Explosive Particle Dispersion in Plasma Turbulence

TL;DR

This study uses kinetic simulations to analyze particle dispersion in plasma turbulence, revealing normal diffusion at long times and explosive Richardson-like dispersion at intermediate times, with implications for astrophysical and laboratory plasmas.

Contribution

First self-consistent kinetic simulation study demonstrating explosive particle dispersion in plasma turbulence across different plasma beta values.

Findings

Particles undergo normal diffusion at long times.

Explosive dispersion occurs at intermediate times, consistent with Richardson prediction.

Higher plasma beta results in more diffusive particle behavior.

Abstract

Particle dynamics are investigated in plasma turbulence, using self-consistent kinetic simulations, in two dimensions. In steady state, the trajectories of single protons and proton-pairs are studied, at different values of plasma "beta" (ratio between kinetic and magnetic pressure). For single-particle displacements, results are consistent with fluids and magnetic field line dynamics, where particles undergo normal diffusion for very long times, with higher "beta" being more diffusive. In an intermediate time range, with separations lying in the inertial range, particles experience an explosive dispersion in time, consistent with the Richardson prediction. These results, obtained for the first time with a self-consistent kinetic model, are relevant for astrophysical and laboratory plasmas, where turbulence is crucial for heating, mixing and acceleration processes.