ABSTRACT

The high current heats a small volume of plasma in the gap between the two electrodes, generating quasithermal plasma, with the temperatures of electrons and heavy particles almost equal. Thermal plasma generated in the channel is rapidly expanding from the narrow channel into water, forming a plasma bubble. High electric conductivity in the plasma channel leads to the shifting of the high electric fields from the channel to the bubble. The plasma bubble can be characterized by both a very high temperature gradient and a large electric field. The energy required to form and sustain the plasma bubble is provided by joule heating in the narrow conductive channel in water. The plasma discharge generates ultraviolet radiation and converts surrounding water molecules into active radical species due to the high energy level produced by the discharge. Various electrode geometries have been studied for the generation of plasma discharges in liquid.