Keyword: cathode
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MOXBA01 Beam Commissioning of PAL-XFEL gun, undulator, laser, linac 6
 
  • J.H. Han
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  The Pohang Accelerator Laboratory X-ray Free electron Laser (PAL-XFEL) project aims at the generation of X-ray FEL radiation for photon users. The machine consists of a 10 GeV normal-conducting S-band linear accelerator (linac) and two undulator beamlines initially. The hard X-ray beamline will provide FEL radiation between 0.6 and 0.1 nm or shorter. The soft X-ray line will provide FEL radiation between 4.5 and 1 nm. The linac and hard X-ray beamline construction was complete by the end of 2015. The installation of the soft X-ray line is ongoing. High power RF conditioning of the linac started in late autumn 2015. Beam commissioning of the linac started in April 2016. We report the beam commissioning status.  
slides icon Slides MOXBA01 [4.978 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOXBA01  
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MOPMW027 Design of a Perpendicular Biased 2nd Harmonic Cavity for the Fermilab Booster cavity, booster, Windows, impedance 451
 
  • C.-Y. Tan, J.E. Dey, K.L. Duel, R.L. Madrak, W. Pellico, E. Prebys, J. Reid, G.V. Romanov, D. Sun, I. Terechkine
    Fermilab, Batavia, Illinois, USA
  
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
A perpendicular biased 2nd harmonic cavity is currently being designed and built for the Fermilab Booster. The purpose is to flatten the bucket at injection and thus change the longitudinal beam distribution to decrease space charge effects. It can also help with transition crossing. A model cavity has been built to verify various CST Microwave studio and COMSOL results and a test stand has been built to ensure that the Y567 tube is able to operate at twice the Booster fundamental frequencies. Also discussed are the RF windows which are critical to the design. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW027  
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MOPMY015 Design Study of Electron Gun for CEPC 650 MHz Klystron gun, klystron, electron, simulation 546
 
  • .. Zaib-un-Nisa, D.D. Dong, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, Z.S. Zhou
    IHEP, People's Republic of China
  • S. Fukuda
    KEK, Ibaraki, Japan
  
  This paper presents the design and simulation of an electron gun for 800 kW CW klystron of which frequency is 650 MHz for CEPC project. An electron gun with a modulating anode is designed using DGUN software. The uniform beam trajectories, with a beam perveance of 0.64μA/V 3/2 are simulated. We employed a Ba-dispenser cathode of radius 35 mm with Φ10 hole at the center and obtained a current density on cathode less than 0.45 A/cm2. The beam trajectories were also simulated over whole tube length with a magnetic field of 207 Gauss. Expecting functions using the modulating anode gun are also described. Proposed beam tester and whole CEPC klystron layout are also shown in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY015  
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MOPMY035 Theoretical Analysis and Simulation of a Compact Frequency Multiplier for High Power Millimeter and Terahertz Sources cavity, electron, coupling, space-charge 576
 
  • A.R. Vrielink, S.G. Tantawi, F. Toufexis
    SLAC, Menlo Park, California, USA
  
  As the demands on accelerating gradients and the temporal resolution of beam diagnostics and manipulation schemes grow, millimeter-wave and terahertz (THz) accelerator structures may present a natural solution. The recent advent of a radiofrequency undulator and the development of a 0.45 THz accelerator demonstrate growing interest in this frequency regime; however, growth in this area is limited by the lack of efficient, compact high power sources. We present a novel vacuum electronic device featuring an interaction between a radially bunched electron beam and azimuthally traveling waves. The use of an inward traveling radial sheet beam mitigates space charge effects at the low operating energy of 10-30 keV and allows for a high input beam current of approximately 0.5-10 A. Based on preliminary calculations, these devices could operate from 50 GHz to 250 GHz with tens of kiloWatts of output power, while the expected efficiency would scale from 60% at 80 GHz to 15% at 230 GHz. Here we present the underlying theory, possible structure design, and preliminary results from analytical calculations and simulation.
Tantawi, S. et al. Phys. Rev. Lett. 112, 164802 (April, 2014)
Nanni, E. et al. Nat. Commun. 6, 8486 (October, 2015) 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY035  
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MOPOR033 Simulations of Dark Current from the BERLinPro Booster Module cavity, electron, booster, simulation 671
 
  • M. McAteer, M. Abo-Bakr, B.C. Kuske, A. Neumann
    HZB, Berlin, Germany
  
  Funding: Work supported by the German Bundesministerium f\"ur Bildung und Forschung, Land Berlin and grants of Helmholtz Association
Dark current emitted from the surface of high-field RF cavities can contribute to radiation levels and cryo budget and can cause damage to sensitive accelerator components such as the photocathode. The superconducting niobium cavities in the booster module of BERLinPro will have surface fields strong enough to produce significant dark current from field emission, so simulations were made using Astra to track the propagation of emitted electrons from the surfaces of the cavities to examine the effects of dark current in the BERLinPro injector. Results of these simulations, including optimization of the layout to reduce propagation of electrons to the cathode and an estimation of power from dark current deposited throughout the injector, are presented. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR033  
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MOPOW018 Feasibility Study of Photocathode Opearation of Thermionic RF Gun at KU-FEL FEL, operation, electron, gun 754
 
  • H. Zen, T. Kii, K. Masuda, K. Morita, T. Murata, T. Nogi, H. Ohgaki, S. Suphakul, K. Torgasin
    Kyoto University, Kyoto, Japan
  • R. Kuroda
    AIST, Tsukuba, Ibaraki, Japan
  
