Charged particle diffusion in isotropic random magnetic fields

TL;DR

This paper studies how charged particles diffuse in fully isotropic turbulent magnetic fields without a mean field, proposing models for different energy ranges and validating them with simulations.

Contribution

It introduces two theoretical models for particle diffusion in isotropic turbulence and compares them with simulation results, filling a gap in understanding without a mean magnetic field.

Findings

Good agreement between theoretical models and simulations.

Different energy regimes require distinct diffusion models.

Abstract

The investigation of the diffusive transport of charged particles in a turbulent magnetic field remains a subject of considerable interest. Research has most frequently concentrated on determining the diffusion coefficient in the presence of a mean magnetic field. Here we consider diffusion of charged particles in fully three-dimensional isotropic turbulent magnetic fields with no mean field, which may be pertinent to many astrophysical situations. We identify different ranges of particle energy depending upon the ratio of the Larmor radius of the charged particle to the characteristic outer length scale of the turbulence. Two different theoretical models are proposed to calculate the diffusion coefficient, each applicable to a distinct range of particle energies. The theoretical results are compared with those from computer simulations, showing good agreement.