A SELF-CROWBAR SWITCH FOR A GAS-PUFF Z-PINCH DRIVEN BY A PULSED POWER GENERATOR

A self-crowbar switch for a gas-puff z-pinch, driven by a pulsed power generator with output voltage 600 kV, pulse width 70 ns, and characteristic impedance of 3 Ω, has been built and tested successfully. Discharges with pulsed gas injection are placed into four groups dependent on the delay between the pulsed power generator trigger time and the gas-puff trigger time. For short delay times (<2.8 ms), vacuum discharge occurs. For moderate delay times (2.8-3.8 ms), a z-pinch plasma is produced without using the self-crowbar switch, and the plasma exists for a much longer time than the voltage pulse, that is, 700 ns compared to 70 ns. For relatively longer delay times (3.8-6 ms), the self-crowbar switch operates, and the decay time of the current becomes approximately 2.5 μs. Moreover, a z-pinch occurs after self-crowbarring. For long delay times (>6 ms), a z-pinch does not occur. The self-crowbar switch is believed to operate by photoionization of puffed gas which has reached the switch region.