NAPAC2019 - List of Keywords (gun)

Paper	Title	Other Keywords	Page
MOZBB5	Magnetized Electron Source for JLEIC Cooler	cathode, electron, solenoid, high-voltage	83
	R. Suleiman, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M.A. Mamun, M. Poelker, M.G. Tiefenback, Y.W. Wang, S. Zhang JLab, Newport News, Virginia, USA J.R. Delayen, G.A. Krafft, S.A.K. Wijethunga, J.T. Yoskowitz ODU, Norfolk, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and supported by Laboratory Directed Research and Development funding. Magnetized bunched-beam electron cooling is a critical part of the Jefferson Lab Electron Ion Collider (JLEIC). Strong cooling of ion beams will be accomplished inside a cooling solenoid where the ions co-propagate with an electron beam generated from a source immersed in magnetic field. This contribution describes the production and characterization of magnetized electron beam using a compact 300 kV DC high voltage photogun and bialkali-antimonide photocathodes. Beam magnetization was studied using a diagnostic beamline that includes viewer screens for measuring the shearing angle of the electron beamlet passing through a narrow upstream slit. Correlated beam emittance with magnetic field at the photocathode was measured for various laser spot sizes. Measurements of photocathode lifetime were carried out at different magnetized electron beam currents up to 28 mA and high bunch charge up to 0.7 nano-Coulomb was demonstrated.
	Slides MOZBB5 [9.236 MB]
	Poster MOZBB5 [1.564 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBB5
About •	paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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MOPLM06	High Voltage Design of a 350 kV DC Photogun at BNL	electron, cathode, high-voltage, vacuum	102
	W. Liu, O.H. Rahman, E. Wang BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Brookhaven National Laboratory is constructing a 350 kV DC high voltage photogun to provide spin-polarized electron beam for the proposed eRHIC facility. The photogun employs a compact inverted-tapered-geometry ceramic insulator that extends into the vacuum chamber and mechanically holds the cathode electrode. By operating at high voltage, the photogun will provide lower beam emittance, thereby improving the beam transmission through the injector apertures, and prolong the operating lifetime of the photogun. However, high voltage increases the field emission, which can result in high voltage breakdown and even lead to irreparable damage of the ceramic insulator. This work describes the methods to minimize the electric field near the metal-vacuum-insulator interface, and to avoid high voltage breakdown and ceramic insulator damage. The triple point junction shields are designed. The simulated electric field, field emission and beam transportation will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM06
About •	paper received ※ 19 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLM13	Investigations of the Electron Beam Energy Jitter Generated in the Photocathode RF Gun at the Advanced Photon Source Linac	timing, laser, electron, cathode	124
	J.C. Dooling, D. Hui, A.H. Lumpkin, T.L. Smith, Y. Sun, K.P. Wootton, A. Zholents ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357. Characterizations continue of the electron beam properties of a recently installed S-band photocathode (PC) rf gun at the Advanced Photon Source Linac facility. In this case, we have utilized a low-energy spectrometer beam line located 1.3 m downstream of the gun cavity to measure the electron beam energy, energy spread, and energy jitter. The nominal energy was 6.5 MeV using a gun gradient of 110 MV/m, and the energy spread was ~17 keV when driven by a 2.5-ps rms duration UV laser pulse at the selected rf gun phase. An energy jitter of 25 keV was initially observed in the spectrometer focal plane images. This jitter was partly attributed to the presence of both the 2nd and 3rd harmonics of the 119 MHz synchronization signal provided to the phase locked loop of the drive laser oscillator. The addition of a 150-MHz low-pass filter in the 119-MHz line strongly attenuated the two harmonics and resulted in a reduced energy jitter of ~15 keV. Comparisons of the gun performance to ASTRA simulations will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM13
About •	paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLM15	Design of the ASU Photocathode Lab	cathode, electron, diagnostics, emittance	132
	C.J. Knill, S.S. Karkare Arizona State University, Tempe, USA J.V. Conway, B.M. Dunham, K.W. Smolenski Xelera Research LLC, Ithaca, New York, USA H.A. Padmore LBNL, Berkeley, California, USA
	Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams. Recent investigations have shown that it is possible to obtain an order of magnitude smaller intrinsic emittance from photocathodes by precise atomic scale control of the surface, using an appropriate electronic band structure of single crystal cathodes and cryogenically cooling the cathode. Investigating the performance of such cathodes requires atomic scale surface diagnostic techniques connected in ultra-high vacuum (UHV) to the epitaxial thin film growth and surface preparation systems and photo-emission and photocathode diagnostic techniques. Here we report the capabilities and design of the laboratory being built at the Arizona State University for this purpose. The lab houses a 200 kV DC gun with a cryogenically cooled cathode along with a beam diagnostics and ultra fast electron diffraction beamline. The cathode of the gun can be transported in UHV to a suite of UHV growth chambers and surface and photoemission diagnostic techniques.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM15
About •	paper received ※ 26 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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MOPLM16	Design of a 200 kV DC Cryocooled Photoemission Gun for Photocathode Investigations	cathode, electron, emittance, radiation	136
	G.S. Gevorkyan, S.S. Karkare Arizona State University, Tempe, USA I.V. Bazarov, A. Galdi, J.M. Maxson Cornell University, Ithaca, New York, USA L. Cultrera, W.H. Li Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams. Intrinsic emittance of photocathodes limits the brightness of electrons beams produced from photoemission guns. Recent advancements have shown that an order of magnitude improvement in intrinsic emittance over the commonly used polycrystalline metal and semiconductor cathodes is possible via use of single crystalline ordered surfaces of metals, semiconductors and other exotic materials at cryogenic temperatures as cathodes. However, due to practical design considerations, it is not trivial to test such cathodes in existing electron guns. Here we present the design of a 200kV DC electron gun being developed at the Arizona State University for this purpose.
	Poster MOPLM16 [1.549 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM16
About •	paper received ※ 27 August 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019
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MOPLM18	Design of the 2-Stage Laser Transport for the Low Energy RHIC Electron Cooling (LEReC) DC Photogun	laser, electron, cathode, alignment	144
	P. Inacker, S. Bellavia, A.J. Curcio, A.V. Fedotov, W. Fischer, D.M. Gassner, J.P. Jamilkowski, P.K. Kankiya, D. Kayran, D. Lehn, R. Meier, T.A. Miller, M.G. Minty, S.K. Nayak, L.K. Nguyen, L. Smart, C.J. Spataro, A. Sukhanov, J.E. Tuozzolo, Z. Zhao BNL, Upton, 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 electron beam for the recently constructed Low Energy RHIC electron Cooler (LEReC) at Brookhaven National Laboratory is generated by a high-power fiber laser illuminating a photocathode. The pointing stability of the low-energy electron beam, which is crucial to maintain within acceptable limits given the long beam transport, is highly dependent on the center-of-mass (CoM) stability of the laser spot on the photocathode. For reasons of accessibility during operations, the laser itself is located outside the accelerator tunnel, leading to the need to propagate the laser beam 34 m via three laser tables to the photocathode. The challenges to achieving the required CoM stability of 10 microns on the photocathode thus requires mitigation of vibrations along the transport and of weather- and season-related environmental effects, while preserving accessibility and diagnostic capabilities with proactive design. After successful commissioning of the full transport in 2018/19, we report on our solutions to these design challenges. LEReC Photocathode DC Gun Beam Test Results - D. Kayran Conference: C18-04-29, p.TUPMF025 Commissioning of Electron Accelerator LEReC for Bunch Beam Cooling - D.Kayran, NAPAC19
	Poster MOPLM18 [1.970 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM18
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLM24	LCLS-II Injector Commissioning Beam Based Measurements	electron, laser, cathode, MMI	157
	C.M. Zimmer, T.J. Maxwell, F. Zhou SLAC, Menlo Park, California, USA
	Funding: Department of Energy Injector commissioning is underway for the LCLS-II MHz repetition rate FEL, currently under construction at SLAC. Methodology of injector beam-based measurements and early results with low beam charge will be presented, along with the software tools written to automate these various measurements.
	Poster MOPLM24 [10.104 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM24
