Petschek-type reconnection in the high-Lundquist-number regime during nonlinear evolution on the tilt instability

Abstract

The process of fast magnetic reconnection supported by the formation of plasmoid chains in the high Lundquist number ($S$) regime is investigated using a recently developed adaptive finite-element magnetohydrodynamic (MHD) code. We employ a two-dimensional incompressible model with a set of reduced visco-resistive MHD equations. The tilt instability setup is chosen to provide a three-step mechanism, where two curved current sheets initially form on an Alfvénic time scale followed by a second phase of super-Alfvénic growth of plasmoid chains for $S\ge S_c$ (Baty 2020). A third phase is reached where an ensuing stochastic time-dependent reconnection regime with a fast time-averaged rate independent of $S$ is obtained. We reveal the multi-scale current structures during magnetic reconnection, where merging events of plasmoids give rise to monster plasmoids with shocks bounding the outflow regions. At high enough $S$ values (typically for $S\sim 100S_c$), a dynamical Petschek-type reconnection is achieved with pairs of slow-mode shocks emanating from a small central region containing a few plasmoids. Finally, we briefly discuss the relevance of our results to explain the flaring activity in solar corona and internal disruptions in tokamaks.

arXiv admin note: text overlap with arXiv:2003.08660, arXiv:2001.07036

References in corpus (5)

• Instability of current sheets and formation of plasmoid chains
• General Theory of the Plasmoid Instability
• Plasmoid Instability in Evolving Current Sheets and Onset of Fast Reconnection
• Plasmoid-dominated Turbulent Reconnection in a Low $\beta$ Plasma
• Formation of plasmoid chains and fast magnetic reconnection during nonlinear evolution of the tilt instability

Cited by in corpus (1)

• Magnetic reconnection and plasmoid formation driven by the two-dimensional resistive kink instability in a current hole configuration