A study of the high current back lighted thyratron and pseudospark switch

High-current operation of the back-lighted thyratron (BLT) switch is reported. The cathode emission mechanism and discharge formation characteristics common to BLT and pseudospark switches are described. The BLT switch is an optically triggered low-pressure diffuse discharge closing switch that operates at high currents with a self-heated cathode. Operation for square 150 ns pulses of 1-10.5 kA, 2.5-20 kV, <25 Hz, 45 ns risetime and a 500 ns capacitor discharge up to 82 kA at 25 kV including operation at 5 Hz, 17.5 kV, 60 kA is reported. The switch exhibits a risetime and peak current limit at low currents but no high current limit (up to 82 kA). The low current limit is explained as being due to an insufficient heating of the self-heated cathode.<<ETX>>