Modification of the resistive tearing instability with Joule heating by shear flow

Abstract

We investigate the influence of background shear flow on linear resistive tearing instabilities with Joule heating for two compressible plasma slab configurations: a Harris current sheet and a force-free, shearing magnetic field that varies its direction periodically throughout the slab, possibly resulting in multiple magnetic nullplanes. To do so, we exploit the latest version of the open-source, magnetohydrodynamic spectroscopy tool Legolas. Shear flow is shown to dramatically alter tearing behavior in the presence of multiple magnetic nullplanes, where the modes become propagating due to the flow. Finally, the tearing growth rate is studied as a function of resistivity, showing where it deviates from analytic scaling laws, as well as the Alfvén speed, the plasma-β, and the velocity parameters, revealing surprising nuance in whether the velocity acts stabilizing or destabilizing. We show how both slab setups can produce growth rate regimes, which deviate from analytic scaling laws, such that systematic numerical spectroscopic studies are truly necessary, for a complete understanding of linear tearing behavior in flowing plasmas.