Development of Nanosecond Discharge in an Inhomogeneous Electric Field in Water Medium

The results of a study of the development of a nanosecond discharge in a point-to-point gap 2 mm long, filled with distilled water, are presented. Positive voltage pulses with a duration of 13 ns and an amplitude of a matched load of 25 kV (50 kV in the gap) were applied across the gap. Using a four-channel ICCD camera, the dynamics of streamer development was studied while simultaneously measuring voltage and current. It was observed that in the gap positive streamers develop alternately from each electrode when it is an anode. In the final stage, streamers collide and return ionization waves propagate in the direction of both electrodes. It has been established that in the spark stage of the discharge, the discharge current density reaches ~6 × 10⁷ A/cm². A stratified structure is observed after the current declines. It is assumed that during the spark stage of the discharge, the plasma channel experiences self-compression under the influence of a strong magnetic field.