Resistive Tearing Mode Instability in Generalized Harris Current Sheets
The widely adopted initial force-balanced equilibrium prior to the occurrence of magnetic reconnection (MR) is the so-called Harris sheet model with antiparallel magnetic field. This study examines the tearing mode instability of the recently developed generalized Harris sheet equilibrium based on t...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/add682 |
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| Summary: | The widely adopted initial force-balanced equilibrium prior to the occurrence of magnetic reconnection (MR) is the so-called Harris sheet model with antiparallel magnetic field. This study examines the tearing mode instability of the recently developed generalized Harris sheet equilibrium based on two-dimensional, resistive, isotropic, linear, and nonlinear MHD models. The generalized Harris equilibrium incorporating the nonthermal Kappa-like velocity distributions in the Vlasov–Maxwell equations may give rise to a family of plasma and magnetic field profiles with various current layer thicknesses which may be used to study various plasma instabilities and MR. It is shown that the linear growth rate is proportional to ${\delta }^{-2/5}{R}_{m}^{-2/5}$ , where $\delta $ and ${R}_{m}$ are the current layer thickness and magnetic Reynolds number, respectively. The linear eigenmode solutions are used as the initial perturbations of the nonlinear MHD simulations to allow the full evolution of the tearing instability. It is shown that the cases with small ${R}_{m}$ may not be nonlinearly unstable, and the cases with relatively thinner current sheets and larger ${R}_{m}$ may grow faster with larger aspect ratios of magnetic islands. In the generalized kinetic Harris models, the thinning of current sheets may be achieved by the decrease of central temperature or the increase of the drift velocity of charged particles. The asymptotic magnetic field of the equilibrium profiles seems to play a minor role in the linear and nonlinear growth of resistive tearing mode instability. |
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| ISSN: | 1538-4357 |