Investigation of a lower prepulse water dielectric self-break switch

A lower prepulse high power density water dielectric self-break switch has been investigated recently. The switch contains two or four gaps, a prepulse shield and supporting hardware. The configuration and equivalent circuit model of it are introduced while part parameter calculations are provided in this paper. All gaps of the switch are charged approximately linearly from 0 to 1 MV in 80 ns. The discharge current and the input or output voltages of each gap are measured by a Rogowski coil and CuSO₄ resistance dividers respectively. The switches with two gaps and four gaps are experimented respectively. The water switch discharges with a discharge current about 250 to 600 kA after the gaps are charged and has mean field of 600 to 900 kV/cm. The jitter of the same gap is smaller than 4 ns. All two gaps are broke down in 3 ns while all four gaps discharged in 5 ns after the gaps are charged to breakdown voltage. The prepulse is suppressed by the use of a prepulse shield in the switch geometry that prepulse of output is smaller than 50 % that of input.