Fast-pulse breakdown of nonuniform-field pressurised-air spark gaps

Pulse-breakdown data in the nanosecond range are given for 3¿5 mm nonuniform-field air spark gaps at a pressure of 1¿6atm. The 3-electrode gap has a central disc trigger electrode having an edge radius of 0.5 mm. A negative voltage pulse, whose rate of rise increases linearly from 10 to 100kV/ns, is applied to the trigger electrode with various voltages previously applied to the outer main electrodes. Breakdown is initiated with a very low jitter by field emission from the trigger electrode. Comparison with similar data for pressurised uniform-field gaps is made.