Keyword: cathode
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MOIACC002 Development of SRF Gun Applying New Cathode Idea Using a Transparent Superconducting Layer ion, gun, SRF, emittance 1
 
  • T. Konomi, Y. Honda, E. Kako, Y. Kobayashi, S. Michizono, T. Miyajima, K. Umemori, S. Yamaguchi, M. Yamamoto
    KEK, Ibaraki, Japan
  • R. Matsuda
    Mitsubishi Heavy Industries Ltd. (MHI), Takasago, Japan
  • T. Yanagisawa
    MHI-MS, Kobe, Japan
 
  KEK has been developing a superconducting RF gun for CW ERL since 2013. The SRF gun is a combination of a 1.3 GHz, 1.5-cell superconducting RF cavity and a backside excitation type photocathode. The photocathode consists of transparent substrate MgAl2O4, transparent superconductor LiTi2O4 and bi-alkali photocathode K2CsSb. The reason for using transparent superconductor is to reflect RF by using the feature of penetration depth of superconductor, which is defined from London equation. It protects optical components from RF damage. The critical DC magnetic field of the cathode, quantum efficiency and initial emittance were measured. These show the cathode can be used for the SRF gun. The gun cavity was designed to satisfy the photocathode operation. Eight vertical tests of the gun cavity have been performed. The surface peak electric field reaches to 75 MV/m with the dummy cathode rod which was made of bulk niobium.  
slides icon Slides MOIACC002 [2.185 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-MOIACC002  
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MOPSPP004 Investigation of K2CsSb Photocathodes ion, laser, electron, vacuum 4
 
  • V. Bechthold, K. Aulenbacher, M.A. Dehn, S. Friederich
    IKP, Mainz, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
 
  Funding: BMBF-HOPE II
The interest in multi alkali antimonide photocathodes, e.g. K2CsSb, for future ERL projects like BERLinPro (Berlin Energy Recovery Linac Prototype) and MESA (Mainz Energy-Recovering Superconducting Accelerator) has grown in recent years. In particular for the case of RF-sources the investigation of the time response is of great importance. In Mainz we are able to synthesize these kinds of photocathodes and investigate their pulse response at 1 picosecond level using a radio frequency streak method. We present on the one hand the cathode plant which is used for synthesizing the multi alkali antimonide photocathodes and on the other hand first measurements showing pulse responses of K2CsSb at 400 nm laser wavelength. Furthermore, an analyzing chamber has been installed, which allows investigation of lifetime under laser heating and in-situ measurements of the work function using a UHV Kelvin Probe.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-MOPSPP004  
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MOPSPP005 The Small Thermalized Electron Source at Mainz (STEAM) ion, emittance, electron, simulation 9
 
  • S. Friederich, K. Aulenbacher
    IKP, Mainz, Germany
 
  Funding: Work supported by BMBF-HOPE II and DFG through RTG 2128.
The Small Thermalized Electron Source at Mainz (STEAM) is a photoelectron source which will be operated using NEA GaAs excited near its band gap with an infrared laser wavelength to reach smallest emittances. CST simulations indicate that emittance growth due to vacuum space charge effects can be controlled up to bunch charges of several tens of pC. The goal of the project is to demonstrate that the intrinsical high brightness can still be achieved at such charges. The current status will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-MOPSPP005  
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MOPSPP006 SPOCK - a Triode DC Electron Gun With Variable Extraction Gradient ion, controls, emittance, electron 13
 
  • L.M. Hein, K. Aulenbacher, V. Bechthold, M.A. Dehn, S. Friederich, C. Matejcek
    IKP, Mainz, Germany
 
  Funding: German Federal Ministry of Education and Research (BMBF project HOPE-II FKZ 05K16UMA) and the Cluster of Excellence "PRISMA
The electron source concept SPOCK (Short Pulse Source at KPH) is a 100kV DC source design with variable extraction gradient. Due to its triode inspired design the extraction gradient can be reduced for e.g. investigations of cathode physics, but also enhanced to mitigate space charge effects. In the framework of the MESA-Project (Mainz Energy-Recovering Superconducting Accelerator) its design has been further optimized to cope with space charge dominated electron beams. Although it injects its electron beams directly into the LEBT matching section, which excludes any adjustments of the electron spin, the source SPOCK will allow higher bunch charges than the MESA standard source.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-MOPSPP006  
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MOPSPP015 Development of a Multialkali Photocathode DC Gun for High Current Operation ion, gun, laser, vacuum 29
 
  • N. Nishimori
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • R. Hajima, R. Nagai, M. Sawamura
    QST, Tokai, Japan
 
  Funding: This work is partially supported by a JSPS Grant-in-Aid for Scientific Research in Japan (15K13412).
We have developed a DC gun test stand at National Institutes for Quantum Radiological Science and Technology (QST) for high current electron beam generation. The gun test stand consists of an alkali antimonide photocathode preparation chamber, a DC gun with a 250kV-50mA Cockcroft Walton high voltage power supply, and beam line with a water cooled beam dump to accommodate 1.5 kW beam power. We successfully fabricated a Cs3Sb photocathode with quantum efficiency of 5.8 % at 532 nm wavelength and generated 150 keV beam with current up to 4.3 mA with 500 mW laser at 532 nm wavelength. Unfortunately, we encountered a vacuum incident during beam transport of high current beam and the development has been halted. We will fix the vacuum problem and restart the gun development as soon as possible.
 
slides icon Slides MOPSPP015 [22.134 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-MOPSPP015  
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WEICCC004 First Results of Commissioning DC Photo-Gun for RHIC Low Energy Electron Cooler (LEReC) ion, gun, electron, operation 65
 
  • D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, X. Gu, L.R. Hammons, P. Inacker, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, C. Liu, K. Mernick, T.A. Miller, M.G. Minty, V. Ptitsyn, T. Rao, J. Sandberg, S. Seletskiy, P. Thieberger, J.E. Tuozzolo, E. Wang, Z. Zhao
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
Non-magnetized bunched electron cooling of ion beams during low energy RHIC operation requires electron beam energy in the range of 1.6-2.6 MeV, with an average current up to 45 mA, very small energy spread, and low emittance. A 400 kV DC gun equipped with a photocathode and laser system will provide a source of high-quality electron beams. During DC gun test critical elements of LEReC such as laser beam system, cathode exchange system, cathode QE lifetime, DC gun stability, beam instrumentation, the high-power beam dump system, machine protection system and controls has been tested under near- operational conditions [1]. We present the status, experimental results and experience learned during the LEReC DC gun beam testing.
[1] D. Kayran et al., DC Photogun Gun Test for RHIC Low Energy Electron Cooler (LEReC), NAPAC2016 proceedings, WEPOB54.
 
slides icon Slides WEICCC004 [20.769 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-WEICCC004  
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FRIBCC001 ERL17 Workshop, WG1 Summary: Injectors ion, gun, SRF, electron 77
 
  • E. Wang
    BNL, Upton, Long Island, New York, USA
  • K. Aulenbacher
    HIM, Mainz, Germany
 
  The 59th ICFA Advance Beam Dynamics Workshop on Energy Recovery Linacs, hosted by the CERN was held on CERN campus. The working group (WG) 1 ERL injectors focused on high-brightness, high-power CW electron gun and high QE long lifetime semiconductor photocathode. The working group 1 was separated into two sessions: One is electron gun session, which has eight invited talks; another is photocathode session, which has six invited talks and one contributed talk. This report summarizes the state of the art of electron guns and photocathodes discussed in the ERL workshop WG1.  
slides icon Slides FRIBCC001 [3.229 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-FRIBCC001  
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