Arc Voltage Characteristics in Ultrahigh-Pressure Nitrogen Including Supercritical Region

A supercritical (SC) fluid is formed when both pressure and temperature of a fluid exceed the critical point, where distinct gas and liquid phases no longer exist. SC fluids demonstrate combined properties of gas and liquid, which make them interesting to investigate them as an arc extinction medium. This paper focuses on the arc voltage characteristics of industrial grade nitrogen subjected to different filling pressures up to 98 bar including SC region. Pressure, arc duration, current, and distance dependence of the arc are investigated by arc voltage measurement. It has been found that arc voltage increases with filling pressure without any abrupt change during the transition from gas into the SC region. Arc duration and current dependence of the arc voltage are not significant in the investigated parameter range. Arc voltage measurement with different electrode gaps suggests that the electrode voltage drop does not vary with filling pressure.