  Kyoto University Free Electron Laser (KU-FEL) is a mid-infrared FEL driven by a compact linac utilizinig a thermionic RF gun as its electron source*. Recently we succeeded in operating KU-FEL with photocathode operation of the RF gun by using the thermionic cathode (LaB6) as a photocathode. The performance of KU-FEL under the thermionic cathode and photocathode operation will be reported. In addition, some recent application experiment results will also be presented in this presentation.
*H. Zen, et al., Infrared Phys. Techn. 51 (2008) 382. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW018  
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TUPMR013 Heat Transfer Study of PIG Ion Source for 10 MeV Cyclotron ion, ion-source, electron, cyclotron 1256
 
  • F. Zakerhosseini, H. Afarideh, S. Sabounchi
    AUT, Tehran, Iran
  • J.-S. Chai, M. Ghergherehchi
    SKKU, Suwon, Republic of Korea
  
  A PIG Ion source provides H-ions for the 10 MeV cyclotron, which is designed and being manufactured by Amirkabir university of technology. Plasma created in the anode contains the desired ions. Discharge for producing plasma consists of the both ion current from plasma towards the cathode and the secondary electron current from the cathode to the plasma. Secondary electron emission is the result of ion collision on the surface of the cathode. Heat generated by these collisions is considerably high, so a cooling system for ion source is crucial. In this paper heat transfer study of the ion source, temperature distribution and deformation of different parts simulated using ANSYS CFX. Also the thermionic emission of the electrons from cathode in the calculated temperatures by ANSYS simulated Using CST STUDIO. Results showed the maximum temperature of the cathodes is 1992 K, which is far away from the cathode melting point. The thermionic current in 1992 K of cathode simulated and the results showed an electron current of 0.00706 A at 500 V which is negligible in comparison to the discharge current of 1 A. Maximum deformation were about 0.2 mm in cathode edges.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR013  
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TUPMR032 Initial Commissioning of the Rutherford Appleton Laboratory (RAL) Scaled Negative Penning Ion Source interface, plasma, operation, space-charge 1314
 
  • D.C. Faircloth, S.R. Lawrie, T. Rutter, M. Whitehead, T. Wood
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  A new high duty factor, scaled Penning surface plasma source is being developed at RAL. This paper provides initial commissioning results. A stable high-current (up to 100 A) pulsed discharge is obtained, but the anode overheats, caused by poor thermal contact at elevated temperatures. The overheating anode yields a noisy discharge, with low output current, and makes high duty factor operation impossible. The performance of a thermal interface material for aperture plate (plasma electrode) cooling is detailed. An update on the cathode heaters is provided. The anode to source-body fit is analysed at different temperatures for different combinations of mechanical tolerances. This offers insights when compared to ISIS operational sources. A new anode with modified tolerance dimensions for improved fit is being manufactured and will be tested in June 2016.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR032  
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TUPMR056 Development and Investigation of Pulsed Pinch Plasmas for the Application as FAIR Plasma Stripper plasma, ion, electron, heavy-ion 1387
 
  • M. Iberler, T. Ackermann, B. Bohlender, C. Hock, J. Jacoby, D. Mann, A. Puth, J. Wiechula
    IAP, Frankfurt am Main, Germany
  • G. Ge
    GSI, Darmstadt, Germany
  
  Funding: This work is supported by BMBF
The planed Facility for Ion Research (FAIR) is a new international accelerator laboratory at the GSI in Darm-stadt, Germany. The main topic at this facility is aimed to heavy ion research. The FAIR project in comparison to the existing facility GSI extends the research area by raising the energy of ion beams. After creation of the ion beam at the ion source the state charge is low. Therefor the demand for acceleration of the beam to the highest possible energy is a highly ionized charge state of the beam. For beam stripping to get higher charge state, the traditional tools are gas stripper and foil stripper [1, 2]. Hence Plasma is suggested to be a stripper medium. In Frankfurt are different kinds of Pinch Plasmas under investigation for Stripper. The constricting effect on the plasma or conductor is produced by the magnetic field pressure resulting from the current or by the Lorentz force produced by the current flowing in its own magnetic field. In addition to separate the high pressure discharge cham-ber of the accelerator a plasma window will be used [3]. This contribution gives an overview of the plasma proper-ties and shows first results of different beam times at the GSI. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR056  
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TUPOW006 Six-dimensional Phase-space Rotation and its Applications emittance, FEL, simulation, electron 1754
 
  • M. Kuriki, K. Negishi
    HU/AdSM, Higashi-Hiroshima, Japan
  • H. Hayano, R. Kato, K. Ohmi, M. Satoh, Y. Seimiya, J. Urakawa
    KEK, Ibaraki, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  
  Funding: This work is partly supported by Grant-in-Aid for Scientific Research by MEXT, Japan (KAKENHI) 25390126.
Recent progress on the accelerator science requires optimized phase space distributions of the beam for each applications. A classical approach to satisfy the requirements is minimizing the beam emittance with a bunch charge as much as possible. This classical approach is not efficient and not compatible to the beam dynamics nature. 6D phase-space rotation, e.g. z-x and x-y, gives a way to optimize the phase space distribution for various applications. In this article, we discus possible applications of the 6D phase space rotation. The x-y rotation generates the high aspect ratio beam for linear colliders directly without DR (Damping Ring). Combination of bunch clipping with a mechanical slit and x-z rotation can generate micro-bunch structure which is applicable for FEL enhancement and drive beam for dielectric acceleration. We present our theoretical and simulation study on these applications. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW006  
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TUPOW014 Simulation of High Resolution Field Emission Imaging in an rf Photocathode Gun electron, gun, solenoid, simulation 1769
 
  • J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
    TUB, Beijing, People's Republic of China
  • S.P. Antipov, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • W. Gai
    ANL, Argonne, Illinois, USA
  • F.Y. Wang
    SLAC, Menlo Park, California, USA
  