About •	paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLH02	Study of Photocathode Surface Damage due to Ion Back-Bombardment in High Current DC Gun	cathode, simulation, electron, laser	174
	J.P. Biswas Stony Brook University, Stony Brook, USA O.H. Rahman, E. Wang BNL, Upton, New York, USA
	Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704, with the U.S. DOE In high current DC gun, GaAs photocathode lifetime is limited by the ion back-bombardment. While gun operation ions are generated and accelerate back towards the cathode thus remove the activation layer’s material Cesium from the photocathode surface. We have developed an object-oriented code to simulate the ion generation due to dynamic gas pressure and ion trace in the electromagnetic field. The pressure profile varies from cathode position towards the transfer line behind the anode, which signifies the importance of dynamic simulation for ion back-bombardment study. In our surface damage study, we traced the energy and position of the ions on the photocathode surface and performed the Stopping and Range of Ions in Matter(SRIM) simulation to count the number of Cesium atoms removed from the surface due to single bunch impact. Cesium atom removal is directly related to the photocathode Quantum Efficiency(QE) decay. Our new dynamic simulation code can be used in any DC gun to study ion back-bombardment. We have used this new code to better understand the ion generation in prototype BNL 350 KV DC gun, and we have also estimated the normalized QE decay due to ion back-bombardment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH02
About •	paper received ※ 27 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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MOPLH04	Design for HyRES Cathode Nanotip Electron Source	electron, cavity, solenoid, cathode	177
	R.M. Hessami, A.F. Amhaz, P. Musumeci UCLA, Los Angeles, USA
	A new ultrafast electron diffraction (UED) instrument is being developed by UCLA-Colorado University collaboration for the STROBE NSF Center with the goal of using electron and EUV photon beams to reveal the structural dynamics of materials in non-equilibrium states at fundamental atomic and temporal scales. This paper describes the design of the electron beamline of this instrument. In order to minimize the initial emittance, a nanotip photocathode, 25 nm in radius, will be used. This requires a redesign of the cathode and anode components of the electron gun to allow for the tip to be properly aligned. Solenoidal lenses are used to focus the beam transversely to a sub-micron spot at the sample and a radiofrequency (RF) cavity, driven by a continuous wave S-band RF source, longitudinally compresses the beam to below 100 fs, required for atomic resolution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH04
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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MOPLH14	Ultrafast Nonlinear Photoemission from Alkali Antimonide Photocathodes	photon, electron, cathode, laser	203
	W.H. Li, M.B. Andorf, I.V. Bazarov, L. Cultrera, C.J.R. Duncan, A. Galdi, J.M. Maxson, C.A. Pennington Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams. Alkali antimonides photocathodes are a popular choice of electron source for high average brightness beams, due to their high quantum efficiency (QE) and low mean transverse energy (MTE). This paper describes the first measurements of their nonlinear photoemission properties under sub-ps laser illumination. These measurements include wavelength-resolved power dependence, pulse length dependence, and temporal response. The transition between linear and nonlinear photoemission is observed through the wavelength-resolved scan, and implications of nonlinear photoemission are discussed.
	Poster MOPLH14 [0.543 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH14
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLO06	Black Gun Technologies for DC Photoinjectors	vacuum, electron, laser, scattering	247
	E.J. Montgomery, C. Jing, S. Poddar Euclid Beamlabs LLC, Bolingbrook, USA J.E. Butler Euclid TechLabs, LLC, Solon, Ohio, USA S. Zhang JLab, Newport News, Virginia, USA
	Funding: Work supported by the US DOE Office of Science, Office of Nuclear Physics, grant number DESC0019688. Work at Argonne CNM under Contract No. DE-AC02-06CH11357. Euclid Beamlabs is developing a new "Black Gun" concept in direct current (DC) photoinjectors. To reduce electron-stimulated desorption indirectly influenced by stray photoemission, we are testing advanced optical coatings and low-scattering optics compatible with the extreme high vacuum (XHV) environment of modern DC photoinjectors. Stray light in DC photoinjectors (in proportion to the photoemitted charge) causes off-nominal photoemission, initiating electron trajectories which intercept downstream surfaces. This causes electron-stimulated desorption of atoms, which ionize and may back-bombard the cathode, reducing its charge lifetime. Back-bombardment is key for high average current or high repetition rate. First, we report on progress developing optical skimmers based on Butler baffles to collimate both incoming and outgoing laser beams. Second, we describe candidate coatings for reduction of scattered light. Requirements for these coatings are that they be conducting, optically black at the drive laser wavelength, conformally applied to complex geometry, and XHV-compatible with negligible outgassing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO06
About •	paper received ※ 04 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUYBA3	Benchmarking the LCLS-II Photoinjector	simulation, laser, solenoid, emittance	301
	N.R. Neveu, T.J. Maxwell, C.E. Mayes SLAC, Menlo Park, California, USA
	Funding: DOE Contract No. DE-AC02-76SF00515 Commissioning of the LCLS-II photoinjector started in late 2018. Efforts to accurately model the gun and laser profiles is ongoing. Simulations of the photoinjector and solenoid are performed in ASTRA, IMPACT-T and OPAL-T. This work includes efforts to use the laser profile at the virtual cathode as the initial transverse beam distribution, and effects of 2D and 3D field maps. Beam size results are compared to experimental measurements taken at the YAG screen located after the gun.
	Slides TUYBA3 [1.320 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBA3
About •	paper received ※ 29 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUYBA4	Optimization of an SRF Gun Design for UEM Applications	SRF, laser, cavity, electron	305
	A. Liu, P.V. Avrakhov Euclid TechLabs, LLC, Solon, Ohio, USA C. Jing, R.A. Kostin Euclid Beamlabs LLC, Bolingbrook, USA
	Funding: DOE contract DE-SC0018621 Benefiting from the rapid progress on RF photocathode gun technologies in the past two decades, the development of MeV-range ultrafast electron diffraction/microscopy (UED and UEM) has been identified as an enabling instrumentation, which may lead to breakthroughs in fundamental science and applied technologies . Euclid is designing an SRF cavity as the UEM electron gun. As implementing a solenoid for emittance compensation in the gun is limited by the superconductivity performance and available space, the geometry of the first 0.3 cell of the cavity is optimized for transverse focusing and emittance reduction. : T. Chase, et al, "Ultrafast electron diffraction from non- equilibrium phonons in femtosecond laser heated Au films." Applied Physics Letters, 2016
	Slides TUYBA4 [7.583 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBA4
About •	paper received ※ 30 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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TUYBB6	Beam Dynamics in a High Gradient RF Streak Camera	electron, cathode, experiment, photon	326
	F. Toufexis, V.A. Dolgashev, A. Landa SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515. Traditionally, time-resolved experiments in storage ring synchrotron light sources and free-electron lasers are performed with short x-ray pulses with time duration smaller than the time resolution of the phenomenon under study. Typically, storage-ring synchrotron light sources produce x-ray pulses on the order of tens of picoseconds. Newer diffraction limited storage rings produce even longer pulses. We propose to use a high-gradient RF streak camera for time-resolved experiments in storage-ring synchrotron light sources with potential for sub-100 fs resolution. In this work we present a detailed analysis of the effects of the initial time and energy spread of the photo-emitted electrons on the time resolution, as well as a start-to-end beam dynamics simulation in an S-Band system. * F. Toufexis, et al, "Sub-Picosecond X-Ray Streak Camera using High-Gradient RF Cavities", in Proceedings of IPAC’19.
	Slides TUYBB6 [5.958 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBB6
About •	paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUZBA1	Commissioning of the Electron Accelerator LEReC for Bunched Beam Cooling	electron, cavity, operation, cathode	330
