High-current 60 kV multiple-arc spark-gap switch of 1.7 nH inductance

The necessary conditions for obtaining consistent multiple-arc breakdowns in a 60 kV pressurised-air spark gap of 1.7 nH effective inductance have been investigated. Theoretical conclusions, which are confirmed by the experimental results, show that the important factors influencing multiple-arc breakdown are the gap-voltage decay time and the ratio of initial arc-channel impedance to that of the complete gap. The spark gap has also been used with a single 15 kJ capacitor at peak currents of 1.0 MA, the combined inductance of the unit being 14 nH.