  Precisely locating field emission (FE) emitters on a realistic surface in rf structures is technically chal-lenging in general due to the wide emitting phase and the broad energy spread. A method to achieve in situ high resolution FE imaging has been proposed by using solenoids and a collimator to select electrons emitted at certain phases. The phase selection criterion and imaging properties have been studied by the beam dynamics code ASTRA. Detailed results are presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW014  
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TUPOW015 Experiment of High Resolution Field Emission Imaging in an rf Photocathode Gun electron, experiment, gun, background 1772
 
  • J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
    TUB, Beijing, People's Republic of China
  • S.P. Antipov, S.V. Baryshev, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.E. Conde, W. Gai, G. Ha, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • F.Y. Wang
    SLAC, Menlo Park, California, USA
  
  The first in situ high resolution field emission (FE) imaging experiment has been carried out on an L-band photocathode gun test stand at Argonne Wakefield Accelerator facility (AWA). Separated strong emitters have been observed to dominate the field emission. Field enhancement factor, beta, of small regions on the cathode has been measured with the imaging system. It is shown that most strong emitters overlaps with the high beta regions. The post surface examinations reveal the origins of ~75% strong emitters overlap with the spots where rf breakdown have occurred. Detailed results are presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW015  
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TUPOW016 Development of a C-Band 4/8 Mev Dual-Energy Accelerator for Cargo Inspection System gun, controls, bunching, linac 1775
 
  • J.H. Shao, H.B. Chen, W.-H. Huang, Q.X. Jin, Y.H. Liu, J. Shi, C.-X. Tang, X.W. Wu
    TUB, Beijing, People's Republic of China
  
  Modern cargo inspection system applies dual-energy X-ray for material discrimination. Based on the com-pact C-band 6 MeV standing-wave accelerating struc-tures developed at Tsinghua University, a compact C-band 4/8 MeV dual-energy accelerator has been pro-posed, fabricated and tested. Compared with that of the conventional S-band 3/6 MeV dual-energy accelera-tor at Tsinghua University, the volume and the weight of the C-band one has been reduced by ~40% and ~30%, respectively. Detailed review of this C-band dual-energy accelerator is present in the paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW016  
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TUPOW025 First Beam Test of the High Brightness Photo-injector at NSRRC laser, gun, linac, electron 1800
 
  • A.P. Lee, M.C. Chou, N.Y. Huang, J.-Y. Hwang, W.K. Lau, C.C. Liang, M.T. Tsou
    NSRRC, Hsinchu, Taiwan
  • P. Wang
    NTHU, Hsinchu, Taiwan
  
  A High brightness injector at NSRRC is built for a VUV/THz free electron laser (FEL) facility and light source R&D. This injector with a photocathode rf gun with a solenoid for emittance compensation, a UV laser system, a 5.2 m S-band linac as well as various beam diagnostic tools has been installed in the linac test laboratory. The main goal is to produce beams with emittance smaller than 1 mm-mrad at energy of ~100 MeV. The other goal is to compress bunches to ~100 fs with charge of 100 pc and energy of ~30 MeV. In this contribution, an overview of the commissioning results of the photocathode rf gun and the laser system will be given. The first beam observation downstream the lianc will be presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW025  
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TUPOW027 Model Independent Analysis of Beam Jitter on VELA laser, timing, distributed, gun 1806
 
  • J.K. Jones, K.D. Dumbell, A.J. Moss, E.W. Snedden
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide high quality electron beams for accelerator systems development, as well as industrial and scientific applications. A key performance indicator for many applications is the inherent beam jitter on the machine (temporal, momentum and positional). Analysis of this beam jitter indicates that there are several independent mechanisms driving the beam motion. We use model independent analysis to correlate various dominant modes of beam jitter and compare them to simulations. We also compare the dominant modes before and after intervention work on the DLLRF timing system, and determine the relevant changes in beam motion.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW027  
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TUPOW028 Comparison of Model vs. Reality for VELA gun, simulation, laser, solenoid 1810
 
  • M.S. Toplis, J.W. McKenzie, B.D. Muratori, D.J. Scott, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide a high quality electron beam for accelerator systems development, as well as industrial and scientific applications. Currently, the RF gun can deliver short bunches, of the order of 100 fs to a few ps, with a charge of up to 250 pC, at the longer bunch lengths, and up to 4.5 MeV/c beam momentum. A model for the injector has been developed in ASTRA, together with a suite of scripts to create scans of the available parameters around an empirically found arbitrarily optimal working point. The space of parameters consists of everything that can be changed in the control room, and ranges from bunch charge to laser spot size on the cathode, together with all magnet settings where and if necessary. The various scans facilitate the task of identifying where exactly the accelerator is in terms of parameters and trends. Initial comparisons of screen images are made between the model and reality. Ultimately, the goal of the model is to robustly and repeatably establish a desired operating setup on a daily basis from an unknown switch on condition.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW028  
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TUPOW035 First LLRF Tests of BERLinPro Gun Cavity Prototype cavity, gun, controls, linac 1831
 
  • P. Echevarria, J. Knobloch, O. Kugeler, A. Neumann, A. Ushakov
    HZB, Berlin, Germany
  • K.P. Przygoda
    DESY, Hamburg, Germany
  