	D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, K.A. Drees, A.V. Fedotov, W. Fischer, M. Gaowei, D.M. Gassner, X. Gu, R.L. Hulsart, P. Inacker, J.P. Jamilkowski, Y.C. Jing, J. Kewisch, C.J. Liaw, C. Liu, J. Ma, K. Mernick, T.A. Miller, M.G. Minty, L.K. Nguyen, M.C. Paniccia, I. Pinayev, V. Ptitsyn, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, L. Smart, K.S. Smith, A. Sukhanov, P. Thieberger, J.E. Tuozzolo, E. Wang, G. Wang, W. Xu, A. Zaltsman, H. Zhao, Z. Zhao BNL, Upton, 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 brand-new state of the art electron accelerator, LEReC, was built and commissioned at BNL. LEReC accelerator includes a photocathode DC gun, a laser system, a photocathode delivery system, magnets, beam diagnostics, a SRF booster cavity, and a set of Normal Conducting RF cavities to provide sufficient flexibility to tune the beam in the longitudinal phase space. Electron beam quality suitable for cooling in the Relativistic Heavy Ion Collider (RHIC) was achieved [1], which lead to the first demonstration of bunched beam electron cooling of hadron beams [2]. This presentation will discuss commissioning results, achieved beam parameters and performance of the LEReC systems. [1] D.Kayran et al., First results from Commissioning of LEReC, in Proc of IPAC2019 [2] A.Fedotov et al., First electron cooling of hadron beams using a bunched electron beam, presented at NAPAC2019
	Slides TUZBA1 [18.343 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBA1
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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TUZBB4	Space Charge Study of the Jefferson Lab Magnetized Electron Beam	laser, electron, cathode, space-charge	360
	S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft ODU, Norfolk, Virginia, USA J.F. Benesch, F.E. Hannon, C. Hernandez-Garcia, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman, S. Zhang JLab, Newport News, Virginia, USA
	Magnetized electron cooling could result in high luminosity at the proposed Jefferson Lab Electron-Ion Collider (JLEIC). In order to increase the cooling efficiency, a bunched electron beam with high bunch charge and high repetition rate is required. We generated magnetized electron beams with high bunch charge using a new compact DC high voltage photo-gun biased at -300 kV with alkali-antimonide photocathode and a commercial ultrafast laser. This contribution explores how magnetization affects space charge dominated beams as a function of magnetic field strength, gun high voltage, laser pulse width, and laser spot size.
	Slides TUZBB4 [12.582 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB4
About •	paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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TUPLM18	Improving Energy Resolution and Compensating Chromatic Aberration With a TM010 Microwave Cavity	cavity, electron, simulation, laser	411
	C.J.R. Duncan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA P. Cueva, J.M. Maxson, D.A. Muller Cornell University, Ithaca, New York, USA
	Funding: National Science Foundation under Award OIA-1549132, the Center for Bright Beams The intrinsic energy spread of electron sources limits the achievable resolution of electron microscopes in both spectroscopic and spatially resolved measurements. We propose that the TM010 mode of a single radio frequency (RF) cavity be used to dramatically reduce this energy spread in a pulsed beam. We show with analytic approximations, confirmed in simulations, that the non-linear time-energy correlations that develop in an electron gun can be undone by the RF cavity running near-crest. We derive an expression that gives the required RF field strength as a function of accelerating voltage. We explore multiple applications, including EELS and SEM. By pulsing a photocathode with commercially available, high repetition-rate lasers, our scheme could yield competitive energy spread reduction at higher currents when compared with monochromated continuous-wave sources for electron microscopes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM18
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM33	Optimization of Beam Parameters for UEM with Photo-Emission S-Band RF Gun and Alpha Magnet	electron, emittance, laser, simulation	440
	H.R. Lee, P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim University of Science and Technology of Korea (UST), Daejeon, Republic of Korea P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim KAERI, Jeongeup-si, Republic of Korea B.L. Cho KRISS, Daejeon, Republic of Korea M.Y. Han, J.Y. Lee, S.H. Lee Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea H. Suk GIST, Gwangju, Republic of Korea
	Ultrafast Electron Microscopy (UEM) is a powerful tool to observe ultrafast dynamical processes in sample materials at the atomic level. By collaborating with KRISS and GIST, the future accelerator R&D team at KAERI has been developing a UEM facility based on a photo-emission S-band (=2856 MHz) RF gun. Recently, we have added an alpha magnet in the beamline layout of the UEM to improve beam qualities such as emittance, divergence, energy spread, and bunch length. To achieve high spatial and time resolutions, we have been optimizing those beam parameters and other machine parameters by performing numerous ASTRA and ELEGANT code simulations. In this paper, we describe our ASTRA and ELEGANT code optimizations to obtain high-quality beam parameters for the UEM facility with a photo-emission S-band RF gun and an alpha magnet.
	Poster TUPLM33 [0.931 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM33
About •	paper received ※ 30 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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TUPLS10	Troubleshooting and Characterization of Gridded Thermionic Electron Gun	cathode, electron, controls, operation	474
	M.S. Stefani ODU, Norfolk, Virginia, USA F.E. Hannon JLab, Newport News, Virginia, USA
	Jefferson National Laboratory has, in collaboration with Xelera research group, designed and built a gridded thermionic election gun with the potential for magnetization; in an effort to support research towards electron sources that may be utilized for the electron cooling process in the Jefferson Laboratories Electron Ion collider design. Presented here is the process and result of troubleshooting the electron gun components and operation to ensure functionality of the design.
	Poster TUPLS10 [10.691 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS10
About •	paper received ※ 27 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019
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TUPLH03	Double-Bend Achromat Beamline for Injection Into a High-Power Superconducting Electron Linac	solenoid, electron, dipole, cavity	494
	C.H. Boulware, T.L. Grimm, R. Hipple Niowave, Inc., Lansing, Michigan, USA S.M. Lund FRIB, East Lansing, Michigan, USA V.S. Morozov JLab, Newport News, Virginia, USA
	To take advantage of the high duty cycle operation of superconducting electron linacs, commercial systems use thermionic cathode electron guns that fill every RF bucket with an electron bunch. In continuous operation, the exit energy is limited when compared to pulsed systems. Bunch length and energy spread at the exit of the gun are incompatible with low losses in the superconducting cavity. A solenoid double-bend achromatic beamline is in operation at Niowave which allows energy and bunch length filtering of the beam leaving the gun before injection into the superconducting cavity. This system uses two solenoids and two dipoles to produce a round beam, using the edge angles of the dipoles to balance the focusing effects in the two transverse planes. The design allows beam filtering on the symmetry plane where the dispersion is maximum. Additionally, the bend angle moves the electron gun off the high-energy beam axis, allowing multiple-pass operation of the superconducting booster. This contribution will discuss the beam optics design of the double-bend achromat along with the design of the magnets and beam chambers and the operational experience with the system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH03
About •	paper received ※ 28 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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TUPLH24	Performance of CeC PoP Accelerator	electron, FEL, SRF, hadron	526
	I. Pinayev, Z. Altinbas, J.C. Brutus, A.J. Curcio, A. Di Lieto, T. Hayes, R.L. Hulsart, P. Inacker, Y.C. Jing, V. Litvinenko, J. Ma, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, M.G. Minty, G. Narayan, I. Petrushina, F. Severino, K. Shih, Z. Sorrell, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman BNL, Upton, 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 experiment is aimed for demonstration of the proof-of-principle demonstration of reduction energy spread of a single hadron bunch circulating in RHIC. The electron beam should have the required parameters and its orbit and energy should be matched to the hadron beam. In this paper we present the achieved electron beam parameters including emittance, energy spread, and other critical indicators. The operational issues as well as future plans are also discussed.
	Poster TUPLH24 [11.180 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH24
About •	paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEYBA5	Diamond Field Emitter Array Cathode Experimental Tests in RF Gun	cathode, experiment, electron, emittance	618
	K.E. Nichols, H.L. Andrews, D. Kim, E.I. Simakov LANL, Los Alamos, New Mexico, USA S.P. Antipov Euclid Beamlabs LLC, Bolingbrook, USA G. Chen IIT, Chicago, Illinois, USA M.E. Conde, D.S. Doran, G. Ha, W. Liu, J.F. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski ANL, Lemont, Illinois, USA
