NAPAC2016 - List of Keywords (gun)

Paper	Title	Other Keywords	Page
MOPOB06	MAX IV and Solaris Linac Magnets Production Series Measurement Results	ion, linac, storage-ring, septum	79
	M.A.G. Johansson MAX IV Laboratory, Lund University, Lund, Sweden R. Nietubyć NCBJ, Świerk/Otwock, Poland
	The linacs of the MAX IV and Solaris synchrotron radiation light sources, currently in operation in Lund, Sweden, and Kraków, Poland, use various conventional magnet designs. The production series of totally more than 100 magnets of more than 10 types or variants, which were all outsourced to industry, with combined orders for the types that are common to both MAX IV and Solaris, were completed in 2013 with mechanical and magnetic QA conforming to specifications. This article presents an overview of the different magnet types installed in these machines, and mechanical and magnetic measurement results of the full production series.
	Poster MOPOB06 [2.535 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB06
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MOPOB08	Streak Camera Measurements of the APS PC Gun Drive Laser	ion, laser, factory, optics	85
	J.C. Dooling ANL, Argonne, Illinois, USA A.H. Lumpkin Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357. We report recent pulse-duration measurements of the APS PC Gun drive laser at both second harmonic (SH, 527 nm) and fourth harmonic (FH. 263 nm) wavelengths. The drive laser is a Nd:Glass-based CPA with the IR wavelength (1053 nm) twice doubled to obtain UV output for the gun. A Hamamatsu C5680 streak camera and an M5675 synchroscan unit are used for these measurements; the synchroscan unit is tuned to 119 MHz, the 24th subharmonic of the linac operating frequency. Calibration is accomplished both electronically and optically. Electronic calibration utilizes a programmable delay line in the 119 MHz rf path. The optical delay employs an etalon with known spacing between reflecting surfaces; this etalon is coated for the visible, SH wavelength. IR pulse duration is monitored with an autocorrelator. Fitting the streak camera image projected profiles with Gaussians, UV rms pulse durations are found to vary from 2.1 ps to 3.5 ps as the IR varies from 2.2 ps to 5.2 ps.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB08
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TUPOA05	Development of a Fiber Laser for Improving the Pulse Radiolysis System	ion, laser, electron, radiation	299
	Y. Saito, S.Y. Soeta, M. Washio Waseda University, Tokyo, Japan Y. Hosaka, K. Sakaue RISE, Tokyo, Japan
	When material is irradiated by the ionizing radiation, short-lived and highly reactive substance intermediate active species are made and then react with substances. The chemical reaction is determined by intermediate active species in early process. Proving the behavior of intermediate active species is important for understanding and controlling radiation chemical reaction. In Waseda university we been developing a Pulse Radiolysis System, a method to measure the behavior of intermediate species, for radiation chemical analysis with RF electron gun. Currently we are developing a Supercontinuum ray(SC ray)as a probe ray to improve Pulse Radiolysis System. We have introduced a SC ray using Yb fiver laser and PCF(Photonic Crystal Fiber). But this type of prove light isn't stable enough in the visible light region. Therefore we started to study Er fiber laser oscillator as new prove ray source. We have succeeded to oscillate a Er fs laser pulse, second harmonic generation and measurement of hydrated electron in ns time resolution. In this presentation we will report current research about generation of SC ray, Er fiber laser system and dose rate effect against the hydrated electron.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA05
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TUPOA19	50-MeV Run of the IOTA/FAST Electron Accelerator	ion, electron, emittance, cavity	326
	D.R. Edstrom, C.M. Baffes, C.I. Briegel, D.R. Broemmelsiek, K. Carlson, B.E. Chase, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, B.J. Fellenz, E.R. Harms, M.J. Kucera, J.R. Leibfritz, A.H. Lumpkin, D.J. Nicklaus, E. Prebys, P.S. Prieto, J. Reid, A.L. Romanov, J. Ruan, J.K. Santucci, T. Sen, V.D. Shiltsev, Y.-M. Shin, G. Stancari, J.C.T. Thangaraj, R.M. Thurman-Keup, A. Valishev, A. Warner, S.J. Wesseln Fermilab, Batavia, Illinois, USA A.T. Green Northern Illinois Univerity, DeKalb, Illinois, USA A. Halavanau, D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA J. Hyun Sokendai, Ibaraki, Japan P. Kobak BYU-I, Rexburg, USA W.D. Rush KU, Lawrence, Kansas, USA
	Funding: Supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. The low-energy section of the photoinjector-based electron linear accelerator at the Fermilab Accelerator Science & Technology (FAST) facility was recently commissioned to an energy of 50 MeV. This linear accelerator relies primarily upon pulsed SRF acceleration and an optional bunch compressor to produce a stable beam within a large operational regime in terms of bunch charge, total average charge, bunch length, and beam energy. Various instrumentation was used to characterize fundamental properties of the electron beam including the intensity, stability, emittance, and bunch length. While much of this instrumentation was commissioned in a 20 MeV running period prior, some (including a new Martin-Puplett interferometer) was in development or pending installation at that time. All instrumentation has since been recommissioned over the wide operational range of beam energies up to 50 MeV, intensities up to 4 nC/pulse, and bunch structures from ~1 ps to more than 50 ps in length.
	Poster TUPOA19 [4.636 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA19
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TUPOA26	Initial Observations of Micropulse Elongation of Electron Beams in a SCRF Accelerator*	ion, electron, laser, MMI	337
	A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA
	Funding: * Work at Fermilab supported by Fermi Research Alliance, LLC under Contract No. DE-AC02- 07CH11359 with the United States Department of Energy Commissioning at the SCRF accelerator at the Fermilab Accelerator Science and Technology (FAST) Facility has included the implementation of a versatile bunch-length monitor located after the 4-dipole chicane bunch compressor for electron beam energies of 20-50 MeV and integrated charges in excess of 10 nC. The team has initially used a Hamamatsu C5680 synchroscan streak camera. An Al-coated Si screen was used to generate optical transition radiation (OTR) resulting from the beam's interaction with the screen. The chicane bypass beamline allowed the measurements of the bunch length without the compression stage at the downstream beamline location using OTR and the streak camera. The UV component of the drive laser had previously been characterized with a Gaussian fit σ of 3.5-3.7 ps. However, the uncompressed electron beam is expected to elongate due to space charge forces in an initial 1.5-m drift from the gun to the first SCRF accelerator cavity. We have observed electron beam bunch lengths from 5 to 14 ps (σ) for micropulse charges of 60 pC to 800 pC, respectively. Commissioning of the system and initial results with uncompressed and compressed beam will be presented. A.H. Lumpkin et al., Proceedings of FEL14, MOP021, Basel, Switzerland, www. JACoW.org
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA26
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TUPOA51	First Steps Toward Incorporating Image Based Diagnostics into Particle Accelerator Control Systems Using Convolutional Neural Networks	ion, network, controls, solenoid	390
	A.L. Edelen, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA J.P. Edelen Fermilab, Batavia, Illinois, USA
