Particle-in-Cell Simulation of Nanosecond Pulsed Breakdown Process of Nitrogen Spark Switch at Atmospheric Pressure

To study the nitrogen particle breakdown process of nanosecond pulses at atmospheric pressure, the discharge process in the gap is simulated using the particle-in-cell method and the photos of transient streamer propagation are obtained. The results are as follows. Firstly, the breakdown process of nanosecond pulses includes the formation stage and fast propagation stage of the streamer. Secondly, runaway electrons may generate in the head of the streamer and the branches of streamer channel form for the photoionization during the fast propagation stage. Finally, the average propagation velocity of the streamer channel during the streamer fast propagation stage is larger than that during the streamer formation stage.