Design Study of X-band High Efficiency Klystrons for CLIC

The design of two X-band high efficiency (HE) Klystrons are presented in this paper. Based on Core Oscillation Method (COM) and coupled-cell output structure topology, 8MW Klystron for Xbox test stand can yield 58% output efficiency with beam perveance of 1.6uP. Scaling and post-optimization method is used for 50MW Klystron for CLIC accelerating structures design, which can provide 65% output efficiency with beam perveance of 0.75 uP. The peak electric field is lower than 100kV/mm for both cases, which is purposely optimized to avoid RF breakdown. The parameter optimization is done with KlyC1.5D simulation and results are verified by CST PIC simulations.