Electron density fluctuations accelerate the branching of streamer discharges in air

TL;DR

This paper demonstrates that electron density fluctuations due to particle discreteness significantly influence streamer branching in air, providing a quantitative estimate that aligns with experimental observations and highlighting the importance of stochastic effects.

Contribution

It introduces a quantitative analysis of electron density fluctuations as a stochastic factor driving streamer branching in air, aligning theoretical estimates with experimental data.

Findings

Electron density fluctuations are a key stochastic factor in streamer branching.

The derived branching distance estimate agrees within a factor of 2 with experiments.

Stochastic noise accelerates streamer branching compared to deterministic models.

Abstract

Branching is an essential element of streamer discharge dynamics but today it is understood only qualitatively. The variability and irregularity observed in branched streamer trees suggest that stochastic terms are relevant for the description of streamer branching. We here consider electron density fluctuations due to the discrete particle number as a source of stochasticity in positive streamers in air at standard temperature and pressure. We derive a quantitative estimate for the branching distance that agrees within a factor of 2 with experimental values. As branching without noise would occur later, if at all, we conclude that stochastic particle noise is relevant for streamer branching in air at atmospheric pressure.