Microwave switching in evacuated waveguides by metal vapor arcs

Plasma from a triggered electrical discharge between copper electrodes in a vacuum was rapidly expanded into an X-band microwave waveguide. Propagation was interrupted to >40-dB attenuation within 0.5 µs, and the interruption typically lasted from 1-100 µs, depending upon the pulsed arc current and switch geometry. Recovery to normal propagation occurred in less than 1 µs. Most of the microwave energy was reflected from the arc plasma, which might allow its use as a duplexer.