Streamer Evolution Dynamics under Repetitive Nanosecond Pulses in Gas Gap and along Dielectric Surface: Effects of Residual Space and Surface Charges*

Streamer discharges in gas gap and along dielectric surface driven by repetitive nanosecond pulses have been implemented in many advanced low-temperature plasma applications. Streamer discharges driven by repetitive nanosecond pulses probably exhibit complicated evolution features, where the streamer-to-spark transition is a representative scenario. However, evolution mechanisms of streamer discharge have not been fully revealed. Streamer evolution characteristics and dynamics under repetitive nanosecond pulses in gas gap and along dielectric surface were compared.

Evolutions of a streamer discharge excited by repetitive nanosecond pulses were dependent on the voltage polarity in a nitrogen gas gap. Under positive repetitive pulses, a streamer continuously propagated from the needle tip towards the grounded plane electrode. Nevertheless, under negative voltage, a streamer was observed to be constricted around the needle tip.

The streamer discharge along a solid dielectric surface was affected by residual charges in gas gap and at the dielectric surface. The positive streamer propagation velocity generally decreased with increasing the pulse repetition frequency. Effects of residual space and surface charges on streamer evolutions were discussed.

Observations of nonlinear evolution phenomena and effects of residual charges are helpful for obtaining in-depth understanding of streamer discharge and its instability, especially under long-term repetitive pulses.