Influence of temperature on the glow regime of a discharge in air at atmospheric pressure between two point electrodes

This paper presents simulations of the dynamics of air discharges between two point electrodes at atmospheric pressure for two different gas temperatures 300 and 1000 K. Simulation results show that in the early stages of the glow regime, two streamer discharges propagate in the gap and form after their connection a conducting channel between electrodes. In a recent experimental work on nanosecond repetitively pulsed (NRP) discharges at 1000 K between two point electrodes with an interelectrode gap distance of 5 mm, it was found that a glow regime is obtained if the average electric field in the gap is at least equal to the breakdown field. Simulation results show that for the conditions studied in the experiments, the time of connection of both discharges is close to the 10 ns duration of the voltage pulse if the average electric field in the gap in the conduction phase is equal to the breakdown field. Under these conditions, a glow regime is obtained as a conducting channel has just the time to form between electrodes during the voltage pulse and no significant gas heating may occur. At 300 K, we found that a minimal value of the Laplacian electric field of 8-9 kV cm^-1 at atmospheric pressure is necessary to have a stable propagation of the positive streamer without branching in the point-to-point geometry. Then, based on simulation results, we discuss the conditions of existence of the glow regime in NRP discharges at atmospheric pressure and 300 K in a 1 cm interelectrode gap.