Keyword: emittance
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MOIACC002 Development of SRF Gun Applying New Cathode Idea Using a Transparent Superconducting Layer cathode, ion, gun, SRF 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.  
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MOPSPP005 The Small Thermalized Electron Source at Mainz (STEAM) ion, cathode, 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.
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MOPSPP006 SPOCK - a Triode DC Electron Gun With Variable Extraction Gradient ion, cathode, controls, 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.
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WEIBCC004 Studies of CSR and Microbunching at the Jefferson Laboratory ERLs ion, bunching, linac, electron 59
  • C. Tennant, S.V. Benson, D. Douglas, R. Li
    JLab, Newport News, Virginia, USA
  • C.-Y. Tsai
    SLAC, Menlo Park, California, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One attractive feature of energy recovery linacs (ERLs) is they are source limited. However as beam brightness increases so too do the effects of coherent synchrotron radiation (CSR) and the microbunching instability. The Low Energy Recirculator Facility at Jefferson Laboratory provides a test bed to characterize aspects of CSR's effect on the beam by measuring the energy extraction via CSR as a function of bunch compression. Data was recorded with acceleration occuring on the rising part of the RF waveform while the full compression point was moved along the backleg of the machine and the response of the beam measured. Acceleration was moved to the falling part of the RF waveform and the experiment repeated. Initial start-to-end simulations using a 1D CSR model show good agreement with measurements. The experiment motivated the design of a modified Continuous Electron Beam Accelerator Facility style arc with control of CSR and the microbunching gain. Insights gained from that study informed designs for recirculation arcs in an ERL-driven electron cooler for Jefferson Laboratory's Electron Ion Collider. Progress on the design and outstanding challenges of the cooler are discussed.
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