Modeling of a nonequilibrium cylindrical column of a low-current arc discharge

Numerical modeling of a wall-stabilized low-current arc discharge in the high pressure argon plasma is performed with account both of a deviation of the electron temperature from the heavy-particle temperature and of a deviation from the ionization equilibrium. Results are presented for a current range from currents of the order of 100 A down to several A, in which a regime of the discharge varies from the one typical for an arc discharge (local thermodynamic equilibrium (LTE) in the hot core, energy supplied to electrons by the electric field is mainly removed by the electron heat conduction) to the one typical for a glow discharge. (The electron temperature is substantially higher than the heavy-particle temperature and does not change much across the column, the ionization exceeds or substantially exceeds the recombination in every point of the column, energy supplied to electrons by the electric field is mainly locally transferred to heavy particles). On the axis of the discharge, the deviations from LTE become appreciable when the current decreases to several tens A. The deviation from the ionization equilibrium comes into play at higher currents than the deviation from the thermal equilibrium. Comparison with available experimental data is given.