Particles trajectories in magnetic filaments

TL;DR

This paper investigates particle trajectories in harmonic magnetic filaments through analytical and numerical methods, aiming to validate heuristic assumptions about particle trapping in magnetic turbulence relevant to collisionless shock formation.

Contribution

It provides a rigorous analysis of particle motion in harmonic magnetic fields, combining analytical modeling with numerical simulations to confirm heuristic trapping conditions.

Findings

Particles can be trapped inside magnetic filaments under certain conditions.

Analytical and numerical results are consistent, validating heuristic trapping assumptions.

The study offers insights into particle behavior in magnetic turbulence relevant to astrophysical shocks.

Abstract

The motion of a particle in a spatially harmonic magnetic field is a basic problem involved, for example, in the mechanism of formation of a collisionless shock. In such settings, it is generally reasoned that particles entering a Weibel generated turbulence are trapped inside it, provided their Larmor radius in the peak field is smaller than the field coherence length. The goal of this work is to put this heuristic conclusion on firm ground by studying, both analytically and numerically, such motion. A toy model is analyzed, consisting of a relativistic particle entering a region of space occupied by a spatially harmonic field. The particle penetrates the magnetic structure in a direction aligned with the magnetic filaments. Although the conclusions are not trivial, the main result is confirmed.