A detailed investigation of particle energisation mechanisms in models of collapsing magnetic traps

TL;DR

This study investigates particle energisation mechanisms in collapsing magnetic trap models, highlighting the significant role of Fermi acceleration alongside betatron acceleration across different dimensional models.

Contribution

It extends previous research by analyzing particle orbits in 2D and 3D models with various initial conditions, emphasizing the importance of Fermi acceleration.

Findings

Fermi acceleration can significantly energize particles.

Betatron acceleration is not the sole dominant mechanism.

Model outcomes depend on initial conditions and dimensionality.

Abstract

In this paper we provide a detailed investigation of the energisation processes in two-dimensional, two and a half-dimensional and three-dimensional collapsing magnetic trap models. Using kinematic magnetohydrodynamic models of collapsing magnetic traps, we examine the importance of Fermi acceleration in comparison with betatron acceleration in these models. We extend previous work by investigating particle orbits in two-dimensional models without and with a guide field component and from full three-dimensional models. We compare the outcomes for the different models and how they depend on the chosen initial conditions. While in the literature betatron acceleration has been emphasised as the major mechanism for particle energisation in collapsing magnetic traps, we find that Fermi acceleration can play a significant role as well for particle orbits with suitable initial conditions.