Using a non-diffusive hybrid scheme for simulation of filamentary discharges

A pulsed discharge in gas propagates typically in form of moving through the gas avalanches or streamers. Direct fluid modeling of these phenomena demonstrated a good success during last decades mainly due to relative simplicity of realization and rather low computational requirements. The principal limit of fluid approach validity consists in the assumption of continuity of media, i.e. in a continuous distribution of species involved in modeling. This assumption is usually valid inside the avalanche head or inside the streamer channel due to relatively high density of species while it often fails in regions at a distance from the front where the density of species (electrons, mainly) can be below than that is required for fluid approximation. In the present work, a hybrid model based on conventional fluid model coupled to a simplified Random Choice Method is proposed. This approach allows multi-dimensional simulation of avalanches and streamers treating individual particle in non-fluid regions that is of interest for investigation of streamer inception and branching phenomena. In this work, a comparison of the conventional fluid and the developed hybrid approaches is presented for avalanche to streamer transition in plain-plain geometry and for positive streamer development in rod-plain geometry.