Abstract
Abstract Here we detail the dynamic evolution of localized reconnection regions about 3D magnetic null points using numerical simulation. We demonstrate for the first time that reconnection triggered by the localized collapse of a 3D null point that is due to an external magnetohydrodynamic (MHD) wave involves a self-generated oscillation, whereby the current sheet and outflow jets undergo a reconnection reversal process during which back-pressure formation at the jet heads acts to prise open the collapsed field before overshooting the equilibrium into an opposite-polarity configuration. The discovery that reconnection at fully 3D nulls can proceed naturally in a time-dependent and periodic fashion suggests that oscillatory reconnection mechanisms may play a role in explaining periodicity in astrophysical phenomena associated with magnetic reconnection, such as the observed quasi-periodicity of solar and stellar flare emission. Furthermore, we find that a consequence of oscillatory reconnection is the generation of a plethora of freely propagating MHD waves that escape the vicinity of the reconnection region.
Highlights
Magnetic fields play a key role in determining the dynamics of plasmas at all scales: from fusion experiments and laboratory plasmas to planetary magnetospheres, the Sun and stars, and galaxies and accretion disks
Much of our present understanding of reconnection has focused primarily on continuously driven systems, while transient effects that are crucial in many plasma environments are typically neglected
The identification of 3D oscillatory reconnection is a milestone in our understanding of energy release in high magnetic Reynolds number plasmas, demonstrating that reconnection triggered in an aperiodic manner produces both periodic reconnection reversals and periodically excited propagating MHD waves through a self-generated oscillation
Summary
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