	At present, a variety of image-based diagnostics are used in particle accelerator systems. Often times, these are viewed by a human operator who then makes appropriate adjustments to the machine. Given recent advances in using convolutional neural networks (CNNs) for image processing, it should be possible to use image diagnostics directly in control routines (NN-based or otherwise). This is especially appealing for non-intercepting diagnostics that could run continuously during beam operation. Here, we show results of a first step toward implementing such a controller: our trained CNN can predict multiple simulated downstream beam parameters at the Fermilab Accelerator Science and Technology (FAST) facility's low energy beamline using simulated virtual cathode laser images, gun phases, and solenoid strengths.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA51
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TUPOA59	Successful Laboratory-Industrial Partnerships: the Cornell-Friatec Segmented Insulator for High Voltage DC Photocathode Guns	ion, electron, vacuum, high-voltage	405
	K.W. Smolenski, B.M. Dunham Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D.L. Barth, M. Muehlbauer, S. Wacker FRIATEC AG, Mannheim, Germany J.M. Maxson UCLA, Los Angeles, California, USA
	High voltage DC photocathode guns currently offer the most reliable path to electron beams with high current and brightness. The performance of a gun is directly dependent on its vacuum and high voltage capabilities, determined in large part by the ceramic insulators. The insulator must meet XHV standards, bear the load of pressurized SF6 on its exterior, support the massive electrode structures as well as holding off DC voltages up to 750kV. Construction of UHV and high voltage capable insulators require high purity ceramics and metal components proven to minimize thermal stress between the brazed ceramic rings and metal guard rings. The use of replaceable guard rings is a critical way of controlling manufacturing costs while extending the life cycle of the insulator. Successful fabrication requires proven manufacturing methods in flatness, parallelism, and maintaining alignment of many parts during the brazing process. Taking a scalable, modular approach, the insulator design can be applied to a variety of gun voltages and can be used by other projects. The Cornell-Friatec insulator was designed collaboratively and has now been produced in quantity for Cornell and elsewhere.
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TUPOA73	Commissioning and First Results From a Channeling-Radiation Experiment at FAST	ion, detector, electron, radiation	428
	J. Hyun Sokendai, Ibaraki, Japan D.R. Broemmelsiek, D.R. Edstrom, A.L. Romanov, J. Ruan, T. Sen, V.D. Shiltsev Fermilab, Batavia, Illinois, USA A. Halavanau, D. Mihalcea Northern Illinois University, DeKalb, Illinois, USA P. Kobak BYU-I, Rexburg, USA W.D. Rush KU, Lawrence, Kansas, USA
	X-rays have widespread applications in science. Developing compact and high-quality X-ray sources, easy to disseminate, has been an on going challenge. Our group has explored the possible use of channeling radiation driven by a 50 MeV low-emittance electron beam to produce narrowband hard X-rays (photon energy from 40 keV to 140 keV). In this contribution we present the simulated X-ray spectrum including the background bremsstrahlung contribution, and optimization of the relevant electron-beam parameters required to maximize the X-ray brilliance. The results of experiments carried out at Fermilab's FAST facility – which include a 50 MeV superconducting linac and a high-brightness photoinjector – are also discussed. The average brilliance in our experiment is expected to be about one order of magnitude higher than that in previous experiments.
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TUB3IO02	Overview of Electron Source Development for High Repetition Rate FEL Facilities	ion, cathode, electron, emittance	445
	F. Sannibale LBNL, Berkeley, California, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 'fsannibale@lbl.gov An increasing science demand for high-repetition rate (MHz-class) FEL facilities, from IR to X-rays, has been pushing institutions and groups around the world to develop proposals addressing such a need, and some of them have been already funded and are under construction. Such facilities require the development of high-brightness high-repetition rate electron guns, and a number of groups worldwide started to develop R&D programs to develop electron guns capable of operating at this challenging regime. Here we describe the approaches and technologies used by the different programs and discuss advantages and challenges for each of them. A review of the present achievements is included, as well as a brief analysis to understand if the present technology performance is sufficient to operate present and future high repetition rate FEL facilities.
	Slides TUB3IO02 [7.951 MB]
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TUB3CO04	A New Thermionic RF Electron Gun for Synchrotron Light Sources	ion, cathode, coupling, electron	453
	S.V. Kutsaev, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A.V. Smirnov RadiaBeam Systems, Santa Monica, California, USA R.B. Agustsson, J.J. Hartzell, A. Verma RadiaBeam, Santa Monica, California, USA A. Nassiri, Y. Sun, G.J. Waldschmidt, A. Zholents ANL, Argonne, Illinois, USA E.A. Savin MEPhI, Moscow, Russia
	Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Science, under contract DE-SC0015191 and contract No. DE-AC02-06CH11357. A thermionic RF gun is a compact and efficient source of electrons used in many practical applications. RadiaBeam Systems and the Advanced Photon Source of Argonne National Laboratory collaborate in developing of a reliable and robust thermionic RF gun for synchrotron light sources which would offer substantial improvements over existing thermionic RF guns and allow stable operation with up to 1A of beam peak current at a 100 Hz pulse repetition rate and a 1.5 μs RF pulse length. In this paper, we discuss the electromagnetic and engineering design of the cavity, and report the progress towards high power tests of the cathode assembly of the new gun.
	Slides TUB3CO04 [2.661 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB3CO04
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WEPOA05	EBIS Charge Breeder for RAON Facility	ion, electron, vacuum, ISOL	696
	S.A. Kondrashev, J.-W. Kim, Y.K. Kwon, Y.H. Park, H.J. Son IBS, Daejeon, Republic of Korea
	New large scale accelerator facility called RAON is under design in Institute for Basic Science (IBS, Daejeon, Korea). Both technics of rare isotope production Isotope Separation On-Line (ISOL) and In-Flight Fragmentation (IF) will be combined within one facility for the first time to provide wide variety of rare isotope ion beams for nuclear physics experiments and applied research. Electron Beam Ion Source (EBIS) charge breeder will be used to prepare rare isotope ion beams produced by ISOL method for efficient acceleration. Beams of different rare isotopes will be charge-bred by an EBIS charge breeder to a charge-to-mass ratio (q/A) ≥ 1/4 and accelerated by linac post-accelerator to energies of 18.5 MeV/u. RAON EBIS charge breeder will provide the next step in the development of breeder technology by implementation of electron beam with current up to 3 A and utilization of wide (8') warm bore of 6 T superconducting solenoid. The design of RAON EBIS charge breeder and results of dumping of high power DC and pulsed electron beam into collector will be presented and discussed.
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WEPOA06	New Coolers for Ion Ion Colliders	ion, electron, collider, proton	700
	V.V. Parkhomchuk BINP SB RAS, Novosibirsk, Russia
