Monte Carlo simulations of air showers in atmospheric electric fields

TL;DR

This paper uses Monte Carlo simulations to study how atmospheric electric fields, especially during thunderstorms, influence cosmic ray air shower development and radio detection, highlighting significant effects at fields around 1 kV/cm.

Contribution

It provides the first detailed simulation-based analysis of electric field impacts on air shower development and potential runaway electron breakdown at high altitudes.

Findings

Electric fields of about 1 kV/cm significantly alter electron and positron energy distributions.

Runaway electron breakdown may occur at high altitudes in strong electric fields.

Electric fields influence the electromagnetic component of air showers.

Abstract

The development of cosmic ray air showers can be influenced by atmospheric electric fields. Under fair weather conditions these fields are small, but the strong fields inside thunderstorms can have a significant effect on the electromagnetic component of a shower. Understanding this effect is particularly important for radio detection of air showers, since the radio emission is produced by the shower electrons and positrons. We perform Monte Carlo simulations to calculate the effects of different electric field configurations on the shower development. We find that the electric field becomes important for values of the order of 1 kV/cm. Not only can the energy distribution of electrons and positrons change significantly for such field strengths, it is also possible that runaway electron breakdown occurs at high altitudes, which is an important effect in lightning initiation.