A 120–240 GHz step tunable megawatt gyrotron

Abstract

A pulsed (3μsec) gyrotron oscillator which can be scaled to cw operation has generated high output powers at frequencies between 126 and 243 GHz. Peak powers of 645 kW and total efficiencies of 28% were measured. By varying the cavity magnetic field, step tuning through a sequence of TEm,p,1 modes with p = 2,3 and 4 was observed. The highest order mode observed was the TE22,4,1 at 243 GHz, which corresponds to a cavity diameter of 12 free space wavelengths. An output power of 470 kW was measured in this mode at 80 kV and 35 A.