Design and testing of high power, repetitively pulsed, solid-state closing switches

Pulsed power physics experiments often require high-power, repetitively pulsed closing switches. Traditionally, ignitrons have been used in these applications when medium high voltage, high current switches are required. The availability of high power thyristors now provides the designer with the tool to install a switch based on solid-state technology. The solid-state switches show promise for low frequency, repetitively pulsed closing switches in medium voltage systems to a voltage rating of a few tens of kV and for currents to a few hundred kA. This paper presents a procedure for designing repetitively pulsed closing switches. Starting with the expected lifetime of the switch and taking the cyclic stress loading into account, all other critical design parameters are evaluated when designing a solid-state device to its full capability without overstressing the device. Based on the procedure, the preliminary design of a 12.5 kV, 80 kA, 3 ms, 2 Hz switch is presented. Experimental results for a 73 kA, 7 ms, 11 kV, air-cooled switch are given. The paper concludes with comments about the pulsed power capability of 125 mm thyristors. Test results of a 180 kA/800 μs current pulse with a di/dt value of 1200 A/μs are included