|MOD03||Alkali Cathode Testing for LCLS-II at APEX||280|
Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
Electron sources of high brightness and high bunch charge (~300 pC) with MHz repetition rate are one of the key technologies for next generation X-FEL facilities such as the LCLS-II at SLAC and the Euro XFEL at DESY. The Advanced Photoinjector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is developing such an electron source based on high quantum efficiency (QE) alkali photocathodes and the VHF-Gun, a new scheme normal conducting RF gun developed at LBNL. The VHF-Gun already demonstrated stable CW operation with high gradient (~ 20 MV/m), high gun voltage (~ 750 kV) and low vacuum pressure (~ 3 E-10 torr) laying the foundation for the generation of high brightness electron beams. In this paper, we report the test and characterization of several different alkali cathodes in high average current (several hundreds of pC/bunch with MHz repetition rate) operation at APEX. Measurements include cathode life time, QE map evolution and thermal emittance characterization, to investigate the compatibility of such cathodes with the challenging requirements of LCLS-II.
|Slides MOD03 [6.030 MB]|
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