Simulation of High-Efficiency Klystrons with the COM and CSM bunching

The two types of high effective bunching in powerful klystrons are discussed. The first bunching type, named COM, is intended for standard klystron structure with first harmonic cavities only. The second bunching type, named CSM, is realized in klystron structures which includes cavities of second and third harmonics. Both bunching types allow to reach the klystron efficiency up to 90%.