Onset of secondary instabilities and plasma heating during magnetic reconnection in strongly magnetized regions of the low solar atmosphere

Abstract

We numerically study magnetic reconnection on different spatial scales and at different heights in the weakly ionized plasma of the low solar atmosphere (around $300-800$~km above the solar surface) within a reactive 2.5 D multi-fluid plasma-neutral model. We consider a strongly magnetized plasma ($\beta \sim 6\%$) evolving from a force-free magnetic configuration and perturbed to initialize formation of a reconnection current sheet. On large scales, the resulting current sheets are observed to undergo a secondary 'plasmoid' instability. A series of simulations at different scales demonstrate a cascading current sheet formation process that terminates for current sheets with width of ~2m and length of $\sim 100$~m, corresponding to the critical current sheet aspect ratio of $\sim 50$. We also observe that the plasmoid instability is the primary physical mechanism accelerating the magnetic reconnection in this plasma parameter regime. After plasmoid instabilities appear, the reconnection rate sharply increases to a value of $\sim$ 0.035, observed to be independent of the Lundquist number. These characteristics are very similar to magnetic reconnection in fully ionized plasmas. In this low $\beta$ guide field reconnection regime, both the recombination and collisionless effects are observed to have a small contribution to the reconnection rate. The simulations show that it is difficult to heat the dense weakly ionized photospheric plasmas to above $2\times 10^4$~K during the magnetic reconnection process. However, the plasmas in the low solar chromosphere can be heated above $3\times 10^4$~K with reconnection magnetic fields of $500$~G or stronger.

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Cited by in corpus (18)

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• Flame-like Ellerman Bombs and Their Connection to Solar UV Bursts
• Subarcsecond blobs in flare-related coronal jets
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• Coalescence Instability in Chromospheric Partially Ionised Plasmas
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• Decimetric type U solar radio bursts and associated EUV phenomena on 2011 February 9
• Magnetic reconnection in partially ionized plasmas