Journal article
Tearing-mediated Reconnection in Magnetohydrodynamic Poorly Ionized Plasmas. I. Onset and Linear Evolution
The Astrophysical journal, Vol.967(2), p.136
06/01/2024
DOI: 10.3847/1538-4357/ad35c0
Abstract
In high-Lundquist-number plasmas, reconnection proceeds via the onset of tearing, followed by a nonlinear phase during which plasmoids continuously form, merge, and are ejected from the current sheet (CS). This process is understood in fully ionized, magnetohydrodynamic plasmas. However, many plasma environments, such as star-forming molecular clouds and the solar chromosphere, are poorly ionized. We use theory and computation to study tearing-mediated reconnection in such poorly ionized systems. In this paper, we focus on the onset and linear evolution of this process. In poorly ionized plasmas, magnetic nulls on scales below v A,n0/nu ni0, with v A,n0 the neutral Alfv & eacute;n speed and nu ni0 the neutral-ion collision frequency, will self-sharpen via ambipolar diffusion. This sharpening occurs at an increasing rate, inhibiting the onset of reconnection. Once the CS becomes thin enough, however, ions decouple from neutrals and the thinning of the CS slows, allowing the onset of tearing in a time of order nu ni 0 - 1 . We find that the wavelength and growth rate of the mode that first disrupts the forming sheet can be predicted from a poorly ionized tearing dispersion relation; as the plasma recombination rate increases and ionization fraction decreases, the growth rate becomes an increasing multiple of nu ni0 and the wavelength becomes a decreasing fraction of v A,n0/nu ni0.
Details
- Title: Subtitle
- Tearing-mediated Reconnection in Magnetohydrodynamic Poorly Ionized Plasmas. I. Onset and Linear Evolution
- Creators
- Elizabeth A. Tolman - Flatiron InstituteMatthew W. Kunz - Princeton UniversityJames M. Stone - Institute for Advanced StudyLev Arzamasskiy - Institute for Advanced Study
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.967(2), p.136
- DOI
- 10.3847/1538-4357/ad35c0
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Publisher
- IOP Publishing Ltd
- Number of pages
- 16
- Grant note
- W.M. Keck Foundation Fund at the Institute for Advanced Study; W.M. Keck Foundation Simons Foundation
- Language
- English
- Date published
- 06/01/2024
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9985113641302771
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