Simulation of spark discharges in high-pressure air sustained by repetitive high-voltage nanosecond pulses

A model of discharges produced by a train of nanosecond high-voltage pulses is developed. Results of simulation of the discharge dynamics are presented. They allow one to trace, in qualitative agreement with observations, the discharge evolution after bridging the gap by the first streamer: (a) heating of the gas in the channel by low-current pulses, (b) transition to high-current pulses (spark breakdown) and (c) establishment, after a couple of high-current pulses, of a quasi-stationary stage. Simple analytical estimates of discharge parameters at the quasi-stationary stage are given.