanced. An example is when the electron beam is generated by a central source (well) and the electron motion corresponds to the natural expansion of the electron cloud (three-dimensional device). In this paper we will present the design and challenges of a bi-dimensional rf source, a cylindrical klystron, composed by concentric pancake resonant cavities. In this case, space charge forces are naturally balanced in the azimuthal direction.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW042
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MOPMY013	Design Study of Collector for CEPC 650 MHz Klystron	klystron, simulation, operation, interface	540
	S.C. Wang, D.D. Dong, S. Fukuda, G. Pei, O. Xiao, .. Zaib-un-Nisa, Z.S. Zhou IHEP, Beijing, People's Republic of China S. Fukuda KEK, Ibaraki, Japan
	This paper presents the design and simulation of collector for CEPC 650 MHz high-power CW klystron. Power dissipation in collector is optimised by universal beam spread curve using EGUN code, and beam trajectory in collector is verified by Magic code. The thermal analysis is done by ANSYS-CFX, and groove number and water flow rate are optimized by fluid-solid coupled heat transfer simulation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY013
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MOPMY015	Design Study of Electron Gun for CEPC 650 MHz Klystron	klystron, cathode, electron, simulation	546
	.. Zaib-un-Nisa, D.D. Dong, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, Z.S. Zhou IHEP, People's Republic of China S. Fukuda KEK, Ibaraki, Japan
	This paper presents the design and simulation of an electron gun for 800 kW CW klystron of which frequency is 650 MHz for CEPC project. An electron gun with a modulating anode is designed using DGUN software. The uniform beam trajectories, with a beam perveance of 0.64μA/V 3/2 are simulated. We employed a Ba-dispenser cathode of radius 35 mm with Φ10 hole at the center and obtained a current density on cathode less than 0.45 A/cm². The beam trajectories were also simulated over whole tube length with a magnetic field of 207 Gauss. Expecting functions using the modulating anode gun are also described. Proposed beam tester and whole CEPC klystron layout are also shown in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY015
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MOPOR026	Measurement of the Energy Distribution Function of Electrons Generated by Radio-frequency Induced Multipacting in a Beam Pipe	electron, multipactoring, radio-frequency, diagnostics	664
	M. Van Gompel, F. Caspers, P. Costa Pinto, R. Leber, A. Romano, R. Salemme, M. Taborelli CERN, Geneva, Switzerland
	The development of Electron Multipacting (EM) in high intensity particle accelerators depends, amongst others, on the Secondary Electron Yield (SEY) of surfaces facing the beam. In-situ studies of electron clouds in particle accelerators must cope with operation schedule and other technical constrains. To overcome these difficulties, CERN implemented a Multipactor test bench, where EM is generated by Radio-Frequency (RF), using the beam pipes as a coaxial resonators. This tool was already successfully used to assess the effectiveness of low SEY carbon coatings on dipoles of the SPS at CERN and to study the conditioning dynamics of beam pipes. In this paper we present the development of an in-house built Retarding Field Energy Analyser (RFEA) to measure the Electrons Energy Distribution Function (EEDF) in the Multipactor test bench. The design of the electrodes was based on simulations in order to optimize sensitivity and energy resolution. The setup was tested with an electron gun at different energies before insertion in the Multipactor test bench. The evolution of the EEDF is measured at different RF powers. Feasibility to perform measurements in the machine is discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR026
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MOPOW016	Status of Design and Development of Delhi Light Source at IUAC, Delhi	laser, electron, undulator, radiation	748
	S. Ghosh, R.K. Bhandari, G.K. Chaudhari, V.J. Joshi, D. Kabiraj, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, P. Patra, B.K. Sahu, A.S. Sharma, A.S. Sthuthikkatt Reghu IUAC, New Delhi, India A. Aryshev, M.K. Fukuda, S. Fukuda, N. Terunuma, J. Urakawa, J. Urakawa KEK, Ibaraki, Japan A. Deshpande SAMEER, Mumbai, India V. Naik, A. Roy VECC, Kolkata, India T. Rao BNL, Upton, Long Island, New York, USA
	Funding: The project is supported jointly by Board of Research in Nuclear Sciences (BRNS) and IUAC The demand for the photon beams for basic research is growing in India. To address the requirements, a project to develop a compact Light Source based on the principle of Free Electron Laser has been initiated at the Inter University Accelerator Centre (IUAC). In the first phase of the project, a normal conducting RF gun will be used to produce electron beam of energy ~ 8 MeV by using copper photocathode and subsequently by Cs2Te photocathode. A high power fiber laser with short pulse length is planned to be used to produce the pre-bunched electron beam by splitting the single laser pulse in to 16 pulses ("comb beam"). The electron beam will be injected in to a compact, variable gap undulator magnet to produce the THz radiation whose frequency can be tuned by varying the undulator field strength and the time separation of the comb beam. In the second and third phases of the project, superconducting RF gun and superconducting accelerating structure will be used to increase the energy of the electron beam up to ~ 40 MeV which will be used to produce IR radiation by using long undulator magnets and to produce X-rays by colliding the electron beam with another high power laser beam.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW016
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MOPOW018	Feasibility Study of Photocathode Opearation of Thermionic RF Gun at KU-FEL	FEL, cathode, operation, electron	754
	H. Zen, T. Kii, K. Masuda, K. Morita, T. Murata, T. Nogi, H. Ohgaki, S. Suphakul, K. Torgasin Kyoto University, Kyoto, Japan R. Kuroda AIST, Tsukuba, Ibaraki, Japan
	Kyoto University Free Electron Laser (KU-FEL) is a mid-infrared FEL driven by a compact linac utilizinig a thermionic RF gun as its electron source. Recently we succeeded in operating KU-FEL with photocathode operation of the RF gun by using the thermionic cathode (LaB6) as a photocathode. The performance of KU-FEL under the thermionic cathode and photocathode operation will be reported. In addition, some recent application experiment results will also be presented in this presentation. H. Zen, et al., Infrared Phys. Techn. 51 (2008) 382.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW018
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MOPOW036	Design Optimization of an X-band based FEL	linac, FEL, simulation, emittance	793
	A.A. Aksoy Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey A. Latina, J. Pfingstner, D. Schulte CERN, Geneva, Switzerland Z. Nergiz Nigde University, Nigde, Turkey
	A design effort for a new generation of compact, cost-effective, power-efficient FEL facilities, based on X-band technology, has been launched. High-frequency X-band acceleration implies strong wakefields, tight alignment and mechanical tolerances, and challenging stability issues. In this paper a design is proposed for the injector and the linacs, including the two bunch compressors. RF gun and injector simulations have been performed, successfully meeting the stringent requirements in terms of minimum projected emittance, sliced emittance and minimum bunch length. In the design of the linac and bunch compressors wakefield effects and misalignment have been taken into account. Start-to-end tracking simulations through the optimized lattice are presented and discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW036
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TUOCA02	APEX Phase-II Commissioning Results at the Lawrence Berkeley National Laboratory	electron, cavity, linac, space-charge	1041
	F. Sannibale, J.A. Doyle, J. Feng, D. Filippetto, G.L. Harris, M.J. Johnson, T.D. Kramasz, D. Leitner, C.E. Mitchell, J.R. Nasiatka, H.A. Padmore, H.J. Qian, H. Rasool, J.W. Staples, S.P. Virostek, R.P. Wells, M.S. Zolotorev LBNL, Berkeley, California, USA S.M. Gierman, R.K. Li, J.F. Schmerge, T. Vecchione, F. Zhou SLAC, Menlo Park, California, USA C. Pagani, D. Sertore INFN/LASA, Segrate (MI), Italy
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 Science needs in the last decade have been pushing the accelerator community to the development of high repetition rates (MHz/GHz-class) linac-based schemes capable of generating high brightness electron beams. Examples include X-ray FELs; ERLs for light source, electron cooling and IR to EUV FEL applications; inverse Compton scattering X-ray or gamma sources; and ultrafast electron diffraction and microscopy. The high repetition rate requirement has profound implications on the technology choice for most of the accelerator parts, and in particular for the electron gun. The successful performance of the GHz room-temperature RF photo-injectors running at rates <~ 100 Hz, cannot be scaled up to higher rates because of the excessive heat load that those regimes would impose on the gun cavity. In response to this gun need, we have developed at Berkeley the VHF-Gun, a lower-frequency room-temperature RF photo-gun capable of CW operation and optimized for the performance required by MHz-class X-ray FELs. The Advanced Photo-injector EXperiment (APEX) was funded and built for demonstrating the VHF gun performance, and the results of its last phase of commissioning are presented.
	Slides TUOCA02 [12.015 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOCA02
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TUOCA03	Commissioning of the European XFEL Injector	emittance, laser, controls, operation	1044
	F. Brinker DESY, Hamburg, Germany
	The European XFEL Injector consists of an L-Band RF photoinjector, a TESLA type 1.3 GHz module, a 3rd harmonic RF section, a laser heater and an extensive diagnostic section to determine projected and slice properties of the beam. The commissioning of the complete system has been started in December 2015 after several years of construction. We will report on commissioning results and persepctives for the later XFEL operation.
	Slides TUOCA03 [5.182 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOCA03
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TUPMR006	The ELENA Electron Cooler	electron, solenoid, vacuum, antiproton	1236
	G. Tranquille, J. Cenede, A. Frassier, L.V. Jørgensen, A.J. Kolehmainen, B. Moles, M.A. Timmins CERN, Geneva, Switzerland
	The ELENA (Extra Low ENergy Antiproton) ring will deliver antiprotons at an energy of just 100 keV to experiments aiming to precisely measure the properties of anti-hydrogen atoms. A crucial component of this decelerator ring is the electron cooler which will be used to counter the beam blow-up as the antiproton energy is reduced from 5.3 MeV to 100 keV. The electron cooler will operate at energies below 350 eV in a longitudinal guiding field of 100 G such that the perturbations to the ring can be easily corrected. We will present the design considerations as well as the production status of the cooler.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR006
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TUPMR029	Advanced EBIS Charge Breeder for Rare Isotope Science Project	electron, ion, solenoid, vacuum	1304
	S.A. Kondrashev, J.-W. Kim, Y.H. Park IBS, Daejeon, Republic of Korea H.J. Son Handong Global University, Pohang, Republic of Korea
	Rare Isotope Science Project (RISP) is under development in Korea to provide wide variety of intense rare isotope beams for nuclear physics experiments and applied science using both Isotope Separation On-Line (ISOL) and In-Flight Fragmentation (IF) techniques. Electron Beam Ion Source (EBIS) charge breeder is a key element to efficiently accelerate rare isotope ion beams produced by ISOL method. These beams will be charge-bred by an EBIS charge breeder to a charge-to-mass ratio (q/A) ≥ - and accelerated by linac post-accelerator to energies of 18.5 MeV/u. Utilization of 3 A electron beam and 6 T superconducting solenoid with wide (8) warm bore diameter will allow high efficient and fast charge breeding of rare isotope beams with exceptional degree of purity. The main features of RISP EBIS charge breeder design and current status of the project will be presented and discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR029
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TUPMY015	Ultrafast Electron Guns for the Efficient Acceleration using Single-Cycle THz Pulses	electron, acceleration, laser, injection	1578
	A. Fallahi, F.X. Kärtner, A. Yahaghi CFEL, Hamburg, Germany M. Fakhari DESY, Hamburg, Germany
	Funding: European Research Council (ERC) Over the past decades, advances in ultrafast technologies led to the production of intense ultrashort THz to optical pulses reaching single-cycle pulse duration. Using such pulses for electron acceleration offers advantages in terms of higher thresholds for materials breakdown, thus introducing a promising path towards increasing acceleration gradients. Conventional accelerator technology is based on either continuous wave or long pulse operation, where resonant or guiding structures are usually employed. We introduce novel structures for electron acceleration which operate with single-cycle pulses named as single-cycle ultrafast guns. The operating frequencies considered here are at THz wavelengths inspired by the recent progress in the optical generation of intense single-cycle THz pulses. We begin with designing guns for low energy pulses and proceed with structures designed for high energy pulses. More importantly, it is shown that the already achieved THz pulse energies of 20 uJ are enough to realize relativistic fields for electron acceleration. These structures will underpin future devices for fabricating miniaturized electron guns and linear accelerators.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY015
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TUPMY041	Delivery Status of the ELI-NP Gamma Beam System	solenoid, laser, linac, vacuum	1635
	S. Tomassini, D. Alesini, A. Battisti, R. Boni, F. Cioeta, A. Delle Piane, E. Di Pasquale, G. Di Pirro, A. Falone, A. Gallo, S.I. Incremona, V.L. Lollo, A. Mostacci, S. Pioli, R. Ricci, U. Rotundo, A. Stella, C. Vaccarezza, A. Vannozzi, A. Variola INFN/LNF, Frascati (Roma), Italy A. Bacci, D.T. Palmer, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy N. Bliss STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom F. Cardelli INFN-Roma1, Rome, Italy K. Cassou, Z.F. Zomer LAL, Orsay, France G. D'Auria Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy A. Giribono, V. Pettinacci INFN-Roma, Roma, Italy C. Hill STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom L. Palumbo Rome University La Sapienza, Roma, Italy L. Piersanti University of Rome La Sapienza, Rome, Italy
	The ELI-NP GBS is a high intensity and monochromatic gamma source under construction in Magurele (Romania). The design and construction of the Gamma Beam System complex as well as the integration of the technical plants and the commissioning of the overall facility, was awarded to the Eurogammas Consortium in March 2014. The delivery of the facility has been planned in for 4 stages and the first one was fulfilled in October 31st 2015. The engineering aspects related to the delivery stage 1 are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY041
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TUPOR019	RF Injector Beam Dynamics Optimization and Injected Beam Energy Constraints for LCLS-II	cavity, laser, emittance, electron	1699
	C.E. Mitchell, H.J. Qian, J. Qiang, F. Sannibale, M. Venturini LBNL, Berkeley, California, USA P. Emma, T.O. Raubenheimer, J.F. Schmerge, F. Zhou SLAC, Menlo Park, California, USA
	Funding: Work supported by the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231. LCLS-II is a proposed high-repetition rate (>1 MHz) Free Electron Laser (FEL) X-ray light source, based on a CW, superconducting linac, to be built at SLAC National Accelerator Laboratory. The injector technology is based on a high-repetition rate RF photoinjector gun developed as part of the Advanced Photoinjector Experiment (APEX) at Lawrence Berkeley National Laboratory. Exploration of the injector design settings is performed using a multiobjective genetic optimizer to optimize the beam quality at the injector exit (~100 MeV). In this paper, we describe the current status of LCLS-II injector design optimization, with a focus on the sensitivity of the optimized solutions to the beam energy at the injector exit, which is constrained by the requirements of the downstream laser heater system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR019
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TUPOW002	Current Status of the Milliampere Booster for the Mainz Energy-recovering Superconducting Accelerator	electron, simulation, experiment, linac	1741
	R.G. Heine, K. Aulenbacher, L.M. Hein, C. Matejcek IKP, Mainz, Germany
	Funding: Work supported by German Science Foundation (DFG) under the Cluster of Excellence "PRISMA" EXC1098/2014 The Milliampere Booster (MAMBO) is the injector linac for the Mainz Energy-recovering Superconducting Accelerator MESA. The MESA facility is currently under design at the Institut für Kernphysik (KPH) at Johannes Gutenberg University of Mainz (JGU). In this paper we will present the current design status of the linac.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW002
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TUPOW003	High Average RF Power Tests With 2 RF Vacuum Windows at PITZ	operation, vacuum, Windows, emittance	1744
	Y. Renier, G. Asova, M. A. Bakr, P. Boonpornprasert, J.D. Good, M. Groß, C. Hernandez-Garcia, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, O. Lishilin, G. Loisch, D. Malyutin, D. Melkumyan, A. Oppelt, M. Otevřel, G. Pathak, T. Rublack, I.V. Rybakov, F. Stephan, G. Vashchenko, Q.T. Zhao DESY Zeuthen, Zeuthen, Germany M. Bousonville, S. Choroba, S. Lederer DESY, Hamburg, Germany
	The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was built with the aim to develop and characterize electron sources for future usage at FLASH and at the European XFEL. Recently, the main focus at PITZ has been the study of gun reliability and photoinjector performance at high average power. The goal is to get stable and reliable operation with 6.4 MW peak power in the gun at 650 us RF pulse length and 10 Hz repetition rate. To achieve this, a new RF feed system with two RF windows was installed at PITZ in 2014. During this test, the old gun 4.2 with a modified back-plane design for better cathode contact has been used. In this contribution the results of the RF conditioning of gun 4.2 with a detailed interlock analysis will be reported as well as results from recent electron beam characterization.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW003
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TUPOW014	Simulation of High Resolution Field Emission Imaging in an rf Photocathode Gun	electron, cathode, solenoid, simulation	1769
	J.H. Shao, H.B. Chen, J. Shi, X.W. Wu TUB, Beijing, People's Republic of China S.P. Antipov, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA W. Gai ANL, Argonne, Illinois, USA F.Y. Wang SLAC, Menlo Park, California, USA
	Precisely locating field emission (FE) emitters on a realistic surface in rf structures is technically chal-lenging in general due to the wide emitting phase and the broad energy spread. A method to achieve in situ high resolution FE imaging has been proposed by using solenoids and a collimator to select electrons emitted at certain phases. The phase selection criterion and imaging properties have been studied by the beam dynamics code ASTRA. Detailed results are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW014
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TUPOW015	Experiment of High Resolution Field Emission Imaging in an rf Photocathode Gun	cathode, electron, experiment, background	1772
	J.H. Shao, H.B. Chen, J. Shi, X.W. Wu TUB, Beijing, People's Republic of China S.P. Antipov, S.V. Baryshev, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, G. Ha, E.E. Wisniewski ANL, Argonne, Illinois, USA F.Y. Wang SLAC, Menlo Park, California, USA
	The first in situ high resolution field emission (FE) imaging experiment has been carried out on an L-band photocathode gun test stand at Argonne Wakefield Accelerator facility (AWA). Separated strong emitters have been observed to dominate the field emission. Field enhancement factor, beta, of small regions on the cathode has been measured with the imaging system. It is shown that most strong emitters overlaps with the high beta regions. The post surface examinations reveal the origins of ~75% strong emitters overlap with the spots where rf breakdown have occurred. Detailed results are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW015
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TUPOW016	Development of a C-Band 4/8 Mev Dual-Energy Accelerator for Cargo Inspection System	cathode, controls, bunching, linac	1775
	J.H. Shao, H.B. Chen, W.-H. Huang, Q.X. Jin, Y.H. Liu, J. Shi, C.-X. Tang, X.W. Wu TUB, Beijing, People's Republic of China
	Modern cargo inspection system applies dual-energy X-ray for material discrimination. Based on the com-pact C-band 6 MeV standing-wave accelerating struc-tures developed at Tsinghua University, a compact C-band 4/8 MeV dual-energy accelerator has been pro-posed, fabricated and tested. Compared with that of the conventional S-band 3/6 MeV dual-energy accelera-tor at Tsinghua University, the volume and the weight of the C-band one has been reduced by ~40% and ~30%, respectively. Detailed review of this C-band dual-energy accelerator is present in the paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW016
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TUPOW018	Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation	radiation, electron, experiment, space-charge	1782
	Z. Zhang, H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, X.L. Su, C.-X. Tang, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, L.M. Zheng, Z. Zhou TUB, Beijing, People's Republic of China W. Gai ANL, Argonne, Illinois, USA
	High peak current electron bunch trains with tunable terahertz (THz) spacing are produced and measured experimentally. An initial picosecond periodic modulation in the temporal profile of a relativistic electron beam is magnified by the longitudinal space charge forces. As opposed to trying to reduce its smearing effect for large beam current, we take advantages of the nonlinear space charge oscillation through controlling the plasma phase advance. The spacing of the bunch train can be varied continuously either by tuning the velocity bunching of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. The narrow-band μJ-level THz radiation from the bunch train are also measured with tunable central frequency of the spectral from ~0.5 THz to 1.6 THz. The bunch train measurements are consistent with the particle tracking simulations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW018
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TUPOW025	First Beam Test of the High Brightness Photo-injector at NSRRC	laser, linac, electron, cathode	1800
	A.P. Lee, M.C. Chou, N.Y. Huang, J.-Y. Hwang, W.K. Lau, C.C. Liang, M.T. Tsou NSRRC, Hsinchu, Taiwan P. Wang NTHU, Hsinchu, Taiwan
	A High brightness injector at NSRRC is built for a VUV/THz free electron laser (FEL) facility and light source R&D. This injector with a photocathode rf gun with a solenoid for emittance compensation, a UV laser system, a 5.2 m S-band linac as well as various beam diagnostic tools has been installed in the linac test laboratory. The main goal is to produce beams with emittance smaller than 1 mm-mrad at energy of ~100 MeV. The other goal is to compress bunches to ~100 fs with charge of 100 pc and energy of ~30 MeV. In this contribution, an overview of the commissioning results of the photocathode rf gun and the laser system will be given. The first beam observation downstream the lianc will be presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW025
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TUPOW027	Model Independent Analysis of Beam Jitter on VELA	laser, cathode, timing, distributed	1806
	J.K. Jones, K.D. Dumbell, A.J. Moss, E.W. Snedden STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide high quality electron beams for accelerator systems development, as well as industrial and scientific applications. A key performance indicator for many applications is the inherent beam jitter on the machine (temporal, momentum and positional). Analysis of this beam jitter indicates that there are several independent mechanisms driving the beam motion. We use model independent analysis to correlate various dominant modes of beam jitter and compare them to simulations. We also compare the dominant modes before and after intervention work on the DLLRF timing system, and determine the relevant changes in beam motion.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW027
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TUPOW028	Comparison of Model vs. Reality for VELA	cathode, simulation, laser, solenoid	1810
	M.S. Toplis, J.W. McKenzie, B.D. Muratori, D.J. Scott, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide a high quality electron beam for accelerator systems development, as well as industrial and scientific applications. Currently, the RF gun can deliver short bunches, of the order of 100 fs to a few ps, with a charge of up to 250 pC, at the longer bunch lengths, and up to 4.5 MeV/c beam momentum. A model for the injector has been developed in ASTRA, together with a suite of scripts to create scans of the available parameters around an empirically found arbitrarily optimal working point. The space of parameters consists of everything that can be changed in the control room, and ranges from bunch charge to laser spot size on the cathode, together with all magnet settings where and if necessary. The various scans facilitate the task of identifying where exactly the accelerator is in terms of parameters and trends. Initial comparisons of screen images are made between the model and reality. Ultimately, the goal of the model is to robustly and repeatably establish a desired operating setup on a daily basis from an unknown switch on condition.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW028
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TUPOW029	Transverse Cavity Tuning at the Advanced Photon Source	cavity, linac, dipole, LabView	1814
	G.J. Waldschmidt, L.H. Morrison, T.L. Smith ANL, Argonne, Ilinois, USA
	A 15-cell transverse deflecting cavity based on a SLAC design was fabricated at the Advanced Photon Source and is being prepared for installation into the Injector Test Stand. A beadpull method for tuning was selected in lieu of the nodal position method to minimize the possibility of contamination and surface damage to the irises. The process has been successfully documented for many accelerating mode structures, but there has been limited application to dipole mode structures. In this paper, we will discuss the methodology for tuning and conditioning a 2.8 GHz backward-traveling wave deflecting cavity.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW029
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TUPOW034	Status Report of the Berlin Energy Recovery Linac Project BERLinPro	SRF, cavity, linac, vacuum	1827