	For crucial contributions in the proof of principle of electron cooling, for leading contribution to the experimental and theoretical development of electron cooling, and for achievement of the planned parameters of coolers for facilities in laboratories around the world the 2016 "Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators" was awarded to Vasili Parkhomchuk. In this paper new future coolers for ion*ion collider will be discussed.
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WEPOA12	Interleaving Lattice Design for APS Linac	ion, lattice, linac, electron	713
	S. Shin, Y. Sun, A. Zholents ANL, Argonne, Illinois, USA
	In order to realize and test advanced accelerator concepts and hardware, the existing beamline with both old and new components are being reconfigured in Linac Extension Area (LEA) of APS linac. Photo injector, which had been installed in the beginning of APS linac, will provide low emittance electron beam into the LEA. The thermionic RF gun beam for storage ring and photo-cathode RF gun beam for LEA will be operated though the LINAC in an interleaved fashion. In this presentation, technical issues as well as beam dynamics on the design for interleaving operation will be described.
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WEPOA40	Construction Status of a RF-Injector with a CNT-Tip Cathode for High Brightness Field-Emission Tests	ion, cathode, electron, emittance	785
	Y.-M. Shin, G. Fagerberg, M. Figora Northern Illinois University, DeKalb, Illinois, USA A.T. Green Northern Illinois Univerity, DeKalb, Illinois, USA
	We have been constructing a S-band RF-injector system for field-emission tests of a CNT-tip cathode. A pulsed Sband klystron is installed and fully commissioned with 5.5 MW peak power in a 2.5 microsecond pulse length and 1 Hz repetition rate. A single-cell RFgun is designed to produce with 0.5 - 1 pC electron bunches in a photo-emission mode within a 50 fs - 3 ps at 0.5- 1 MeV. The measured RF system jitters are within 1 % in magnitude and 0.2° in phase, which would induce 3.4 keV and 0.25 keV of energy jitters, corresponding to 80 fs and 5 fs of temporal jitters, respectively. Our PIC simulations indicate that the designed bunch compressor reduces the TOAjitter by about an order of magnitude. Emission current and beam brightness of the field-emitted beam are improved by implanting CNT tips on the cathode surface, since they reduce the emission area, while providing high current emission. Once the system is completely commissioned in field-emission mode, the CNT-tip cathode will be tested in terms of klystron-power levels to map out its I-V characteristics under pulse emission condition.
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WEPOA42	RF Design of a 1.3-GHz High Average Beam Power SRF Electron Source	ion, cathode, electron, simulation	789
	N. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA I.V. Gonin, R.D. Kephart, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	There is a significant interest in developing high-average power electron sources, particularly those integrated with Superconducting Radio Frequency (SRF) accelerator systems. Even though there are examples of high-average-power electron sources, they are not compact, highly efficient, or available at a reasonable cost. Adapting the recent advances in SRF cavities, RF power sources, and innovative solutions for an SRF gun and cathode system, we have developed a design concept for a compact SRF high-average power electron linac. This design will produce electron beams with energies up to 10 MeV. In this paper, we present the design results of our cathode structure integrated with modified 9-cell accelerating structure.
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WEPOB19	Summary of Cs2te Photocathode Performance and Improvements in the High-Gradient, High-Charge AWA Drive Gun	cathode, ion, operation, wakefield	934
	E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, C.-J. Jing, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford ANL, Argonne, Illinois, USA S.P. Antipov, C.-J. Jing, J.Q. Qiu Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The AWA L-band, high-charge photoinjector for the 70 MeV drive beamline has been operating for almost 3 years at the Argonne Wakefield Accelerator (AWA) facility. at Argonne National Laboratory (ANL). The gun operates at high-field (85 MV/m peak field on the cathode) and has a high quantum efficiency (QE) Cesium telluride photocathode with a large area (30 mm diameter). It produces high-charge, short pulse, single bunches (Q > 100 nC) as well as long bunch-trains (Q > 600 nC) for wakefield experiments (high peak current). During the first two years of operation, photocathode performance was evaluated and areas of improvement were identified. After study, consideration and consultation, steps were taken to improve the performance of the photocathode. So far, in total, three photocathodes have been fabricated on-site, installed and operated in the gun. Improvements made to the photocathode plug, vacuum system, and gun operation are detailed. The results include vastly improved conditioning times, better cathode performance, and QE above 4% for over 11 months.
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WEPOB25	Analytical Modeling of Electron Back-Bombardment Induced Current Increase in Un-Gated Thermionic Cathode Rf Guns	ion, cathode, electron, simulation	953
	J.P. Edelen Fermilab, Batavia, Illinois, USA J.R. Harris Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA Y. Sun ANL, Argonne, Illinois, USA
	In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, field-enhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.
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WEPOB26	Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun	ion, cathode, electron, experiment	956
	J.P. Edelen Fermilab, Batavia, Illinois, USA J.R. Harris Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA Y. Sun ANL, Argonne, Illinois, USA
	Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an un-gated thermionic cathode RF gun to high average current.
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WEPOB54	DC Photogun Gun Test for RHIC Low Energy Electron Cooler (LEReC).	ion, electron, laser, cavity	1008
	D. Kayran, Z. Altinbas, D.R. Beavis, S. Bellavia, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, J. Halinski, K. Hamdi, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, G.J. Mahler, T.A. Miller, S.K. Nayak, T. Rao, S. Seletskiy, B. Sheehy, J.E. Tuozzolo, Z. Zhao BNL, Upton, Long Island, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. Non-magnetized bunched electron cooling of low-energy RHIC requires electron beam energy in range of 1.6-2.6 MeV, with average current up to 45 mA, very small energy spread, and low emittance [1]. A 400 kV DC gun equipped with photocathode and laser delivery system will serve as a source of high-quality electron beam. Acceleration will be achieved by an SRF 704 MHz booster cavity and other RF components that are scheduled to be operational in early 2018. The DC gun testing in its installed location in RHIC will start in early 2017. During this stage we plan to test the critical equipment in close to operation conditions: laser beam delivery system, cathode QE lifetime, DC gun, beam instrumentation, high power beam dump system, and controls. In this paper, we describe the gun test set up, major components, and parameters to be achieved and measured during the gun beam test. [1] A. Fedotov. Bunched beam electron cooling for Low Energy RHIC operation. ICFA Beam Dynamics letter, No. 65, p. 22 (December 2014)
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WEPOB58	Cathode Puck Insertion System Design for the LEReC Photoemission DC Electron Gun	ion, cathode, vacuum, insertion	1021