	Funding: LANL/LDRD Diamond Field Emitter Array (DFEA) cathodes are arbitrarily shaped arrays of sharp (~50 nm tip size) nano-diamond pyramids with bases on the order of 3 to 25 microns and pitches 5 microns and greater. These cathodes have demonstrated very high bunch charge in tests at the L-band RF gun at the Argonne National Laboratory (ANL) Advanced Cathode Test Stand (ACTS). Intrinsically shaped electron beams have a variety of applications, but primarily to achieve high transformer ratios for Dielectric Wakefield Accelerators (DWA) when used in conjunction with Emittance Exchange (EEX) systems. Here we will present results from a number of recent cathode tests including bunch charge and YAG images. We have demonstrated shaped beam transport down the 2.54-meter beamline. In addition we will present emission simulations that demonstrate shielding effects for this geometry.
	Slides WEYBA5 [13.017 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBA5
About •	paper received ※ 01 September 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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WEYBB4	Progress of Liquid Lithium Stripper for FRIB	operation, vacuum, MMI, electron	636
	T. Kanemura, J. Gao, R. Madendorp, F. Marti, Y. Momozaki FRIB, East Lansing, Michigan, USA M.J. LaVere MSU, East Lansing, Michigan, USA Y. Momozaki ANL, Lemont, Illinois, USA
	Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 The Facility for Rare Isotope Beams (FRIB) at Michigan State University is building a heavy ion linear accelerator (linac) to produce rare isotopes by the fragmentation method. At energies between 16 and 20 MeV/u ions are further stripped by a charge stripper increasing the energy gain downstream in the linac. The main challenges in the stripper design are high power deposited by the ions in the stripping media and radiation damage to the media itself. To overcome these challenges, self-recovering stripper media are the most suitable solutions. The FRIB baseline choice is a high-velocity thin film of liquid lithium. Because liquid lithium is highly reactive with air, we have implemented rigorous safety measures. Since May 2018, the lithium stripper system has been operated safely at an offline test site to accumulate operational experience. Recently, we successfully completed a 10-day long unattended continuous operation without any issue, which proved the reliability of the system. The next step is to characterize the lithium film stability with diagnostics. In 2020, we plan to bring the lithium stripper into the accelerator tunnel and commission it with ion beams. Jie Wei, et al., TU1A04, Proceedings of LINAC 2012, Tel-Aviv, Israel
	Slides WEYBB4 [6.012 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBB4
About •	paper received ※ 03 September 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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WEPLM53	50 kW CW Multi-Beam Klystron	cavity, klystron, electron, cathode	717
	S.V. Shchelkunov Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA J.L. Hirshfield, V.E. Teryaev Omega-P, Inc., New Haven, Connecticut, USA
	Funding: Funded by the US Department of Energy; grant DE-SC-0018471. Main components, which are the electron gun, cavity-chain, magnetic system, and partially- grounded depressed four-stage collector, of a novel klystron were conceptually designed. This klystron is to deliver 50 kW CW at 952.6 MHz and to serve as a microwave power source for ion acceleration at the Electron Ion Collider (EIC) being developed at Thomas Jefferson National Accelerator Facility. The efficiency is 80%, a number to which the power consumption by the solenoid and filament are already factored in. The tube is a combination of proven technologies put together: it uses multiple beams to have its perveance low to boost beam-power to RF-power efficiency. It uses a partially grounded depressed collector to recover energy thereby increasing the overall efficiency. A low operating voltage of 14kV makes the tube more user-friendly avoiding need for costly modulators and oil insulation. A sectioned solenoid is used to insure superb beam-matching to all components downstream of the electron gun, increasing the tube performances. Details of the components designs will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM53
About •	paper received ※ 14 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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THYBA4	Status of the Magnetized Thermionic Electron Source at Jefferson Lab	cathode, electron, emittance, diagnostics	931
	F.E. Hannon, D.B. Bullard, C. Hernandez-Garcia, M.A. Mamun, M. Poelker, R. Suleiman JLab, Newport News, Virginia, USA J.V. Conway, B.M. Dunham, R.G. Eichhorn, C.E. Mayes, K.W. Smolenski, N.W. Taylor Xelera Research LLC, Ithaca, New York, USA C.M. Gulliford, V.O. Kostroun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA M.S. Stefani ODU, Norfolk, Virginia, USA
	A 125kV DC gridded thermionic gun has been de-signed and constructed through a collaboration between Jefferson Lab and Xelera Research LLC. The gun has been recently installed at the Gun Test Stand diagnostic line at Jefferson Lab where transverse and longitudinal parameter space will be experimentally explored. The status and results characterizing the commissioning and trouble-shooting the thermionic gun are presented.
	Slides THYBA4 [13.653 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THYBA4
About •	paper received ※ 28 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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THYBB3	Compact 1 MeV Electron Accelerator	cavity, GUI, vacuum, electron	942
	S.V. Kuzikov IAP/RAS, Nizhny Novgorod, Russia S.P. Antipov, P.V. Avrakhov Euclid TechLabs, LLC, Solon, Ohio, USA
	The cost of the accelerating structure in modern medical accelerators and industrial linacs is substantial. This comes to no surprise, as the accelerating waveguide is a set of diamond-turned copper resonators brazed together. Such a multistep manufacturing process is not only expensive, but also prone to manufacturing errors, which decrease the production yield. In the big picture, the cost of the accelerating waveguide precludes the use of accelerators as a replacement option for radioactive sources. Here we present a new cheap brazeless electron accelerating structure made out of two copper plates tightened together by means of an additional stainless steel plate. This additional plate, having sharp blades, is aimed to provide vacuum inside the whole system. The designed X-band 1 MeV structure consists of eight different length cells and accelerates field-emitted electrons from copper cathode. The structure is fed by 9 GHz magnetron which produces 240 kW, 1 µs pulses. The average gradient is as high as 10.6 MV/m, maximum surface fields do not exceed 50 MV/m.
	Slides THYBB3 [19.559 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THYBB3
About •	paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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THZBA5	First Electron Cooling of Hadron Beams Using a Bunched Electron Beam	electron, cavity, MMI, laser	957
	A.V. Fedotov, Z. Altinbas, M. Blaskiewicz, J.M. Brennan, D. Bruno, J.C. Brutus, M.R. Costanzo, K.A. Drees, W. Fischer, J.M. Fite, M. Gaowei, D.M. Gassner, X. Gu, J. Halinski, K. Hamdi, L.R. Hammons, T. Hayes, R.L. Hulsart, P. Inacker, J.P. Jamilkowski, Y.C. Jing, P.K. Kankiya, D. Kayran, J. Kewisch, D. Lehn, C.J. Liaw, C. Liu, J. Ma, G.J. Mahler, M. Mapes, A. Marusic, K. Mernick, C. Mi, R.J. Michnoff, T.A. Miller, M.G. Minty, S.K. Nayak, L.K. Nguyen, M.C. Paniccia, I. Pinayev, S. Polizzo, V. Ptitsyn, T. Rao, G. Robert-Demolaize, T. Roser, J. Sandberg, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, L. Smart, K.S. Smith, H. Song, A. Sukhanov, R. Than, P. Thieberger, S.M. Trabocchi, J.E. Tuozzolo, P. Wanderer, E. Wang, G. Wang, D. Weiss, B.P. Xiao, T. Xin, W. Xu, A. Zaltsman, H. Zhao, Z. Zhao BNL, Upton, New York, USA
	Funding: Work supported by the U.S. Department of Energy. The Low Energy RHIC electron Cooler (LEReC) was recently constructed and commissioned at BNL. The LEReC is the first electron cooler based on the RF acceleration of electron bunches (previous electron coolers all used DC beams). Bunched electron beams are necessary for cooling hadron beams at high energies. The challenges of such an approach include generation of electron beams suitable for cooling, delivery of electron beams of the required quality to the cooling sections without degradation of beam emittances and energy spread, achieving required small angles between electrons and ions in the cooling sections, precise energy matching between the two beams, high-current operation of the electron accelerator, as well as several physics effects related to bunched beam cooling. Following successful commissioning of the electron accelerator in 2018, the focus of the LEReC project in 2019 was on establishing electron-ion interactions and demonstration of cooling process using electron energy of 1.6MeV (ion energy of 3.85GeV/n), which is the lowest energy of interest. Here we report on the first demonstration of Au ion cooling in RHIC using this new approach.
	Slides THZBA5 [16.417 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THZBA5
About •	paper received ※ 16 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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Paper