	M. Abo-Bakr, W. Anders, 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, P. Kuske, J. Kuszynski, D. Malyutin, A.N. Matveenko, M. McAteer, A. Meseck, C.J. Metzger-Kraus, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, J. Rahn, J. Rudolph, M. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker 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 at the Berlin Adlershof site. The project is intended to expand the required accelerator physics and technology knowledge mandatory for the design, construction and operation of future synchrotron light sources. The project goal is the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the project progress: since spring 2015 the building is under construction, ready for occupancy in January 2017. The planning phase for the first project stage is completed for the warm machine parts, the SRF gun and partly for the SRF booster. Most of the components have been ordered and are in fabrication with some already delivered. An update of the status of the various subprojects as well as a summary of future activities will be given. Project milestones and details of the timeline will be reviewed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW034
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TUPOW035	First LLRF Tests of BERLinPro Gun Cavity Prototype	cavity, controls, linac, cathode	1831
	P. Echevarria, J. Knobloch, O. Kugeler, A. Neumann, A. Ushakov HZB, Berlin, Germany K.P. Przygoda DESY, Hamburg, Germany
	The goal of Berlin Energy Recovery Linac Project (BERLinPro) is the generation of a 50 MeV, 100-mA low emittance (below 1 mm mrad) CW electron beam at 2 ps rms bunch duration or below. Three different types of 1.3 GHz SRF modules will be employed: the electron gun, the booster and the main linac. Precise RF amplitude and phase control are needed due to the beam recovery pro-cess. In this paper we describe the first tests of the Low Level RF control of the first injector prototype at the HoBiCaT facility, implemented in the digital VME-based LLRF controller developed by Cornell University. Tuner movement control by an mTCA.4 system, together with further plans of using this technology will be also presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW035
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TUPOW036	Recent Developments and Operational Status of the Compact ERL at KEK	operation, linac, emittance, laser	1835
	T. Obina, M. Adachi, S. Adachi, T. Akagi, M. Akemoto, D.A. Arakawa, S. Araki, S. Asaoka, M. Egi, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X.J. Jin, E. Kako, Y. Kamiya, H. Katagiri, R. Kato, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondo, T. Konomi, A. Kosuge, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sakanaka, S. Sasaki, K. Satoh, Y. Seimiya, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, N. Terunuma, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, J. Urakawa, K. Watanabe, M. Yamamoto, N. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida KEK, Ibaraki, Japan R. Hajima, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma QST, Tokai, Japan M. Kuriki Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	The Compact Energy Recovery Linac (cERL) at KEK is a test accelerator in order to develop key components to realize remarkable ERL performance as a future light source. After the beam commissioning in December 2013, the legal current limit has been increased step-by-step like 1 uA, 10 uA, and 100 uA. Survey for the source of beam losses has been conducted in each step, and the study on beam dynamics and tuning has also been carried out. As a next step, 1 mA operation is scheduled in February 2016. In parallel to the increase in beam current, a laser Compton scattering (LCS) system which can provide high-flux X-ray to a beamline has been successfully commissioned. We report recent progress in various kinds of beam tuning: improvement of electron gun performance, high bunch charge operation, mitigation of beam losses, LCS optics tuning and bunch compression for THz radiation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW036
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TUPOW039	Simulation Study of the Beam Halo Formation for Beam Loss Estimation and Mitigation at KEK Compact ERL	simulation, cavity, operation, electron	1843
	O. Tanaka, T. Miyajima, N. Nakamura, T. Obina, M. Shimada, R. Takai KEK, Ibaraki, Japan
	Funding: Work supported by the "Grant-in-Aid for Creative Scientific Research" of JSPS (KAKENHI 15K04747) At KEK Compact ERL (cERL) we are aiming to produce high-current and low-emittance electron beams (up to 10 mA) without significant beam loss. We believe that beam halo makes a significant impact into the beam loss. Therefore, we are performing beam loss simulations to meet the results of the beam loss measurements. In particular, a simulation of the bunch tail originated from the electron gun was performed to understand the mechanisms of the beam halo formation. Since some measured beam profiles demonstrated unexpected halo particles, several factors such as misalignment of beam line elements and kicks from the steering coils were added into the simulation. Simulation study results are compared with the related beam loss and halo measurements here. Sakanaka et al., these proceedings
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW039
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TUPOW045	Pre-bunched Electron Beam Emittance Simulation and Measurement	electron, simulation, emittance, radiation	1864
	Yu.D. Kliuchevskaia, S.M. Polozov MEPhI, Moscow, Russia A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	LUCX facility at KEK is used as the high brightness pre-bunched electron beam source for radiation experiments. Emittance measurement and optimization is one of the important research activities for newly developed operation mode of the facility. Characterization of the pre-bunched beam (THz sequence of a hundred femtosecond bunches) properties opens a possibility to establish detailed simulation of the THz FEL radiation yield and continuously improve pre-bunched beam dynamics insight. Emittance has been measured by the Q-scan method. The measurement results and possible ways of emittance optimization are discussed. The measurement results are compared with beam dynamics simulation done by self-consistent BEAMDULAC-BL code.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW045
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TUPOW047	Generation of a Coherent Cherenkov Radiation by using Electron Bunch Tilting	radiation, electron, target, experiment	1870
	K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan R. Kuroda, Y. Taira AIST, Tsukuba, Ibaraki, Japan M. Nishida, M. Washio Waseda University, Tokyo, Japan J. Urakawa KEK, Ibaraki, Japan
	We have been developing a compact accelerator based a laser photocathode rf electron gun at Waseda University. Low emittance and short bunched electron beam can be generated from the gun. Also, the rf transverse deflecting cavity was developed for the bunch length measurement. We performed an experiment for generating a coherent Cherenkov radiation using bunch tilting. The rf transverse deflector can give a tilt for the electron bunch, and the tilt angle was set to the Cherenkov radiating angle which determined by the target refractive index. We successfully demonstrated a coherent Cherenkov radiation and the characterization of the radiation. The principle of coherent Cherenkov radiation generation, the experimental results and future prospective will be presented at the conference.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW047
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TUPOY010	6/9 MeV S-band Standing Wave Accelerating Structure for Container X-ray Inspection System at RTX	electron, cavity, linac, radiation	1924
	P. Buaphad, H.D. Park, S. Song, S.Y. Yoo RTX, Daejeon, Republic of Korea H.K. Cha, S.S. Cha, J.H. Ha, Y. Kim, B.C. Lee KAERI, Daejon, Republic of Korea
	Recently, there is a need of X-ray inspection system around the world to combat terrorism, drug and weapons smuggling, illegal immigration, and trade fraud. A compact standing wave (SW) linear accelerator (linac) for container X-ray inspection system has been produced at Radiation Technology eXcellence (RTX) to meet this growing need. The RF accelerating structure uses standing wave side-coupled structure fed by a 5 MW e2v magnetron with frequency of 2856 MHz. The electrons are accelerated from DC gun with energy of 25 keV to the final energy of 6 or 9 MeV at the X-ray target and generate X-ray with the dose rate of 8 Gy/min at 1 m after X-ray target. In this paper, we describe the design and optimization of side-coupled RF structure operating at π/2 mode. The beam dynamic of particle along the RF structure is also included in this paper by using ASTRA code.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY010
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TUPOY015	Design of Electron Gun and S-Band Structure for Medical Electron Linear Accelerator	electron, cavity, cathode, linac	1930
	N. Juntong, R. Chimchang SLRI, Nakhon Ratchasima, Thailand S. Rimjaem, C. Saisa-ard Chiang Mai University, Chiang Mai, Thailand
	Linear accelerator technology has been widely utilized for cancer treatment in hospital. This radiotherapy utilizes an accelerated electron beam to create the x-ray beam. The idea to fabricate the prototype of medical electron linac with low cost for domestic use in Thailand was proposed and the budget has been granted. In the first phase, the electron beam energy of the machine will be 6 MeV or equivalent to x-ray energy of 6 MV. The electron gun is a diode type for the simple and low cost fabrication. The design and simulation study of diode gun will be presented together with an analysis of an electron beam in this gun. The S-Band 6 MeV side-coupled RF cavity has been designed to be the accelerating structure of the machine. The electromagnetic fields of the structure have been studied. The electron behaviour when they traverse this cavity will be studied using a particle tracking code. Progression of the project is also presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY015
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TUPOY032	Design and Simulation of a Thermionic Electron Gun for a 1 MeV Parallel Feed Cockcroft-Walton Industrial Accelerator	electron, cathode, simulation, space-charge	1976
	M. Nazari, F. Abbasi Shahid Beheshti University, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran M. Jafarzadeh ILSF, Tehran, Iran
	Electron accelerators are made of different parts and one of the main part of every electron accelerator is its electron gun. In this article a diode electron gun is designed and simulated for a 1MeV parallel feed Cockcroft-Walton accelerator for industrial applications. The pierce configuration is selected for focusing electrode. Simulations are carried out using CST Particle Studio. The gun is thermionic with indirect heating of spherical dispenser cathode that is made from porous tungsten which is impregnated with barium compounds. The gun maximum achievable current is 200 mA at 10 kV and required current in our accelerator is about 100 mA.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY032
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TUPOY033	Design, Simulation and Comparison of Electrostatic Accelerating Tubes for a 1MeV Parallel Feed Cockcroft-Walton Industrial Accelerator	electron, simulation, industrial-accelerators, vacuum	1979
	M. Nazari, F. Abbasi Shahid Beheshti University, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran M. Jafarzadeh ILSF, Tehran, Iran
	In this article accelerating tubes whit different geometries and different constructions are designed and simulated for a 1 MeV parallel feed Cockcroft-Walton electrostatic industrial accelerator. Simulations are carried out using CST Particle Studio. The accelerating tubes with different focusing electrode and accelerating electrode geometries are designed and simulated and compared with each other. Finally whit respect to the comparisons best geometry is selected. In this tube a 1 MV DC voltage is applied at several stages during the accelerating electrodes. Maximum electron beam current in the tube is 200 mA. In this application accelerating electrodes and focusing electrodes are made of stainless steel and insulators between electrodes are made of Borosilicate glass.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY033
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TUPOY040	Advancements in Single-shot Electron Diffraction on VELA at Daresbury Laboratory	electron, laser, cavity, cathode	1988
	J.W. McKenzie, S.L. Mathisen, M.D. Roper, M. Surman STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D.M.P. Holland STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J.G. Underwood UCL, London, United Kingdom
	Electron diffraction on VELA at Daresbury Laboratory was first demonstrated in 2014. Since then, we have studied the machine parameter optimisation for single-shot diffraction patterns from single-crystal gold and silicon samples at bunch charges down to 60 fC. We present bunch length measurements for electron diffraction setups determined with a transverse deflecting cavity. We also discuss the current limitations of VELA for electron diffraction and the improvements to be made.
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WEOAB02	Record Performance of SRF Gun with CsK2Sb Photocathode	cathode, laser, electron, cavity	2085
	I. Pinayev, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, D.M. Gassner, M. Harvey, T. Hayes, R.L. Hulsart, J.P. Jamilkowski, Y.C. Jing, D. Kayran, R. Kellermann, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, K. Mernick, R.J. Michnoff, T.A. Miller, M.G. Minty, G. Narayan, P. Orfin, D. Phillips, T. Rao, J. Reich, T. Roser, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, V. Soria, Z. Sorrell, R. Than, C. Theisen, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman, 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. High-gradient CW photo-injectors operating at high ac-celerating gradients promise to revolutionize many sci-ences and applications. They can establish the basis for super-bright monochromatic X-ray and gamma-ray sources, high luminosity hadron colliders, nuclear- waste transmutation or a new generation of microchip produc-tion. In this paper we report on our operation of a super-conducting RF electron gun with a record-high accelerat-ing gradient at the CsK2Sb photocathode (i.e. ~ 20 MV/m) generating a record-high bunch charge (i.e., 2 nC). We briefly describe the system and then detail our experimental results.
	Slides WEOAB02 [28.500 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAB02
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WEPMB014	Cavity Performance of the Prototype KEK Superconducting RF Gun	cathode, cavity, target, SRF	2148
	T. Konomi, E. Kako, E. Kako, Y. Kobayashi, Y. Kobayashi, K. Umemori, K. Umemori, S. Yamaguchi KEK, Ibaraki, Japan R. Matsuda Mitsubishi Heavy Industries Ltd. (MHI), Takasago, Japan T. Yanagisawa MHI, Hiroshima, Japan
	A superconducting RF (SRF) gun can generate a high current and high energy beam. It has a possibility to achieve requirement from high performance ERL and high repetition FEL. Target values of the L-band KEK SRF gun are that beam repetition is 1.3 GHz, beam current is 100 mA, beam energy is 2 MeV, emittance is 1 mm mrad or less. The number of cell is 1.5. Accelerating energy of 2 MeV corresponds to 42 MV/m of maximum surface field. The photocathode is designed to be illuminated by excitation laser from backside. The SRF gun cavity consists of the 1.5 cell accelerating cavity, cathode plug and choke filter for protecting the heating of cathode plug. To evaluate these parts individually, these parts are added step by step. High gradient test of the accelerating cell without cathode plug and choke filter was done. The surface peak electric field reached 66 MV/m, and this meet the target value 42 MV/m sufficiently. Next high gradient test will be done after adding the choke filter. The choke filter is designed to be simple to wash choke cell easier. In this conference, we will report the design, fabrication and high gradient performance of the SRF gun cavity with choke filter.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB014
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WEPMB026	MHI-MS's Production Activities of Superconducting Cavity	cavity, SRF, electron, superconducting-RF	2180
	H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa MHI-MS, Kobe, Japan E. Kako, T. Konomi, H. Nakai, K. Umemori KEK, Ibaraki, Japan
	Mitsubishi Heavy Industries Mechatronics Systems, Ltd. (MHI-MS), a subsidiary of MHI, took over MHI's accelerator business on October 1, 2015, and has been developing the business since that time. MHI-MS has developed manufacturing process of superconducting cavities continuously. In this presentation, recent progress will be reported.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB026
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WEPMR007	Electron Lens Construction for the Integrable Optics Test Accelerator at Fermilab	electron, solenoid, optics, focusing	2271
	M.W. McGee, K. Carlson, L.E. Nobrega, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy. The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p⁺) diagnostic test ring. Construction of an electron lens for IOTA is necessary for both electron and proton operation. Components required for the Electron Lens design include; a 0.8 T conventional water-cooled main solenoid, and magnetic bending and focusing elements. The foundation of the design relies on repurposing the Fermilab Tevatron Electron Lens II (TELII) gun and collector under ultra-high vacuum (UHV) conditions.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR007
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WEPMY013	A Spatially Separated Two Frequency RF Gun Design for Beam Brightness Improvement	emittance, laser, cavity, brightness	2572
	Z. Zhang, C.-X. Tang, Z. Zhang TUB, Beijing, People's Republic of China H.J. Qian LBNL, Berkeley, California, USA
	Recent theoretical and experimental studies shows that transverse beam brightness of photoinjector can be improved by cigar beam photoemission, and beam peak current are then increased with a RF buncher following the gun. We apply this concept to a S-band photoinjector by adding a harmonic RF buncher closely to a S-band RF gun, forming a compact spatially separated two frequency RF gun, targeting a 200 pC beam with emittance < 0.2 mm·mrad and 30 A peak current. Both S/X-band and S/C-band combinations are considered, and an optimized solution with 30 A peak current and 0.1 mm·mrad slice emittance are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY013
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WEPMY037	Cold Model Cavity for 20-K Cryocooled C-band Photocathode RF Gun	simulation, cavity, coupling, impedance	2635
	T. Tanaka, M. Inagaki, R. Nagashima, K. Nakao, K. Nogami, T. Sakai, K. Takatsuka LEBRA, Funabashi, Japan M.K. Fukuda, T. Takatomi, N. Terunuma, J. Urakawa, M. Yoshida KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). A cryocooled 2.6-cell C-band photocathode RF gun is under development at Nihon University in collaboration with KEK. The RF characteristics of a pillbox-type 2.6-cell C-band RF cavity at 20 K were in agreement with the theoretical predictions. The result of the cold test for a cavity with the input coupler confirmed the same characteristics. Based on these results a refined cold model of the 20-K cryocooled photocathode RF gun has been designed using SUPERFISH and CST-STUDIO. The separation between the TM01 pi and the TM01 half-pi modes has been increased from 20 MHz to 52 MHz by extending the diameter of the cavity iris and reducing the disk thickness. The 2.6-cell structure has been modified from pillbox to ellipsoid-like type. The end-plate of the 0.6-cell cavity has a center hole for bead-pull measurements of the on-axis electric filed through the entire structure. Mounting of a photocathode assembly in the end-plate has not been considered, since the purpose is solely to measure the low-power and low-temperature RF characteristics. A new design for the input coupler has been employed. The cavity will be completed early in 2016.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY037
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WEPMY038	Optimization of C-band RF Input Coupler as a Mode Converter for 20-K Cryocooled Photocathode RF Gun	cavity, coupling, simulation, insertion	2638
	T. Tanaka, M. Inagaki, R. Nagashima, K. Nakao, K. Nogami, T. Sakai, K. Takatsuka LEBRA, Funabashi, Japan M.K. Fukuda, T. Takatomi, N. Terunuma, J. Urakawa, M. Yoshida KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). Development of a cryocooled 2.6-cell C-band photocathode RF gun has been conducted at Nihon University in collaboration with KEK. An RF mode converter from square TE10 to circular TM01 mode has been employed as an RF input coupler that has a coupling coefficient of approximately 20 at 20 K to the 2.6-cell accelerating structure. In the previous design, the circular waveguide in the mode converter formed part of the accelerating cavity. After the cold test of the cavity completed in 2014, the coupler design was modified to work as a pure mode converter with a VSWR of 1 at 5712 MHz. From the design simulation using CST-STUDIO, the insertion loss in the converter is 0.2 %. The TM010 and TM011 modes excited in the circular waveguide were separated by several ten MHz from the accelerating frequency. The simulation has suggested that the amplitude of the transverse electric filed on the axis in the circular waveguide is reduced to approximately 2 % of that in the longitudinal direction.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY038
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WEPMY039	Time Response Measurements for Transmission-Type GaAs/GaAsP Superlattice Photocathodes	electron, laser, cavity, brightness	2641
	N. Yamamoto, X.J. Jin KEK, Ibaraki, Japan M. Hosaka, Y. Takashima, K. Yamaguchi Nagoya University, Nagoya, Japan M. Katoh UVSOR, Okazaki, Japan
	Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. Recently we have developed the strain compensated superlattice (SL) photocathode. In the strain compensated SLs, the equivalent compressive and tensile strains introduced in the well and barrier SL layers so that strain relaxation is effectively suppressed with increasing the SL layer thickness and high crystal quality can be expected. In this study, we fabricated the GaAs/GaAsP strain compensated SLs with the thickness up to 90-pair SL layers. Up to now, the electron spin polarization of 92 % and the quantum efficiency of 1.6 % were simultaneously achieved from 24-pair sample. In this study, to compare the time response performances with the SL thicknesses, the measurements were carried out for conventional and strain compensated SL PCs. We show the measurement results and discuss the physics.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY039
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WEPOR007	Recent Improvements in Drive Beam Stability in CTF3	feedback, klystron, operation, linac	2677
	L. Malina, R. Corsini, D. Gamba, T. Persson, P.K. Skowroński CERN, Geneva, Switzerland
	The proposed Compact Linear Collider (CLIC) uses a high intensity, low energy drive beam producing the RF power to accelerate the low intensity main beam with 100 MeV/m gradient. This scheme puts stringent requirements on drive beam stability in terms of phase, energy and current. Finding and understanding the sources of jitter plays a key role in their mitigation. In this paper, we report on the recent studies in the CLIC Test Facility (CTF3). New jitter and drift sources were identified and adequate beam-based feed-backs were implemented and commissioned. Finally, we present the resulting improvement of drive beam stability.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR007
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WEPOY015	Longitudinal Bram Dynamics at Rf-Compressor	space-charge, simulation, electron, brightness	3011
	A.V. Andrianov BINP SB RAS, Novosibirsk, Russia
	Nowadays the usage of charged particle beams for study of nature became widespread. Modern experiments are require particle beams with duration around hundreds femtosecond. Relatively simple and cheap method of production such pulses is using RF-gun with photocathode and then the special insertion device which compress the beam. The paper described the RF-compressor for the electron beam. In result of work was obtained a device configuration. Electromagnetic field configuration and distribution were simulated for the configuration. Beam dynamics was computed in this field distribution. Incoming beam parameters are following: beam length is 1-5ps, beam charge is 0.1-2pC and energy is 3MeV. Output beam duration was compressed to less than 150fs. Influence of RF-compressor at beam parameters was estimated.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY015
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WEPOY024	Beam Dynamics Simulations of the Thomx Linac	emittance, solenoid, laser, electron	3036
	L. Garolfi, C. Bruni, M. El Khaldi, P. Lepercq, C. Vallerand LAL, Orsay, France N. Faure PMB-ALCEN, PEYNIER, France
	ThomX Compton light source is designed to maximise the average X-ray flux providing a compact and tunable machine which can operate in hospitals or in museums. These constraints impose the choice of a high collision rate which is based on S-band Linac whose energy is 50-70 MeV combined to an electron storage ring. As most of the performances of the electron beam at the interaction point depend on the beam quality at the ring entrance, the linear accelerator must be carefully designed and especially the photo-injector. Simulations have been carried out in order to optimise the emittance for the ring entrance. Indeed, for a bunch charge of 1 nC, space charge effects usually dominate the total beam emittance. The latter can be minimized at the end of the Linac by means of emittance compensation. The best configuration across all the parameters will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY024
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WEPOY037	Optimization of THz Radiation Pulses at FLUTE	electron, radiation, simulation, linac	3067
	M. Yan, A.-S. Müller, M.J. Nasse, M. Schuh, M. Schwarz KIT, Karlsruhe, Germany
	The accelerator test facility FLUTE (Ferninfrarot Linac Und Test Experiment) will allow research and development in electron accelerator technology as well as photon science. Electron bunches of durations in the femtosecond range will be provided to generate intense THz radiation. Start-to-end simulation of the accelerator has been performed with the bunch length as the optimization objective. Based on the resulting charge distribution the expected THz field properties can be calculated. In this paper we combine the two tools and present first results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY037
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WEPOY039	GIOTTO: A Genetic Code for Demanding Beam-dynamics Optimizations	electron, software, space-charge, interface	3073
	A. Bacci Istituto Nazionale di Fisica Nucleare, Milano, Italy V. Petrillo Universita' degli Studi di Milano, Milano, Italy M. Rossetti Conti Universita' degli Studi di Milano & INFN, Milano, Italy
	GIOTTO is a software based on a Genetic Algorithm (GA). Its development started in 2007 with a work published on NIMB (263, 2007, 488-496) and presented at PAC07 (THPAN031). When the parameters, defining an acceleration machine beam line, are strongly correlated in nonlinear way, the GAs are a powerful tool to coup with these difficulties. These conditions are typically generated by space-charge, as in the high brightness e-beam photo-injectors or when the Velocity Bunching compression technique (VB) is used. The power of GIOTTO is the adaptability to different cases, given by its own structure that permits to drive different external codes in series, the possibility to define a user dependent multi objective fitness function and function constraints on the beam dynamics, as well as the possibility to turn off the genetic optimization to perform statistical analysis (machine jitters). Up today it has been used in Thomson/Compton sources, ultra-short e-bunches generation by VB, focusing channel and dog-leg lines optimizations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY039
