Transient regime of pulsed breakdown in low-conductive water solutions

The transient regime of pulsed electrical breakdown in both distilled and low-conductive water (σ<15 µS cm -1 ) has been investigated in a point-to-plane electrode system using quasi-rectangular voltage pulses with a repetition frequency of 25 Hz. Two individual current pulses were observed within the interval of voltages of 18.5-20 kV. The appearance of the transient regime was limited by the minimal capacitance of the storage capacitor C ≅4 nF. While the time lag of the first current was not apparently affected by the capacitance of the storage capacitor, a growth in time lag of the second current pulse was observed as the capacitance was increased. The distortion of the electric field at the head and an increase of the leader channel resistance due to accumulation of the electrostatic charge on the inside wall of the gaseous channel are two most likely mechanisms effective in the transient regime. The enhancement of OH radical production in such a regime can be surmised from spectroscopic observations.