Title

Other Keywords

Page

MOZBB5

Magnetized Electron Source for JLEIC Cooler

cathode, electron, solenoid, high-voltage

83

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

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and supported by Laboratory Directed Research and Development funding.
Magnetized bunched-beam electron cooling is a critical part of the Jefferson Lab Electron Ion Collider (JLEIC). Strong cooling of ion beams will be accomplished inside a cooling solenoid where the ions co-propagate with an electron beam generated from a source immersed in magnetic field. This contribution describes the production and characterization of magnetized electron beam using a compact 300 kV DC high voltage photogun and bialkali-antimonide photocathodes. Beam magnetization was studied using a diagnostic beamline that includes viewer screens for measuring the shearing angle of the electron beamlet passing through a narrow upstream slit. Correlated beam emittance with magnetic field at the photocathode was measured for various laser spot sizes. Measurements of photocathode lifetime were carried out at different magnetized electron beam currents up to 28 mA and high bunch charge up to 0.7 nano-Coulomb was demonstrated.

Slides MOZBB5 [9.236 MB]

Poster MOZBB5 [1.564 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBB5

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paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019

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MOPLM06

High Voltage Design of a 350 kV DC Photogun at BNL

electron, cathode, high-voltage, vacuum

102

W. Liu, O.H. Rahman, E. Wang
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Brookhaven National Laboratory is constructing a 350 kV DC high voltage photogun to provide spin-polarized electron beam for the proposed eRHIC facility. The photogun employs a compact inverted-tapered-geometry ceramic insulator that extends into the vacuum chamber and mechanically holds the cathode electrode. By operating at high voltage, the photogun will provide lower beam emittance, thereby improving the beam transmission through the injector apertures, and prolong the operating lifetime of the photogun. However, high voltage increases the field emission, which can result in high voltage breakdown and even lead to irreparable damage of the ceramic insulator. This work describes the methods to minimize the electric field near the metal-vacuum-insulator interface, and to avoid high voltage breakdown and ceramic insulator damage. The triple point junction shields are designed. The simulated electric field, field emission and beam transportation will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM06

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paper received ※ 19 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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MOPLM13

Investigations of the Electron Beam Energy Jitter Generated in the Photocathode RF Gun at the Advanced Photon Source Linac

timing, laser, electron, cathode

124

J.C. Dooling, D. Hui, A.H. Lumpkin, T.L. Smith, Y. Sun, K.P. Wootton, A. Zholents
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357.
Characterizations continue of the electron beam properties of a recently installed S-band photocathode (PC) rf gun at the Advanced Photon Source Linac facility. In this case, we have utilized a low-energy spectrometer beam line located 1.3 m downstream of the gun cavity to measure the electron beam energy, energy spread, and energy jitter. The nominal energy was 6.5 MeV using a gun gradient of 110 MV/m, and the energy spread was ~17 keV when driven by a 2.5-ps rms duration UV laser pulse at the selected rf gun phase. An energy jitter of 25 keV was initially observed in the spectrometer focal plane images. This jitter was partly attributed to the presence of both the 2nd and 3rd harmonics of the 119 MHz synchronization signal provided to the phase locked loop of the drive laser oscillator. The addition of a 150-MHz low-pass filter in the 119-MHz line strongly attenuated the two harmonics and resulted in a reduced energy jitter of ~15 keV. Comparisons of the gun performance to ASTRA simulations will also be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM13

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paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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MOPLM15

Design of the ASU Photocathode Lab

cathode, electron, diagnostics, emittance

132

C.J. Knill, S.S. Karkare
Arizona State University, Tempe, USA
J.V. Conway, B.M. Dunham, K.W. Smolenski
Xelera Research LLC, Ithaca, New York, USA
H.A. Padmore
LBNL, Berkeley, California, USA

Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Recent investigations have shown that it is possible to obtain an order of magnitude smaller intrinsic emittance from photocathodes by precise atomic scale control of the surface, using an appropriate electronic band structure of single crystal cathodes and cryogenically cooling the cathode. Investigating the performance of such cathodes requires atomic scale surface diagnostic techniques connected in ultra-high vacuum (UHV) to the epitaxial thin film growth and surface preparation systems and photo-emission and photocathode diagnostic techniques. Here we report the capabilities and design of the laboratory being built at the Arizona State University for this purpose. The lab houses a 200 kV DC gun with a cryogenically cooled cathode along with a beam diagnostics and ultra fast electron diffraction beamline. The cathode of the gun can be transported in UHV to a suite of UHV growth chambers and surface and photoemission diagnostic techniques.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM15

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paper received ※ 26 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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MOPLM16

Design of a 200 kV DC Cryocooled Photoemission Gun for Photocathode Investigations

cathode, electron, emittance, radiation

136

G.S. Gevorkyan, S.S. Karkare
Arizona State University, Tempe, USA
I.V. Bazarov, A. Galdi, J.M. Maxson
Cornell University, Ithaca, New York, USA
L. Cultrera, W.H. Li
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams.
Intrinsic emittance of photocathodes limits the brightness of electrons beams produced from photoemission guns. Recent advancements have shown that an order of magnitude improvement in intrinsic emittance over the commonly used polycrystalline metal and semiconductor cathodes is possible via use of single crystalline ordered surfaces of metals, semiconductors and other exotic materials at cryogenic temperatures as cathodes. However, due to practical design considerations, it is not trivial to test such cathodes in existing electron guns. Here we present the design of a 200kV DC electron gun being developed at the Arizona State University for this purpose.

Poster MOPLM16 [1.549 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM16

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paper received ※ 27 August 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019

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MOPLM18

Design of the 2-Stage Laser Transport for the Low Energy RHIC Electron Cooling (LEReC) DC Photogun

laser, electron, cathode, alignment

144

P. Inacker, S. Bellavia, A.J. Curcio, A.V. Fedotov, W. Fischer, D.M. Gassner, J.P. Jamilkowski, P.K. Kankiya, D. Kayran, D. Lehn, R. Meier, T.A. Miller, M.G. Minty, S.K. Nayak, L.K. Nguyen, L. Smart, C.J. Spataro, A. Sukhanov, J.E. Tuozzolo, Z. Zhao
BNL, Upton, 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 electron beam for the recently constructed Low Energy RHIC electron Cooler (LEReC) at Brookhaven National Laboratory is generated by a high-power fiber laser illuminating a photocathode. The pointing stability of the low-energy electron beam, which is crucial to maintain within acceptable limits given the long beam transport, is highly dependent on the center-of-mass (CoM) stability of the laser spot on the photocathode. For reasons of accessibility during operations, the laser itself is located outside the accelerator tunnel, leading to the need to propagate the laser beam 34 m via three laser tables to the photocathode. The challenges to achieving the required CoM stability of 10 microns on the photocathode thus requires mitigation of vibrations along the transport and of weather- and season-related environmental effects, while preserving accessibility and diagnostic capabilities with proactive design. After successful commissioning of the full transport in 2018/19, we report on our solutions to these design challenges.
LEReC Photocathode DC Gun Beam Test Results - D. Kayran Conference: C18-04-29, p.TUPMF025
Commissioning of Electron Accelerator LEReC for Bunch Beam Cooling - D.Kayran, NAPAC19

Poster MOPLM18 [1.970 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM18

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paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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MOPLM24

LCLS-II Injector Commissioning Beam Based Measurements

electron, laser, cathode, MMI

157

C.M. Zimmer, T.J. Maxwell, F. Zhou
SLAC, Menlo Park, California, USA

Funding: Department of Energy
Injector commissioning is underway for the LCLS-II MHz repetition rate FEL, currently under construction at SLAC. Methodology of injector beam-based measurements and early results with low beam charge will be presented, along with the software tools written to automate these various measurements.