  The goal of Berlin Energy Recovery Linac Project (BERLinPro) is the generation of a 50 MeV, 100-mA low emittance (below 1 mm mrad) CW electron beam at 2 ps rms bunch duration or below. Three different types of 1.3 GHz SRF modules will be employed: the electron gun, the booster and the main linac. Precise RF amplitude and phase control are needed due to the beam recovery pro-cess. In this paper we describe the first tests of the Low Level RF control of the first injector prototype at the HoBiCaT facility, implemented in the digital VME-based LLRF controller developed by Cornell University. Tuner movement control by an mTCA.4 system, together with further plans of using this technology will be also presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW035  
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TUPOY015 Design of Electron Gun and S-Band Structure for Medical Electron Linear Accelerator electron, gun, cavity, linac 1930
 
  • N. Juntong, R. Chimchang
    SLRI, Nakhon Ratchasima, Thailand
  • S. Rimjaem, C. Saisa-ard
    Chiang Mai University, Chiang Mai, Thailand
  
  Linear accelerator technology has been widely utilized for cancer treatment in hospital. This radiotherapy utilizes an accelerated electron beam to create the x-ray beam. The idea to fabricate the prototype of medical electron linac with low cost for domestic use in Thailand was proposed and the budget has been granted. In the first phase, the electron beam energy of the machine will be 6 MeV or equivalent to x-ray energy of 6 MV. The electron gun is a diode type for the simple and low cost fabrication. The design and simulation study of diode gun will be presented together with an analysis of an electron beam in this gun. The S-Band 6 MeV side-coupled RF cavity has been designed to be the accelerating structure of the machine. The electromagnetic fields of the structure have been studied. The electron behaviour when they traverse this cavity will be studied using a particle tracking code. Progression of the project is also presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY015  
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TUPOY032 Design and Simulation of a Thermionic Electron Gun for a 1 MeV Parallel Feed Cockcroft-Walton Industrial Accelerator electron, gun, simulation, space-charge 1976
 
  • M. Nazari, F. Abbasi
    Shahid Beheshti University, Tehran, Iran
  • F. Ghasemi
    NSTRI, Tehran, Iran
  • M. Jafarzadeh
    ILSF, Tehran, Iran
  
  Electron accelerators are made of different parts and one of the main part of every electron accelerator is its electron gun. In this article a diode electron gun is designed and simulated for a 1MeV parallel feed Cockcroft-Walton accelerator for industrial applications. The pierce configuration is selected for focusing electrode. Simulations are carried out using CST Particle Studio. The gun is thermionic with indirect heating of spherical dispenser cathode that is made from porous tungsten which is impregnated with barium compounds. The gun maximum achievable current is 200 mA at 10 kV and required current in our accelerator is about 100 mA.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY032  
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TUPOY040 Advancements in Single-shot Electron Diffraction on VELA at Daresbury Laboratory electron, laser, cavity, gun 1988
 
  • J.W. McKenzie, S.L. Mathisen, M.D. Roper, M. Surman
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • D.M.P. Holland
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • J.G. Underwood
    UCL, London, United Kingdom
  
  Electron diffraction on VELA at Daresbury Laboratory was first demonstrated in 2014. Since then, we have studied the machine parameter optimisation for single-shot diffraction patterns from single-crystal gold and silicon samples at bunch charges down to 60 fC. We present bunch length measurements for electron diffraction setups determined with a transverse deflecting cavity. We also discuss the current limitations of VELA for electron diffraction and the improvements to be made.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY040  
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TUPOY050 Microtron-based Intense Neutron Source microtron, cavity, neutron, electron 2014
 
  • G.M. Kazakevich, R.J. Abrams, R.P. Johnson, S.A. Kahn
    Muons, Inc, Illinois, USA
  • M.A.C. Cummings
    Northern Illinois University, DeKalb, Illinois, USA
  
  Funding: Funded by DOE SBIR grant DE-SC0013795
An L-Band 7.7-9.8 MeV CW relatively inexpensive microtron with a warm accelerating cavity for multi-purpose applications in nuclear medicine and radiation industry is proposed. The microtron with a photo-neutron converter is intended to serve as an intense source of photo-neutrons with yield up to 4·1012 n/s for nuclear medicine or/and producing of short lived isotopes, as a source of gamma-radiation with dose rates up to 130 kR/min·m with a heavy bremsstrahlung target, and as a source of the electron beam with total energy of 9.8 MeV at the average current up to 4.4 mA for various radiation treatments. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY050  
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TUPOY055 Study on Electro-polishing of Nb Surface by Periodic Reverse Current Method with Sodium Hydroxide Solution experiment, cavity, operation, SRF 2020
 
  • J. Taguchi, A. Namekawa
    Nomura Plating Co, Ltd., Osaka, Japan
  • H. Hayano, T. Saeki
    KEK, Ibaraki, Japan
  • C.E. Reece, H. Tian
    JLab, Newport News, Virginia, USA
  
  Electropolishing is one of the best methods of Nb surface finishing of the superconducting cavity to obtain high accelerating gradient. Mixed solution of hydrofluoric acid and sulfuric acid is generally used in the electropolishing of Nb. But this solution is very dangerous and because the corrosion of the metal occurs by hydrofluoric acid, all equipment must be made of high density polyethylene or fluorocarbon resin. This causes the expensive cost of electropolishing instrument. In addition, this solution produces sulfur compound on the Nb surface in the electropolishing reaction. This sulfur compound can be field emission sources on the inner surface of cavity and degrades acceleration performance. In this poster, we report noble electropolishing method using periodic reverse current and sodium hydroxide solution. The reaction produces no sulfur content and the equipment is less expensive because the instrument can be made of usual plastic material. As the result of experiments with Nb-coupon samples, we found that the surface roughness is equivalent to the conventional electropolishing method.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY055  
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WEOAB02 Record Performance of SRF Gun with CsK2Sb Photocathode gun, laser, electron, cavity 2085
 
