Time Evolution of Pulsed Streamer Discharge in Water

Pulsed positive streamers in water were observed in the needle-to-plate electrode configuration with a gap of 20 mm. The characteristics of streamer propagation were investigated by using an intensified charge-coupled device camera. A few branching with a channel diameter of ~250 mum was observed. The streamers in water did not reach the plate electrode at the stable operation voltage range below the transition to spark. Under the present experimental condition, the propagation velocity of the streamer head was 3 times 10⁴ m/s, which is one order of magnitude lower than that of the streamer in air.