PHOTOCONDUCTIVE SEMICONDUCTOR SWITCHES

Optically activated GaAs switches operated in their high-gain mode are being used or tested for pulsed power applications as diverse as low- impedance, high-current firing sets in munitions; high-impedance, low- current Pockels cell or Q-switch drivers for lasers; high-voltage driv ers for laser diode arrays; high-voltage, high-current, compact accele rators; and pulsers for ground penetrating radar. This paper will desc ribe the properties of high-gain photoconductive semiconductor switche s (PCSS), and how they are used in a variety of pulsed power applicati ons. For firing sets, we have switched up to 7 kA in a very compact pa ckage. For driving Q switches, the load is the small (30 pF) capacitan ce of the P switch which is charged to 6 kV. We have demonstrated that we can modulate a laser beam with a subnanosecond rise time. Using PC SS, we have demonstrated gain switching a series-connected laser diode array, obtaining an optical output,vith a peak power of 50 kW and a p ulse duration of 100 ps. For accelerators, we are using PCSS to switch a 260 kV, 60 kA Blumlein. A pulser suitable for use in ground-penetra ting radar has been demonstrated at 100 kV, 1.3 kA. This paper will de scribe the specific project requirements and switch parameters in all of these applications, and emphasize the switch research and developme nt that is being pursued to address the important issues.