  • I. Pinayev, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, D.M. Gassner, M. Harvey, T. Hayes, R.L. Hulsart, J.P. Jamilkowski, Y.C. Jing, D. Kayran, R. Kellermann, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, K. Mernick, R.J. Michnoff, T.A. Miller, M.G. Minty, G. Narayan, P. Orfin, D. Phillips, T. Rao, J. Reich, T. Roser, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, V. Soria, Z. Sorrell, R. Than, C. Theisen, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman, Z. Zhao
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
High-gradient CW photo-injectors operating at high ac-celerating gradients promise to revolutionize many sci-ences and applications. They can establish the basis for super-bright monochromatic X-ray and gamma-ray sources, high luminosity hadron colliders, nuclear- waste transmutation or a new generation of microchip produc-tion. In this paper we report on our operation of a super-conducting RF electron gun with a record-high accelerat-ing gradient at the CsK2Sb photocathode (i.e. ~ 20 MV/m) generating a record-high bunch charge (i.e., 2 nC). We briefly describe the system and then detail our experimental results. 		 
slides icon Slides WEOAB02 [28.500 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAB02  
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WEOAB03 Photoemission Properties of LaB6 and CeB6 Under Various Temperature and Incident Photon Energy Conditions laser, photon, electron, vacuum 2088
 
  • K. Morita, T. Katsurayama, T. Kii, K. Masuda, T. Murata, K. Nagasaki, T. Nogi, H. Ohgaki, S. Suphakul, K. Torgasin, H. Yamashita, H. Zen
    Kyoto University, Kyoto, Japan
  
  Recently, thermionic cathode materials such as LaB6, Ir5Ce and dispenser cathodes have been also used as photocathode since they have low work function, reasonably high quantum efficiency, and long lifetime*,**. However, the effect of cathode temperature and laser wavelength on quantum efficiency is known only for limited conditions. Although it is expected to be able to lengthen the required wavelength of photocathode drive laser by heating cathodes, laser with photon energy under the work function has not been tested. Revealing them enables us to design the cost minimum accelerators. In this research, photoemission properties of LaB6 and CeB6 with various excitation photon energies will be investigated under various temperatures of the materials. Those materials have similar work function, but CeB6 have one order of magnitude smaller Richardson constant than LaB6***. By comparing photoemission properties of these materials, impact of Richardson constant on the photoemission properties will be investigated.
* S. Thorin et al. Proc of FEL2009, 310
** D. Satoh et al. Proc of IPAC2014, 679
*** J.M. Lafferty, J. Appl. Phys. 22, (1951), 299
 		 
slides icon Slides WEOAB03 [0.996 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAB03  
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WEPMB014 Cavity Performance of the Prototype KEK Superconducting RF Gun cavity, target, gun, SRF 2148
 
  • T. Konomi, E. Kako, E. Kako, Y. Kobayashi, Y. Kobayashi, K. Umemori, K. Umemori, S. Yamaguchi
    KEK, Ibaraki, Japan
  • R. Matsuda
    Mitsubishi Heavy Industries Ltd. (MHI), Takasago, Japan
  • T. Yanagisawa
    MHI, Hiroshima, Japan
  
  A superconducting RF (SRF) gun can generate a high current and high energy beam. It has a possibility to achieve requirement from high performance ERL and high repetition FEL. Target values of the L-band KEK SRF gun are that beam repetition is 1.3 GHz, beam current is 100 mA, beam energy is 2 MeV, emittance is 1 mm mrad or less. The number of cell is 1.5. Accelerating energy of 2 MeV corresponds to 42 MV/m of maximum surface field. The photocathode is designed to be illuminated by excitation laser from backside. The SRF gun cavity consists of the 1.5 cell accelerating cavity, cathode plug and choke filter for protecting the heating of cathode plug. To evaluate these parts individually, these parts are added step by step. High gradient test of the accelerating cell without cathode plug and choke filter was done. The surface peak electric field reached 66 MV/m, and this meet the target value 42 MV/m sufficiently. Next high gradient test will be done after adding the choke filter. The choke filter is designed to be simple to wash choke cell easier. In this conference, we will report the design, fabrication and high gradient performance of the SRF gun cavity with choke filter.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB014  
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WEPMR016 Vertical Electropolishing Studies at Cornell with KEK and Marui cavity, target, SRF, niobium 2295
 
  • F. Furuta, G.M. Ge, T. Gruber, J.J. Kaufman, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, T. Saeki
    KEK, Ibaraki, Japan
  
  Cornell's SRF group has developed Vertical Electro-Polishing (VEP) and applied on 1.3GHz Niobium SRF cavities as the primary surface treatment. High-Q and high voltage performances of VEP'ed SRF cavities had been successfully demonstrated at Cornell. In 2014, new VEP R&D collaboration has started between Cornell, KEK, and Marui Galvanizing Co. Ltd. (MGI). MGI and KEK has developed their original VEP cathode named 'i-cathode Ninja'® which has four retractable wing-shape parts per cell for single-/9-cell cavities. We will report the results of VEP process using 'i-cathode Ninja'® on single cell cavity at Cornell.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR016  
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WEPMY040 Fabrication of Two Dimensional Nano-Scale Photocathode Arrays in Transparent Conductor for High Coherence Beam Generation electron, laser, photon, simulation 2645
 
  • T. Shibuya
    TIT, Tokyo, Japan
  • N. Hayashizaki
    RLNR, Tokyo, Japan
  • M. Yoshida
    KEK, Ibaraki, Japan
  