	C.J. Liaw, V. De Monte, L. DeSanto, K. Hamdi, M. Mapes, T. Rao, A.N. Steszyn, J.E. Tuozzolo, J. Walsh BNL, Upton, Long Island, New York, USA K.W. Smolenski Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. DOE. The operation of LEReC is to provide an electron cooling to improve the luminosity of the RHIC heavy ion beam at lower energies in a range of 2.5-25 GeV/nucleon. The electron beam is generated in a DC Electron Gun (DC gun) designed and built by the Cornell High Energy Synchrotron Source Group. This DC gun will operate around the clock for at least two weeks without maintenance. This paper presents the design of a reliable cathode puck insertion system, which includes a multi-pucks storage device, a transfer mechanism, a puck insertion device, a vacuum/control system, and a transport scheme.
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WEPOB59	Performance of CEC Pop Gun During Commissioning	ion, cathode, laser, cavity	1024
	I. Pinayev, W. Fu, Y. Hao, M. Harvey, T. Hayes, J.P. Jamilkowski, Y.C. Jing, P. K. Kankiya, D. Kayran, R. Kellermann, V. Litvinenko, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, G. Narayan, M.C. Paniccia, W.E. Pekrul, T. Rao, F. Severino, B. Sheehy, J. Skaritka, K.S. Smith, J.E. Tuozzolo, E. Wang, G. Wang, W. Xu, A. Zaltsman, Z. Zhao BNL, Upton, Long Island, New York, USA I. Petrushina SUNY SB, Stony Brook, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The Coherent Electron Cooling Proof-of-Principle (CeC PoP) experiment employs a high-gradient CW photo-injector based on the superconducting RF cavity. Such guns operating at high accelerating gradients promise to revolutionize many sciences 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 production. In this paper we report on our operation of a superconducting RF electron gun with a high accelerating gradient at the CsK2Sb photo-cathode (i.e. ~ 20 MV/m) generating a record-high bunch charge (above 4 nC). We give short description of the system and then detail our experimental results.
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WEPOB60	Commissioning of CeC PoP Accelerator	ion, cavity, electron, hadron	1027
	I. Pinayev, Z. Altinbas, J.C.B. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, W. Fu, D.M. Gassner, Y. Hao, M. Harvey, T. Hayes, R.L. Hulsart, J.P. Jamilkowski, Y.C. Jing, P. K. Kankiya, D. Kayran, R. Kellermann, V. Litvinenko, G.J. Mahler, M. Mapes, K. Mernick, R.J. Michnoff, K. Mihara, T.A. Miller, G. Narayan, P. Orfin, M.C. Paniccia, D. Phillips, T. Rao, F. Severino, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, V. Soria, Z. Sorrell, R. Than, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, W. Xu, A. Zaltsman, Z. Zhao BNL, Upton, Long Island, New York, USA I. Petrushina SUNY SB, Stony Brook, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Coherent electron cooling is new cooling technique to be tested at BNL. Presently we are in the commissioning stage of the accelerator system. In this paper we present status of various systems and achieved beam parameters as well as operational experience. Near term future plans are also discussed.
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WEPOB67	K2CsSb Photocathode Performance in QWR SRF Gun	cathode, ion, multipactoring, vacuum	1042
	E. Wang, Y. Hao, Y.C. Jing, V. Litvinenko, I. Pinayev, T. Rao, J. Skaritka, G. Wang, T. Xin BNL, Upton, Long Island, New York, USA
	In 2016 run of Coherent Electron Cooling, we have successfully tested the performance of a number of K2CsSb cathodes. These cathodes with QE of 6%-10% were fabricated in Instrumentation Division, a few miles away, transported to RHIC tunnel under UHV conditions, attached to the CeC gun, kept in storage, and inserted in the gun as needed. A maximum bunch charge of 4.6 nC was generated in the gun when the QE was 1.8 %. With careful conditioning at increasing accelerating fields, it was possible to maintain the QE of several cathodes for more than a week. For the cathodes that experienced degradation, the primary cause was multipacting when the power into the gun was increased. In the initial runs, the entire 20 mm substrate face was coated with the cathode material causing cathode induced multipacting. For subsequent measurements, the substrate was masked to coat only the central 9 mm of the substrate. By optimizing the procedure for boosting the power to the gun and covering all viewports to minimize dark current, we were able to minimize QE degradation. In this paper we discuss the cathode preparation, transfer to the gun and operational experience with the cathodes in 112 MHz gun.
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THPOA46	Benchmark of RF Photoinjector and Dipole Using ASTRA, GPT, and OPAL	ion, simulation, emittance, dipole	1194
	N.R. Neveu IIT, Chicago, Illinois, USA A. Adelmann PSI, Villigen PSI, Switzerland G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea C.J. Metzger-Kraus HZB, Berlin, Germany N.R. Neveu, J.G. Power ANL, Argonne, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA S.J. Russell LANL, Los Alamos, New Mexico, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Grant no. DE-SC0015479, and contract No. DE-AC02-06CH11357. With the rapid improvement in computing resources and codes in recent years, accelerator facilities can now achieve and rely on accurate beam dynamics simulations. These simulations include single particle effects (e.g. particle tracking in a magnetic field) as well as collective effects such as space charge (SC), and coherent synchrotron radiation (CSR). Using portions of the Argonne Wakefield Accelerator (AWA) as the benchmark model, we simulated beam dynamics with three particle tracking codes. The AWA rf photoinjector was benchmarked, primarily to study SC, in ASTRA, GPT, and OPAL-T using a 1 nC beam. A 20° dipole magnet was used to benchmark CSR effects in GPT and OPAL-T by bending a 1nC beam at energies between 2 MeV and 100 MeV. In this paper we present the results, and discuss the similarities and differences between the codes.
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THPOA51	Improvement of X-Ray Generation by Using Laser Compton Scattering in Laser Undulator Compact X-Ray Source(LUCX)	ion, laser, electron, photon	1207
	M.K. Fukuda, S. Araki, Y. Honda, Y. Sumitomo, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Washio RISE, Tokyo, Japan
	Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We have been developing a compact X-ray source based on the laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. We have started to take X-ray images such as refraction contrast images and phase contrast imaging with Talbot interferometer. In this accelerator, 6-10keV X-rays are generated by LCS. An electron beam is produced by a 3.6cell RF-gun and accelerated to 18-24MeV by a 12cell accelerating tube. A laser pulse is stored in a 4-mirror planar optical cavity to enhance the power. To increase the flux of LCS X-rays, we perform an optimization of the beam-loading compensation, improvement of the intensity of an electron beam and a laser light at the collision point. We report the result of the X-ray generation in this accelerator.
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THPOA56	Primary Study of the Photocathode Electron Gun With a Cone Cathode and Radial Polarization Laser	cathode, ion, laser, emittance	1216
	R. Huang, Q.K. Jia USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: This work is partly supported by the National Nature Science Foundation of China under Grant No. 11375199. The linearly polarized laser with oblique incidence can achieve a higher quantum efficiency (QE) of metal cathodes than that with the normal incidence, which however requires the wavefront shaping for better performance. To maintain the high QE and simplify the system, we propose a cone cathode electron gun with a radial polarization laser at normal incidence. The primary analytical estimation and numerical simulations are explored for its effect on the emittance of the electron beam.
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Paper

