Expansion of Solar Coronal Hot Electrons in an Inhomogeneous Magnetic Field: 1-D PIC Simulation

TL;DR

This study uses 1-D PIC simulations to explore how hot electrons move in inhomogeneous magnetic fields during solar flares, revealing the roles of wave interactions and magnetic confinement in electron transport.

Contribution

First simulation-based investigation of hot electron transport in magnetic mirror fields during solar flares, highlighting wave-particle interactions and electron confinement effects.

Findings

Langmuir and ion acoustic waves generated in cold and hot plasma regions.

Electron temperature anisotropy leads to whistler wave generation.

Whistler waves scatter electrons, affecting their escape from hot regions.

Abstract

The expansion of hot electrons in flaring magnetic loops is crucial to understanding the dynamics of solar flares. In this paper we investigate, for the first time, the transport of hot electrons in a magnetic mirror field based on a 1-D particle-in-cell (PIC) simulation. The hot electrons with small pitch angle transport into the cold plasma, which leads to the generation of Langmuir waves in the cold plasma and ion acoustic waves in the hot plasma. The large pitch angle electrons can be confined by the magnetic mirror, resulting in the different evolution time scale between electron parallel and perpendicular temperature. This will cause the formation of electron temperature anisotropy, which can generate the whistler waves near the interface between hot electrons and cold electrons. The whistler waves can scatter the large pitch angle electrons to smaller value through the cyclotron resonance, leading to electrons escaping from the hot region. These results indicate that the whistler waves may play an important role in the transport of electrons in flaring magnetic loops. The findings from this study provide some new insights to understand the electron dynamics of solar flares.