The Influence of Different Turbulence Models on the Diffusion Coefficients of Energetic Particles

TL;DR

This study investigates how different turbulence models affect energetic particle diffusion, finding that the diffusion coefficients' dependence on particle rigidity is consistent across models, emphasizing the importance of fundamental quantities over turbulence specifics.

Contribution

The paper demonstrates that turbulence model choice has limited impact on diffusion coefficients, highlighting the dominance of particle rigidity and Kubo number in transport behavior.

Findings

Diffusion coefficients show similar rigidity dependence across turbulence models.

Turbulence influence on particle transport is less significant than previously thought.

Validation of numerical results with two independent test-particle codes.

Abstract

We explore the influence of turbulence on the transport of energetic particles by using test-particle simulations. We compute parallel and perpendicular diffusion coefficients for two-component turbulence, isotropic turbulence, a model based on Goldreich-Sridhar scaling, noisy reduced magnetohydrodynamic turbulence, and a noisy slab model. We show that diffusion coefficients have a similar rigidity dependence regardless which turbulence model is used and, thus, we conclude that the influence of turbulence on particle transport is not as strong as originally thought. Only fundamental quantities such as particle rigidity and the Kubo number are relevant. In the current paper we also confirm the unified nonlinear transport theory for noisy slab turbulence. To double-check the validity and accuracy of our numerical results, we use a second test-particle code. We show that both codes provide very similar results confirming the validity of our conclusions.