Three-dimensional non-linear instability of spontaneous fast magnetic reconnection

T Shimizu,K Kondoh,M Ugai

doi:10.1186/bf03352924

Abstract

Abstract Three-dimensional instability of spontaneous fast magnetic reconnection is studied using MHD (magnetohydro- dynamic) simulation. Previous two-dimensional MHD studies have demonstrated that, if a current-driven anomalous resistivity is assumed, two-dimensional fast magnetic reconnection occurs and two-dimensional largescale magnetic loops, i.e., plasmoids, are ejected from the reconnection region. In most two-dimensional MHD studies, the structure of the current sheet is initially one-dimensinal. On the other hand, in recent space plasma observations, fully three-dimensional magnetic loops frequently appear even in the almost one-dimensional current sheet. This suggests that the classical two-dimensional fast magnetic reconnection may be unstable to any three-dimensional perturbation, resulting in three-dimensional fast magnetic reconnection. In this paper, we show that a three-dimensional resistive perturbation destabilizes two-dimensional fast magnetic reconnection and results in three-dimensional fast magnetic reconnection. The resulting three-dimensional fast reconnection repeatedly ejects three-dimensional magnetic loops downstream. The obtained numerical results are similar to the pulsating downflows observed in solar flares. According to the Fourier analysis of the ejected magnetic loops, the time evolution of this three-dimensional instability is fully non-linear.

Highlights

Fast magnetic reconnection provides a physical mechanism by which magnetic energy is explosively converted into plasma kinetic and thermal energies
We show that a three-dimensional resistive perturbation destabilizes two-dimensional fast magnetic reconnection and results in three-dimensional fast magnetic reconnection
Summary In this paper, we have shown that 2D fast magnetic reconnection caused by a current-driven anomalous resistivity is unstable to a 3D resistive perturbation

Summary

Introduction

Fast magnetic reconnection provides a physical mechanism by which magnetic energy is explosively converted into plasma kinetic and thermal energies. In order to theoretically explain the observation data, they suggested that 3D fast magnetic reconnection may occur even in a uniform (1D) current sheet and, the ejected 3D magnetic loops may be strongly localized in the current sheet direction.

Results

Conclusion