Study of a 40 kV multistage spark gap operated in air at atmospheric pressure

The electrical properties of a multistage spark gap have been studied and a compact 40 kV four-stage switch is described. The switch can be operated in atmospheric air with a 50 ns delay time and a +or-5 ns jitter, when triggered at breakdown voltage. Both these values are shorter, by a factor of 3, than those of similar two-electrode spark gap. The discharge gaps, besides the electrical connection, have been coupled to each other, optically, by means of an axial hole through the switch. This coupling, which gives rise to a simultaneous ignition in the gaps, is mainly responsible for reduction of the jitter and the delay time. The simultaneity of the gap ignitions has been shown by investigating the short light pulses (about 2 ns halfwidth) emitted from the spark of each gap. The switch is also capable to work with high repetition rate. More than 1200 Hz with a 4 kA peak current has been obtained, when operating the switch in air at atmospheric pressure.