Streamer Propagation in a Large-Volume Underwater Corona Discharge Reactor

The underwater electrical discharges have received extensive attention in water or wastewater treatment. It is important to generate a large-volume underwater corona discharge at a relatively low voltage for its practical applications in water and wastewater treatment. A coaxial rod-cylinder electrode configuration has been developed for generating a large-volume corona discharge in water. The electrical characteristics of the corona discharges in water were investigated. The temporal evolution images of the streamer propagation were observed by an ultrahigh-speed frame camera system. The effect of water conductivity on the corona discharges was studied. The results show that the maximum of the measured current and the dissipated energy per pulse increase as the water conductivity increases while the maximum streamer length and the number of ignition seams per centimeter of the anode during one pulse duration decrease with increasing water conductivity. It was found that the propagation velocity of the streamer is ~30 km/s, and the water conductivity has no significant influence on it.