Design of a W-band second harmonic gyrotron based on a continuous operation solenoid

The design of a W-band second harmonic gyrotron based on a 1.8 T continuous operation solenoid is presented. A compact triode MIG is designed to generate gyrating electron beam. The gyrotron operates at the TE 0,2 mode with a conventional cylindrical cavity. And we designed a high efficiency quasi-optical mode converter with a dimpled wall laucher, the mode conversion efficiency is 97% and the Gaussian content of the output beam is 98%. When driven by a 40 kV, 1.5 A electron beam, 12.8 kW output power can be obtained, corresponding to an efficiency of 21.3%.