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THOAB02	Concept of RF Linac for Intra-pulse Multi-energy Scan	klystron, linac, electron, experiment	3180
	A.K. Krasnykh, J. Neilson, A.D. Yeremian SLAC, Menlo Park, California, USA
	Funding: Work supported in part by US Department of Energy under contract DE-AC02-76SF00515 A material discrimination based on X-Ray systems is typically achieved by alternating photon pulses of two different energies. A new approach relies on the ability to generate X-ray pulses with an end-point energy that varies in a controlled fashion during the duration of the pulse. An intra-pulse multi-energy X-ray beam device will greatly enhance current cargo screening capabilities. This method originally was described in the AS&E patents. This paper addresses a linac concept for the proposed scan and describes some proof of concept experiments carried out at SLAC. A. Arodzero et al., 'System and methods for intra-pulse multi-energy and adaptive multi-energy X-ray cargo inspection', US Patent 8,457, 274, 2013
	Slides THOAB02 [1.776 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOAB02
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THOAB03	Ultrafast Electron Microscopy using 100 Femtosecond Relativistic-Energy Electron Beam	electron, emittance, brightness, laser	3183
	J. Yang, K. Kan, K. Tanimura, Y. Yoshida ISIR, Osaka, Japan J. Urakawa KEK, Ibaraki, Japan
	An ultrafast detection technique on 100 fs time scales over sub-nanometer (even atomic) spatial dimensions has long been a goal for the scientists to reveal and understand the ultrafast structural-change induced dynamics in materials. In this paper, the generation of femtosecond electron pulses using the RF gun and the first prototype of femtosecond time-resolved relativistic-energy ultrafast electron microscopy (UEM) are reported. Finally, both relativistic-energy electron diffraction and image measurements in the UEM prototype are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOAB03
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THPMB025	The Effect of Magnetic Field on the Secondary Electron Yield in the Ultra-High Vacuum Environment	electron, permanent-magnet, vacuum, synchrotron-radiation	3281
	J. Wang, Y. Wang, W. Wei, Y.H. Xu, B. Zhang, T. Zhang, Y.X. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	A secondary electron emission measurement system has been designed and used to study the secondary electron emission (SEE) of different materials with an independently adjustable energy of 50 eV to 5 keV at National Synchrotron Radiation Laboratory. Here, we obtained the characteristics of the SEE yield from Pd film coatings, under the condition of magnetic field and without magnetic field. Then it was analysed that the effect of magnetic field on the secondary electron yield in the ultra-high vacuum environment. The results show that magnetic field shielding is critical to avoid the influence of magnetic field during secondary electron yield (SEY) measurements.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB025
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THPMB048	Design and Optimisation of the ELENA Electron Cooler Gun and Collector	electron, solenoid, simulation, cathode	3354
	G. Tranquille, J. Cenede CERN, Geneva, Switzerland
	Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler. The performance of the cooler is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the quality of the guiding magnetic field and the efficient recuperation of the electrons in the collector ensure that the cooler performance is optimal. We have used COMSOL Multiphysics to design and optimise the complete electron cooler with particular attention to the gun and collector. This software suite uses physics interfaces for modelling common applications and then allows the user to combine the different interfaces in one multi-physics simulation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB048
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THPMB052	Studies on Electron Beam Injector System for Linac-based Coherent Thz Source in Thailand	electron, undulator, linac, simulation	3366
	W. Thongpakdi, S. Rimjaem Chiang Mai University, Chiang Mai, Thailand
	Funding: The Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and the Development and Promotion of Science and Technology Talents Project (DPST). At the Plasma and Beam Physics Research Facility, Chiang Mai University, a thermionic cathode RF electron gun and alpha magnet are used together as an injector system for a linac-based THz source. Investigate the optimal performance of the injector system, beam dynamic simulations are performed by computer codes PARMELA, ASTRA and ELEGANT. The input 3D field distributions of the RF-gun for PARMELA and ASTRA simulations are obtained from the RF modeling program CST Microwave Studio. The beam transport calculation using the program ELEGANT is performed to study behavior of electrons from the gun exit through the alpha magnet, a travelling wave linac, magnet elements, drift tubes, and related beam diagnostic components. Energy slits inside the alpha magnet vacuum chamber is used to select electrons with desired kinetic energies. The alpha magnet compresses electron bunches with certain bunch length before the beam entering the linac to obtain minimum energy spread and shortest bunch length at the experimental station. Results of electron beam optimization with appropriated conditions for generation of intense coherent THz radiation will be reported and discussed in this contribution. This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and DPST.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB052
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THPMB056	Witness Beam Production with an RF Gun and a Travelling Wave Booster Linac for AWAKE Experiment at CERN	emittance, linac, booster, proton	3378
	O. Mete Apsimon, G.X. Xia UMAN, Manchester, United Kingdom R. Apsimon, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S. Döbert CERN, Geneva, Switzerland
	Funding: This work is supported by the Cockcroft Institute Core Grant and STFC. AWAKE is a unique experiment that aims to demonstrate the proton driven plasma wakefield acceleration. In this experiment, proton bunches from the SPS accelerator will be injected into a 10m long pre-formed plasma section to form wakefields of hundreds MV/m to several GV/m. A second beam, e.g., the witness beam, will be injected after the protons in an appropriate phase to gain energy from the wakefields. A photo-injector will be utilised to deliver this second beam. It consists of an S-band RF gun followed by a meter long accelerating travelling wave structure (ATS). The RF gun was recuperated from existing PHIN photo-injector. A 3D RF design of the ATS was done by using the CST code and the field maps produced were used to characterise the electron beam dynamics under space charge effect by using the PARMELA code. The impact of the mechanical errors on the beam dynamics were investigated.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB056
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THPMY043	Collimation System Design for LCLS-II	undulator, linac, collimation, electron	3755
	M.W. Guetg, P. Emma, M. Santana-Leitner, J.J. Welch, F. Zhou SLAC, Menlo Park, California, USA
	Funding: DOE contract \#DE-AC02-76SF00515 The planned LCLS-II FEL has an average beam power of up to 1.2 MW and a repetition rate of up to 1 MHz, both of which entail serious challenges for beam halo collimation. This paper summarizes the efforts to assess the proposed collimation system. The undulator section is specifically focused on due to its high loss sensitivity (maximal 12 mW). This proceedings concentrate on field emissions of the gun. Different dark current distribution, linac configurations and simulation programs were used to increase assurance of the results. Filled phase-space tracking further supplemented an independent prove of the collimation system effectiveness and expands to include beam-halo originating from different sources than the gun.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY043
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THPOR046	CEPC 650 MHz Klystron Development	klystron, simulation, electron, operation	3891
	Z.S. Zhou, D. Dong, S. Fukuda, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, .. Zaib-un-Nisa IHEP, Beijing, People's Republic of China S. Fukuda KEK, Ibaraki, Japan
	The CEPC collider beam power is about 100 MW, so the efficiency of amplifier is very important for cost of project implementation. The high power klystron is the more attractive because of its potential for higher eﬃciency than solid state amplifier. For CEPC klystron output power is not so high, the operation voltage can be a safe value. Advantage for single beam: reliable, low phase noise, some perspective technology can be used to improve efficiency. The accelerating frequency is 650 MHz, output power is a maximum power of 800kW, and efficiency is about 70%. In this paper, the specifications and developments of 650 MHz CW klystron, including the klystron gun prototype and future high efficiency consideration are summarized.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR046
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THPOW001	Design of a 4.6-Cell RF Gun for the PHIL accelerator at LAL	emittance, cavity, impedance, coupling	3922
	P. Chen, C. Bruni, S. Chancé, L. Garolfi, A. Gonnin, P. Lepercq, T. Vinatier LAL, Orsay, France
	A photo-injector with 4.6-cell and resonate frequency of 2.998 GHz has been designed and studied to replace the 2.5-cell RF gun + booster association. The cavity iris shape and dimensions were simulated systematically to optimize the shunt impedance. In this study, electron beam reaches to 9.7 MeV with a moderate peak accelerat-ing gradient of 80 MV/m. Considering a beam charge of 1 nC/bunch, average transverse emittance of ~ 5.9 πmm mrad and energy spread of ~ 0.8% can be obtained at the exit of the gun. The RF input power is only 10.2 MW due to the high shunt impedance. Asymmetry of the electric field due to the coupling port has also been studied using 3D codes for RF and beam dynamics calculations. We will present the RF design and beam calculations results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW001
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THPOW002	Electromagnetic, Thermal, and Structural Analysis of a THOMX RF Gun Using ANSYS	cavity, electron, coupling, simulation	3925
	M. El Khaldi, J. Bonis, A. Camara, L. Garolfi, A. Gonnin LAL, Orsay, France
	Photocathode RF guns are used in the first stage of electron beam generation and acceleration. The RF gun of THOMX is a 2.5 cell standing wave copper cavity with resonance frequency of 2998.55 MHz at 30 °C under vacuum. The metal photocathode such as copper or magnesium is inserted into the backplane of the cavity. Due to high repetition rates up to 50 Hz with the average dissipated power into the internal surfaces up to 1.5 kW, causing a heating and deformation of the cavity shape. Therefore, the cooling system of the device has to be well designed to take under control the deformations of the structure, providing a temperature increase as small and uniform as possible. For this purpose a fully coupled electromagnetic-thermal-structural finite element analysis on this gun has been performed with Ansys workbench. Numerical results show that the gun could operate at 3 μs RF pulse length and 50 Hz repetition rate with an average dissipated power of 1.5 kW. The gun average temperature is around 30 °C while the incoming water temperature is around 24°C. Internal speed of water is 2.5 m/s which corresponds to 15 l/min for the incoming water. The total pressure drop is around 0.4 bar
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW002
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THPOW003	Highlights on Metallic Photocathodes Used in SRF Gun	cathode, SRF, laser, emittance	3928
	R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate HZDR, Dresden, Germany P.N. Lu, H. Vennekate TU Dresden, Dresden, Germany
	For the accelerator-based light sources and the electron colliders, the development of photoinjectors has become a key technology. Especially for the superconducting radio frequency cavity based injector (SRF Gun), the searching for better photocathodes is always a principal technical challenge. To use metallic photocathodes for ELBE SRF Gun is the primary choice to prevent cavity contamination. In this contribution, we will report the investigation of Magnesium (Mg) in ELBE SRF gun, including laser cleaning treatment and the measurement on quantum efficiency, Schottky effect, dark current and damage threshold. The work is supported by the European Community under the FP7 programme (EuCARD-2 and LA3NET) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW003
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THPOW007	Cs2Te Photocathode Response Time Measurements and Femtosecond Comb Electron Beam Generation as a Milestone Towards Pre-Bunched Thz Fel Realization	electron, radiation, laser, FEL	3941
	A. Aryshev, Y. Honda, K. Lekomtsev, M. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Funding: Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan and JSPS KAKENHI: 23226020 and 24654076 Currently there is a rapidly growing demand to increase the brightness of electron beams generated by conventional RF guns as well as to decrease the cost of the injector accelerator system for many research facilities worldwide. To address this demand we investigate one of the most important parameter of the high Q.E. conventional semiconductor Cs2Te photocathode, its response time. It sets the principle limitation for generated bunch length and hence maximum achievable beam brightness of electron diffraction and pre-bunched THz FEL facility's injectors. The experimental investigation was done at KEK: LUCX facility. The Cs2Te photocathode response time better than 250 fs was demonstrated. The generation of 4 micro-bunch comb electron beam with variable time separation as a crucial technology for pre-bunched THz FEL realization was achieved.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW007
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THPOW008	DC Photoemission Gun Upgrade at the Compact ERL	operation, high-voltage, FEL, vacuum	3944
	N. Nishimori, R. Hajima, R. Nagai JAEA, Ibaraki-ken, Japan Y. Honda, T. Miyajima, T. Uchiyama, M. Yamamoto KEK, Ibaraki, Japan M. Mori JAEA/Kansai, Kyoto, Japan
	Funding: This work is partially supported by a JSPS Grant-in-Aid for Scientific Research in Japan (15H03594). The DC photoemission gun at the compact ERL (cERL) has stably provided beam for ERL commissioning and laser Compton scattering experiments since April 2013. The operational voltage has however been limited to 390 kV due to failures of two segments out of the ten segmented insulator. In order to recover 500 kV operation, we installed an additional two segmented insulator on the existing ten segmented insulator during summer shutdown in 2015. The details of the gun upgrade and the operational experience of the upgraded cERL gun will be presented.
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THPOW009	Optimal Design of a Photocathode Electron Gun with High-brightness and High-repetition Rate Based on Genetic Algorithm	impedance, electron, cavity, laser	3947
	Zh. X. Tang, X.M. Yang, W.Q. Zhang DICP, Dalian, People's Republic of China Y.J. Pei, Y. Yu USTC/NSRL, Hefei, Anhui, People's Republic of China
	A low RF frequency of normal conducting photocathode gun with high-brightness and high-repetition rate is designed as an electron source of the Next Generation Light Source (NGLS). In order to optimize the performance of the gun, a genetic multi-objective algorithm has been used. A genetic algorithm is used because of the inherent complexity of the large number of parameters of the cavity geometry available for optimization. On the other hand, the multiplicity of requirements on the beam, which include beam emittance, beam pulse length, energy chirp, as well as pulse shape and peak current, leads to a multi-objective approach for the optimization technique. In this paper, we present the status of the optimization simulations, using the SUPERFISH and PERMELA particle-in-cell code.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW009
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THPOW010	Study on Characteristics of Asymmetric Centre Iris of Photocathode Microwave Electron Gun	electron, emittance, electromagnetic-fields, cathode	3951
	Zh. X. Tang, X.M. Yang, W.Q. Zhang DICP, Dalian, People's Republic of China Y.J. Pei USTC/NSRL, Hefei, Anhui, People's Republic of China
	The characteristics of asymmetric iris between first cell and second cell of 1.6 cell photocathode gun are studied. For π-mode, the RF radial field of two sides of the iris is non anti-symmetric. Thus, the RF transverse force at the iris is not negligible. In this paper, we present the status of the optimization simulations, using the SUPERFISH and PARMELA particle-in-cell code. Numerical results of beam dynamics show that it can improve the emittance at the exit of the gun.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW010
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THPOW011	The Measurement System of the Electron Gun with Double-anode Structure	cathode, electron, vacuum, high-voltage	3954
	F.L. Shang, J. Li, L. Shang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: National Natural Science Foundation of China(11175181); National Natural Science Foundation of China(10875116) The double-anode structure with an intermediate electrode has been proposed to overcome the strong space-charge force on the cathode and improve the transverse focusing, which make the goal of high perveance and high compression ratio achieved. This gun plays a key role as the external injecting electron source of the independently-tunable-cells (ITC) RF gun. In order to understand the quality of the beam, a measurement system has been designed. The papers present the measurement system and the result of the test.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW011
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THPOW018	Simulations of Field Emitted Dark Current Dynamics in DC Photoinjectors	simulation, electron, cavity, space-charge	3971
	P.J. Tipping, J.W. McKenzie, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Field emission is a concern in injectors with DC photoelectron guns because of the constant generation of dark current, which is accelerated down the beam line and can deteriorate the photoemitted bunch quality and lead to hardware damage. Simulations were carried out on the co-propagation of a field emitted, dark current halo and a photoemitted bunch in a typical 350 kV gun as used in an ERL or FEL injector, followed by a single cell buncher cavity. The photoemitted bunch repelled the halo longitudinally, leaving the area in the centre of the bunch with very low dark current, surrounded by two peaks of relatively high current at the front and back of the bunch. The peaks in current occur at all levels of dark current and were about 3.5 times the amplitude of the undisturbed dark current. The buncher caused the dark current to overcompress, forming a 'ghost' pulse an order of magnitude larger than the initial level of dark current, in front of the photoemitted bunch.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW018
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THPOW019	Beam Characterisation and Machine Developments at VELA	experiment, cathode, electron, space-charge	3975
	D. Angal-Kalinin, A.D. Brynes, F. Jackson, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.L. Militsyn, B.D. Muratori, T.C.Q. Noakes, M.D. Roper, Y.M. Saveliev, D.J. Scott, R.J. Smith, E.W. Snedden, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S.D. Barrett, C.P. Topping, A. Wolski The University of Liverpool, Liverpool, United Kingdom C.S. Edmonds, F. Jackson, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.D. Muratori, Y.M. Saveliev, D.J. Scott, C.P. Topping, P.H. Williams, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom
	An overview is presented of developments on VELA (Versatile Electron Linear Accelerator), an RF photo-injector with two user stations at Daresbury Laboratory. Numerous commissioning, machine development, beam characterisation and user experiments have been completed in the past year. A new beamline and a dedicated multiuser station have been commissioned and the first experiments performed. A number of measures have been taken to improve the stability of machine by mitigating a phase drift, laser beam transport drift and a coherent ~1 Hz beam oscillation. The 6D phase space of the electron beam has been characterised through quad scans, transverse tomography and with a transverse deflecting cavity.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW019
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THPOW020	S-Band Photoinjector Investigations by Multiobjective Genetic Optimizer	emittance, laser, brightness, cathode	3979
	H.J. Qian, D. Filippetto, F. Sannibale LBNL, Berkeley, California, USA
	Photoinjectors has witnessed great progress in the past few decades, with low duty cycle high gradient guns, such as normal conducting S/L band gun, pushing the peak beam brightness frontier, and CW guns, such as DC gun, SRF gun and VHF gun, pushing the average beam brightness frontier. Due to different degrees of complexity, pulsed high gradient photoinjectors are usually optimized by manual scans, while CW photoinjectors are optimized by multi-objective genetic optimizers. In this paper, a multi-objective genetic optimizer is used to revisit S-band photoinjector beam brightness optimizations, showing a trade-off between peak current and transverse emittance, with the optimized injector layout depending on bunch charge and peak current. For 200 pC case, the final beam core brightness at injector exit is close to cathode maximum brightness in the 'cigar beam' regime. Assuming a thermal emittance of 0.5 μm/mm and a beam charge of 200 pC, about 90 nm slice emittance at 20 A peak current is achieved.
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THPOW025	Photocathode Growth and Characterization Advances at Cornell University	electron, photon, emittance, cathode	3990
	L. Cultrera, A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, H. Lee, R.A. Lipton, T.P. Moore Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Alkali-antimonides based photocathodes have demonstrated outstanding performance in high brightness electron beam production suitable for a wide range of applications such as FELs, ERLs and UED and for use in photomultiplier devices with picosecond resolution aimed at photon counting application in medicine and High Energy Physics. The photocathode laboratory at Cornell University is dedicated to studying the growth procedures and characterizing the properties in a wide range of photocathodes materials. Different experimental arrangements and alkali metal sources have been successfully explored to date to synthesize photosensitive materials. Recent work on commissioning a new growth chamber equipped with effusion cells loaded with pure metal allowing uniform deposition over large area substrates resulted on successful growth of photocathodes with extended sensitivity in the IR part of the spectrum and high efficiency alkali antimonides containing Rb metal. This and other advances aimed at demonstrating superior photocathodes will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW025
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THPOW026	LLNL X-band RF Gun Results	laser, electron, emittance, dipole	3993
	R.A. Marsh, G.G. Anderson, C.P.J. Barty, D.J. Gibson LLNL, Livermore, California, USA Y. Hwang UCI, Irvine, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 An X-band test station and Inverse Compton Scattering (ICS) x-ray source has been built and commissioned at LLNL. The electron beam source is a unique 5.59 cell RF photoinjector, which will be described in detail, including: quantum efficiency, emittance measurements, energy spread and jitter, final focus spot size and stability, laser profile and final transport, and consistency with expectations based on beam dynamics simulations.
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THPOW028	Automated Design for Standing Wave Electron Photoguns: TOPGUN RF Design	toolkit, simulation, coupling, cavity	3999
	A.D. Cahill UCLA, Los Angeles, California, USA M. Dal Forno, V.A. Dolgashev SLAC, Menlo Park, California, USA
	Funding: DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515 Systematic design of RF photoguns involves multiple RF simulations in conjunction with beam dynamic simulations. RF simulations include tuning gun frequency, matching the gun to the feeding RF circuit, balancing the on axis electric fields between gun cells, minimizing surface electric and magnetic fields and power consumption, and optimizing separation of resonant mode frequencies. We created a tool that allows this multiple parameter optimization to be done automatically. We used SUPERFISH to accomplish the RF simulations. We present an example of the rf photogun TOPGUN design using these tools.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW028
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THPOW059	UV Pulse Shaping with a-BBO Crystals for the Photocathode RF Gun	laser, electron, flattop, optics	4079
	D. Wang, W.-H. Huang, L.X. Yan TUB, Beijing, People's Republic of China
	Recently, manipulation with the drive laser plays a significant role in high brightness electron beam production by the photocathode RF gun. The method based on pulse stacking with birefringent crystal serials was tried to longitudinally shape ultraviolet laser pulse. Using four or five pieces of a-BBO crystals to stack an input UV pulse with appropriate initial duration into 16 or 32 sub-pulses to form quasi flattop UV laser pulse, which can be applied for emittance optimization of the electron beam based on the photocathode RF gun. Moreover, the negative slop of the energy transmittance of a-BBO serials is also revealed to be a passive stabilization mechanism for energy jitter reduction in the driving laser. With appropriate design of a-BBO serials, this method can fulfill the requirements for driving laser in a broad scope of applications such as x-ray FELs and high-power Terahertz(THz) radiation production.
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THPOY027	Commissioning Status of SuperKEKB Injector Linac	electron, emittance, linac, injection	4152
	M. Satoh, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Iwase, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, S. Kazama, M. Kikuchi, H. Koiso, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, D. Satoh, Y. Seimiya, T. Shidara, A. Shirakawa, M. Suetake, H. Sugimoto, T. Suwada, M. Tanaka, M. Tawada, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou KEK, Ibaraki, Japan
	The SuperKEKB main ring is currently being constructed for aiming at the peak luminosity of 8 x 10³⁵ cm^-2s⁻¹. The electron/positron injector linac upgrade is also going on for increasing the intensity of bunch charge with keeping the small emittance. The key upgrade issues are the construction of positron damping ring, a new positron capture system, and a low emittance photo-cathode rf electron source. The injector linac beam commissioning started in the October of 2013. In this paper, we report the present status and future plan of SuperKEKB injector commissioning.

