The criterion for infinite positron feedback in dynamics of relativistic runaway electron avalanches

TL;DR

This paper develops a kinetic model to determine the electric field conditions under which positron feedback in relativistic runaway electron avalanches becomes infinite, potentially explaining terrestrial gamma-ray flashes.

Contribution

It introduces a new kinetic approach to derive the criterion for infinite positron feedback in thunderstorms, focusing on positron effects which dominate at observed electric field strengths.

Findings

Derived the criterion for infinite positron feedback at various altitudes.

Provided electric field parameter ranges for infinite feedback conditions.

Discussed the implications for terrestrial gamma-ray flashes.

Abstract

Relativistic runaway electron avalanches (RREA) accelerated by thunderstorm large-scale electric fields are one of the sources of atmospheric gamma radiation. In strong electric fields, RREAs can multiply by the relativistic feedback. Infinite relativistic feedback makes avalanches self-sustainable and hypothetically can cause a terrestrial gamma-ray flash (TGF). This paper introduces a kinetic approach to study the relativistic feedback caused by positrons since positron feedback dominates for the directly observed electric field strengths. With this approach, the criterion for infinite positron feedback within thunderstorms is derived. Discovered criterion allows obtaining the thunderstorm electric field parameters required for infinite positron feedback for any altitude. The possibility of derived thunderstorm conditions is discussed.