Poster MOPLM24 [10.104 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM24

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paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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MOPLH02

Study of Photocathode Surface Damage due to Ion Back-Bombardment in High Current DC Gun

cathode, simulation, electron, laser

174

J.P. Biswas
Stony Brook University, Stony Brook, USA
O.H. Rahman, E. Wang
BNL, Upton, New York, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704, with the U.S. DOE
In high current DC gun, GaAs photocathode lifetime is limited by the ion back-bombardment. While gun operation ions are generated and accelerate back towards the cathode thus remove the activation layer’s material Cesium from the photocathode surface. We have developed an object-oriented code to simulate the ion generation due to dynamic gas pressure and ion trace in the electromagnetic field. The pressure profile varies from cathode position towards the transfer line behind the anode, which signifies the importance of dynamic simulation for ion back-bombardment study. In our surface damage study, we traced the energy and position of the ions on the photocathode surface and performed the Stopping and Range of Ions in Matter(SRIM) simulation to count the number of Cesium atoms removed from the surface due to single bunch impact. Cesium atom removal is directly related to the photocathode Quantum Efficiency(QE) decay. Our new dynamic simulation code can be used in any DC gun to study ion back-bombardment. We have used this new code to better understand the ion generation in prototype BNL 350 KV DC gun, and we have also estimated the normalized QE decay due to ion back-bombardment.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH02

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paper received ※ 27 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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MOPLH04

Design for HyRES Cathode Nanotip Electron Source

electron, cavity, solenoid, cathode

177

R.M. Hessami, A.F. Amhaz, P. Musumeci
UCLA, Los Angeles, USA

A new ultrafast electron diffraction (UED) instrument is being developed by UCLA-Colorado University collaboration for the STROBE NSF Center with the goal of using electron and EUV photon beams to reveal the structural dynamics of materials in non-equilibrium states at fundamental atomic and temporal scales. This paper describes the design of the electron beamline of this instrument. In order to minimize the initial emittance, a nanotip photocathode, 25 nm in radius, will be used. This requires a redesign of the cathode and anode components of the electron gun to allow for the tip to be properly aligned. Solenoidal lenses are used to focus the beam transversely to a sub-micron spot at the sample and a radiofrequency (RF) cavity, driven by a continuous wave S-band RF source, longitudinally compresses the beam to below 100 fs, required for atomic resolution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH04

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paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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MOPLH14

Ultrafast Nonlinear Photoemission from Alkali Antimonide Photocathodes

photon, electron, cathode, laser

203

W.H. Li, M.B. Andorf, I.V. Bazarov, L. Cultrera, C.J.R. Duncan, A. Galdi, J.M. Maxson, C.A. Pennington
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams.
Alkali antimonides photocathodes are a popular choice of electron source for high average brightness beams, due to their high quantum efficiency (QE) and low mean transverse energy (MTE). This paper describes the first measurements of their nonlinear photoemission properties under sub-ps laser illumination. These measurements include wavelength-resolved power dependence, pulse length dependence, and temporal response. The transition between linear and nonlinear photoemission is observed through the wavelength-resolved scan, and implications of nonlinear photoemission are discussed.

Poster MOPLH14 [0.543 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH14

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paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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MOPLO06

Black Gun Technologies for DC Photoinjectors

vacuum, electron, laser, scattering

247

E.J. Montgomery, C. Jing, S. Poddar
Euclid Beamlabs LLC, Bolingbrook, USA
J.E. Butler
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Zhang
JLab, Newport News, Virginia, USA

Funding: Work supported by the US DOE Office of Science, Office of Nuclear Physics, grant number DESC0019688. Work at Argonne CNM under Contract No. DE-AC02-06CH11357.
Euclid Beamlabs is developing a new "Black Gun" concept in direct current (DC) photoinjectors. To reduce electron-stimulated desorption indirectly influenced by stray photoemission, we are testing advanced optical coatings and low-scattering optics compatible with the extreme high vacuum (XHV) environment of modern DC photoinjectors. Stray light in DC photoinjectors (in proportion to the photoemitted charge) causes off-nominal photoemission, initiating electron trajectories which intercept downstream surfaces. This causes electron-stimulated desorption of atoms, which ionize and may back-bombard the cathode, reducing its charge lifetime. Back-bombardment is key for high average current or high repetition rate. First, we report on progress developing optical skimmers based on Butler baffles to collimate both incoming and outgoing laser beams. Second, we describe candidate coatings for reduction of scattered light. Requirements for these coatings are that they be conducting, optically black at the drive laser wavelength, conformally applied to complex geometry, and XHV-compatible with negligible outgassing.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO06

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paper received ※ 04 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUYBA3

Benchmarking the LCLS-II Photoinjector

simulation, laser, solenoid, emittance

301

N.R. Neveu, T.J. Maxwell, C.E. Mayes
SLAC, Menlo Park, California, USA

Funding: DOE Contract No. DE-AC02-76SF00515
Commissioning of the LCLS-II photoinjector started in late 2018. Efforts to accurately model the gun and laser profiles is ongoing. Simulations of the photoinjector and solenoid are performed in ASTRA, IMPACT-T and OPAL-T. This work includes efforts to use the laser profile at the virtual cathode as the initial transverse beam distribution, and effects of 2D and 3D field maps. Beam size results are compared to experimental measurements taken at the YAG screen located after the gun.

Slides TUYBA3 [1.320 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBA3

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paper received ※ 29 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUYBA4

Optimization of an SRF Gun Design for UEM Applications

SRF, laser, cavity, electron

305

A. Liu, P.V. Avrakhov
Euclid TechLabs, LLC, Solon, Ohio, USA
C. Jing, R.A. Kostin
Euclid Beamlabs LLC, Bolingbrook, USA

Funding: DOE contract DE-SC0018621
Benefiting from the rapid progress on RF photocathode gun technologies in the past two decades, the development of MeV-range ultrafast electron diffraction/microscopy (UED and UEM) has been identified as an enabling instrumentation, which may lead to breakthroughs in fundamental science and applied technologies *. Euclid is designing an SRF cavity as the UEM electron gun. As implementing a solenoid for emittance compensation in the gun is limited by the superconductivity performance and available space, the geometry of the first 0.3 cell of the cavity is optimized for transverse focusing and emittance reduction.
*: T. Chase, et al, "Ultrafast electron diffraction from non- equilibrium phonons in femtosecond laser heated Au films." Applied Physics Letters, 2016

Slides TUYBA4 [7.583 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBA4

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paper received ※ 30 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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TUYBB6

Beam Dynamics in a High Gradient RF Streak Camera

electron, cathode, experiment, photon

326

F. Toufexis, V.A. Dolgashev, A. Landa
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
Traditionally, time-resolved experiments in storage ring synchrotron light sources and free-electron lasers are performed with short x-ray pulses with time duration smaller than the time resolution of the phenomenon under study. Typically, storage-ring synchrotron light sources produce x-ray pulses on the order of tens of picoseconds. Newer diffraction limited storage rings produce even longer pulses. We propose to use a high-gradient RF streak camera for time-resolved experiments in storage-ring synchrotron light sources with potential for sub-100 fs resolution. In this work we present a detailed analysis of the effects of the initial time and energy spread of the photo-emitted electrons on the time resolution, as well as a start-to-end beam dynamics simulation in an S-Band system.
* F. Toufexis, et al, "Sub-Picosecond X-Ray Streak Camera using High-Gradient RF Cavities", in Proceedings of IPAC’19.