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MOXBA01

Beam Commissioning of PAL-XFEL

undulator, laser, linac, cathode

6

J.H. Han
PAL, Pohang, Kyungbuk, Republic of Korea

The Pohang Accelerator Laboratory X-ray Free electron Laser (PAL-XFEL) project aims at the generation of X-ray FEL radiation for photon users. The machine consists of a 10 GeV normal-conducting S-band linear accelerator (linac) and two undulator beamlines initially. The hard X-ray beamline will provide FEL radiation between 0.6 and 0.1 nm or shorter. The soft X-ray line will provide FEL radiation between 4.5 and 1 nm. The linac and hard X-ray beamline construction was complete by the end of 2015. The installation of the soft X-ray line is ongoing. High power RF conditioning of the linac started in late autumn 2015. Beam commissioning of the linac started in April 2016. We report the beam commissioning status.

Slides MOXBA01 [4.978 MB]

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MOPMB005

Study of Short Bunches at the Free Electron Laser CLIO

radiation, cavity, electron, simulation

78

V. Khodnevych, N. Delerue, S. Jenzer
LAL, Orsay, France
J.P. Berthet, F. Glotin, J.-M. Ortega, R. Prazeres
CLIO/ELISE/LCP, Orsay, France
V. Khodnevych
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine

Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01).
CLIO is a Free Electron Laser based on a thermionic electron gun. In its normal operating mode it delivers electron 8 pulses but studies are ongoing to shorten the pulses to about 1 ps. We report on simulations showing how the pulse can be shortened and the expected signal yield from several bunch length diagnostics (Coherent Transition Radiation, Coherent Smith Purcell Radiation).

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MOPMB009

Electron Beam Probe for the Bunch Length Measurements at BERLinPro

electron, diagnostics, simulation, operation

92

D. Malyutin, A.N. Matveenko
HZB, Berlin, Germany

For the successful operation of various accelerator facilities a detailed bunch characterization is required. A complete description can be achieved using various diagnostic systems installed along an accelerator beamline. Ideally the diagnostic should be able to measure parameters of a single bunch in a non-destructive manner. For bunch length measurements this results in a complicated task especially for bunch duration below 1 ps. One of the possible solutions is a diagnostic based on the interaction of a low energy electron beam with electro-magnetic fields of the relativistic bunch. The bunch length can be readily deduced from the resulting scatter. In this paper bunch length measurement technique based on a low energy electron beam is introduced. Results of numerical simulations of measurements are presented. A possible setup of such diagnostic system for BERLinPro facility is proposed.

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MOPMB015

Technical Design Considerations About the SINBAD-ARES Linac

linac, laser, electron, acceleration

112

B. Marchetti, R.W. Aßmann, U. Dorda, K. Flöttmann, M. Hachmann, I. Hartl, J. Herrmann, M. Hüning, G. Kube, F. Ludwig, F. Mayet, M. Pelzer, I. Peperkorn, S. Pfeiffer, H. Schlarb, M. Titberidze, G. Vashchenko, M.K. Weikum, L. Winkelmann, K. Wittenburg, J. Zhu
DESY, Hamburg, Germany
R. Rossmanith
KIT, Karlsruhe, Germany

The SINBAD facility (Short and INnovative Bunches and Accelerators at Desy) is foreseen to host various experiments in the field of production of ultra-short electron bunches and novel high gradient acceleration technique. The SINBAD linac, also called ARES (Accelerator Research experiment at SINBAD), will be a conventional S-band linear RF accelerator allowing the production of low charge (0.5 pC - few pC) ultra-short electron bunches (FWHM, length <= 1 fs - few fs) having 100 MeV energy. In this paper we present the current status of the technical design considerations, motivate the foreseen diagnostics for the RF gun commissioning and present examples of foreseen applications.

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MOPMB027

Beam Parameter Measurement After Relocation of S-Band Linear Accelerator

electron, linac, simulation, laser

146

I. Nozawa, M. Gohdo, K. Kan, T. Kondoh, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Ultrashort electron bunches have been applied in many scientific fields including accelerator physics and radiation chemistry. Pulse radiolysis is application in radiation chemistry, which is a pump-probe measurement using an electron bunch and a laser pulse. Our laboratory aims to generate the electron bunches with durations of less-than femtoseconds using an S-band linear accelerator (linac) at Osaka University in order to improve the time resolution of the pulse radiolysis system. Recently, the linac system was relocated for expanding application using ultrashort electron bunches. The parameters of generated electron bunches including the bunch lengths will be reported.

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MOPMB054

A High Sensitivity Faraday Cup for Ultrashort Electron Bunches

electron, simulation, laser, experiment

214

S. Setiniyaz, I.H. Baek, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, S.V. Miginsky, J.H. Nam, S. Park, N. Vinokurov
KAERI, Daejon, Republic of Korea
S.V. Miginsky, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

The UED (Ultrafast Electron Diffraction) beamline of KAERI (Korea Atomic Energy Research Institute) WCI (World Class Institute) Center has been successfully commissioned. A S-band co-axial RF photogun with 1.5 cylindrically symmetric cells was used to remove multiple modes of the electric filed inside the cavity. It is designed to generate sub-picosecond electron bunches with energy up to 3.3~MeV. We have developed a system consists of an in-air Faraday cup (FC) and a preamplifier for charge measurement. Tests performed utilizing 3.3~MeV electrons show the system were able to measure ultrashort bunches with tens of femtosecond pulse duration at 10 fC sensitivity. In this paper, we shall present the design, calibration and test results of this system.

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MOPMR001

Micro-mover Development and Test in the PAL-XFEL

solenoid, electron, cavity, controls

229

B.G. Oh, J.H. Han, H. Heo, J.H. Hong, H.-S. Kang, C. Kim, D.E. Kim, K.-H. Park, Y.J. Suh
PAL, Pohang, Kyungbuk, Republic of Korea

Two micro-movers, which are able to control the horizontal, vertical and longitudinal positions as well as the yaw and pitch angles remotely, were developed and installed in the PAL-XFEL linac. The solenoid micro-mover in the gun section allows beam-based alignment of an electron beam to the solenoid field and the gun RF field. The X-band cavity micro-mover minimizes the transverse wake field effect caused by transverse misalignment between the beam and X-band cavity. Two micro-movers has similar specifications and the same mechanism, but the sizes are different from each other. In this paper, we present the design, manufacture and test results of the micro-movers.