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Other Keywords

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MOPOB06

MAX IV and Solaris Linac Magnets Production Series Measurement Results

ion, linac, storage-ring, septum

79

M.A.G. Johansson
MAX IV Laboratory, Lund University, Lund, Sweden
R. Nietubyć
NCBJ, Świerk/Otwock, Poland

The linacs of the MAX IV and Solaris synchrotron radiation light sources, currently in operation in Lund, Sweden, and Kraków, Poland, use various conventional magnet designs. The production series of totally more than 100 magnets of more than 10 types or variants, which were all outsourced to industry, with combined orders for the types that are common to both MAX IV and Solaris, were completed in 2013 with mechanical and magnetic QA conforming to specifications. This article presents an overview of the different magnet types installed in these machines, and mechanical and magnetic measurement results of the full production series.

Poster MOPOB06 [2.535 MB]

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MOPOB08

Streak Camera Measurements of the APS PC Gun Drive Laser

ion, laser, factory, optics

85

J.C. Dooling
ANL, Argonne, Illinois, USA
A.H. Lumpkin
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
We report recent pulse-duration measurements of the APS PC Gun drive laser at both second harmonic (SH, 527 nm) and fourth harmonic (FH. 263 nm) wavelengths. The drive laser is a Nd:Glass-based CPA with the IR wavelength (1053 nm) twice doubled to obtain UV output for the gun. A Hamamatsu C5680 streak camera and an M5675 synchroscan unit are used for these measurements; the synchroscan unit is tuned to 119 MHz, the 24th subharmonic of the linac operating frequency. Calibration is accomplished both electronically and optically. Electronic calibration utilizes a programmable delay line in the 119 MHz rf path. The optical delay employs an etalon with known spacing between reflecting surfaces; this etalon is coated for the visible, SH wavelength. IR pulse duration is monitored with an autocorrelator. Fitting the streak camera image projected profiles with Gaussians, UV rms pulse durations are found to vary from 2.1 ps to 3.5 ps as the IR varies from 2.2 ps to 5.2 ps.

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TUPOA05

Development of a Fiber Laser for Improving the Pulse Radiolysis System

ion, laser, electron, radiation

299

Y. Saito, S.Y. Soeta, M. Washio
Waseda University, Tokyo, Japan
Y. Hosaka, K. Sakaue
RISE, Tokyo, Japan

When material is irradiated by the ionizing radiation, short-lived and highly reactive substance intermediate active species are made and then react with substances. The chemical reaction is determined by intermediate active species in early process. Proving the behavior of intermediate active species is important for understanding and controlling radiation chemical reaction. In Waseda university we been developing a Pulse Radiolysis System, a method to measure the behavior of intermediate species, for radiation chemical analysis with RF electron gun. Currently we are developing a Supercontinuum ray(SC ray)as a probe ray to improve Pulse Radiolysis System. We have introduced a SC ray using Yb fiver laser and PCF(Photonic Crystal Fiber). But this type of prove light isn't stable enough in the visible light region. Therefore we started to study Er fiber laser oscillator as new prove ray source. We have succeeded to oscillate a Er fs laser pulse, second harmonic generation and measurement of hydrated electron in ns time resolution. In this presentation we will report current research about generation of SC ray, Er fiber laser system and dose rate effect against the hydrated electron.

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TUPOA19

50-MeV Run of the IOTA/FAST Electron Accelerator

ion, electron, emittance, cavity

326

D.R. Edstrom, C.M. Baffes, C.I. Briegel, D.R. Broemmelsiek, K. Carlson, B.E. Chase, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, B.J. Fellenz, E.R. Harms, M.J. Kucera, J.R. Leibfritz, A.H. Lumpkin, D.J. Nicklaus, E. Prebys, P.S. Prieto, J. Reid, A.L. Romanov, J. Ruan, J.K. Santucci, T. Sen, V.D. Shiltsev, Y.-M. Shin, G. Stancari, J.C.T. Thangaraj, R.M. Thurman-Keup, A. Valishev, A. Warner, S.J. Wesseln
Fermilab, Batavia, Illinois, USA
A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA
A. Halavanau, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Hyun
Sokendai, Ibaraki, Japan
P. Kobak
BYU-I, Rexburg, USA
W.D. Rush
KU, Lawrence, Kansas, USA

Funding: Supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC.
The low-energy section of the photoinjector-based electron linear accelerator at the Fermilab Accelerator Science & Technology (FAST) facility was recently commissioned to an energy of 50 MeV. This linear accelerator relies primarily upon pulsed SRF acceleration and an optional bunch compressor to produce a stable beam within a large operational regime in terms of bunch charge, total average charge, bunch length, and beam energy. Various instrumentation was used to characterize fundamental properties of the electron beam including the intensity, stability, emittance, and bunch length. While much of this instrumentation was commissioned in a 20 MeV running period prior, some (including a new Martin-Puplett interferometer) was in development or pending installation at that time. All instrumentation has since been recommissioned over the wide operational range of beam energies up to 50 MeV, intensities up to 4 nC/pulse, and bunch structures from ~1 ps to more than 50 ps in length.

Poster TUPOA19 [4.636 MB]

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TUPOA26

Initial Observations of Micropulse Elongation of Electron Beams in a SCRF Accelerator*

ion, electron, laser, MMI

337

A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

Funding: * Work at Fermilab supported by Fermi Research Alliance, LLC under Contract No. DE-AC02- 07CH11359 with the United States Department of Energy
Commissioning at the SCRF accelerator at the Fermilab Accelerator Science and Technology (FAST) Facility has included the implementation of a versatile bunch-length monitor located after the 4-dipole chicane bunch compressor for electron beam energies of 20-50 MeV and integrated charges in excess of 10 nC. The team has initially used a Hamamatsu C5680 synchroscan streak camera. An Al-coated Si screen was used to generate optical transition radiation (OTR) resulting from the beam's interaction with the screen. The chicane bypass beamline allowed the measurements of the bunch length without the compression stage at the downstream beamline location using OTR and the streak camera. The UV component of the drive laser had previously been characterized with a Gaussian fit σ of 3.5-3.7 ps**. However, the uncompressed electron beam is expected to elongate due to space charge forces in an initial 1.5-m drift from the gun to the first SCRF accelerator cavity. We have observed electron beam bunch lengths from 5 to 14 ps (σ) for micropulse charges of 60 pC to 800 pC, respectively. Commissioning of the system and initial results with uncompressed and compressed beam will be presented.
**A.H. Lumpkin et al., Proceedings of FEL14, MOP021, Basel, Switzerland, www. JACoW.org

