Unstable magnetic reconnection self-generates turbulence

TL;DR

This study demonstrates how unstable magnetic reconnection can self-generate turbulence through a three-dimensional current-sheet instability, leading to a transition from laminar flow to fully developed turbulence without external forcing.

Contribution

The paper introduces high-resolution 3D simulations showing self-sustained turbulence arising from magnetic reconnection in magnetohydrodynamic flows, highlighting the role of current-sheet instability.

Findings

Reconnection transitions from laminar to turbulent flow.

Current-sheet instability triggers stochastic reconnection.

Turbulent energy is transferred from magnetic to kinetic fields.

Abstract

Magnetic reconnection and turbulence are deeply intertwined in magnetohydrodynamic flows, yet how reconnection self-generates turbulence remains unclear. Using an ensemble of high-resolution three-dimensional direct numerical simulations of an unstable magnetised jet with an initially weak mean field, we demonstrate a self-sustained transition from laminar reconnection to fully developed turbulence in the absence of external forcing. We show that a three-dimensional current-sheet instability triggers stochastic reconnection, leading to persistent turbulent energy injection. Energy-budget analysis reveals that the coupling between the turbulent electromotive force and the magnetic mean shear dominates turbulent production, with magnetic fluctuations subsequently transferring energy to the kinetic field through a nonlinear cascade.