Relativistic runaway electron avalanches within complex thunderstorm electric field structures

TL;DR

This paper introduces a new mechanism called reactor feedback for relativistic runaway electron avalanches in complex thunderstorm electric fields, supported by a novel simulation method, enhancing understanding of gamma-ray emissions in thunderstorms.

Contribution

It presents a new reactor feedback mechanism for RREAs in non-uniform electric fields and a numerical simulation approach for heterogeneous thunderstorm environments.

Findings

Reactor feedback enables additional RREA multiplication in complex electric fields.

The simulation method models RREA dynamics within heterogeneous electric field structures.

Conditions for terrestrial gamma-ray flash (TGF) occurrence are derived.

Abstract

Relativistic runaway electron avalanches (RREAs) are generally accepted as a source of thunderstorms gamma-ray radiation. Avalanches can multiply in the electric field via the relativistic feedback mechanism based on processes with gamma-rays and positrons. This paper shows that a non-uniform electric field geometry can lead to the new RREAs multiplication mechanism - "reactor feedback", due to the exchange of high-energy particles between different accelerating regions within a thundercloud. A new method for the numerical simulation of RREA dynamics within heterogeneous electric field structures is proposed. The developed analytical description and the numerical simulation enables us to derive necessary conditions for TGF occurrence in the system with the reactor feedback Observable properties of TGFs influenced by the proposed mechanism are discussed.