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TUPOA51

First Steps Toward Incorporating Image Based Diagnostics into Particle Accelerator Control Systems Using Convolutional Neural Networks

ion, network, controls, solenoid

390

A.L. Edelen, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
J.P. Edelen
Fermilab, Batavia, Illinois, USA

At present, a variety of image-based diagnostics are used in particle accelerator systems. Often times, these are viewed by a human operator who then makes appropriate adjustments to the machine. Given recent advances in using convolutional neural networks (CNNs) for image processing, it should be possible to use image diagnostics directly in control routines (NN-based or otherwise). This is especially appealing for non-intercepting diagnostics that could run continuously during beam operation. Here, we show results of a first step toward implementing such a controller: our trained CNN can predict multiple simulated downstream beam parameters at the Fermilab Accelerator Science and Technology (FAST) facility's low energy beamline using simulated virtual cathode laser images, gun phases, and solenoid strengths.

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TUPOA59

Successful Laboratory-Industrial Partnerships: the Cornell-Friatec Segmented Insulator for High Voltage DC Photocathode Guns

ion, electron, vacuum, high-voltage

405

K.W. Smolenski, B.M. Dunham
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D.L. Barth, M. Muehlbauer, S. Wacker
FRIATEC AG, Mannheim, Germany
J.M. Maxson
UCLA, Los Angeles, California, USA

High voltage DC photocathode guns currently offer the most reliable path to electron beams with high current and brightness. The performance of a gun is directly dependent on its vacuum and high voltage capabilities, determined in large part by the ceramic insulators. The insulator must meet XHV standards, bear the load of pressurized SF6 on its exterior, support the massive electrode structures as well as holding off DC voltages up to 750kV. Construction of UHV and high voltage capable insulators require high purity ceramics and metal components proven to minimize thermal stress between the brazed ceramic rings and metal guard rings. The use of replaceable guard rings is a critical way of controlling manufacturing costs while extending the life cycle of the insulator. Successful fabrication requires proven manufacturing methods in flatness, parallelism, and maintaining alignment of many parts during the brazing process. Taking a scalable, modular approach, the insulator design can be applied to a variety of gun voltages and can be used by other projects. The Cornell-Friatec insulator was designed collaboratively and has now been produced in quantity for Cornell and elsewhere.

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TUPOA73

Commissioning and First Results From a Channeling-Radiation Experiment at FAST

ion, detector, electron, radiation

428

J. Hyun
Sokendai, Ibaraki, Japan
D.R. Broemmelsiek, D.R. Edstrom, A.L. Romanov, J. Ruan, T. Sen, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA
A. Halavanau, D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA
P. Kobak
BYU-I, Rexburg, USA
W.D. Rush
KU, Lawrence, Kansas, USA

X-rays have widespread applications in science. Developing compact and high-quality X-ray sources, easy to disseminate, has been an on going challenge. Our group has explored the possible use of channeling radiation driven by a 50 MeV low-emittance electron beam to produce narrowband hard X-rays (photon energy from 40 keV to 140 keV). In this contribution we present the simulated X-ray spectrum including the background bremsstrahlung contribution, and optimization of the relevant electron-beam parameters required to maximize the X-ray brilliance. The results of experiments carried out at Fermilab's FAST facility – which include a 50 MeV superconducting linac and a high-brightness photoinjector – are also discussed. The average brilliance in our experiment is expected to be about one order of magnitude higher than that in previous experiments.

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TUB3IO02

Overview of Electron Source Development for High Repetition Rate FEL Facilities

ion, cathode, electron, emittance

445

F. Sannibale
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 'fsannibale@lbl.gov
An increasing science demand for high-repetition rate (MHz-class) FEL facilities, from IR to X-rays, has been pushing institutions and groups around the world to develop proposals addressing such a need, and some of them have been already funded and are under construction. Such facilities require the development of high-brightness high-repetition rate electron guns, and a number of groups worldwide started to develop R&D programs to develop electron guns capable of operating at this challenging regime. Here we describe the approaches and technologies used by the different programs and discuss advantages and challenges for each of them. A review of the present achievements is included, as well as a brief analysis to understand if the present technology performance is sufficient to operate present and future high repetition rate FEL facilities.

Slides TUB3IO02 [7.951 MB]

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TUB3CO04

A New Thermionic RF Electron Gun for Synchrotron Light Sources

ion, cathode, coupling, electron

453

S.V. Kutsaev, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A.V. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
R.B. Agustsson, J.J. Hartzell, A. Verma
RadiaBeam, Santa Monica, California, USA
A. Nassiri, Y. Sun, G.J. Waldschmidt, A. Zholents
ANL, Argonne, Illinois, USA
E.A. Savin
MEPhI, Moscow, Russia

Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Science, under contract DE-SC0015191 and contract No. DE-AC02-06CH11357.
A thermionic RF gun is a compact and efficient source of electrons used in many practical applications. RadiaBeam Systems and the Advanced Photon Source of Argonne National Laboratory collaborate in developing of a reliable and robust thermionic RF gun for synchrotron light sources which would offer substantial improvements over existing thermionic RF guns and allow stable operation with up to 1A of beam peak current at a 100 Hz pulse repetition rate and a 1.5 μs RF pulse length. In this paper, we discuss the electromagnetic and engineering design of the cavity, and report the progress towards high power tests of the cathode assembly of the new gun.

Slides TUB3CO04 [2.661 MB]

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WEPOA05

EBIS Charge Breeder for RAON Facility

ion, electron, vacuum, ISOL

696

S.A. Kondrashev, J.-W. Kim, Y.K. Kwon, Y.H. Park, H.J. Son
IBS, Daejeon, Republic of Korea

New large scale accelerator facility called RAON is under design in Institute for Basic Science (IBS, Daejeon, Korea). Both technics of rare isotope production Isotope Separation On-Line (ISOL) and In-Flight Fragmentation (IF) will be combined within one facility for the first time to provide wide variety of rare isotope ion beams for nuclear physics experiments and applied research. Electron Beam Ion Source (EBIS) charge breeder will be used to prepare rare isotope ion beams produced by ISOL method for efficient acceleration. Beams of different rare isotopes will be charge-bred by an EBIS charge breeder to a charge-to-mass ratio (q/A) ≥ 1/4 and accelerated by linac post-accelerator to energies of 18.5 MeV/u. RAON EBIS charge breeder will provide the next step in the development of breeder technology by implementation of electron beam with current up to 3 A and utilization of wide (8') warm bore of 6 T superconducting solenoid. The design of RAON EBIS charge breeder and results of dumping of high power DC and pulsed electron beam into collector will be presented and discussed.

