Scalings pertaining to current sheet disruption mediated by the plasmoid instability
Abstract
Analytic scaling relations are derived for a phenomenological model of the plasmoid instability in an evolving current sheet, including the effects of reconnection outflow. Two scenarios are considered, where the plasmoid instability can be triggered either by an injected initial perturbation or by the natural noise of the system (here referred to as the system noise). The two scenarios lead to different scaling relations because the initial noise decays when the linear growth of the plasmoid instability is not sufficiently fast to overcome the advection loss caused by the reconnection outflow, whereas the system noise represents the lowest level of fluctuations in the system. The leading order approximation for the current sheet width at disruption takes the form of a power law multiplied by a logarithmic factor, and from that, the scaling relations for the wavenumber and the linear growth rate of the dominant mode are obtained. When the effects of the outflow are neglected, the scaling relations agree, up to the leading order approximation, with previously derived scaling relations based on a principle of least time. The analytical scaling relations are validated with numerical solutions of the model.
 Publication:

Physics of Plasmas
 Pub Date:
 September 2019
 DOI:
 10.1063/1.5110332
 arXiv:
 arXiv:1909.02970
 Bibcode:
 2019PhPl...26i2112H
 Keywords:

 Physics  Plasma Physics;
 Astrophysics  Solar and Stellar Astrophysics;
 Physics  Space Physics
 EPrint:
 Accepted for publication in Physics of Plasmas