Overmoded high power millimeter generator with resonant cavity reflector under high order mode

An overmoded high power millimeter generator with resonant cavity reflector which works under TM035 mode is designed. The reflection coefficient of the resonant cavity reflector to TM01 mode is larger than 0.9 from 58 GHz to 62 GHz. The process of interaction between beam and microwave is analyzed based on particle in cell simulations. By optimizing the length between the resonant cavity reflector and the slow-wave structure for this device, the simulated output power is 1.06 GW at 60.2 GHz frequency with a 570 kV, 6.0 kA electron beam guided by an external magnetic field of 4 T. The corresponding beam-wave conversion efficiency is about 31%, and the starting time is about 3.3 ns.