Nanosecond rf-Power Switch for Gyrotron-Driven Millimeter-Wave Accelerators

Abstract

Terahertz accelerators can achieve potential gradients beyond 200 MV/m. Gyrotrons are the only power sources capable of producing megawatt-level, microsecond-long pulses in this frequency range, yet nanosecond-long pulses are required for breakdown-free operation. The authors explore the possibility of using a single GaAs wafer to enable production of the required pulse widths, with rise and fall times that closely track the illuminating laser's pulse length. They demonstrate and quantify the reflective properties and laser-induced photoconductive effect of GaAs in the millimeter-wave regime, for use in a laser-operated shutter.