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WEPOA06

New Coolers for Ion Ion Colliders

ion, electron, collider, proton

700

V.V. Parkhomchuk
BINP SB RAS, Novosibirsk, Russia

For crucial contributions in the proof of principle of electron cooling, for leading contribution to the experimental and theoretical development of electron cooling, and for achievement of the planned parameters of coolers for facilities in laboratories around the world the 2016 "Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators" was awarded to Vasili Parkhomchuk. In this paper new future coolers for ion*ion collider will be discussed.

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WEPOA12

Interleaving Lattice Design for APS Linac

ion, lattice, linac, electron

713

S. Shin, Y. Sun, A. Zholents
ANL, Argonne, Illinois, USA

In order to realize and test advanced accelerator concepts and hardware, the existing beamline with both old and new components are being reconfigured in Linac Extension Area (LEA) of APS linac. Photo injector, which had been installed in the beginning of APS linac, will provide low emittance electron beam into the LEA. The thermionic RF gun beam for storage ring and photo-cathode RF gun beam for LEA will be operated though the LINAC in an interleaved fashion. In this presentation, technical issues as well as beam dynamics on the design for interleaving operation will be described.

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WEPOA40

Construction Status of a RF-Injector with a CNT-Tip Cathode for High Brightness Field-Emission Tests

ion, cathode, electron, emittance

785

Y.-M. Shin, G. Fagerberg, M. Figora
Northern Illinois University, DeKalb, Illinois, USA
A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA

We have been constructing a S-band RF-injector system for field-emission tests of a CNT-tip cathode. A pulsed Sband klystron is installed and fully commissioned with 5.5 MW peak power in a 2.5 microsecond pulse length and 1 Hz repetition rate. A single-cell RFgun is designed to produce with 0.5 - 1 pC electron bunches in a photo-emission mode within a 50 fs - 3 ps at 0.5- 1 MeV. The measured RF system jitters are within 1 % in magnitude and 0.2° in phase, which would induce 3.4 keV and 0.25 keV of energy jitters, corresponding to 80 fs and 5 fs of temporal jitters, respectively. Our PIC simulations indicate that the designed bunch compressor reduces the TOAjitter by about an order of magnitude. Emission current and beam brightness of the field-emitted beam are improved by implanting CNT tips on the cathode surface, since they reduce the emission area, while providing high current emission. Once the system is completely commissioned in field-emission mode, the CNT-tip cathode will be tested in terms of klystron-power levels to map out its I-V characteristics under pulse emission condition.

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WEPOA42

RF Design of a 1.3-GHz High Average Beam Power SRF Electron Source

ion, cathode, electron, simulation

789

N. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
I.V. Gonin, R.D. Kephart, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

There is a significant interest in developing high-average power electron sources, particularly those integrated with Superconducting Radio Frequency (SRF) accelerator systems. Even though there are examples of high-average-power electron sources, they are not compact, highly efficient, or available at a reasonable cost. Adapting the recent advances in SRF cavities, RF power sources, and innovative solutions for an SRF gun and cathode system, we have developed a design concept for a compact SRF high-average power electron linac. This design will produce electron beams with energies up to 10 MeV. In this paper, we present the design results of our cathode structure integrated with modified 9-cell accelerating structure.

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WEPOB19

Summary of Cs2te Photocathode Performance and Improvements in the High-Gradient, High-Charge AWA Drive Gun

cathode, ion, operation, wakefield

934

E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, C.-J. Jing, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford
ANL, Argonne, Illinois, USA
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
The AWA L-band, high-charge photoinjector for the 70 MeV drive beamline has been operating for almost 3 years at the Argonne Wakefield Accelerator (AWA) facility. at Argonne National Laboratory (ANL). The gun operates at high-field (85 MV/m peak field on the cathode) and has a high quantum efficiency (QE) Cesium telluride photocathode with a large area (30 mm diameter). It produces high-charge, short pulse, single bunches (Q > 100 nC) as well as long bunch-trains (Q > 600 nC) for wakefield experiments (high peak current). During the first two years of operation, photocathode performance was evaluated and areas of improvement were identified. After study, consideration and consultation, steps were taken to improve the performance of the photocathode. So far, in total, three photocathodes have been fabricated on-site, installed and operated in the gun. Improvements made to the photocathode plug, vacuum system, and gun operation are detailed. The results include vastly improved conditioning times, better cathode performance, and QE above 4% for over 11 months.

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WEPOB25

Analytical Modeling of Electron Back-Bombardment Induced Current Increase in Un-Gated Thermionic Cathode Rf Guns

ion, cathode, electron, simulation

953

J.P. Edelen
Fermilab, Batavia, Illinois, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
Y. Sun
ANL, Argonne, Illinois, USA

In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, field-enhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.

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WEPOB26

Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun

ion, cathode, electron, experiment

956

J.P. Edelen
Fermilab, Batavia, Illinois, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
Y. Sun
ANL, Argonne, Illinois, USA

Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an un-gated thermionic cathode RF gun to high average current.

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WEPOB54

DC Photogun Gun Test for RHIC Low Energy Electron Cooler (LEReC).

ion, electron, laser, cavity

1008

D. Kayran, Z. Altinbas, D.R. Beavis, S. Bellavia, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, J. Halinski, K. Hamdi, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, G.J. Mahler, T.A. Miller, S.K. Nayak, T. Rao, S. Seletskiy, B. Sheehy, J.E. Tuozzolo, Z. Zhao
BNL, Upton, Long Island, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
Non-magnetized bunched electron cooling of low-energy RHIC requires electron beam energy in range of 1.6-2.6 MeV, with average current up to 45 mA, very small energy spread, and low emittance [1]. A 400 kV DC gun equipped with photocathode and laser delivery system will serve as a source of high-quality electron beam. Acceleration will be achieved by an SRF 704 MHz booster cavity and other RF components that are scheduled to be operational in early 2018. The DC gun testing in its installed location in RHIC will start in early 2017. During this stage we plan to test the critical equipment in close to operation conditions: laser beam delivery system, cathode QE lifetime, DC gun, beam instrumentation, high power beam dump system, and controls. In this paper, we describe the gun test set up, major components, and parameters to be achieved and measured during the gun beam test.
[1] A. Fedotov. Bunched beam electron cooling for Low Energy RHIC operation. ICFA Beam Dynamics letter, No. 65, p. 22 (December 2014)

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WEPOB58

Cathode Puck Insertion System Design for the LEReC Photoemission DC Electron Gun

ion, cathode, vacuum, insertion

1021

C.J. Liaw, V. De Monte, L. DeSanto, K. Hamdi, M. Mapes, T. Rao, A.N. Steszyn, J.E. Tuozzolo, J. Walsh
BNL, Upton, Long Island, New York, USA
K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. DOE.
The operation of LEReC is to provide an electron cooling to improve the luminosity of the RHIC heavy ion beam at lower energies in a range of 2.5-25 GeV/nucleon. The electron beam is generated in a DC Electron Gun (DC gun) designed and built by the Cornell High Energy Synchrotron Source Group. This DC gun will operate around the clock for at least two weeks without maintenance. This paper presents the design of a reliable cathode puck insertion system, which includes a multi-pucks storage device, a transfer mechanism, a puck insertion device, a vacuum/control system, and a transport scheme.

