Design and low-power RF test of a C-band cryogenic RF gun

Next-generation photoinjectors with high brightness are under development for advanced accelerator facilities, such as Free-Electron Laser, Ultrafast Electron Diffraction, and Ultrafast Electron Microscopy. A feasible and prospective method to produce electron beams with higher quality is based on high gradient acceleration technology. The gradient could be as high as 200 MV/m at the photocathode in a C-band RF gun in a 20 K cryostat. In this paper, a new cryogenic C-band photocathode electron gun is systematically designed and optimized in both beam dynamics and RF design. Moreover, a test platform has been set up for some preliminary experiments with a 3-cell prototype. The results on the RF characteristics at cryogenic temperatures are in good agreement with the design and simulation, and will pave the way for the practical operation of the cryogenic electron gun and the design of other cryogenic structures.