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MOPMR035

Bunch Length Measurements using a Transverse Deflecting Cavity on VELA

cavity, laser, electron, simulation

323

J.W. McKenzie, S.R. Buckley, L.S. Cowie, P. Goudket, M. Jenkins, B.L. Militsyn, A.J. Moss, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A. Wolski
The University of Liverpool, Liverpool, United Kingdom

The VELA facility at Daresbury Laboratory in the UK includes a 5 MeV/c 2.5 cell S-band photoinjector gun. This gun operates in the "blow-out" regime with a sub-200 fs length drive laser: the resulting bunch length is determined by space-charge effects. We present measurements made with an S-band transverse deflecting cavity to characterise the bunch length as a function of charge, and as a function of the gun operating phase.

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MOPMW001

A New Buncher for the ESRF Linac Injector

linac, electron, beam-loading, cavity

389

A.S. Setty, A.S. Chauchat, D. Jousse
Thales Communications & Security (TCS), Gennevilliers Cedex, France
H. Delamare, J. Jacob, B. Ogier, T.P. Perron, E. Rabeuf, C. Richard, V. Serrière, R. Versteegen
ESRF, Grenoble, France

The electron linac was designed to be able to deliver more than 2.5 A in less than 2 ns at 200 MeV within an energy spread of 1% for positrons production at ESRF *. The 200 MeV electron linac was commissioned in 1991. A new gun, a cleaner, a pre-buncher cavity and 4 shielded lenses were tested and installed on the injector in 2008 **. Then, a new Buncher for the ESRF electron linac injector was manufactured and commissioned in 2015. Meanwhile, some new settings were performed to reduce the energy spread for both cases: the long pulse mode and the short pulse mode. The simulations and measurements will be presented.
* D. Tronc et Al. "Electron injector for light source", Proc. EPAC88, Italy, Rome, June 1988.
** T. Perron et Al. "New preinjector for the ESRF booster", Proc. EPAC08, Italy, Genoa, June 2008.

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MOPMW005

Design of Linac with the New Gaskets Clamping Fabrication Technique

vacuum, coupling, impedance, linac

403

F. Cardelli
INFN-Roma1, Rome, Italy
D. Alesini
INFN/LNF, Frascati (Roma), Italy
M. Magi, L. Palumbo
University of Rome La Sapienza, Rome, Italy
F. Pellegrino, V. Pettinacci
INFN-Roma, Roma, Italy

Recently, a new technique for the realization of high gradient accelerating structures based on the use of gaskets without brazing processes, has been successfully tested at high power on a 1.6 cells RF gun (D. Alesini, et al, PRST 18, 02001, 2015). The new technique developed at the Laboratories of Frascati of the INFN (Italy) in the framework of the SPARC_LAB project has been also adopted for the ELI-NP RF gun. The use of the special gaskets that simultaneously guarantee the vacuum seal and a perfect RF contact allow to avoid the brazing process, strongly reducing the cost, the realization time and the risk of failure. Moreover, without copper annealing due to the brazing process, it is possible, in principle, to decrease the breakdown rate increasing, at the same time, the maximum achievable gradient. The extension of this new fabrication process to complex LINAC structures is the next step on the application of this new technique on particle accelerator. In the paper, we discuss how to extend this process to S-band and C-band Travelling Wave accelerating structures illustrating their electromagnetic design and their mechanical realization.

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MOPMW039

TM01 Mode Launcher for Use in High Brightness Photoguns

quadrupole, electron, impedance, cavity

491

A.D. Cahill
UCLA, Los Angeles, California, USA
M. Dal Forno, V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515
Photo rf guns are a source of electron beams for X-ray FELs such as LCLS and European XFEL. In existing photoguns power is coupled into the cavity by waveguides through the cell walls, like LCLS, or through coaxial coupling, at the European XFEL. We are considering feeding a gun using a circular waveguide with the TM01 mode. To do that we need a mode launcher, a matched device that couples the rectangular TE01 mode waveguide to a TM01 mode in a circular waveguide. Use of the mode launcher reduces complexity of the gun cavity and increases flexibility of positioning the input waveguide relative to the gun body. Mode launchers have been successfully used at SLAC and elsewhere for X-band high gradient tests. Because the existing mode launchers were not built for high brightness guns, they have a significant quadrupole field component. High brightness rf guns have tight requirements on output beam properties, and this quadrupole component adversely affects the beam. We have designed a mode launcher free of this disadvantage. We present design considerations, methodology, and an example S-band mode launcher.

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MOPMW042

Multi-Dimensional RF Sources Design

klystron, electron, cavity, space-charge

501

M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: Work supported by the US DOE under contract DE-AC02-76SF00515.
Vacuum electronic devices, such as rf sources for accelerator applications, must provide high rf power with high efficiency. To achieve these requirements, multi-beam klystron and sheet-beam klystron devices have been developed. Multi-beam klystrons, at high frequency employ separate output cavities; hence they have the disadvantage that combining all the rf pulses, generated by all the beams, is challenging. Sheet-beam klystrons have problems with instabilities and with space charge forces that makes the beam not naturally confined. We are proposing an alternative approach that reduces space charge problems, by adopting geometries in which the space charge forces are naturally balanced. An example is when the electron beam is generated by a central source (well) and the electron motion corresponds to the natural expansion of the electron cloud (three-dimensional device). In this paper we will present the design and challenges of a bi-dimensional rf source, a cylindrical klystron, composed by concentric pancake resonant cavities. In this case, space charge forces are naturally balanced in the azimuthal direction.

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MOPMY013

Design Study of Collector for CEPC 650 MHz Klystron

klystron, simulation, operation, interface

540

S.C. Wang, D.D. Dong, S. Fukuda, G. Pei, O. Xiao, .. Zaib-un-Nisa, Z.S. Zhou
IHEP, Beijing, People's Republic of China
S. Fukuda
KEK, Ibaraki, Japan

This paper presents the design and simulation of collector for CEPC 650 MHz high-power CW klystron. Power dissipation in collector is optimised by universal beam spread curve using EGUN code, and beam trajectory in collector is verified by Magic code. The thermal analysis is done by ANSYS-CFX, and groove number and water flow rate are optimized by fluid-solid coupled heat transfer simulation.

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MOPMY015

Design Study of Electron Gun for CEPC 650 MHz Klystron

klystron, cathode, electron, simulation

546

.. Zaib-un-Nisa, D.D. Dong, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, Z.S. Zhou
IHEP, People's Republic of China
S. Fukuda
KEK, Ibaraki, Japan

This paper presents the design and simulation of an electron gun for 800 kW CW klystron of which frequency is 650 MHz for CEPC project. An electron gun with a modulating anode is designed using DGUN software. The uniform beam trajectories, with a beam perveance of 0.64μA/V 3/2 are simulated. We employed a Ba-dispenser cathode of radius 35 mm with Φ10 hole at the center and obtained a current density on cathode less than 0.45 A/cm². The beam trajectories were also simulated over whole tube length with a magnetic field of 207 Gauss. Expecting functions using the modulating anode gun are also described. Proposed beam tester and whole CEPC klystron layout are also shown in this paper.

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MOPOR026

Measurement of the Energy Distribution Function of Electrons Generated by Radio-frequency Induced Multipacting in a Beam Pipe

electron, multipactoring, radio-frequency, diagnostics

664

M. Van Gompel, F. Caspers, P. Costa Pinto, R. Leber, A. Romano, R. Salemme, M. Taborelli
CERN, Geneva, Switzerland

The development of Electron Multipacting (EM) in high intensity particle accelerators depends, amongst others, on the Secondary Electron Yield (SEY) of surfaces facing the beam. In-situ studies of electron clouds in particle accelerators must cope with operation schedule and other technical constrains. To overcome these difficulties, CERN implemented a Multipactor test bench, where EM is generated by Radio-Frequency (RF), using the beam pipes as a coaxial resonators. This tool was already successfully used to assess the effectiveness of low SEY carbon coatings on dipoles of the SPS at CERN and to study the conditioning dynamics of beam pipes. In this paper we present the development of an in-house built Retarding Field Energy Analyser (RFEA) to measure the Electrons Energy Distribution Function (EEDF) in the Multipactor test bench. The design of the electrodes was based on simulations in order to optimize sensitivity and energy resolution. The setup was tested with an electron gun at different energies before insertion in the Multipactor test bench. The evolution of the EEDF is measured at different RF powers. Feasibility to perform measurements in the machine is discussed.

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MOPOW016

Status of Design and Development of Delhi Light Source at IUAC, Delhi

laser, electron, undulator, radiation

748

S. Ghosh, R.K. Bhandari, G.K. Chaudhari, V.J. Joshi, D. Kabiraj, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, P. Patra, B.K. Sahu, A.S. Sharma, A.S. Sthuthikkatt Reghu
IUAC, New Delhi, India
A. Aryshev, M.K. Fukuda, S. Fukuda, N. Terunuma, J. Urakawa, J. Urakawa
KEK, Ibaraki, Japan
A. Deshpande
SAMEER, Mumbai, India
V. Naik, A. Roy
VECC, Kolkata, India
T. Rao
BNL, Upton, Long Island, New York, USA

Funding: The project is supported jointly by Board of Research in Nuclear Sciences (BRNS) and IUAC
The demand for the photon beams for basic research is growing in India. To address the requirements, a project to develop a compact Light Source based on the principle of Free Electron Laser has been initiated at the Inter University Accelerator Centre (IUAC). In the first phase of the project, a normal conducting RF gun will be used to produce electron beam of energy ~ 8 MeV by using copper photocathode and subsequently by Cs2Te photocathode. A high power fiber laser with short pulse length is planned to be used to produce the pre-bunched electron beam by splitting the single laser pulse in to 16 pulses ("comb beam"). The electron beam will be injected in to a compact, variable gap undulator magnet to produce the THz radiation whose frequency can be tuned by varying the undulator field strength and the time separation of the comb beam. In the second and third phases of the project, superconducting RF gun and superconducting accelerating structure will be used to increase the energy of the electron beam up to ~ 40 MeV which will be used to produce IR radiation by using long undulator magnets and to produce X-rays by colliding the electron beam with another high power laser beam.

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MOPOW018

Feasibility Study of Photocathode Opearation of Thermionic RF Gun at KU-FEL

FEL, cathode, operation, electron

754

H. Zen, T. Kii, K. Masuda, K. Morita, T. Murata, T. Nogi, H. Ohgaki, S. Suphakul, K. Torgasin
Kyoto University, Kyoto, Japan
R. Kuroda
AIST, Tsukuba, Ibaraki, Japan

Kyoto University Free Electron Laser (KU-FEL) is a mid-infrared FEL driven by a compact linac utilizinig a thermionic RF gun as its electron source*. Recently we succeeded in operating KU-FEL with photocathode operation of the RF gun by using the thermionic cathode (LaB6) as a photocathode. The performance of KU-FEL under the thermionic cathode and photocathode operation will be reported. In addition, some recent application experiment results will also be presented in this presentation.
*H. Zen, et al., Infrared Phys. Techn. 51 (2008) 382.

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MOPOW036

Design Optimization of an X-band based FEL

linac, FEL, simulation, emittance

793

A.A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
A. Latina, J. Pfingstner, D. Schulte
CERN, Geneva, Switzerland
Z. Nergiz
Nigde University, Nigde, Turkey

A design effort for a new generation of compact, cost-effective, power-efficient FEL facilities, based on X-band technology, has been launched. High-frequency X-band acceleration implies strong wakefields, tight alignment and mechanical tolerances, and challenging stability issues. In this paper a design is proposed for the injector and the linacs, including the two bunch compressors. RF gun and injector simulations have been performed, successfully meeting the stringent requirements in terms of minimum projected emittance, sliced emittance and minimum bunch length. In the design of the linac and bunch compressors wakefield effects and misalignment have been taken into account. Start-to-end tracking simulations through the optimized lattice are presented and discussed.

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TUOCA02

APEX Phase-II Commissioning Results at the Lawrence Berkeley National Laboratory

electron, cavity, linac, space-charge

1041

F. Sannibale, J.A. Doyle, J. Feng, D. Filippetto, G.L. Harris, M.J. Johnson, T.D. Kramasz, D. Leitner, C.E. Mitchell, J.R. Nasiatka, H.A. Padmore, H.J. Qian, H. Rasool, J.W. Staples, S.P. Virostek, R.P. Wells, M.S. Zolotorev
LBNL, Berkeley, California, USA
S.M. Gierman, R.K. Li, J.F. Schmerge, T. Vecchione, F. Zhou
SLAC, Menlo Park, California, USA
C. Pagani, D. Sertore
INFN/LASA, Segrate (MI), Italy

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
Science needs in the last decade have been pushing the accelerator community to the development of high repetition rates (MHz/GHz-class) linac-based schemes capable of generating high brightness electron beams. Examples include X-ray FELs; ERLs for light source, electron cooling and IR to EUV FEL applications; inverse Compton scattering X-ray or gamma sources; and ultrafast electron diffraction and microscopy. The high repetition rate requirement has profound implications on the technology choice for most of the accelerator parts, and in particular for the electron gun. The successful performance of the GHz room-temperature RF photo-injectors running at rates <~ 100 Hz, cannot be scaled up to higher rates because of the excessive heat load that those regimes would impose on the gun cavity. In response to this gun need, we have developed at Berkeley the VHF-Gun, a lower-frequency room-temperature RF photo-gun capable of CW operation and optimized for the performance required by MHz-class X-ray FELs. The Advanced Photo-injector EXperiment (APEX) was funded and built for demonstrating the VHF gun performance, and the results of its last phase of commissioning are presented.

Slides TUOCA02 [12.015 MB]

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TUOCA03

Commissioning of the European XFEL Injector

emittance, laser, controls, operation

1044

F. Brinker
DESY, Hamburg, Germany

The European XFEL Injector consists of an L-Band RF photoinjector, a TESLA type 1.3 GHz module, a 3rd harmonic RF section, a laser heater and an extensive diagnostic section to determine projected and slice properties of the beam. The commissioning of the complete system has been started in December 2015 after several years of construction. We will report on commissioning results and persepctives for the later XFEL operation.

Slides TUOCA03 [5.182 MB]

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TUPMR006

The ELENA Electron Cooler

electron, solenoid, vacuum, antiproton

1236

G. Tranquille, J. Cenede, A. Frassier, L.V. Jørgensen, A.J. Kolehmainen, B. Moles, M.A. Timmins
CERN, Geneva, Switzerland

The ELENA (Extra Low ENergy Antiproton) ring will deliver antiprotons at an energy of just 100 keV to experiments aiming to precisely measure the properties of anti-hydrogen atoms. A crucial component of this decelerator ring is the electron cooler which will be used to counter the beam blow-up as the antiproton energy is reduced from 5.3 MeV to 100 keV. The electron cooler will operate at energies below 350 eV in a longitudinal guiding field of 100 G such that the perturbations to the ring can be easily corrected. We will present the design considerations as well as the production status of the cooler.

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TUPMR029

Advanced EBIS Charge Breeder for Rare Isotope Science Project

electron, ion, solenoid, vacuum

1304

S.A. Kondrashev, J.-W. Kim, Y.H. Park
IBS, Daejeon, Republic of Korea
H.J. Son
Handong Global University, Pohang, Republic of Korea

Rare Isotope Science Project (RISP) is under development in Korea to provide wide variety of intense rare isotope beams for nuclear physics experiments and applied science using both Isotope Separation On-Line (ISOL) and In-Flight Fragmentation (IF) techniques. Electron Beam Ion Source (EBIS) charge breeder is a key element to efficiently accelerate rare isotope ion beams produced by ISOL method. These beams will be charge-bred by an EBIS charge breeder to a charge-to-mass ratio (q/A) ≥ - and accelerated by linac post-accelerator to energies of 18.5 MeV/u. Utilization of 3 A electron beam and 6 T superconducting solenoid with wide (8) warm bore diameter will allow high efficient and fast charge breeding of rare isotope beams with exceptional degree of purity. The main features of RISP EBIS charge breeder design and current status of the project will be presented and discussed.

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TUPMY015

Ultrafast Electron Guns for the Efficient Acceleration using Single-Cycle THz Pulses

electron, acceleration, laser, injection

1578

A. Fallahi, F.X. Kärtner, A. Yahaghi
CFEL, Hamburg, Germany
M. Fakhari
DESY, Hamburg, Germany

Funding: European Research Council (ERC)
Over the past decades, advances in ultrafast technologies led to the production of intense ultrashort THz to optical pulses reaching single-cycle pulse duration. Using such pulses for electron acceleration offers advantages in terms of higher thresholds for materials breakdown, thus introducing a promising path towards increasing acceleration gradients. Conventional accelerator technology is based on either continuous wave or long pulse operation, where resonant or guiding structures are usually employed. We introduce novel structures for electron acceleration which operate with single-cycle pulses named as single-cycle ultrafast guns. The operating frequencies considered here are at THz wavelengths inspired by the recent progress in the optical generation of intense single-cycle THz pulses. We begin with designing guns for low energy pulses and proceed with structures designed for high energy pulses. More importantly, it is shown that the already achieved THz pulse energies of 20 uJ are enough to realize relativistic fields for electron acceleration. These structures will underpin future devices for fabricating miniaturized electron guns and linear accelerators.

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TUPMY041

Delivery Status of the ELI-NP Gamma Beam System

solenoid, laser, linac, vacuum

1635

S. Tomassini, D. Alesini, A. Battisti, R. Boni, F. Cioeta, A. Delle Piane, E. Di Pasquale, G. Di Pirro, A. Falone, A. Gallo, S.I. Incremona, V.L. Lollo, A. Mostacci, S. Pioli, R. Ricci, U. Rotundo, A. Stella, C. Vaccarezza, A. Vannozzi, A. Variola
INFN/LNF, Frascati (Roma), Italy
A. Bacci, D.T. Palmer, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
N. Bliss
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
F. Cardelli
INFN-Roma1, Rome, Italy
K. Cassou, Z.F. Zomer
LAL, Orsay, France
G. D'Auria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Giribono, V. Pettinacci
INFN-Roma, Roma, Italy
C. Hill
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
L. Palumbo
Rome University La Sapienza, Roma, Italy
L. Piersanti
University of Rome La Sapienza, Rome, Italy

The ELI-NP GBS is a high intensity and monochromatic gamma source under construction in Magurele (Romania). The design and construction of the Gamma Beam System complex as well as the integration of the technical plants and the commissioning of the overall facility, was awarded to the Eurogammas Consortium in March 2014. The delivery of the facility has been planned in for 4 stages and the first one was fulfilled in October 31st 2015. The engineering aspects related to the delivery stage 1 are presented.

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TUPOR019

RF Injector Beam Dynamics Optimization and Injected Beam Energy Constraints for LCLS-II

cavity, laser, emittance, electron

1699

C.E. Mitchell, H.J. Qian, J. Qiang, F. Sannibale, M. Venturini
LBNL, Berkeley, California, USA
P. Emma, T.O. Raubenheimer, J.F. Schmerge, F. Zhou
SLAC, Menlo Park, California, USA

Funding: Work supported by the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
LCLS-II is a proposed high-repetition rate (>1 MHz) Free Electron Laser (FEL) X-ray light source, based on a CW, superconducting linac, to be built at SLAC National Accelerator Laboratory. The injector technology is based on a high-repetition rate RF photoinjector gun developed as part of the Advanced Photoinjector Experiment (APEX) at Lawrence Berkeley National Laboratory. Exploration of the injector design settings is performed using a multiobjective genetic optimizer to optimize the beam quality at the injector exit (~100 MeV). In this paper, we describe the current status of LCLS-II injector design optimization, with a focus on the sensitivity of the optimized solutions to the beam energy at the injector exit, which is constrained by the requirements of the downstream laser heater system.

