Occurrence Rates and Heating Effects of Tangential and Rotational Discontinuities as Obtained from Three-dimensional Simulation of Magnetohydrodynamic Turbulence

TL;DR

This study uses 3D MHD simulations to analyze the occurrence and heating effects of tangential and rotational discontinuities in the solar wind, revealing their different roles in plasma heating and turbulence.

Contribution

The paper introduces new methods to identify and distinguish TDs and RDs in 3D MHD simulations, providing insights into their occurrence rates and heating effects.

Findings

RDs are more prevalent over time among discontinuities.

TDs are associated with extreme plasma parameters or instabilities.

TDs exhibit higher average and perpendicular temperatures.

Abstract

In solar wind, magnetohydrodynamic (MHD) discontinuities are ubiquitous and often found to be at the origin of turbulence intermittency. They may also play a key role in the turbulence dissipation and heating of the solar wind. The tangential (TD) and rotational (RD) discontinuities are the two most important types of discontinuities. Recently, the connection between turbulence intermittency and proton thermodynamics has been being investigated observationally. Here we present numerical results from three-dimensional MHD simulation with pressure anisotropy and define new methods to identify and to distinguish TDs and RDs. Three statistical results obtained about the relative occurrence rates and heating effects are highlighted: (1) RDs tend to take up the majority of the discontinuities along with time; (2) the thermal states embedding TDs tend to be associated with extreme plasma parameters or instabilities, while RDs do not; (3) TDs have a higher average T as well as perpendicular temperature $T_\perp$. The simulation shows that TDs and RDs evolve and contribute to solar wind heating differently. These results will inspire our understanding of the mechanisms that generate discontinuities and cause plasma heating.