Energetic Particle Diffusion In Structured Turbulence

TL;DR

This paper investigates how inhomogeneities in plasma turbulence, modeled as spatially varying envelopes, affect energetic particle transport, revealing significant reductions in cross-field diffusion compared to homogeneous turbulence models.

Contribution

It introduces a novel approach using turbulence envelopes to study the impact of inhomogeneities on particle transport, highlighting the importance of phase coherence in diffusion processes.

Findings

Cross-field transport is significantly reduced in inhomogeneous turbulence.

Reduction in diffusion can reach an order of magnitude.

Breaking wave phase coherence impacts particle diffusion.

Abstract

In the full-orbit particle simulations of energetic particle transport in plasmas, the plasma turbulence is typically described as a homogeneous superposition of linear Fourier modes. The turbulence evolution is, however, typically a nonlinear process, and, particularly in the heliospheric context, the solar wind plasma is inhomogeneous due to the transient structures, as observed by remote and in-situ measurements. In this work, we study the effects of the inhomogeneities on energetic particle transport by using spatially distributed, superposed turbulence envelopes. We find that the cross-field transport is significantly reduced, when compared to the results obtained with homogeneous turbulence. The reduction can reach an order of magnitude when the enveloping breaks the wave phase coherence along the mean magnetic field direction.