Streamer Breakdown Development in Undercritical Electric Field

The different regimes of nanosecond pulsed-periodic discharge development in a point-to-plane geometry are investigated. The development of a discharge burst at a frequency of 1 kHz is investigated with nanosecond temporal resolution. Kinetic and gasdynamic effects that control the transition from streamer to spark discharge are demonstrated. It was shown that subsequent streamers have higher velocities and smaller channel diameters than the initial streamer. Thus, the self-focusing of the periodic discharge due to the inhomogeneous excitation and heating of the gas in the previous discharge channel has been demonstrated. Discharge transitions into a short-circuit mode cause an increased release of energy. This energy release leads to a sharp increase in the intensity of gasdynamic perturbations, effective mixing of the recombining channel's plasma with the surrounding air, loss of the symmetry of the initial conditions, and generation of multiple channels. This process leads to the self-restriction of the energy release during the high-current phase of the discharge because of an effective decrease of inhomogeneities in the heat and concentration.