Spatial coupling of particle and fluid models for streamers: where nonlocality matters

TL;DR

This paper presents a spatial coupling method for particle and fluid models of streamer ionization fronts, addressing nonlocal effects and optimizing the interface to balance accuracy and computational efficiency.

Contribution

It introduces a novel spatial coupling approach that combines particle and fluid models for streamers, improving accuracy in high-field ionization front simulations.

Findings

Optimal interface position minimizes computational effort.

Coupled model accurately reproduces pure particle model results.

Discrepancies linked to electron density gradients in the leading edge.

Abstract

Particle models for streamer ionization fronts contain correct electron energy distributions, runaway effects and single electron statistics. Conventional fluid models are computationally much more efficient for large particle numbers, but create too low ionization densities in high fields. To combine their respective advantages, we here show how to couple both models in space. We confirm that the discrepancies between particle and fluid fronts arise from the steep electron density gradients in the leading edge of the fronts. We find the optimal position for the interface between models that minimizes computational effort and reproduces the results of a pure particle model.