  Electron beam quality for particle source of diffractometer is mainly characterized by transverse and longitudinal coherent length, beam current density and so on. In order to improve a transverse coherent length, it is practically essential to minimize electrons emission area size as small as possible. However, the size of photoemission area is limited by focused laser beam size on the surface of cathode, and the scale is several microns. Aim to get definite overlap between the focused laser and emitters for effective irradiation, as well as to realize generation of nano-scale size electron beam, nano-scale photocathode arrays in transparent conductor are essential. Therefore, I propose to fabricate the nano-scale emission area in replace of limiting the focused laser size on the photocathode for achieving high coherence beam. The fabrication process of this novel nano-scale emitter configuration and its fundamental properties are presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY040  
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THPMB048 Design and Optimisation of the ELENA Electron Cooler Gun and Collector electron, gun, solenoid, simulation 3354
 
  • G. Tranquille, J. Cenede
    CERN, Geneva, Switzerland
  
  Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler. The performance of the cooler is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the quality of the guiding magnetic field and the efficient recuperation of the electrons in the collector ensure that the cooler performance is optimal. We have used COMSOL Multiphysics to design and optimise the complete electron cooler with particular attention to the gun and collector. This software suite uses physics interfaces for modelling common applications and then allows the user to combine the different interfaces in one multi-physics simulation.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB048  
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THPMR052 Compact, Microtron-Based Gamma Source microtron, electron, injection, cavity 3522
 
  • R.J. Abrams, M.A.C. Cummings, R.P. Johnson, S.A. Kahn, G.M. Kazakevich
    Muons, Inc, Illinois, USA
  
  Funding: This work was supported U.S. DOE SBIR Grant DE-SC0013795.
The conceptual design of a prototype S-band pulsed, 9.5 MeV compact microtron with type-II injection is described. Estimates of parameters such as beam current and cathode lifetime, and comparisons with X-band and C-band parameters are presented. The electron beam can be extracted at various energies up to 9.5 MeV. Estimated yields of gammas produced at 6.5 MeV operation and estimated yields of gammas and neutrons produced at 9.5 MeV are presented. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR052  
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THPMW037 Pulsed Power Systems for ESS Klystrons klystron, operation, electronics, high-voltage 3634
 
  • I. Roth, M.P.J. Gaudreau, M.K. Kempkes
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
  • J. Domenge
    Sigma Phi Electronics, Wissembourg, France
  • J.L. Lancelot
    Sigmaphi, Vannes, France
  
  Diversified Technologies, Inc. (DTI) is building three long pulse solid-state klystron transmitters to meet spallation source requirements. Two of the three will be installed at CEA Saclay and the National Institute of Nuclear and Particle Physics (IN2P3) in 2015, to be used as test stands for the European Spallation Source (ESS), The third system will be installed at Oak Ridge National Laboratory (ORNL) for the Spallation Neutron Source (SNS).  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW037  
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THPMY017 A Comparison of Surface Properties of Metallic Thin Film Photocathodes electron, laser, vacuum, survey 3691
 
  • S. Mistry, M.D. Cropper
    Loughborough University, Leicestershre, United Kingdom
  • A.N. Hannah, L.B. Jones, K.J. Middleman, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  In this work physical vapour deposition magnetron sputtering has been employed to deposit metallic thin films onto Cu, Mo and Si substrates. The use of metallic thin films offers several advantages: (i) metal photocathodes present a fast response time and a relative insensitivity to the vacuum environment (ii) metallic thin films when prepared and transferred in vacuum can offer smoother and cleaner cathode surfaces. The photocathodes developed here will ultimately be used to drive NCRF guns such as that used in VELA and the proposed CLARA light source test facility. The samples grown on Si substrates were used to investigate the morphology and thickness of the film. The samples grown onto Cu and Mo substrates were analysed and tested as photocathodes in a surface characterisation chamber, where X-Ray photoelectron spectroscopy was employed to determine surface chemistry and a Kelvin probe apparatus used to determine work function. QE measurements were enabled using a 266 nm UV laser.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY017  
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THPOW003 Highlights on Metallic Photocathodes Used in SRF Gun gun, SRF, laser, emittance 3928
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate
    HZDR, Dresden, Germany
  • P.N. Lu, H. Vennekate
    TU Dresden, Dresden, Germany
  
  For the accelerator-based light sources and the electron colliders, the development of photoinjectors has become a key technology. Especially for the superconducting radio frequency cavity based injector (SRF Gun), the searching for better photocathodes is always a principal technical challenge. To use metallic photocathodes for ELBE SRF Gun is the primary choice to prevent cavity contamination. In this contribution, we will report the investigation of Magnesium (Mg) in ELBE SRF gun, including laser cleaning treatment and the measurement on quantum efficiency, Schottky effect, dark current and damage threshold.
The work is supported by the European Community under the FP7 programme (EuCARD-2 and LA3NET) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW003  
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THPOW004 Pulse Response Measurements of NEA Photocathodes at Different Laser Wavelengths laser, electron, cavity, photon 3931
 
  • M.A. Dehn, K. Aulenbacher, V. Bechthold
    IKP, Mainz, Germany
  
  For high average electron beam currents the length of the electron bunches must match the acceptance of the accelerator. At Johannes Gutenberg-University Mainz we are able to measure the longitudinal pulse response of NEA photocathodes (GaAs) under photo excitation of different wavelengths. A time resolution of < 2 ps at a beam energy of 100 keV is achieved, furthermore, a high dynamic range allows to investigate long ranging tails of the response (longitudinal halo). This serves to identify the best possible operation mode for high current photo sources.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW004  
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THPOW005 A Study of CsK2Sb Multi-alkali Photocathode by Ultraviolet Photoelectron Spectroscopy at UVSOR electron, laser, experiment, vacuum 3934
 
  • M. Urano, M. Kuriki, K. Negishi
    HU/AdSM, Higashi-Hiroshima, Japan
  • T. Konomi, Y. Seimiya, N. Yamamoto
    KEK, Ibaraki, Japan
  
