Parallel klystron operation at the Advanced Photon Source storage ring

A parallel-klystron topology has been designed and tested at the Advanced Photon Source to supply rf power to the 7-GeV storage ring rf cavities. The rf power output of two 1.1-MW, 352-MHz rf stations is combined utilizing a 3-dB/90-degree hybrid. The two outputs of the hybrid then supply rf power to two sectors of storage-ring cavities. Feedback control loops maintain the proper output phase and amplitude from each rf station at the combining hybrid input ports so that the correct power balance and phase relationship is maintained between the two sectors of storage ring cavities. Downstream mechanical phase shifters correct for phase changes when only one of the two rf stations is used in single-ended mode. EPICS is utilized to monitor and control the parallel-klystron system.