Study on pulsed breakdown characteristics in high pressurized nitrogen gas including supercritical state

In this study, the experimental studies of the breakdown characteristics and post-breakdown phenomena of nanosecond pulse electric discharge in high pressure fluids including supercritical state of nitrogen have reported. A series of experiments of dielectric property, breakdown voltage were measured in the conditions of the pressure range of 0.1 to 13.0 MPa with the temperature of 298 K by applied to two type gap electrode configurations. For study of post-breakdown phenomena, the visualizations of pulse discharges were conducted using a Nd:YAG laser system as Schlieren diagnostics. The experimental results show as follow: 1) the measured breakdown voltage increase with increasing almost linearly pressure against at the experimental condition in which the phase variation changes from a gas to supercritical phases; 2) the dielectric recovery of SCN₂ phase was recognized up to 1 kHz at nearly-complete except voltage dispersion; 3) shock wave velocity was estimated to about 400 m/s at the condition of P = 4 MPa, T = 298 K corresponding to SCN₂ phase.