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TUPOW002

Current Status of the Milliampere Booster for the Mainz Energy-recovering Superconducting Accelerator

electron, simulation, experiment, linac

1741

R.G. Heine, K. Aulenbacher, L.M. Hein, C. Matejcek
IKP, Mainz, Germany

Funding: Work supported by German Science Foundation (DFG) under the Cluster of Excellence "PRISMA" EXC1098/2014
The Milliampere Booster (MAMBO) is the injector linac for the Mainz Energy-recovering Superconducting Accelerator MESA. The MESA facility is currently under design at the Institut für Kernphysik (KPH) at Johannes Gutenberg University of Mainz (JGU). In this paper we will present the current design status of the linac.

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TUPOW003

High Average RF Power Tests With 2 RF Vacuum Windows at PITZ

operation, vacuum, Windows, emittance

1744

Y. Renier, G. Asova, M. A. Bakr, P. Boonpornprasert, J.D. Good, M. Groß, C. Hernandez-Garcia, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, O. Lishilin, G. Loisch, D. Malyutin, D. Melkumyan, A. Oppelt, M. Otevřel, G. Pathak, T. Rublack, I.V. Rybakov, F. Stephan, G. Vashchenko, Q.T. Zhao
DESY Zeuthen, Zeuthen, Germany
M. Bousonville, S. Choroba, S. Lederer
DESY, Hamburg, Germany

The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was built with the aim to develop and characterize electron sources for future usage at FLASH and at the European XFEL. Recently, the main focus at PITZ has been the study of gun reliability and photoinjector performance at high average power. The goal is to get stable and reliable operation with 6.4 MW peak power in the gun at 650 us RF pulse length and 10 Hz repetition rate. To achieve this, a new RF feed system with two RF windows was installed at PITZ in 2014. During this test, the old gun 4.2 with a modified back-plane design for better cathode contact has been used. In this contribution the results of the RF conditioning of gun 4.2 with a detailed interlock analysis will be reported as well as results from recent electron beam characterization.

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TUPOW014

Simulation of High Resolution Field Emission Imaging in an rf Photocathode Gun

electron, cathode, solenoid, simulation

1769

J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
TUB, Beijing, People's Republic of China
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
W. Gai
ANL, Argonne, Illinois, USA
F.Y. Wang
SLAC, Menlo Park, California, USA

Precisely locating field emission (FE) emitters on a realistic surface in rf structures is technically chal-lenging in general due to the wide emitting phase and the broad energy spread. A method to achieve in situ high resolution FE imaging has been proposed by using solenoids and a collimator to select electrons emitted at certain phases. The phase selection criterion and imaging properties have been studied by the beam dynamics code ASTRA. Detailed results are presented in this paper.

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TUPOW015

Experiment of High Resolution Field Emission Imaging in an rf Photocathode Gun

cathode, electron, experiment, background

1772

J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
TUB, Beijing, People's Republic of China
S.P. Antipov, S.V. Baryshev, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, G. Ha, E.E. Wisniewski
ANL, Argonne, Illinois, USA
F.Y. Wang
SLAC, Menlo Park, California, USA

The first in situ high resolution field emission (FE) imaging experiment has been carried out on an L-band photocathode gun test stand at Argonne Wakefield Accelerator facility (AWA). Separated strong emitters have been observed to dominate the field emission. Field enhancement factor, beta, of small regions on the cathode has been measured with the imaging system. It is shown that most strong emitters overlaps with the high beta regions. The post surface examinations reveal the origins of ~75% strong emitters overlap with the spots where rf breakdown have occurred. Detailed results are presented in this paper.

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TUPOW016

Development of a C-Band 4/8 Mev Dual-Energy Accelerator for Cargo Inspection System

cathode, controls, bunching, linac

1775

J.H. Shao, H.B. Chen, W.-H. Huang, Q.X. Jin, Y.H. Liu, J. Shi, C.-X. Tang, X.W. Wu
TUB, Beijing, People's Republic of China

Modern cargo inspection system applies dual-energy X-ray for material discrimination. Based on the com-pact C-band 6 MeV standing-wave accelerating struc-tures developed at Tsinghua University, a compact C-band 4/8 MeV dual-energy accelerator has been pro-posed, fabricated and tested. Compared with that of the conventional S-band 3/6 MeV dual-energy accelera-tor at Tsinghua University, the volume and the weight of the C-band one has been reduced by ~40% and ~30%, respectively. Detailed review of this C-band dual-energy accelerator is present in the paper.

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TUPOW018

Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation

radiation, electron, experiment, space-charge

1782

Z. Zhang, H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, X.L. Su, C.-X. Tang, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, L.M. Zheng, Z. Zhou
TUB, Beijing, People's Republic of China
W. Gai
ANL, Argonne, Illinois, USA

High peak current electron bunch trains with tunable terahertz (THz) spacing are produced and measured experimentally. An initial picosecond periodic modulation in the temporal profile of a relativistic electron beam is magnified by the longitudinal space charge forces. As opposed to trying to reduce its smearing effect for large beam current, we take advantages of the nonlinear space charge oscillation through controlling the plasma phase advance. The spacing of the bunch train can be varied continuously either by tuning the velocity bunching of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. The narrow-band μJ-level THz radiation from the bunch train are also measured with tunable central frequency of the spectral from ~0.5 THz to 1.6 THz. The bunch train measurements are consistent with the particle tracking simulations.

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TUPOW025

First Beam Test of the High Brightness Photo-injector at NSRRC

laser, linac, electron, cathode

1800

A.P. Lee, M.C. Chou, N.Y. Huang, J.-Y. Hwang, W.K. Lau, C.C. Liang, M.T. Tsou
NSRRC, Hsinchu, Taiwan
P. Wang
NTHU, Hsinchu, Taiwan

A High brightness injector at NSRRC is built for a VUV/THz free electron laser (FEL) facility and light source R&D. This injector with a photocathode rf gun with a solenoid for emittance compensation, a UV laser system, a 5.2 m S-band linac as well as various beam diagnostic tools has been installed in the linac test laboratory. The main goal is to produce beams with emittance smaller than 1 mm-mrad at energy of ~100 MeV. The other goal is to compress bunches to ~100 fs with charge of 100 pc and energy of ~30 MeV. In this contribution, an overview of the commissioning results of the photocathode rf gun and the laser system will be given. The first beam observation downstream the lianc will be presented in this paper.

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TUPOW027

Model Independent Analysis of Beam Jitter on VELA

laser, cathode, timing, distributed

1806

J.K. Jones, K.D. Dumbell, A.J. Moss, E.W. Snedden
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide high quality electron beams for accelerator systems development, as well as industrial and scientific applications. A key performance indicator for many applications is the inherent beam jitter on the machine (temporal, momentum and positional). Analysis of this beam jitter indicates that there are several independent mechanisms driving the beam motion. We use model independent analysis to correlate various dominant modes of beam jitter and compare them to simulations. We also compare the dominant modes before and after intervention work on the DLLRF timing system, and determine the relevant changes in beam motion.

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TUPOW028

Comparison of Model vs. Reality for VELA

cathode, simulation, laser, solenoid

1810

M.S. Toplis, J.W. McKenzie, B.D. Muratori, D.J. Scott, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide a high quality electron beam for accelerator systems development, as well as industrial and scientific applications. Currently, the RF gun can deliver short bunches, of the order of 100 fs to a few ps, with a charge of up to 250 pC, at the longer bunch lengths, and up to 4.5 MeV/c beam momentum. A model for the injector has been developed in ASTRA, together with a suite of scripts to create scans of the available parameters around an empirically found arbitrarily optimal working point. The space of parameters consists of everything that can be changed in the control room, and ranges from bunch charge to laser spot size on the cathode, together with all magnet settings where and if necessary. The various scans facilitate the task of identifying where exactly the accelerator is in terms of parameters and trends. Initial comparisons of screen images are made between the model and reality. Ultimately, the goal of the model is to robustly and repeatably establish a desired operating setup on a daily basis from an unknown switch on condition.

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TUPOW029

Transverse Cavity Tuning at the Advanced Photon Source

cavity, linac, dipole, LabView

1814

G.J. Waldschmidt, L.H. Morrison, T.L. Smith
ANL, Argonne, Ilinois, USA

A 15-cell transverse deflecting cavity based on a SLAC design was fabricated at the Advanced Photon Source and is being prepared for installation into the Injector Test Stand. A beadpull method for tuning was selected in lieu of the nodal position method to minimize the possibility of contamination and surface damage to the irises. The process has been successfully documented for many accelerating mode structures, but there has been limited application to dipole mode structures. In this paper, we will discuss the methodology for tuning and conditioning a 2.8 GHz backward-traveling wave deflecting cavity.

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TUPOW034

Status Report of the Berlin Energy Recovery Linac Project BERLinPro

SRF, cavity, linac, vacuum

1827

M. Abo-Bakr, W. Anders, 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, P. Kuske, J. Kuszynski, D. Malyutin, A.N. Matveenko, M. McAteer, A. Meseck, C.J. Metzger-Kraus, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, J. Rahn, J. Rudolph, M. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker
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 at the Berlin Adlershof site. The project is intended to expand the required accelerator physics and technology knowledge mandatory for the design, construction and operation of future synchrotron light sources. The project goal is the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the project progress: since spring 2015 the building is under construction, ready for occupancy in January 2017. The planning phase for the first project stage is completed for the warm machine parts, the SRF gun and partly for the SRF booster. Most of the components have been ordered and are in fabrication with some already delivered. An update of the status of the various subprojects as well as a summary of future activities will be given. Project milestones and details of the timeline will be reviewed.

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TUPOW035

First LLRF Tests of BERLinPro Gun Cavity Prototype

cavity, controls, linac, cathode

1831

P. Echevarria, J. Knobloch, O. Kugeler, A. Neumann, A. Ushakov
HZB, Berlin, Germany
K.P. Przygoda
DESY, Hamburg, Germany

The goal of Berlin Energy Recovery Linac Project (BERLinPro) is the generation of a 50 MeV, 100-mA low emittance (below 1 mm mrad) CW electron beam at 2 ps rms bunch duration or below. Three different types of 1.3 GHz SRF modules will be employed: the electron gun, the booster and the main linac. Precise RF amplitude and phase control are needed due to the beam recovery pro-cess. In this paper we describe the first tests of the Low Level RF control of the first injector prototype at the HoBiCaT facility, implemented in the digital VME-based LLRF controller developed by Cornell University. Tuner movement control by an mTCA.4 system, together with further plans of using this technology will be also presented.

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TUPOW036

Recent Developments and Operational Status of the Compact ERL at KEK

operation, linac, emittance, laser

1835

T. Obina, M. Adachi, S. Adachi, T. Akagi, M. Akemoto, D.A. Arakawa, S. Araki, S. Asaoka, M. Egi, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X.J. Jin, E. Kako, Y. Kamiya, H. Katagiri, R. Kato, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondo, T. Konomi, A. Kosuge, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sakanaka, S. Sasaki, K. Satoh, Y. Seimiya, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, N. Terunuma, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, J. Urakawa, K. Watanabe, M. Yamamoto, N. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
KEK, Ibaraki, Japan
R. Hajima, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
QST, Tokai, Japan
M. Kuriki
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

The Compact Energy Recovery Linac (cERL) at KEK is a test accelerator in order to develop key components to realize remarkable ERL performance as a future light source. After the beam commissioning in December 2013, the legal current limit has been increased step-by-step like 1 uA, 10 uA, and 100 uA. Survey for the source of beam losses has been conducted in each step, and the study on beam dynamics and tuning has also been carried out. As a next step, 1 mA operation is scheduled in February 2016. In parallel to the increase in beam current, a laser Compton scattering (LCS) system which can provide high-flux X-ray to a beamline has been successfully commissioned. We report recent progress in various kinds of beam tuning: improvement of electron gun performance, high bunch charge operation, mitigation of beam losses, LCS optics tuning and bunch compression for THz radiation.

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TUPOW039

Simulation Study of the Beam Halo Formation for Beam Loss Estimation and Mitigation at KEK Compact ERL

simulation, cavity, operation, electron

1843

O. Tanaka, T. Miyajima, N. Nakamura, T. Obina, M. Shimada, R. Takai
KEK, Ibaraki, Japan

Funding: Work supported by the "Grant-in-Aid for Creative Scientific Research" of JSPS (KAKENHI 15K04747)
At KEK Compact ERL (cERL) we are aiming to produce high-current and low-emittance electron beams (up to 10 mA) without significant beam loss. We believe that beam halo makes a significant impact into the beam loss. Therefore, we are performing beam loss simulations to meet the results of the beam loss measurements*. In particular, a simulation of the bunch tail originated from the electron gun was performed to understand the mechanisms of the beam halo formation. Since some measured beam profiles demonstrated unexpected halo particles, several factors such as misalignment of beam line elements and kicks from the steering coils were added into the simulation. Simulation study results are compared with the related beam loss and halo measurements here.
* Sakanaka et al., these proceedings

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TUPOW045

Pre-bunched Electron Beam Emittance Simulation and Measurement

electron, simulation, emittance, radiation

1864

Yu.D. Kliuchevskaia, S.M. Polozov
MEPhI, Moscow, Russia
A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

LUCX facility at KEK is used as the high brightness pre-bunched electron beam source for radiation experiments. Emittance measurement and optimization is one of the important research activities for newly developed operation mode of the facility. Characterization of the pre-bunched beam (THz sequence of a hundred femtosecond bunches) properties opens a possibility to establish detailed simulation of the THz FEL radiation yield and continuously improve pre-bunched beam dynamics insight. Emittance has been measured by the Q-scan method. The measurement results and possible ways of emittance optimization are discussed. The measurement results are compared with beam dynamics simulation done by self-consistent BEAMDULAC-BL code.

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TUPOW047

Generation of a Coherent Cherenkov Radiation by using Electron Bunch Tilting

radiation, electron, target, experiment

1870

K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
R. Kuroda, Y. Taira
AIST, Tsukuba, Ibaraki, Japan
M. Nishida, M. Washio
Waseda University, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

We have been developing a compact accelerator based a laser photocathode rf electron gun at Waseda University. Low emittance and short bunched electron beam can be generated from the gun. Also, the rf transverse deflecting cavity was developed for the bunch length measurement. We performed an experiment for generating a coherent Cherenkov radiation using bunch tilting. The rf transverse deflector can give a tilt for the electron bunch, and the tilt angle was set to the Cherenkov radiating angle which determined by the target refractive index. We successfully demonstrated a coherent Cherenkov radiation and the characterization of the radiation. The principle of coherent Cherenkov radiation generation, the experimental results and future prospective will be presented at the conference.

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TUPOY010

6/9 MeV S-band Standing Wave Accelerating Structure for Container X-ray Inspection System at RTX

electron, cavity, linac, radiation

1924

P. Buaphad, H.D. Park, S. Song, S.Y. Yoo
RTX, Daejeon, Republic of Korea
H.K. Cha, S.S. Cha, J.H. Ha, Y. Kim, B.C. Lee
KAERI, Daejon, Republic of Korea

Recently, there is a need of X-ray inspection system around the world to combat terrorism, drug and weapons smuggling, illegal immigration, and trade fraud. A compact standing wave (SW) linear accelerator (linac) for container X-ray inspection system has been produced at Radiation Technology eXcellence (RTX) to meet this growing need. The RF accelerating structure uses standing wave side-coupled structure fed by a 5 MW e2v magnetron with frequency of 2856 MHz. The electrons are accelerated from DC gun with energy of 25 keV to the final energy of 6 or 9 MeV at the X-ray target and generate X-ray with the dose rate of 8 Gy/min at 1 m after X-ray target. In this paper, we describe the design and optimization of side-coupled RF structure operating at π/2 mode. The beam dynamic of particle along the RF structure is also included in this paper by using ASTRA code.

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TUPOY015

Design of Electron Gun and S-Band Structure for Medical Electron Linear Accelerator

electron, cavity, cathode, linac

1930

N. Juntong, R. Chimchang
SLRI, Nakhon Ratchasima, Thailand
S. Rimjaem, C. Saisa-ard
Chiang Mai University, Chiang Mai, Thailand

Linear accelerator technology has been widely utilized for cancer treatment in hospital. This radiotherapy utilizes an accelerated electron beam to create the x-ray beam. The idea to fabricate the prototype of medical electron linac with low cost for domestic use in Thailand was proposed and the budget has been granted. In the first phase, the electron beam energy of the machine will be 6 MeV or equivalent to x-ray energy of 6 MV. The electron gun is a diode type for the simple and low cost fabrication. The design and simulation study of diode gun will be presented together with an analysis of an electron beam in this gun. The S-Band 6 MeV side-coupled RF cavity has been designed to be the accelerating structure of the machine. The electromagnetic fields of the structure have been studied. The electron behaviour when they traverse this cavity will be studied using a particle tracking code. Progression of the project is also presented.

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TUPOY032

Design and Simulation of a Thermionic Electron Gun for a 1 MeV Parallel Feed Cockcroft-Walton Industrial Accelerator

electron, cathode, simulation, space-charge

1976

M. Nazari, F. Abbasi
Shahid Beheshti University, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
M. Jafarzadeh
ILSF, Tehran, Iran

Electron accelerators are made of different parts and one of the main part of every electron accelerator is its electron gun. In this article a diode electron gun is designed and simulated for a 1MeV parallel feed Cockcroft-Walton accelerator for industrial applications. The pierce configuration is selected for focusing electrode. Simulations are carried out using CST Particle Studio. The gun is thermionic with indirect heating of spherical dispenser cathode that is made from porous tungsten which is impregnated with barium compounds. The gun maximum achievable current is 200 mA at 10 kV and required current in our accelerator is about 100 mA.

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TUPOY033

Design, Simulation and Comparison of Electrostatic Accelerating Tubes for a 1MeV Parallel Feed Cockcroft-Walton Industrial Accelerator

electron, simulation, industrial-accelerators, vacuum

1979

M. Nazari, F. Abbasi
Shahid Beheshti University, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
M. Jafarzadeh
ILSF, Tehran, Iran

In this article accelerating tubes whit different geometries and different constructions are designed and simulated for a 1 MeV parallel feed Cockcroft-Walton electrostatic industrial accelerator. Simulations are carried out using CST Particle Studio. The accelerating tubes with different focusing electrode and accelerating electrode geometries are designed and simulated and compared with each other. Finally whit respect to the comparisons best geometry is selected. In this tube a 1 MV DC voltage is applied at several stages during the accelerating electrodes. Maximum electron beam current in the tube is 200 mA. In this application accelerating electrodes and focusing electrodes are made of stainless steel and insulators between electrodes are made of Borosilicate glass.

