Simulation of a 0.33-THz Second Harmonic Gyrotron Based on Double Confocal Cavity

Confocal cylindrical waveguide performs many good characters, such as big power capacity and low mode density, which are good for designing high harmonic terahertz gyrotron. Motivated by improving beam-wave interaction efficiency of quasi-optical gyrotron, a novel gyrotron beam-wave interaction structure based on double confocal waveguide has been proposed and theoretically analyzed in this paper. A 0.33 THz second harmonic gyrotron oscillator based on double confocal cavity has been designed and simulated by PIC code. It is indicated that double confocal cavity is able to enhance the output power and the interaction efficiency of quasi-optical gyrotron. Besides, the mode characteristic of double confocal waveguide is investigated with the simulation results.