Generation of Pulse Corona Discharge in Point-to-Plane Geometry Under Supercritical Conditions

Summary form only given. Generation of plasma under supercritical conditions is an unexplored area in plasma science. The known media of plasma applications include gas and liquid states with pressures from vacuum to atmospheric and above. Discharge development depends on the E/n ratio and the density of the media. In gaseous phase, the distance between the molecules is relatively large and electrical discharge can be achieved by using relatively low voltage. Concurrently, in liquid phase due to the densely packed molecules the required voltage for plasma generation is high. Some studies on plasma application for pollution control showed that small amount of dispersed liquid droplets increase the efficiency of the chemical utilization of the high energy electrons and reduce the required voltage at the same time. Supercritical fluid offers the unique advantage of having areas of low and high density that coexist in the fluid. This means that the discharge generated under these conditions starts in the low density gas like area where the required voltage for discharge initiation is low. Then the streamers rapidly propagate to the high density liquid like clusters, where the discharge propagation is controlled by mechanisms typical for the liquids. Our previous results on plasma generation under supercritical CO₂ conditions in wire to cylinder pulsed power reactor suggest significant reduction of the breakdown voltage. At the same time the experiments conducted for point-to-plane configuration showed that the possibility for plasma generation extends far beyond the critical conditions (T=304 K, P=73.8 bar). In this paper we extend the knowledge on the dependence of the voltage required for plasma initiation on the pressure, temperature and density of the supercritical media. Furthermore, three different point-to-plane geometries are investigated to provide insight of the configuration influence on the plasma generation