Three-dimensional simulation of thermodynamics on confined turbulence in a large-scale CME-flare current sheet

TL;DR

This paper presents detailed 3D simulations of a solar CME and its current sheet, revealing complex plasmoid dynamics, thermodynamics, and reconnection processes that enhance understanding of solar eruptions.

Contribution

It introduces high-resolution 3D simulations of CME current sheets, highlighting the roles of thermal conduction, turbulence, and plasmoid instabilities in energy release and magnetic reconnection.

Findings

Maximum temperature of about 20 MK in the current sheet.

Downward plasmoids maintain twisted magnetic fields until annihilation.

Turbulent reconnection dominates in the upper current sheet.

Abstract

Turbulence plays a key role for forming the complex geometry of the large-scale current sheet (CS) and fast energy release in a solar eruption. In this paper, we present full 3D high-resolution simulations for the process of a moderate Coronal Mass Ejection (CME) and the thermodynamical evolution of the highly confined CS. Copious elongated blobs are generated due to tearing and plasmoid instabilities giving rise to a higher reconnection rate and undergo the splitting, merging and kinking processes in a more complex way in 3D. A detailed thermodynamical analysis shows that the CS is mainly heated by adiabatic and numerical viscous terms, and thermal conduction is the dominant factor that balances the energy inside the CS. Accordingly, the temperature of the CS reaches to a maximum of about 20 MK and the range of temperatures is relatively narrow. From the face-on view in the synthetic Atmospheric Imaging Assembly 131 $\mathring{A}$, the downflowing structures with similar morphology to supra-arcade downflows are mainly located between the post-flare loops and loop-top, while moving blobs can extend spikes higher above the loop-top. The downward-moving plasmoids can keep the twisted magnetic field configuration until the annihilation at the flare loop-top, indicating that plasmoid reconnection dominates in the lower CS. Meanwhile, the upward-moving ones turn into turbulent structures before arriving at the bottom of the CME, implying that turbulent reconnection dominates in the upper CS. The spatial distributions of the turbulent energy and anisotropy are addressed, which show a significant variation in the spectra with height.