Solid state switches for electric gun applications

The Army Research Laboratory has conducted experimental evaluations on commercially available solid state switches for application to electric gun systems. These switches were developed largely for the electric power industry and were designed for high average current, long term operation. Operating these devices at the short pulse lengths required by electric guns enables the peak currents to exceed the nominal ratings by more than an order of magnitude. These devices are all thyristor types chosen for high surge current capability and low forward drop losses. The investigation includes thyristors of domestic and foreign manufacture and also novel control structures and packaging. The silicon wafers vary in diameter from 50 mm to 100 mm and have a minimum off-state blocking voltage rating of 2 kV. The evaluations were performed using pulsers with low impedances (10 to 250 milliohms), with pulse widths varying from 0.5 ms (FWHM) to 2.0 ms (FWHM). The inverse capabilities of symmetric devices under short circuit conditions were studied and the ability to withstand full voltage reversals after high forward surge currents was demonstrated. Series, parallel and phased operation of multiple switches was also demonstrated.