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TUPOY040

Advancements in Single-shot Electron Diffraction on VELA at Daresbury Laboratory

electron, laser, cavity, cathode

1988

J.W. McKenzie, S.L. Mathisen, M.D. Roper, M. Surman
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D.M.P. Holland
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
J.G. Underwood
UCL, London, United Kingdom

Electron diffraction on VELA at Daresbury Laboratory was first demonstrated in 2014. Since then, we have studied the machine parameter optimisation for single-shot diffraction patterns from single-crystal gold and silicon samples at bunch charges down to 60 fC. We present bunch length measurements for electron diffraction setups determined with a transverse deflecting cavity. We also discuss the current limitations of VELA for electron diffraction and the improvements to be made.

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WEOAB02

Record Performance of SRF Gun with CsK2Sb Photocathode

cathode, laser, electron, cavity

2085

I. Pinayev, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, D.M. Gassner, M. Harvey, T. Hayes, R.L. Hulsart, J.P. Jamilkowski, Y.C. Jing, D. Kayran, R. Kellermann, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, K. Mernick, R.J. Michnoff, T.A. Miller, M.G. Minty, G. Narayan, P. Orfin, D. Phillips, T. Rao, J. Reich, T. Roser, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, V. Soria, Z. Sorrell, R. Than, C. Theisen, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman, 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.
High-gradient CW photo-injectors operating at high ac-celerating gradients promise to revolutionize many sci-ences and applications. They can establish the basis for super-bright monochromatic X-ray and gamma-ray sources, high luminosity hadron colliders, nuclear- waste transmutation or a new generation of microchip produc-tion. In this paper we report on our operation of a super-conducting RF electron gun with a record-high accelerat-ing gradient at the CsK2Sb photocathode (i.e. ~ 20 MV/m) generating a record-high bunch charge (i.e., 2 nC). We briefly describe the system and then detail our experimental results.

Slides WEOAB02 [28.500 MB]

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WEPMB014

Cavity Performance of the Prototype KEK Superconducting RF Gun

cathode, cavity, target, SRF

2148

T. Konomi, E. Kako, E. Kako, Y. Kobayashi, Y. Kobayashi, K. Umemori, K. Umemori, S. Yamaguchi
KEK, Ibaraki, Japan
R. Matsuda
Mitsubishi Heavy Industries Ltd. (MHI), Takasago, Japan
T. Yanagisawa
MHI, Hiroshima, Japan

A superconducting RF (SRF) gun can generate a high current and high energy beam. It has a possibility to achieve requirement from high performance ERL and high repetition FEL. Target values of the L-band KEK SRF gun are that beam repetition is 1.3 GHz, beam current is 100 mA, beam energy is 2 MeV, emittance is 1 mm mrad or less. The number of cell is 1.5. Accelerating energy of 2 MeV corresponds to 42 MV/m of maximum surface field. The photocathode is designed to be illuminated by excitation laser from backside. The SRF gun cavity consists of the 1.5 cell accelerating cavity, cathode plug and choke filter for protecting the heating of cathode plug. To evaluate these parts individually, these parts are added step by step. High gradient test of the accelerating cell without cathode plug and choke filter was done. The surface peak electric field reached 66 MV/m, and this meet the target value 42 MV/m sufficiently. Next high gradient test will be done after adding the choke filter. The choke filter is designed to be simple to wash choke cell easier. In this conference, we will report the design, fabrication and high gradient performance of the SRF gun cavity with choke filter.

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WEPMB026

MHI-MS's Production Activities of Superconducting Cavity

cavity, SRF, electron, superconducting-RF

2180

H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
MHI-MS, Kobe, Japan
E. Kako, T. Konomi, H. Nakai, K. Umemori
KEK, Ibaraki, Japan

Mitsubishi Heavy Industries Mechatronics Systems, Ltd. (MHI-MS), a subsidiary of MHI, took over MHI's accelerator business on October 1, 2015, and has been developing the business since that time. MHI-MS has developed manufacturing process of superconducting cavities continuously. In this presentation, recent progress will be reported.

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WEPMR007

Electron Lens Construction for the Integrable Optics Test Accelerator at Fermilab

electron, solenoid, optics, focusing

2271

M.W. McGee, K. Carlson, L.E. Nobrega, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.
The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p⁺) diagnostic test ring. Construction of an electron lens for IOTA is necessary for both electron and proton operation. Components required for the Electron Lens design include; a 0.8 T conventional water-cooled main solenoid, and magnetic bending and focusing elements. The foundation of the design relies on repurposing the Fermilab Tevatron Electron Lens II (TELII) gun and collector under ultra-high vacuum (UHV) conditions.

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WEPMY013

A Spatially Separated Two Frequency RF Gun Design for Beam Brightness Improvement

emittance, laser, cavity, brightness

2572

Z. Zhang, C.-X. Tang, Z. Zhang
TUB, Beijing, People's Republic of China
H.J. Qian
LBNL, Berkeley, California, USA

Recent theoretical and experimental studies shows that transverse beam brightness of photoinjector can be improved by cigar beam photoemission, and beam peak current are then increased with a RF buncher following the gun. We apply this concept to a S-band photoinjector by adding a harmonic RF buncher closely to a S-band RF gun, forming a compact spatially separated two frequency RF gun, targeting a 200 pC beam with emittance < 0.2 mm·mrad and 30 A peak current. Both S/X-band and S/C-band combinations are considered, and an optimized solution with 30 A peak current and 0.1 mm·mrad slice emittance are presented.

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WEPMY037

Cold Model Cavity for 20-K Cryocooled C-band Photocathode RF Gun

simulation, cavity, coupling, impedance

2635

T. Tanaka, M. Inagaki, R. Nagashima, K. Nakao, K. Nogami, T. Sakai, K. Takatsuka
LEBRA, Funabashi, Japan
M.K. Fukuda, T. Takatomi, N. Terunuma, J. Urakawa, M. Yoshida
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
A cryocooled 2.6-cell C-band photocathode RF gun is under development at Nihon University in collaboration with KEK. The RF characteristics of a pillbox-type 2.6-cell C-band RF cavity at 20 K were in agreement with the theoretical predictions. The result of the cold test for a cavity with the input coupler confirmed the same characteristics. Based on these results a refined cold model of the 20-K cryocooled photocathode RF gun has been designed using SUPERFISH and CST-STUDIO. The separation between the TM01 pi and the TM01 half-pi modes has been increased from 20 MHz to 52 MHz by extending the diameter of the cavity iris and reducing the disk thickness. The 2.6-cell structure has been modified from pillbox to ellipsoid-like type. The end-plate of the 0.6-cell cavity has a center hole for bead-pull measurements of the on-axis electric filed through the entire structure. Mounting of a photocathode assembly in the end-plate has not been considered, since the purpose is solely to measure the low-power and low-temperature RF characteristics. A new design for the input coupler has been employed. The cavity will be completed early in 2016.

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WEPMY038

Optimization of C-band RF Input Coupler as a Mode Converter for 20-K Cryocooled Photocathode RF Gun

cavity, coupling, simulation, insertion

2638

T. Tanaka, M. Inagaki, R. Nagashima, K. Nakao, K. Nogami, T. Sakai, K. Takatsuka
LEBRA, Funabashi, Japan
M.K. Fukuda, T. Takatomi, N. Terunuma, J. Urakawa, M. Yoshida
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
Development of a cryocooled 2.6-cell C-band photocathode RF gun has been conducted at Nihon University in collaboration with KEK. An RF mode converter from square TE10 to circular TM01 mode has been employed as an RF input coupler that has a coupling coefficient of approximately 20 at 20 K to the 2.6-cell accelerating structure. In the previous design, the circular waveguide in the mode converter formed part of the accelerating cavity. After the cold test of the cavity completed in 2014, the coupler design was modified to work as a pure mode converter with a VSWR of 1 at 5712 MHz. From the design simulation using CST-STUDIO, the insertion loss in the converter is 0.2 %. The TM010 and TM011 modes excited in the circular waveguide were separated by several ten MHz from the accelerating frequency. The simulation has suggested that the amplitude of the transverse electric filed on the axis in the circular waveguide is reduced to approximately 2 % of that in the longitudinal direction.

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WEPMY039

Time Response Measurements for Transmission-Type GaAs/GaAsP Superlattice Photocathodes

electron, laser, cavity, brightness

2641

N. Yamamoto, X.J. Jin
KEK, Ibaraki, Japan
M. Hosaka, Y. Takashima, K. Yamaguchi
Nagoya University, Nagoya, Japan
M. Katoh
UVSOR, Okazaki, Japan

Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. Recently we have developed the strain compensated superlattice (SL) photocathode. In the strain compensated SLs, the equivalent compressive and tensile strains introduced in the well and barrier SL layers so that strain relaxation is effectively suppressed with increasing the SL layer thickness and high crystal quality can be expected. In this study, we fabricated the GaAs/GaAsP strain compensated SLs with the thickness up to 90-pair SL layers. Up to now, the electron spin polarization of 92 % and the quantum efficiency of 1.6 % were simultaneously achieved from 24-pair sample. In this study, to compare the time response performances with the SL thicknesses, the measurements were carried out for conventional and strain compensated SL PCs. We show the measurement results and discuss the physics.

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WEPOR007

Recent Improvements in Drive Beam Stability in CTF3

feedback, klystron, operation, linac

2677

L. Malina, R. Corsini, D. Gamba, T. Persson, P.K. Skowroński
CERN, Geneva, Switzerland

The proposed Compact Linear Collider (CLIC) uses a high intensity, low energy drive beam producing the RF power to accelerate the low intensity main beam with 100 MeV/m gradient. This scheme puts stringent requirements on drive beam stability in terms of phase, energy and current. Finding and understanding the sources of jitter plays a key role in their mitigation. In this paper, we report on the recent studies in the CLIC Test Facility (CTF3). New jitter and drift sources were identified and adequate beam-based feed-backs were implemented and commissioned. Finally, we present the resulting improvement of drive beam stability.

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WEPOY015

Longitudinal Bram Dynamics at Rf-Compressor

space-charge, simulation, electron, brightness

3011

A.V. Andrianov
BINP SB RAS, Novosibirsk, Russia

Nowadays the usage of charged particle beams for study of nature became widespread. Modern experiments are require particle beams with duration around hundreds femtosecond. Relatively simple and cheap method of production such pulses is using RF-gun with photocathode and then the special insertion device which compress the beam. The paper described the RF-compressor for the electron beam. In result of work was obtained a device configuration. Electromagnetic field configuration and distribution were simulated for the configuration. Beam dynamics was computed in this field distribution. Incoming beam parameters are following: beam length is 1-5ps, beam charge is 0.1-2pC and energy is 3MeV. Output beam duration was compressed to less than 150fs. Influence of RF-compressor at beam parameters was estimated.

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WEPOY024

Beam Dynamics Simulations of the Thomx Linac

emittance, solenoid, laser, electron

3036

L. Garolfi, C. Bruni, M. El Khaldi, P. Lepercq, C. Vallerand
LAL, Orsay, France
N. Faure
PMB-ALCEN, PEYNIER, France

ThomX Compton light source is designed to maximise the average X-ray flux providing a compact and tunable machine which can operate in hospitals or in museums. These constraints impose the choice of a high collision rate which is based on S-band Linac whose energy is 50-70 MeV combined to an electron storage ring. As most of the performances of the electron beam at the interaction point depend on the beam quality at the ring entrance, the linear accelerator must be carefully designed and especially the photo-injector. Simulations have been carried out in order to optimise the emittance for the ring entrance. Indeed, for a bunch charge of 1 nC, space charge effects usually dominate the total beam emittance. The latter can be minimized at the end of the Linac by means of emittance compensation. The best configuration across all the parameters will be presented.

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WEPOY037

Optimization of THz Radiation Pulses at FLUTE

electron, radiation, simulation, linac

3067

M. Yan, A.-S. Müller, M.J. Nasse, M. Schuh, M. Schwarz
KIT, Karlsruhe, Germany

The accelerator test facility FLUTE (Ferninfrarot Linac Und Test Experiment) will allow research and development in electron accelerator technology as well as photon science. Electron bunches of durations in the femtosecond range will be provided to generate intense THz radiation. Start-to-end simulation of the accelerator has been performed with the bunch length as the optimization objective. Based on the resulting charge distribution the expected THz field properties can be calculated. In this paper we combine the two tools and present first results.

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WEPOY039

GIOTTO: A Genetic Code for Demanding Beam-dynamics Optimizations

electron, software, space-charge, interface

3073

A. Bacci
Istituto Nazionale di Fisica Nucleare, Milano, Italy
V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
M. Rossetti Conti
Universita' degli Studi di Milano & INFN, Milano, Italy

GIOTTO is a software based on a Genetic Algorithm (GA). Its development started in 2007 with a work published on NIMB (263, 2007, 488-496) and presented at PAC07 (THPAN031). When the parameters, defining an acceleration machine beam line, are strongly correlated in nonlinear way, the GAs are a powerful tool to coup with these difficulties. These conditions are typically generated by space-charge, as in the high brightness e-beam photo-injectors or when the Velocity Bunching compression technique (VB) is used. The power of GIOTTO is the adaptability to different cases, given by its own structure that permits to drive different external codes in series, the possibility to define a user dependent multi objective fitness function and function constraints on the beam dynamics, as well as the possibility to turn off the genetic optimization to perform statistical analysis (machine jitters). Up today it has been used in Thomson/Compton sources, ultra-short e-bunches generation by VB, focusing channel and dog-leg lines optimizations.

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THOAB02

Concept of RF Linac for Intra-pulse Multi-energy Scan

klystron, linac, electron, experiment

3180

A.K. Krasnykh, J. Neilson, A.D. Yeremian
SLAC, Menlo Park, California, USA

Funding: Work supported in part by US Department of Energy under contract DE-AC02-76SF00515
A material discrimination based on X-Ray systems is typically achieved by alternating photon pulses of two different energies. A new approach relies on the ability to generate X-ray pulses with an end-point energy that varies in a controlled fashion during the duration of the pulse. An intra-pulse multi-energy X-ray beam device will greatly enhance current cargo screening capabilities. This method originally was described in the AS&E patents*. This paper addresses a linac concept for the proposed scan and describes some proof of concept experiments carried out at SLAC.
* A. Arodzero et al., 'System and methods for intra-pulse multi-energy and adaptive multi-energy X-ray cargo inspection', US Patent 8,457, 274, 2013

Slides THOAB02 [1.776 MB]

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THOAB03

Ultrafast Electron Microscopy using 100 Femtosecond Relativistic-Energy Electron Beam

electron, emittance, brightness, laser

3183

J. Yang, K. Kan, K. Tanimura, Y. Yoshida
ISIR, Osaka, Japan
J. Urakawa
KEK, Ibaraki, Japan

An ultrafast detection technique on 100 fs time scales over sub-nanometer (even atomic) spatial dimensions has long been a goal for the scientists to reveal and understand the ultrafast structural-change induced dynamics in materials. In this paper, the generation of femtosecond electron pulses using the RF gun and the first prototype of femtosecond time-resolved relativistic-energy ultrafast electron microscopy (UEM) are reported. Finally, both relativistic-energy electron diffraction and image measurements in the UEM prototype are presented.

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THPMB025

The Effect of Magnetic Field on the Secondary Electron Yield in the Ultra-High Vacuum Environment

electron, permanent-magnet, vacuum, synchrotron-radiation

3281

J. Wang, Y. Wang, W. Wei, Y.H. Xu, B. Zhang, T. Zhang, Y.X. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

A secondary electron emission measurement system has been designed and used to study the secondary electron emission (SEE) of different materials with an independently adjustable energy of 50 eV to 5 keV at National Synchrotron Radiation Laboratory. Here, we obtained the characteristics of the SEE yield from Pd film coatings, under the condition of magnetic field and without magnetic field. Then it was analysed that the effect of magnetic field on the secondary electron yield in the ultra-high vacuum environment. The results show that magnetic field shielding is critical to avoid the influence of magnetic field during secondary electron yield (SEY) measurements.

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THPMB048

Design and Optimisation of the ELENA Electron Cooler Gun and Collector

electron, solenoid, simulation, cathode

3354

G. Tranquille, J. Cenede
CERN, Geneva, Switzerland

Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler. The performance of the cooler is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the quality of the guiding magnetic field and the efficient recuperation of the electrons in the collector ensure that the cooler performance is optimal. We have used COMSOL Multiphysics to design and optimise the complete electron cooler with particular attention to the gun and collector. This software suite uses physics interfaces for modelling common applications and then allows the user to combine the different interfaces in one multi-physics simulation.

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THPMB052

Studies on Electron Beam Injector System for Linac-based Coherent Thz Source in Thailand

electron, undulator, linac, simulation

3366

W. Thongpakdi, S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand

Funding: The Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and the Development and Promotion of Science and Technology Talents Project (DPST).
At the Plasma and Beam Physics Research Facility, Chiang Mai University, a thermionic cathode RF electron gun and alpha magnet are used together as an injector system for a linac-based THz source. Investigate the optimal performance of the injector system, beam dynamic simulations are performed by computer codes PARMELA, ASTRA and ELEGANT. The input 3D field distributions of the RF-gun for PARMELA and ASTRA simulations are obtained from the RF modeling program CST Microwave Studio. The beam transport calculation using the program ELEGANT is performed to study behavior of electrons from the gun exit through the alpha magnet, a travelling wave linac, magnet elements, drift tubes, and related beam diagnostic components. Energy slits inside the alpha magnet vacuum chamber is used to select electrons with desired kinetic energies. The alpha magnet compresses electron bunches with certain bunch length before the beam entering the linac to obtain minimum energy spread and shortest bunch length at the experimental station. Results of electron beam optimization with appropriated conditions for generation of intense coherent THz radiation will be reported and discussed in this contribution.
This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and DPST.

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THPMB056

Witness Beam Production with an RF Gun and a Travelling Wave Booster Linac for AWAKE Experiment at CERN

emittance, linac, booster, proton

3378

O. Mete Apsimon, G.X. Xia
UMAN, Manchester, United Kingdom
R. Apsimon, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S. Döbert
CERN, Geneva, Switzerland

Funding: This work is supported by the Cockcroft Institute Core Grant and STFC.
AWAKE is a unique experiment that aims to demonstrate the proton driven plasma wakefield acceleration. In this experiment, proton bunches from the SPS accelerator will be injected into a 10m long pre-formed plasma section to form wakefields of hundreds MV/m to several GV/m. A second beam, e.g., the witness beam, will be injected after the protons in an appropriate phase to gain energy from the wakefields. A photo-injector will be utilised to deliver this second beam. It consists of an S-band RF gun followed by a meter long accelerating travelling wave structure (ATS). The RF gun was recuperated from existing PHIN photo-injector. A 3D RF design of the ATS was done by using the CST code and the field maps produced were used to characterise the electron beam dynamics under space charge effect by using the PARMELA code. The impact of the mechanical errors on the beam dynamics were investigated.

