Stress Test of Nanosecond Semiconductor Cavity Switches With Subterahertz Gyrotrons

Nanosecond semiconductor switches based on resonant cavity with reversibly variable Q-factor are the most prospective devices for generating unlimited series of coherent pulses in subterahertz frequency bands. The pulse duration stretches from nanoseconds to tens of seconds for the same device. Although the subterahertz switches have already been tested with various continuous-wave generators, e.g., semiconductor transistors and backward wave oscillators, they are intended to be used with gyrotrons, the most powerful generators of coherent microwave radiation for subterahertz bands. Here, we present results of several experiments with continuous wave and pulsed gyrotrons with frequencies around 300 GHz, pulse durations up to 10 s, and stressful microwave power up to 180 kW. A simple generalized theoretical estimation for the microwave power limit of the switches is provided and found to be in a good agreement with the performed experiments, avoiding blind zones in subterahertz measurements.