Reconnection-Driven Energy Cascade in Magnetohydrodynamic Turbulence

TL;DR

This study uses advanced 3D magnetohydrodynamic simulations to show how magnetic reconnection alters the energy cascade in turbulence, leading to steeper spectra and the formation of plasmoids, with implications for astrophysical phenomena.

Contribution

It reveals how rapid magnetic reconnection and plasmoid formation fundamentally change the classical turbulence energy cascade in MHD systems.

Findings

Steepened energy spectra with a spectral index of -2.2

Formation of chains of small magnetic flux ropes (plasmoids)

Altered turbulence anisotropy due to plasmoid dynamics

Abstract

Magnetohydrodynamic turbulence regulates the transfer of energy from large to small scales in many astrophysical systems, including the solar atmosphere. We perform three-dimensional magnetohydrodynamic simulations with unprecedentedly large magnetic Reynolds number to reveal how rapid reconnection of magnetic field lines changes the classical paradigm of the turbulent energy cascade. By breaking elongated current sheets into chains of small magnetic flux ropes (or plasmoids), magnetic reconnection leads to a new range of turbulent energy cascade, where the rate of energy transfer is controlled by the growth rate of the plasmoids. As a consequence, the turbulent energy spectra steepen and attain a spectral index of -2.2 that is accompanied by changes in the anisotropy of turbulence eddies. The omnipresence of plasmoids and their consequences on, e.g., solar coronal heating, can be further explored with current and future spacecraft and telescopes.