Tearing Instability of Weakly Anisotropic Embedded Thin Current Sheets in Space Plasmas

Le résumé fourni par la source

Abstract Current sheets are widely observed in the solar wind and planetary magnetosphere, where they play a fundamental role in magnetic reconnection, plasma heating, and turbulence evolution. A novel equilibrium current sheet model has been developed that incorporates a thin ion-scale current sheet embedded in a thicker current sheet with weak anisotropy. Such anisotropic embedded thin current sheets are considered essential for the onset of magnetic reconnection in the planetary magnetotail. However, the linear stability of anisotropic embedded thin current sheets has not yet been theoretically investigated. In this study, we derive the basic equation describing the evolution of the perturbed magnetic potential in a one-dimensional configuration ( B z = 0). The resulting integro-differential equation is solved using finite element methods. We find that the enhancement of ion anisotropy significantly reduces the growth rate of the tearing mode and increases the critical wavelength. The ion anisotropy stabilizes the current sheet by supplying the anisotropic component of the resonant current. These findings elucidate the influence of tearing instability in current sheets and provide theoretical insight for investigating magnetic reconnection.

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