Arc Voltage Distribution Measurement in Tube Constricted Ultrahigh-Pressure Nitrogen Arc

This work contributes to the fundamental understanding of axial voltage distribution of the arc burning inside polytetrafluoroethylene (PTFE) tube at very high filling pressures of nitrogen. The arc peak current of 85 A at a frequency of 190 Hz with a fixed initial rate of rise of recovery voltage (IRRRV) of approximately 50 V/µs is used throughout the study. Arc burning at three different filling pressures are studied: 1 bar, 20 bar, and 40 bar. To examine the axial voltage distribution in the arc, the arc voltage at three different axial position of the arc is independently measured. For some cases, a 3 cubic centimeter heating volume is attached to the ring electrode, which produces a back flow. For the cases with a heating volume, the pressure rise in the heating volume is also measured. It is observed that the pressure rise in the heating volume increases with the filling pressure. In the presence of the heating volume at a high filling pressure (i.e., 20 bar, 40 bar), the voltage drop increases significantly near the vent due to the relatively cold gas flow.