On the production of energetic electrons at the negative streamer head at moderate overvoltage

The generation of energetic electrons by the streamer with a negatively charged head is analyzed using a self-consistent two-dimensional Particle-in-Cell Monte Carlo collision model. The streamer is generated in the vicinity of the cathode at a moderate gap overvoltage and propagates toward the anode due to self-consistent electron/ion multiplication in front of the streamer head. We obtained the generation of energetic electrons with energy exceeding 1 keV at the streamer head when the electric field at the streamer head starts exceeding ∼200 kV/cm. It was found that a small number of energetic electrons can significantly accelerate the streamer propagation and even change the streamer propagation path.