Streamer-to-spark transition in interacting multi-channel pulsed discharges with gasdynamic effects

Abstract

The development of a streamer-to-spark transition in atmospheric-pressure air driven by a capacitor discharge in a resistor–capacitor circuit is simulated. The radial gasdynamic expansion of interacting plasma channels, along with the current–voltage characteristics, translational temperatures, electron density, pressure, and current density, is analyzed. The simulation results demonstrate that when the plasma channels are closely spaced in a linear configuration, the gasdynamic expansion of the inner filaments is spatially constrained. Consequently, the reduced electric field inside these inner filaments becomes significantly lower than that in the peripheral channels, which carry the bulk of the electric current. A quantitative criterion is established to define the transition between the mutual interaction of plasma channels and their independent development. Furthermore, the gasdynamic study demonstrates that modeling a spark discharge in atmospheric-pressure air at temperatures up to 7000 K does not strictly require a variable molar mass approach. The standard equation of state with a constant molar mass, coupled with density evaluation from the mixture continuity equation, yields no significant errors, at least from a gasdynamic perspective.