Dissipation in PIC simulations of moderate to low \b{eta} plasma turbulence

TL;DR

This study uses fully-kinetic PIC simulations to analyze turbulence decay in electron-positron plasmas at moderate to low beta, revealing magnetic reconnection's role in energy dissipation and non-thermal particle features.

Contribution

First detailed PIC simulation analysis of turbulence decay in low beta electron-positron plasmas highlighting magnetic reconnection's dissipation role.

Findings

Energy decay rate similar in both simulations

Magnetic energy spectrum follows k^-1.3 slope

Lower beta shows non-thermal particle distribution with E^-1 slope

Abstract

We simulate decaying turbulence in electron-positron pair plasmas using a fully- kinetic particle-in-cell (PIC) code. We run two simulations with moderate-to-low plasma beta. The energy decay rate is found to be similar in both the cases. The perpendicular wave-number spectrum of magnetic energy shows a slope of k^-1.3 in both the cases. The particle energy distribution function shows the formation of a non-thermal feature in the case of lower plasma beta, with a slope close to E^-1. The role of thin turbulent current sheets in this process is investigated. The heating by E_{\parallel}.J_{\parallel} term dominates the E_{\perp}.J_{\perp} term. Regions of strong E_{\parallel}.J_{\parallel} are spatially well-correlated with regions of intense current sheets, which also appear correlated with regions of strong E_{\parallel} in the low beta simulation, suggesting an important role of magnetic reconnection in the dissipation of low beta plasma turbulence.