Submillimeter-wave harmonic gyrotron experiment

A theoretical and experimental investigation of the operation at submillimeter wavelengths of a harmonic gyrotron is reported. Using a waveguide cavity with an iris at the output end of the straight section, 14 different second-harmonic modes were observed with frequencies of 301--503 GHz, output powers of 1-22 kW, and a 12-MHz emission frequency bandwidth. The highest output power was 22 kW, with a total efficiency of 3.5% at 467 GHz, and an output power of 15 kW with a 6% efficiency was obtained at 417 GHz. Research was conducted using a 65--75 kV up to 10-A electron gun with 1--1.5 μs pulse-length and a 4-Hz repetition rate, which produced a helical electron beam in magnetic fields of up to 14 T. These results represent the first operation of a high-power harmonic gyrotron in the submillimeter region