Breakdown Time of a Triggered Vacuum and Low-Pressure Switch

Characterization of a triggered vacuum and low-pressure switch has been performed with breakdown performance data obtained for different trigger locations and current levels, gas pressures, and main gap voltages and currents. Results presented reveal a dependence of breakdown, or switch closure time, on the switched current level, rather than main gap voltage, for gap spacings from 1.5 to 10 mm. Breakdown time has been found to increase sharply with increases in switched current levels up to 0.8 kA, then remains constant or changes slightly for current level increases up to 6 kA. In other tests, increasing the trigger current from 0.23 to 0.7 kA has been found to halve the breakdown time of the switch over a wide operating range. The introduction of H2, N2, or A at pressures >1 Pa, resulted in shorter total breakdown times.