Quantitative modeling of streamer discharge branching in air

TL;DR

This paper uses a 3D fluid model with stochastic photoionization to simulate and analyze the branching behavior of positive streamer discharges in air, confirming the role of photoionization as a noise source for branching.

Contribution

It introduces a stochastic 3D simulation approach that validates the role of photoionization in streamer branching and tests Zheleznyak's model against experimental data.

Findings

Branching probability matches experimental observations.

Photoionization noise triggers streamer branching.

Branching sensitivity to photoionization levels is confirmed.

Abstract

Streamer discharges are the primary mode of electric breakdown of air in lightning and high voltage technology. Streamer channels branch many times, which determines the developing tree-like discharge structure. Understanding these branched structures is for example important to describe streamer coronas in lightning research. We simulate branching of positive streamers in air using a 3D fluid model where photoionization is included as a discrete and stochastic process. The probability and morphology of branching are in good agreement with dedicated experiments. This demonstrates that photoionization indeed provides the noise that triggers branching, and we show that branching is remarkably sensitive to the amount of photoionization. Our comparison is therefore one of the first sensitive tests for Zheleznyak's photoionization model, confirming its validity.