  Photocathode is one of the most important components in the next-generation accelerators, especially based on linear accelerators. Photocathode performance depends not only on electronic state in its bulk material but also on the surface condition. CsK2Sb multi-alkali photocathode is a candidate for the high brightness electron source because of its high quantum efficiency by green laser and its high robustness. We have carried out an UPS (UV Photoelectron Spectroscopy) experiment at UVSOR facility, synchrotron radiation light source in Aichi Japan. We have compared the UPS spectra among several samples, each one has a different quantum efficiency, and try to find physics which decide photocathode's performance. In this case, we focused some characters correlated to the quantum efficiency. I'm going to present a result of this analysis.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW005  
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THPOW006 A Study of Operational Lifetime of CsK2Sb Photo-cathode laser, vacuum, electron, storage-ring 3938
 
  • A. Yokota, R. Kaku, M. Kuriki, K. Negishi, M. Urano
    HU/AdSM, Higashi-Hiroshima, Japan
  • Y. Seimiya
    KEK, Ibaraki, Japan
  
  A high performance electron beam generated with a laser photo-cathode is one of the most important pieces in the advanced accelerator. Because the CsK2Sb photo-cathode is robust with more than 10 % quantum efficiency (QE) by green laser (532nm), it is considered to be the best candidates of the cathode for Energy Recovery Lin-ac (ERL) and Free Electron Laser (FEL) requiring a high brightness beam. We developed a system to evaporate the cathode as a thin film in vacuum to study the cathode performance. The cathode operational lifetime regarding not only on time, but also extracted charge density was studied. We found the lifetime is long enough for practical use in an accelerator.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW006  
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THPOW010 Study on Characteristics of Asymmetric Centre Iris of Photocathode Microwave Electron Gun gun, electron, emittance, electromagnetic-fields 3951
 
  • Zh. X. Tang, X.M. Yang, W.Q. Zhang
    DICP, Dalian, People's Republic of China
  • Y.J. Pei
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The characteristics of asymmetric iris between first cell and second cell of 1.6 cell photocathode gun are studied. For π-mode, the RF radial field of two sides of the iris is non anti-symmetric. Thus, the RF transverse force at the iris is not negligible. In this paper, we present the status of the optimization simulations, using the SUPERFISH and PARMELA particle-in-cell code. Numerical results of beam dynamics show that it can improve the emittance at the exit of the gun.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW010  
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THPOW011 The Measurement System of the Electron Gun with Double-anode Structure gun, electron, vacuum, high-voltage 3954
 
  • F.L. Shang, J. Li, L. Shang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: National Natural Science Foundation of China(11175181); National Natural Science Foundation of China(10875116)
The double-anode structure with an intermediate electrode has been proposed to overcome the strong space-charge force on the cathode and improve the transverse focusing, which make the goal of high perveance and high compression ratio achieved. This gun plays a key role as the external injecting electron source of the independently-tunable-cells (ITC) RF gun. In order to understand the quality of the beam, a measurement system has been designed. The papers present the measurement system and the result of the test. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW011  
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THPOW015 Study of the Performance of Cs2Te Cathodes in the PHIN RF Photoinjector using Long Pulse Trains vacuum, operation, laser, electron 3960
 
  • C. Heßler, E. Chevallay, S. Döbert, V. Fedosseev, F. Friebel, I. Martini, M. Martyanov, H. Neupert, V. Nistor, M. Taborelli
    CERN, Geneva, Switzerland
  
  The drive beam of CLIC requires unusually high peak and average currents which is challenging for the electron source. As an alternative to the thermionic electron gun foreseen in the baseline design, a photoinjector option is under study at CERN using the PHIN photoinjector, which was designed for a bunch charge of 2.3 nC and 1200 ns train length. During operation with nominal train length in 2014, a large pressure increase in the vacuum system, attributed to a heating of the Faraday cup, caused a degradation of the photocathode. To overcome this problem a vacuum window has been installed to separate the Faraday cup from the rest of the vacuum system. In addition the train length has been further increased to 1600 ns to advance the beam parameters towards CLIC requirements. In this paper recent improved photocathode lifetime measurements carried out under these new conditions will be presented and compared with earlier measurements. Furthermore, the utilized Cs2Te cathode has been analyzed with X-ray Photoelectron Spectroscopy (XPS) before and after its usage in PHIN to get a better understanding of photocathode surface deterioration effects, which will also be discussed.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW015  
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THPOW016 Transverse Energy Spread Measurements from GaAs Photocathodes at Variable Wavelengths electron, detector, laser, photon 3964
 
  • T.C.Q. Noakes, R. Beech, L.B. Jones, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • H.E. Scheibler, A.S. Terekhov
    ISP, Novosibirsk, Russia
  
  The transverse energy spread spectrometer (TESS) is an instrument specially developed at Daresbury Laboratory to measure the intrinsic transverse and longitudinal energy distributions from photocathode materials. Early work on the instrument has focussed on its use for the characterisation of GaAs photocathodes such as those commonly used in DC photoinjectors. More recently work has been conducted to extend the range of materials which can be evaluated using this apparatus, in particular by incorporating a monochromated white light source. New results are presented using the white light source to measure the energy spread of a GaAs photocathode across a range of different wavelengths to evaluate how this changes with excess energy.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW016  
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THPOW017 VELA Photoinjector Cavity RF Investigations cavity, simulation, operation, electron 3968
 