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THPMY043

Collimation System Design for LCLS-II

undulator, linac, collimation, electron

3755

M.W. Guetg, P. Emma, M. Santana-Leitner, J.J. Welch, F. Zhou
SLAC, Menlo Park, California, USA

Funding: DOE contract \#DE-AC02-76SF00515
The planned LCLS-II FEL has an average beam power of up to 1.2 MW and a repetition rate of up to 1 MHz, both of which entail serious challenges for beam halo collimation. This paper summarizes the efforts to assess the proposed collimation system. The undulator section is specifically focused on due to its high loss sensitivity (maximal 12 mW). This proceedings concentrate on field emissions of the gun. Different dark current distribution, linac configurations and simulation programs were used to increase assurance of the results. Filled phase-space tracking further supplemented an independent prove of the collimation system effectiveness and expands to include beam-halo originating from different sources than the gun.

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THPOR046

CEPC 650 MHz Klystron Development

klystron, simulation, electron, operation

3891

Z.S. Zhou, D. Dong, S. Fukuda, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, .. Zaib-un-Nisa
IHEP, Beijing, People's Republic of China
S. Fukuda
KEK, Ibaraki, Japan

The CEPC collider beam power is about 100 MW, so the efficiency of amplifier is very important for cost of project implementation. The high power klystron is the more attractive because of its potential for higher eﬃciency than solid state amplifier. For CEPC klystron output power is not so high, the operation voltage can be a safe value. Advantage for single beam: reliable, low phase noise, some perspective technology can be used to improve efficiency. The accelerating frequency is 650 MHz, output power is a maximum power of 800kW, and efficiency is about 70%. In this paper, the specifications and developments of 650 MHz CW klystron, including the klystron gun prototype and future high efficiency consideration are summarized.

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THPOW001

Design of a 4.6-Cell RF Gun for the PHIL accelerator at LAL

emittance, cavity, impedance, coupling

3922

P. Chen, C. Bruni, S. Chancé, L. Garolfi, A. Gonnin, P. Lepercq, T. Vinatier
LAL, Orsay, France

A photo-injector with 4.6-cell and resonate frequency of 2.998 GHz has been designed and studied to replace the 2.5-cell RF gun + booster association. The cavity iris shape and dimensions were simulated systematically to optimize the shunt impedance. In this study, electron beam reaches to 9.7 MeV with a moderate peak accelerat-ing gradient of 80 MV/m. Considering a beam charge of 1 nC/bunch, average transverse emittance of ~ 5.9 πmm mrad and energy spread of ~ 0.8% can be obtained at the exit of the gun. The RF input power is only 10.2 MW due to the high shunt impedance. Asymmetry of the electric field due to the coupling port has also been studied using 3D codes for RF and beam dynamics calculations. We will present the RF design and beam calculations results.

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THPOW002

Electromagnetic, Thermal, and Structural Analysis of a THOMX RF Gun Using ANSYS

cavity, electron, coupling, simulation

3925

M. El Khaldi, J. Bonis, A. Camara, L. Garolfi, A. Gonnin
LAL, Orsay, France

Photocathode RF guns are used in the first stage of electron beam generation and acceleration. The RF gun of THOMX is a 2.5 cell standing wave copper cavity with resonance frequency of 2998.55 MHz at 30 °C under vacuum. The metal photocathode such as copper or magnesium is inserted into the backplane of the cavity. Due to high repetition rates up to 50 Hz with the average dissipated power into the internal surfaces up to 1.5 kW, causing a heating and deformation of the cavity shape. Therefore, the cooling system of the device has to be well designed to take under control the deformations of the structure, providing a temperature increase as small and uniform as possible. For this purpose a fully coupled electromagnetic-thermal-structural finite element analysis on this gun has been performed with Ansys workbench. Numerical results show that the gun could operate at 3 μs RF pulse length and 50 Hz repetition rate with an average dissipated power of 1.5 kW. The gun average temperature is around 30 °C while the incoming water temperature is around 24°C. Internal speed of water is 2.5 m/s which corresponds to 15 l/min for the incoming water. The total pressure drop is around 0.4 bar

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THPOW003

Highlights on Metallic Photocathodes Used in SRF Gun

cathode, SRF, laser, emittance

3928

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

For the accelerator-based light sources and the electron colliders, the development of photoinjectors has become a key technology. Especially for the superconducting radio frequency cavity based injector (SRF Gun), the searching for better photocathodes is always a principal technical challenge. To use metallic photocathodes for ELBE SRF Gun is the primary choice to prevent cavity contamination. In this contribution, we will report the investigation of Magnesium (Mg) in ELBE SRF gun, including laser cleaning treatment and the measurement on quantum efficiency, Schottky effect, dark current and damage threshold.
The work is supported by the European Community under the FP7 programme (EuCARD-2 and LA3NET) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.

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THPOW007

Cs2Te Photocathode Response Time Measurements and Femtosecond Comb Electron Beam Generation as a Milestone Towards Pre-Bunched Thz Fel Realization

electron, radiation, laser, FEL

3941

A. Aryshev, Y. Honda, K. Lekomtsev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan and JSPS KAKENHI: 23226020 and 24654076
Currently there is a rapidly growing demand to increase the brightness of electron beams generated by conventional RF guns as well as to decrease the cost of the injector accelerator system for many research facilities worldwide. To address this demand we investigate one of the most important parameter of the high Q.E. conventional semiconductor Cs2Te photocathode, its response time. It sets the principle limitation for generated bunch length and hence maximum achievable beam brightness of electron diffraction and pre-bunched THz FEL facility's injectors. The experimental investigation was done at KEK: LUCX facility. The Cs2Te photocathode response time better than 250 fs was demonstrated. The generation of 4 micro-bunch comb electron beam with variable time separation as a crucial technology for pre-bunched THz FEL realization was achieved.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW007

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THPOW008

DC Photoemission Gun Upgrade at the Compact ERL

operation, high-voltage, FEL, vacuum

3944

N. Nishimori, R. Hajima, R. Nagai
JAEA, Ibaraki-ken, Japan
Y. Honda, T. Miyajima, T. Uchiyama, M. Yamamoto
KEK, Ibaraki, Japan
M. Mori
JAEA/Kansai, Kyoto, Japan

Funding: This work is partially supported by a JSPS Grant-in-Aid for Scientific Research in Japan (15H03594).
The DC photoemission gun at the compact ERL (cERL) has stably provided beam for ERL commissioning and laser Compton scattering experiments since April 2013. The operational voltage has however been limited to 390 kV due to failures of two segments out of the ten segmented insulator. In order to recover 500 kV operation, we installed an additional two segmented insulator on the existing ten segmented insulator during summer shutdown in 2015. The details of the gun upgrade and the operational experience of the upgraded cERL gun will be presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW008

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THPOW009

Optimal Design of a Photocathode Electron Gun with High-brightness and High-repetition Rate Based on Genetic Algorithm

impedance, electron, cavity, laser

3947

Zh. X. Tang, X.M. Yang, W.Q. Zhang
DICP, Dalian, People's Republic of China
Y.J. Pei, Y. Yu
USTC/NSRL, Hefei, Anhui, People's Republic of China

A low RF frequency of normal conducting photocathode gun with high-brightness and high-repetition rate is designed as an electron source of the Next Generation Light Source (NGLS). In order to optimize the performance of the gun, a genetic multi-objective algorithm has been used. A genetic algorithm is used because of the inherent complexity of the large number of parameters of the cavity geometry available for optimization. On the other hand, the multiplicity of requirements on the beam, which include beam emittance, beam pulse length, energy chirp, as well as pulse shape and peak current, leads to a multi-objective approach for the optimization technique. In this paper, we present the status of the optimization simulations, using the SUPERFISH and PERMELA particle-in-cell code.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW009

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THPOW010

Study on Characteristics of Asymmetric Centre Iris of Photocathode Microwave Electron Gun

electron, emittance, electromagnetic-fields, cathode

3951

Zh. X. Tang, X.M. Yang, W.Q. Zhang
DICP, Dalian, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

The characteristics of asymmetric iris between first cell and second cell of 1.6 cell photocathode gun are studied. For π-mode, the RF radial field of two sides of the iris is non anti-symmetric. Thus, the RF transverse force at the iris is not negligible. In this paper, we present the status of the optimization simulations, using the SUPERFISH and PARMELA particle-in-cell code. Numerical results of beam dynamics show that it can improve the emittance at the exit of the gun.

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THPOW011

The Measurement System of the Electron Gun with Double-anode Structure

cathode, electron, vacuum, high-voltage

3954

F.L. Shang, J. Li, L. Shang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: National Natural Science Foundation of China(11175181); National Natural Science Foundation of China(10875116)
The double-anode structure with an intermediate electrode has been proposed to overcome the strong space-charge force on the cathode and improve the transverse focusing, which make the goal of high perveance and high compression ratio achieved. This gun plays a key role as the external injecting electron source of the independently-tunable-cells (ITC) RF gun. In order to understand the quality of the beam, a measurement system has been designed. The papers present the measurement system and the result of the test.

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THPOW018

Simulations of Field Emitted Dark Current Dynamics in DC Photoinjectors

simulation, electron, cavity, space-charge

3971

P.J. Tipping, J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Field emission is a concern in injectors with DC photoelectron guns because of the constant generation of dark current, which is accelerated down the beam line and can deteriorate the photoemitted bunch quality and lead to hardware damage. Simulations were carried out on the co-propagation of a field emitted, dark current halo and a photoemitted bunch in a typical 350 kV gun as used in an ERL or FEL injector, followed by a single cell buncher cavity. The photoemitted bunch repelled the halo longitudinally, leaving the area in the centre of the bunch with very low dark current, surrounded by two peaks of relatively high current at the front and back of the bunch. The peaks in current occur at all levels of dark current and were about 3.5 times the amplitude of the undisturbed dark current. The buncher caused the dark current to overcompress, forming a 'ghost' pulse an order of magnitude larger than the initial level of dark current, in front of the photoemitted bunch.

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THPOW019

Beam Characterisation and Machine Developments at VELA

experiment, cathode, electron, space-charge

3975

D. Angal-Kalinin, A.D. Brynes, F. Jackson, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.L. Militsyn, B.D. Muratori, T.C.Q. Noakes, M.D. Roper, Y.M. Saveliev, D.J. Scott, R.J. Smith, E.W. Snedden, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.D. Barrett, C.P. Topping, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
C.S. Edmonds, F. Jackson, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.D. Muratori, Y.M. Saveliev, D.J. Scott, C.P. Topping, P.H. Williams, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

An overview is presented of developments on VELA (Versatile Electron Linear Accelerator), an RF photo-injector with two user stations at Daresbury Laboratory. Numerous commissioning, machine development, beam characterisation and user experiments have been completed in the past year. A new beamline and a dedicated multiuser station have been commissioned and the first experiments performed. A number of measures have been taken to improve the stability of machine by mitigating a phase drift, laser beam transport drift and a coherent ~1 Hz beam oscillation. The 6D phase space of the electron beam has been characterised through quad scans, transverse tomography and with a transverse deflecting cavity.

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THPOW020

S-Band Photoinjector Investigations by Multiobjective Genetic Optimizer

emittance, laser, brightness, cathode

3979

H.J. Qian, D. Filippetto, F. Sannibale
LBNL, Berkeley, California, USA

Photoinjectors has witnessed great progress in the past few decades, with low duty cycle high gradient guns, such as normal conducting S/L band gun, pushing the peak beam brightness frontier, and CW guns, such as DC gun, SRF gun and VHF gun, pushing the average beam brightness frontier. Due to different degrees of complexity, pulsed high gradient photoinjectors are usually optimized by manual scans, while CW photoinjectors are optimized by multi-objective genetic optimizers. In this paper, a multi-objective genetic optimizer is used to revisit S-band photoinjector beam brightness optimizations, showing a trade-off between peak current and transverse emittance, with the optimized injector layout depending on bunch charge and peak current. For 200 pC case, the final beam core brightness at injector exit is close to cathode maximum brightness in the 'cigar beam' regime. Assuming a thermal emittance of 0.5 μm/mm and a beam charge of 200 pC, about 90 nm slice emittance at 20 A peak current is achieved.

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THPOW025

Photocathode Growth and Characterization Advances at Cornell University

electron, photon, emittance, cathode

3990

L. Cultrera, A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, H. Lee, R.A. Lipton, T.P. Moore
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Alkali-antimonides based photocathodes have demonstrated outstanding performance in high brightness electron beam production suitable for a wide range of applications such as FELs, ERLs and UED and for use in photomultiplier devices with picosecond resolution aimed at photon counting application in medicine and High Energy Physics. The photocathode laboratory at Cornell University is dedicated to studying the growth procedures and characterizing the properties in a wide range of photocathodes materials. Different experimental arrangements and alkali metal sources have been successfully explored to date to synthesize photosensitive materials. Recent work on commissioning a new growth chamber equipped with effusion cells loaded with pure metal allowing uniform deposition over large area substrates resulted on successful growth of photocathodes with extended sensitivity in the IR part of the spectrum and high efficiency alkali antimonides containing Rb metal. This and other advances aimed at demonstrating superior photocathodes will be presented.

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THPOW026

LLNL X-band RF Gun Results

laser, electron, emittance, dipole

3993

R.A. Marsh, G.G. Anderson, C.P.J. Barty, D.J. Gibson
LLNL, Livermore, California, USA
Y. Hwang
UCI, Irvine, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
An X-band test station and Inverse Compton Scattering (ICS) x-ray source has been built and commissioned at LLNL. The electron beam source is a unique 5.59 cell RF photoinjector, which will be described in detail, including: quantum efficiency, emittance measurements, energy spread and jitter, final focus spot size and stability, laser profile and final transport, and consistency with expectations based on beam dynamics simulations.

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THPOW028

Automated Design for Standing Wave Electron Photoguns: TOPGUN RF Design

toolkit, simulation, coupling, cavity

3999

A.D. Cahill
UCLA, Los Angeles, California, USA
M. Dal Forno, V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515
Systematic design of RF photoguns involves multiple RF simulations in conjunction with beam dynamic simulations. RF simulations include tuning gun frequency, matching the gun to the feeding RF circuit, balancing the on axis electric fields between gun cells, minimizing surface electric and magnetic fields and power consumption, and optimizing separation of resonant mode frequencies. We created a tool that allows this multiple parameter optimization to be done automatically. We used SUPERFISH to accomplish the RF simulations. We present an example of the rf photogun TOPGUN design using these tools.

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THPOW059

UV Pulse Shaping with a-BBO Crystals for the Photocathode RF Gun

laser, electron, flattop, optics

4079

D. Wang, W.-H. Huang, L.X. Yan
TUB, Beijing, People's Republic of China

Recently, manipulation with the drive laser plays a significant role in high brightness electron beam production by the photocathode RF gun. The method based on pulse stacking with birefringent crystal serials was tried to longitudinally shape ultraviolet laser pulse. Using four or five pieces of a-BBO crystals to stack an input UV pulse with appropriate initial duration into 16 or 32 sub-pulses to form quasi flattop UV laser pulse, which can be applied for emittance optimization of the electron beam based on the photocathode RF gun. Moreover, the negative slop of the energy transmittance of a-BBO serials is also revealed to be a passive stabilization mechanism for energy jitter reduction in the driving laser. With appropriate design of a-BBO serials, this method can fulfill the requirements for driving laser in a broad scope of applications such as x-ray FELs and high-power Terahertz(THz) radiation production.

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THPOY027

Commissioning Status of SuperKEKB Injector Linac

electron, emittance, linac, injection

4152

M. Satoh, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Iwase, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, S. Kazama, M. Kikuchi, H. Koiso, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, D. Satoh, Y. Seimiya, T. Shidara, A. Shirakawa, M. Suetake, H. Sugimoto, T. Suwada, M. Tanaka, M. Tawada, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
KEK, Ibaraki, Japan

The SuperKEKB main ring is currently being constructed for aiming at the peak luminosity of 8 x 10³⁵ cm^-2s⁻¹. The electron/positron injector linac upgrade is also going on for increasing the intensity of bunch charge with keeping the small emittance. The key upgrade issues are the construction of positron damping ring, a new positron capture system, and a low emittance photo-cathode rf electron source. The injector linac beam commissioning started in the October of 2013. In this paper, we report the present status and future plan of SuperKEKB injector commissioning.

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THPOY054

An External Synchronization of PHIL to a High Power Femtosecond Laser

electron, laser, timing, cavity

4228

N. ElKamchi, V. Chaumat
LAL, Orsay, France

The synchronization accuracy between laser systems and RF wave is a crucial ingredient for the successful operation of any particle accelerator based on photo-emission. In the case of ultra-short highly charged electron accelerator, the beam is highly sensitive to timing jitter. Thus, a high level of synchronization accuracy is needed. In this paper, we describe the current synchronization system of PHIL (electron accelerator at LAL), and a new approach to synchronize PHIL externally with a high power femtosecond laser (LASERIX) . The main goal of the experience is to design and study a compact way to obtain ultra-short electron bunches (few tens to few hundreds of femtoseconds) under high charge levels (hundred pC). We continue with a description of different modifications made on PHIL timing master to adapt it to external synchronization.

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THPOY060

Four Beam Generation for Simultaneous Four-Hall Operation at CEBAF

laser, timing, electron, space-charge

4240

R. Kazimi, J.M. Grames, J. Hansknecht, A.S. Hofler, G.E. Lahti, T. E. Plawski, M. Poelker, R. Suleiman, Y.W. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by JSA, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Gov't retains a non-exclusive, paidup, irrevocable, worldwide license to publish or reproduce this for U.S. Gov't purposes.
As part of the CEBAF 12 GeV upgrade at Jefferson Lab, a new experimental hall was added to the existing three halls. To deliver beam to all four halls simultaneous-ly, a new timing pattern for electron bunches is needed at the injector. This pattern change has consequences for the frequency of the lasers at the photogun, beam behavior in the chopping system, beam optics due to space charge, and setup procedures. We have successfully demonstrated this new pattern using the three existing drive lasers. The implementation of the full system will occur when the fourth laser is added and upgrades to the Low Level RF (LLRF) are complete. In this paper we explain the new bunch pattern, the challenges for setting and measuring the pattern such as 180° RF phase ambiguity, addition of the fourth laser to the laser table and LLRF upgrade.

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FRXBB01

Achieved Performance of an All X-band Photo-injector

cathode, laser, electron, emittance

4253

C. Limborg, C. Adolphsen, M.P. Dunning, R.K. Jobe, H. Li, D.J. McCormick, T.O. Raubenheimer, T. Vecchione, A.R. Vrielink, F.Y. Wang, S.P. Weathersby
SLAC, Menlo Park, California, USA

Funding: Work funded by DOE/SU Contract DE-AC02-76-SF00515
Building more compact accelerators to deliver high brightness electron beams for the generation of high flux, highly coherent radiation is a priority for the photon science community. A relatively straightforward reduction in footprint can be achieved by using high-gradient X-Band (11.4 GHz) RF technology. This talk presents the all X-band photo-injector facility at SLAC, covering the benefits of using this technology and highlighting the performance achieved.

Slides FRXBB01 [40.418 MB]

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