Slides TUYBB6 [5.958 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBB6

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paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUZBA1

Commissioning of the Electron Accelerator LEReC for Bunched Beam Cooling

electron, cavity, operation, cathode

330

D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, K.A. Drees, A.V. Fedotov, W. Fischer, M. Gaowei, D.M. Gassner, X. Gu, R.L. Hulsart, P. Inacker, J.P. Jamilkowski, Y.C. Jing, J. Kewisch, C.J. Liaw, C. Liu, J. Ma, K. Mernick, T.A. Miller, M.G. Minty, L.K. Nguyen, M.C. Paniccia, I. Pinayev, V. Ptitsyn, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, L. Smart, K.S. Smith, A. Sukhanov, P. Thieberger, J.E. Tuozzolo, E. Wang, G. Wang, W. Xu, A. Zaltsman, H. Zhao, Z. Zhao
BNL, Upton, 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 brand-new state of the art electron accelerator, LEReC, was built and commissioned at BNL. LEReC accelerator includes a photocathode DC gun, a laser system, a photocathode delivery system, magnets, beam diagnostics, a SRF booster cavity, and a set of Normal Conducting RF cavities to provide sufficient flexibility to tune the beam in the longitudinal phase space. Electron beam quality suitable for cooling in the Relativistic Heavy Ion Collider (RHIC) was achieved [1], which lead to the first demonstration of bunched beam electron cooling of hadron beams [2]. This presentation will discuss commissioning results, achieved beam parameters and performance of the LEReC systems.
[1] D.Kayran et al., First results from Commissioning of LEReC, in Proc of IPAC2019
[2] A.Fedotov et al., First electron cooling of hadron beams using a bunched electron beam, presented at NAPAC2019

Slides TUZBA1 [18.343 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBA1

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paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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TUZBB4

Space Charge Study of the Jefferson Lab Magnetized Electron Beam

laser, electron, cathode, space-charge

360

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

Magnetized electron cooling could result in high luminosity at the proposed Jefferson Lab Electron-Ion Collider (JLEIC). In order to increase the cooling efficiency, a bunched electron beam with high bunch charge and high repetition rate is required. We generated magnetized electron beams with high bunch charge using a new compact DC high voltage photo-gun biased at -300 kV with alkali-antimonide photocathode and a commercial ultrafast laser. This contribution explores how magnetization affects space charge dominated beams as a function of magnetic field strength, gun high voltage, laser pulse width, and laser spot size.

Slides TUZBB4 [12.582 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB4

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paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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TUPLM18

Improving Energy Resolution and Compensating Chromatic Aberration With a TM010 Microwave Cavity

cavity, electron, simulation, laser

411

C.J.R. Duncan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
P. Cueva, J.M. Maxson, D.A. Muller
Cornell University, Ithaca, New York, USA

Funding: National Science Foundation under Award OIA-1549132, the Center for Bright Beams
The intrinsic energy spread of electron sources limits the achievable resolution of electron microscopes in both spectroscopic and spatially resolved measurements. We propose that the TM010 mode of a single radio frequency (RF) cavity be used to dramatically reduce this energy spread in a pulsed beam. We show with analytic approximations, confirmed in simulations, that the non-linear time-energy correlations that develop in an electron gun can be undone by the RF cavity running near-crest. We derive an expression that gives the required RF field strength as a function of accelerating voltage. We explore multiple applications, including EELS and SEM. By pulsing a photocathode with commercially available, high repetition-rate lasers, our scheme could yield competitive energy spread reduction at higher currents when compared with monochromated continuous-wave sources for electron microscopes.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM18

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paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUPLM33

Optimization of Beam Parameters for UEM with Photo-Emission S-Band RF Gun and Alpha Magnet

electron, emittance, laser, simulation

440

H.R. Lee, P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim
KAERI, Jeongeup-si, Republic of Korea
B.L. Cho
KRISS, Daejeon, Republic of Korea
M.Y. Han, J.Y. Lee, S.H. Lee
Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea
H. Suk
GIST, Gwangju, Republic of Korea

Ultrafast Electron Microscopy (UEM) is a powerful tool to observe ultrafast dynamical processes in sample materials at the atomic level. By collaborating with KRISS and GIST, the future accelerator R&D team at KAERI has been developing a UEM facility based on a photo-emission S-band (=2856 MHz) RF gun. Recently, we have added an alpha magnet in the beamline layout of the UEM to improve beam qualities such as emittance, divergence, energy spread, and bunch length. To achieve high spatial and time resolutions, we have been optimizing those beam parameters and other machine parameters by performing numerous ASTRA and ELEGANT code simulations. In this paper, we describe our ASTRA and ELEGANT code optimizations to obtain high-quality beam parameters for the UEM facility with a photo-emission S-band RF gun and an alpha magnet.

Poster TUPLM33 [0.931 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM33

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paper received ※ 30 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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TUPLS10

Troubleshooting and Characterization of Gridded Thermionic Electron Gun

cathode, electron, controls, operation

474

M.S. Stefani
ODU, Norfolk, Virginia, USA
F.E. Hannon
JLab, Newport News, Virginia, USA

Jefferson National Laboratory has, in collaboration with Xelera research group, designed and built a gridded thermionic election gun with the potential for magnetization; in an effort to support research towards electron sources that may be utilized for the electron cooling process in the Jefferson Laboratories Electron Ion collider design. Presented here is the process and result of troubleshooting the electron gun components and operation to ensure functionality of the design.

Poster TUPLS10 [10.691 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS10

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paper received ※ 27 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019

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TUPLH03

Double-Bend Achromat Beamline for Injection Into a High-Power Superconducting Electron Linac

solenoid, electron, dipole, cavity

494

C.H. Boulware, T.L. Grimm, R. Hipple
Niowave, Inc., Lansing, Michigan, USA
S.M. Lund
FRIB, East Lansing, Michigan, USA
V.S. Morozov
JLab, Newport News, Virginia, USA

To take advantage of the high duty cycle operation of superconducting electron linacs, commercial systems use thermionic cathode electron guns that fill every RF bucket with an electron bunch. In continuous operation, the exit energy is limited when compared to pulsed systems. Bunch length and energy spread at the exit of the gun are incompatible with low losses in the superconducting cavity. A solenoid double-bend achromatic beamline is in operation at Niowave which allows energy and bunch length filtering of the beam leaving the gun before injection into the superconducting cavity. This system uses two solenoids and two dipoles to produce a round beam, using the edge angles of the dipoles to balance the focusing effects in the two transverse planes. The design allows beam filtering on the symmetry plane where the dispersion is maximum. Additionally, the bend angle moves the electron gun off the high-energy beam axis, allowing multiple-pass operation of the superconducting booster. This contribution will discuss the beam optics design of the double-bend achromat along with the design of the magnets and beam chambers and the operational experience with the system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH03

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paper received ※ 28 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019

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TUPLH24

Performance of CeC PoP Accelerator

electron, FEL, SRF, hadron

526

I. Pinayev, Z. Altinbas, J.C. Brutus, A.J. Curcio, A. Di Lieto, T. Hayes, R.L. Hulsart, P. Inacker, Y.C. Jing, V. Litvinenko, J. Ma, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, M.G. Minty, G. Narayan, I. Petrushina, F. Severino, K. Shih, Z. Sorrell, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman
BNL, Upton, 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 experiment is aimed for demonstration of the proof-of-principle demonstration of reduction energy spread of a single hadron bunch circulating in RHIC. The electron beam should have the required parameters and its orbit and energy should be matched to the hadron beam. In this paper we present the achieved electron beam parameters including emittance, energy spread, and other critical indicators. The operational issues as well as future plans are also discussed.

Poster TUPLH24 [11.180 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH24

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paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEYBA5

Diamond Field Emitter Array Cathode Experimental Tests in RF Gun

cathode, experiment, electron, emittance

618

K.E. Nichols, H.L. Andrews, D. Kim, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
S.P. Antipov
Euclid Beamlabs LLC, Bolingbrook, USA
G. Chen
IIT, Chicago, Illinois, USA
M.E. Conde, D.S. Doran, G. Ha, W. Liu, J.F. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
ANL, Lemont, Illinois, USA

Funding: LANL/LDRD
Diamond Field Emitter Array (DFEA) cathodes are arbitrarily shaped arrays of sharp (~50 nm tip size) nano-diamond pyramids with bases on the order of 3 to 25 microns and pitches 5 microns and greater. These cathodes have demonstrated very high bunch charge in tests at the L-band RF gun at the Argonne National Laboratory (ANL) Advanced Cathode Test Stand (ACTS). Intrinsically shaped electron beams have a variety of applications, but primarily to achieve high transformer ratios for Dielectric Wakefield Accelerators (DWA) when used in conjunction with Emittance Exchange (EEX) systems. Here we will present results from a number of recent cathode tests including bunch charge and YAG images. We have demonstrated shaped beam transport down the 2.54-meter beamline. In addition we will present emission simulations that demonstrate shielding effects for this geometry.