  • L.S. Cowie, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.A. Mitchell
    Lancaster University, Lancaster, United Kingdom
  • M.D. Roper
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  
  One of two ALPHA-X photocathode gun cavities, designed and fabricated at the Laboratoire de l'Accélérateur Linéaire, has been in operation on the VELA electron accelerator at Daresbury Laboratory since first beam in April 2013. In this time the maximum beam momentum recorded is 5.06 MeV/c. An investigation of the cavity has been performed with the aim of reconciling the expected momentum of over 6 MeV/c with the measured momentum. RF and beam simulation results are presented along with low power RF measurements of the cavity. One source of momentum loss, the flatness of the cathode face, is identified and rectified.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW017  
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THPOW019 Beam Characterisation and Machine Developments at VELA experiment, gun, electron, space-charge 3975
 
  • D. Angal-Kalinin, A.D. Brynes, F. Jackson, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.L. Militsyn, B.D. Muratori, T.C.Q. Noakes, M.D. Roper, Y.M. Saveliev, D.J. Scott, R.J. Smith, E.W. Snedden, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S.D. Barrett, C.P. Topping, A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
  • C.S. Edmonds, F. Jackson, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.D. Muratori, Y.M. Saveliev, D.J. Scott, C.P. Topping, P.H. Williams, A. Wolski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  An overview is presented of developments on VELA (Versatile Electron Linear Accelerator), an RF photo-injector with two user stations at Daresbury Laboratory. Numerous commissioning, machine development, beam characterisation and user experiments have been completed in the past year. A new beamline and a dedicated multiuser station have been commissioned and the first experiments performed. A number of measures have been taken to improve the stability of machine by mitigating a phase drift, laser beam transport drift and a coherent ~1 Hz beam oscillation. The 6D phase space of the electron beam has been characterised through quad scans, transverse tomography and with a transverse deflecting cavity.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW019  
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THPOW020 S-Band Photoinjector Investigations by Multiobjective Genetic Optimizer emittance, laser, brightness, gun 3979
 
  • H.J. Qian, D. Filippetto, F. Sannibale
    LBNL, Berkeley, California, USA
  
  Photoinjectors has witnessed great progress in the past few decades, with low duty cycle high gradient guns, such as normal conducting S/L band gun, pushing the peak beam brightness frontier, and CW guns, such as DC gun, SRF gun and VHF gun, pushing the average beam brightness frontier. Due to different degrees of complexity, pulsed high gradient photoinjectors are usually optimized by manual scans, while CW photoinjectors are optimized by multi-objective genetic optimizers. In this paper, a multi-objective genetic optimizer is used to revisit S-band photoinjector beam brightness optimizations, showing a trade-off between peak current and transverse emittance, with the optimized injector layout depending on bunch charge and peak current. For 200 pC case, the final beam core brightness at injector exit is close to cathode maximum brightness in the 'cigar beam' regime. Assuming a thermal emittance of 0.5 μm/mm and a beam charge of 200 pC, about 90 nm slice emittance at 20 A peak current is achieved.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW020  
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THPOW023 Intrinsic Emittance Reduction in Transmission Mode Photocathodes electron, emittance, scattering, laser 3987
 
  • H. Lee, I.V. Bazarov, L. Cultrera
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  High quantum efficiency (QE) and low emittance electron beams provided by multi-alkali photocathodes make them of great interest for next generation high brightness photoinjectors. Spicer's three-step model well describe the photoemission process, however, some photocathode characteristics such as their thickness have not been completely exploited to further improve the brightness of the generated electron beam. In this work, we report on the emittance and QE of a multi-alkali photocathode grown onto glass substrate operated in transmission and reflection modes at different photon energies. We observed a 20% reduction on the intrinsic emittance from the reflection to the transmission mode operation. This observation can be explained by inelastic electron-phonon scattering events experienced by electrons during their transit towards the cathode surface. This scattering will expect the further emittance reduction than the no scattering at the cryo-temperatures.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW023  
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THPOW025 Photocathode Growth and Characterization Advances at Cornell University electron, photon, emittance, gun 3990
 
  • L. Cultrera, A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, H. Lee, R.A. Lipton, T.P. Moore
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Alkali-antimonides based photocathodes have demonstrated outstanding performance in high brightness electron beam production suitable for a wide range of applications such as FELs, ERLs and UED and for use in photomultiplier devices with picosecond resolution aimed at photon counting application in medicine and High Energy Physics. The photocathode laboratory at Cornell University is dedicated to studying the growth procedures and characterizing the properties in a wide range of photocathodes materials. Different experimental arrangements and alkali metal sources have been successfully explored to date to synthesize photosensitive materials. Recent work on commissioning a new growth chamber equipped with effusion cells loaded with pure metal allowing uniform deposition over large area substrates resulted on successful growth of photocathodes with extended sensitivity in the IR part of the spectrum and high efficiency alkali antimonides containing Rb metal. This and other advances aimed at demonstrating superior photocathodes will be presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW025  
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FRXBB01 Achieved Performance of an All X-band Photo-injector gun, laser, electron, emittance 4253
 
  • C. Limborg, C. Adolphsen, M.P. Dunning, R.K. Jobe, H. Li, D.J. McCormick, T.O. Raubenheimer, T. Vecchione, A.R. Vrielink, F.Y. Wang, S.P. Weathersby
    SLAC, Menlo Park, California, USA
  
  Funding: Work funded by DOE/SU Contract DE-AC02-76-SF00515
Building more compact accelerators to deliver high brightness electron beams for the generation of high flux, highly coherent radiation is a priority for the photon science community. A relatively straightforward reduction in footprint can be achieved by using high-gradient X-Band (11.4 GHz) RF technology. This talk presents the all X-band photo-injector facility at SLAC, covering the benefits of using this technology and highlighting the performance achieved. 		 
slides icon Slides FRXBB01 [40.418 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-FRXBB01  
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