Design, fabrication, and cold-test results of C-band spherical RF pulse compressor prototype

Abstract

Pulse compressor is a useful and common RF structure for Free Electron Laser and Linear Collider Facilities, which can improve the input power of accelerating structures significantly. In this study, we designed, fabricated and tested a prototype of a compact C-band spherical pulse compressor. This pulse compressor utilizes one high Q0 spherical RF resonant cavity that works with two degenerated TE1,1,3 modes and a dual-mode polarized coupler. The cavity and coupler were designed and machined separately and then brazed together. The prototype was tested carefully using vector network analyzer, and a cold-test system was set up to check the working conditions of the spherical pulse compressor with inversed input power Associated with the C-band high-gradient accelerating structures, the peak power gain and energy multiply factor can be as high as 6.1 and 1.85, respectively, in theory. The average power gain is 3.8 in the first 0.372 μs after the phase reverse, which is the accelerator filling time. During the cold test, a peak power multiply factor of 6.04 and an energy multiply factor of 1.83 were achieved. The test results agreed with the design well. The prototype was successfully made as a pre-research for the future energy multiplying scheme of SXFEL.