3D fluid modeling of positive streamer discharges in air with stochastic photoionization

Abstract

Streamer discharges are thin plasma channels that precede lightning and sparks. They usually evolve in bundles as stochastic tree-like structures and are inherently difficult to model due to their multiscale nature. In this paper, we perform a computer investigation of positive streamer discharges in air using contemporary photoionization models. We report on three-dimensional computer simulations under conditions that are available in laboratory spark-gap experiments. The solutions demonstrate a multiscale morphology consisting of streamer fluctuations, branching, and the formation of a discharge tree. Some branches are comparatively thick and noisy, while others are thin, smooth, and carry electric fields exceeding 250 kV/cm at their tips. Our results are consistent with past experiments and clarify the puzzling branching dynamics and stochastic morphology of positive streamer discharges.