Slides WEYBA5 [13.017 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBA5

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paper received ※ 01 September 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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WEYBB4

Progress of Liquid Lithium Stripper for FRIB

operation, vacuum, MMI, electron

636

T. Kanemura, J. Gao, R. Madendorp, F. Marti, Y. Momozaki
FRIB, East Lansing, Michigan, USA
M.J. LaVere
MSU, East Lansing, Michigan, USA
Y. Momozaki
ANL, Lemont, Illinois, USA

Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The Facility for Rare Isotope Beams (FRIB) at Michigan State University is building a heavy ion linear accelerator (linac) to produce rare isotopes by the fragmentation method. At energies between 16 and 20 MeV/u ions are further stripped by a charge stripper increasing the energy gain downstream in the linac. The main challenges in the stripper design are high power deposited by the ions in the stripping media and radiation damage to the media itself. To overcome these challenges, self-recovering stripper media are the most suitable solutions. The FRIB baseline choice is a high-velocity thin film of liquid lithium*. Because liquid lithium is highly reactive with air, we have implemented rigorous safety measures. Since May 2018, the lithium stripper system has been operated safely at an offline test site to accumulate operational experience. Recently, we successfully completed a 10-day long unattended continuous operation without any issue, which proved the reliability of the system. The next step is to characterize the lithium film stability with diagnostics. In 2020, we plan to bring the lithium stripper into the accelerator tunnel and commission it with ion beams.
*Jie Wei, et al., TU1A04, Proceedings of LINAC 2012, Tel-Aviv, Israel

Slides WEYBB4 [6.012 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBB4

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paper received ※ 03 September 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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WEPLM53

50 kW CW Multi-Beam Klystron

cavity, klystron, electron, cathode

717

S.V. Shchelkunov
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
J.L. Hirshfield, V.E. Teryaev
Omega-P, Inc., New Haven, Connecticut, USA

Funding: Funded by the US Department of Energy; grant DE-SC-0018471.
Main components, which are the electron gun, cavity-chain, magnetic system, and partially- grounded depressed four-stage collector, of a novel klystron were conceptually designed. This klystron is to deliver 50 kW CW at 952.6 MHz and to serve as a microwave power source for ion acceleration at the Electron Ion Collider (EIC) being developed at Thomas Jefferson National Accelerator Facility. The efficiency is 80%, a number to which the power consumption by the solenoid and filament are already factored in. The tube is a combination of proven technologies put together: it uses multiple beams to have its perveance low to boost beam-power to RF-power efficiency. It uses a partially grounded depressed collector to recover energy thereby increasing the overall efficiency. A low operating voltage of 14kV makes the tube more user-friendly avoiding need for costly modulators and oil insulation. A sectioned solenoid is used to insure superb beam-matching to all components downstream of the electron gun, increasing the tube performances. Details of the components designs will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM53

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paper received ※ 14 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019

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THYBA4

Status of the Magnetized Thermionic Electron Source at Jefferson Lab

cathode, electron, emittance, diagnostics

931

F.E. Hannon, D.B. Bullard, C. Hernandez-Garcia, M.A. Mamun, M. Poelker, R. Suleiman
JLab, Newport News, Virginia, USA
J.V. Conway, B.M. Dunham, R.G. Eichhorn, C.E. Mayes, K.W. Smolenski, N.W. Taylor
Xelera Research LLC, Ithaca, New York, USA
C.M. Gulliford, V.O. Kostroun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
M.S. Stefani
ODU, Norfolk, Virginia, USA

A 125kV DC gridded thermionic gun has been de-signed and constructed through a collaboration between Jefferson Lab and Xelera Research LLC. The gun has been recently installed at the Gun Test Stand diagnostic line at Jefferson Lab where transverse and longitudinal parameter space will be experimentally explored. The status and results characterizing the commissioning and trouble-shooting the thermionic gun are presented.

Slides THYBA4 [13.653 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THYBA4

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paper received ※ 28 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019

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THYBB3

Compact 1 MeV Electron Accelerator

cavity, GUI, vacuum, electron

942

S.V. Kuzikov
IAP/RAS, Nizhny Novgorod, Russia
S.P. Antipov, P.V. Avrakhov
Euclid TechLabs, LLC, Solon, Ohio, USA

The cost of the accelerating structure in modern medical accelerators and industrial linacs is substantial. This comes to no surprise, as the accelerating waveguide is a set of diamond-turned copper resonators brazed together. Such a multistep manufacturing process is not only expensive, but also prone to manufacturing errors, which decrease the production yield. In the big picture, the cost of the accelerating waveguide precludes the use of accelerators as a replacement option for radioactive sources. Here we present a new cheap brazeless electron accelerating structure made out of two copper plates tightened together by means of an additional stainless steel plate. This additional plate, having sharp blades, is aimed to provide vacuum inside the whole system. The designed X-band 1 MeV structure consists of eight different length cells and accelerates field-emitted electrons from copper cathode. The structure is fed by 9 GHz magnetron which produces 240 kW, 1 µs pulses. The average gradient is as high as 10.6 MV/m, maximum surface fields do not exceed 50 MV/m.

Slides THYBB3 [19.559 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THYBB3

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paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019

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THZBA5

First Electron Cooling of Hadron Beams Using a Bunched Electron Beam

electron, cavity, MMI, laser

957

A.V. Fedotov, Z. Altinbas, M. Blaskiewicz, J.M. Brennan, D. Bruno, J.C. Brutus, M.R. Costanzo, K.A. Drees, W. Fischer, J.M. Fite, M. Gaowei, D.M. Gassner, X. Gu, J. Halinski, K. Hamdi, L.R. Hammons, T. Hayes, R.L. Hulsart, P. Inacker, J.P. Jamilkowski, Y.C. Jing, P.K. Kankiya, D. Kayran, J. Kewisch, D. Lehn, C.J. Liaw, C. Liu, J. Ma, G.J. Mahler, M. Mapes, A. Marusic, K. Mernick, C. Mi, R.J. Michnoff, T.A. Miller, M.G. Minty, S.K. Nayak, L.K. Nguyen, M.C. Paniccia, I. Pinayev, S. Polizzo, V. Ptitsyn, T. Rao, G. Robert-Demolaize, T. Roser, J. Sandberg, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, L. Smart, K.S. Smith, H. Song, A. Sukhanov, R. Than, P. Thieberger, S.M. Trabocchi, J.E. Tuozzolo, P. Wanderer, E. Wang, G. Wang, D. Weiss, B.P. Xiao, T. Xin, W. Xu, A. Zaltsman, H. Zhao, Z. Zhao
BNL, Upton, New York, USA

Funding: Work supported by the U.S. Department of Energy.
The Low Energy RHIC electron Cooler (LEReC) was recently constructed and commissioned at BNL. The LEReC is the first electron cooler based on the RF acceleration of electron bunches (previous electron coolers all used DC beams). Bunched electron beams are necessary for cooling hadron beams at high energies. The challenges of such an approach include generation of electron beams suitable for cooling, delivery of electron beams of the required quality to the cooling sections without degradation of beam emittances and energy spread, achieving required small angles between electrons and ions in the cooling sections, precise energy matching between the two beams, high-current operation of the electron accelerator, as well as several physics effects related to bunched beam cooling. Following successful commissioning of the electron accelerator in 2018, the focus of the LEReC project in 2019 was on establishing electron-ion interactions and demonstration of cooling process using electron energy of 1.6MeV (ion energy of 3.85GeV/n), which is the lowest energy of interest. Here we report on the first demonstration of Au ion cooling in RHIC using this new approach.

Slides THZBA5 [16.417 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THZBA5

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paper received ※ 16 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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