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WEPOB59

Performance of CEC Pop Gun During Commissioning

ion, cathode, laser, cavity

1024

I. Pinayev, W. Fu, Y. Hao, M. Harvey, T. Hayes, J.P. Jamilkowski, Y.C. Jing, P. K. Kankiya, D. Kayran, R. Kellermann, V. Litvinenko, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, G. Narayan, M.C. Paniccia, W.E. Pekrul, T. Rao, F. Severino, B. Sheehy, J. Skaritka, K.S. Smith, J.E. Tuozzolo, E. Wang, G. Wang, W. Xu, A. Zaltsman, Z. Zhao
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Coherent Electron Cooling Proof-of-Principle (CeC PoP) experiment employs a high-gradient CW photo-injector based on the superconducting RF cavity. Such guns operating at high accelerating gradients promise to revolutionize many sciences 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 production. In this paper we report on our operation of a superconducting RF electron gun with a high accelerating gradient at the CsK2Sb photo-cathode (i.e. ~ 20 MV/m) generating a record-high bunch charge (above 4 nC). We give short description of the system and then detail our experimental results.

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WEPOB60

Commissioning of CeC PoP Accelerator

ion, cavity, electron, hadron

1027

I. Pinayev, Z. Altinbas, J.C.B. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, W. Fu, D.M. Gassner, Y. Hao, M. Harvey, T. Hayes, R.L. Hulsart, J.P. Jamilkowski, Y.C. Jing, P. K. Kankiya, D. Kayran, R. Kellermann, V. Litvinenko, G.J. Mahler, M. Mapes, K. Mernick, R.J. Michnoff, K. Mihara, T.A. Miller, G. Narayan, P. Orfin, M.C. Paniccia, D. Phillips, T. Rao, F. Severino, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, V. Soria, Z. Sorrell, R. Than, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, W. Xu, A. Zaltsman, Z. Zhao
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling is new cooling technique to be tested at BNL. Presently we are in the commissioning stage of the accelerator system. In this paper we present status of various systems and achieved beam parameters as well as operational experience. Near term future plans are also discussed.

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WEPOB67

K2CsSb Photocathode Performance in QWR SRF Gun

cathode, ion, multipactoring, vacuum

1042

E. Wang, Y. Hao, Y.C. Jing, V. Litvinenko, I. Pinayev, T. Rao, J. Skaritka, G. Wang, T. Xin
BNL, Upton, Long Island, New York, USA

In 2016 run of Coherent Electron Cooling, we have successfully tested the performance of a number of K2CsSb cathodes. These cathodes with QE of 6%-10% were fabricated in Instrumentation Division, a few miles away, transported to RHIC tunnel under UHV conditions, attached to the CeC gun, kept in storage, and inserted in the gun as needed. A maximum bunch charge of 4.6 nC was generated in the gun when the QE was 1.8 %. With careful conditioning at increasing accelerating fields, it was possible to maintain the QE of several cathodes for more than a week. For the cathodes that experienced degradation, the primary cause was multipacting when the power into the gun was increased. In the initial runs, the entire 20 mm substrate face was coated with the cathode material causing cathode induced multipacting. For subsequent measurements, the substrate was masked to coat only the central 9 mm of the substrate. By optimizing the procedure for boosting the power to the gun and covering all viewports to minimize dark current, we were able to minimize QE degradation. In this paper we discuss the cathode preparation, transfer to the gun and operational experience with the cathodes in 112 MHz gun.

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THPOA46

Benchmark of RF Photoinjector and Dipole Using ASTRA, GPT, and OPAL

ion, simulation, emittance, dipole

1194

N.R. Neveu
IIT, Chicago, Illinois, USA
A. Adelmann
PSI, Villigen PSI, Switzerland
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
C.J. Metzger-Kraus
HZB, Berlin, Germany
N.R. Neveu, J.G. Power
ANL, Argonne, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA
S.J. Russell
LANL, Los Alamos, New Mexico, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Grant no. DE-SC0015479, and contract No. DE-AC02-06CH11357.
With the rapid improvement in computing resources and codes in recent years, accelerator facilities can now achieve and rely on accurate beam dynamics simulations. These simulations include single particle effects (e.g. particle tracking in a magnetic field) as well as collective effects such as space charge (SC), and coherent synchrotron radiation (CSR). Using portions of the Argonne Wakefield Accelerator (AWA) as the benchmark model, we simulated beam dynamics with three particle tracking codes. The AWA rf photoinjector was benchmarked, primarily to study SC, in ASTRA, GPT, and OPAL-T using a 1 nC beam. A 20° dipole magnet was used to benchmark CSR effects in GPT and OPAL-T by bending a 1nC beam at energies between 2 MeV and 100 MeV. In this paper we present the results, and discuss the similarities and differences between the codes.

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THPOA51

Improvement of X-Ray Generation by Using Laser Compton Scattering in Laser Undulator Compact X-Ray Source(LUCX)

ion, laser, electron, photon

1207

M.K. Fukuda, S. Araki, Y. Honda, Y. Sumitomo, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have been developing a compact X-ray source based on the laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. We have started to take X-ray images such as refraction contrast images and phase contrast imaging with Talbot interferometer. In this accelerator, 6-10keV X-rays are generated by LCS. An electron beam is produced by a 3.6cell RF-gun and accelerated to 18-24MeV by a 12cell accelerating tube. A laser pulse is stored in a 4-mirror planar optical cavity to enhance the power. To increase the flux of LCS X-rays, we perform an optimization of the beam-loading compensation, improvement of the intensity of an electron beam and a laser light at the collision point. We report the result of the X-ray generation in this accelerator.

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THPOA56

Primary Study of the Photocathode Electron Gun With a Cone Cathode and Radial Polarization Laser

cathode, ion, laser, emittance

1216

R. Huang, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: This work is partly supported by the National Nature Science Foundation of China under Grant No. 11375199.
The linearly polarized laser with oblique incidence can achieve a higher quantum efficiency (QE) of metal cathodes than that with the normal incidence, which however requires the wavefront shaping for better performance. To maintain the high QE and simplify the system, we propose a cone cathode electron gun with a radial polarization laser at normal incidence. The primary analytical estimation and numerical simulations are explored for its effect on the emittance of the electron beam.

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