Spatially hybrid computations for streamer discharges: II. Fully 3D simulations

TL;DR

This paper advances 3D streamer discharge simulations by developing a hybrid particle-fluid model, improving physical accuracy and computational efficiency, and demonstrating initial results in air.

Contribution

It introduces a fully 3D hybrid model with new transport coefficients, refined interface handling, and initial simulation results for negative streamers in air.

Findings

Transport coefficients derived from swarm simulations for various gases.

Implementation of an extended fluid model aligned with particle dynamics.

First 3D simulation results of negative streamers in air.

Abstract

We recently have presented first physical predictions of a spatially hybrid model that follows the evolution of a negative streamer discharge in full three spatial dimensions; our spatially hybrid model couples a particle model in the high field region ahead of the streamer with a fluid model in the streamer interior where electron densities are high and fields are low. Therefore the model is computationally efficient, while it also follows the dynamics of single electrons including their possible run-away. Here we describe the technical details of our computations, and present the next step in a systematic development of the simulation code. First, new sets of transport coefficients and reaction rates are obtained from particle swarm simulations in air, nitrogen, oxygen and argon. These coefficients are implemented in an extended fluid model to make the fluid approximation as consistent as possible with the particle model, and to avoid discontinuities at the interface between fluid and particle regions. Then two splitting methods are introduced and compared for the location and motion of the fluid-particle-interface in three spatial dimensions. Finally, we present first results of the 3D spatially hybrid model for a negative streamer in air.