Simulations of Energetic Particles Interacting with Nonlinear Anisotropic Dynamical Turbulence

TL;DR

This study uses numerical simulations to analyze how energetic particles diffuse in nonlinear anisotropic turbulence, considering wave effects and damping, with implications for understanding solar wind particle behavior.

Contribution

It introduces a numerical approach to test-particle diffusion in nonlinear anisotropic turbulence, incorporating wave propagation and damping effects, and compares results with solar wind observations.

Findings

Bendover scales and magnetic field ratio significantly influence diffusion coefficients.

Optimal agreement with solar wind data occurs at equal bendover scales and a magnetic field ratio of 0.75.

Dissipation range spectral index has a weak effect on diffusion.

Abstract

We investigate test-particle diffusion in dynamical turbulence based on a numerical approach presented before. For the turbulence we employ the nonlinear anisotropic dynamical turbulence model which takes into account wave propagation effects as well as damping effects. We compute numerically diffusion coefficients of energetic particles along and across the mean magnetic field. We focus on turbulence and particle parameters which should be relevant for the solar system and compare our findings with different interplanetary observations. We vary different parameters such as the dissipation range spectral index, the ratio of the turbulence bendover scales, and the magnetic field strength in order to explore the relevance of the different parameters. We show that the bendover scales as well as the magnetic field ratio have a strong influence on diffusion coefficients whereas the influence of the dissipation range spectral index is weak. The best agreement with solar wind observations can be found for equal bendover scales and a magnetic field ratio of $\delta$B/B0 = 0.75.