A WIDE-BAND PICK-UP FOR MEASURING BEAM SPECTRUM IN KEKB

A wide-band pick-up, which is mounted on the wall of waveguide between the klystron and the rf cavity, has been developed for measuring beam spectrum in KEKB storage-ring. The MAFIA simulation code and Network-Analyzer test-bench have been applied to design the pick-up structure. After investigation of various kinds of structures, a strip-line type pick-up, which has a bandwidth of 5~30GHz, is chosen. Some important considerations are also included, such as to avoid the couple of large fundamental forward power for safety. Measurement results of beam spectrum and synchrotron oscillation are presented in this paper.