Sweet–Parker current slab in a partially ionized plasma

Abstract

The formation of the Sweet-Parker current sheet, in fact a slab, is studied for a partially ionized plasma. The effects arising from the ion-neutral drag, the ambipolar diffusion, the resistivity resulting from electron-neutral and electron-ion collisions, and the Hall electric field are important for determining the dimensions of the current slab as well as the magnetic reconnection rate. It is the Hall effect that transforms the sheet into a slab. Along with the slab configuration, the out-of-plane plasma flow generated jointly by the Hall and the ambipolar effects is an important signature result. Although the ambipolar effect enhances and the Hall effect depletes the reconnection rate, its quantitative estimate may, at best, be considered only a pointer, owing to the lack of information on the precise physical conditions near the reconnection region in astrophysical settings.

Nonlinear instability and intermittent nature of magnetic reconnection in solar chromosphere

“…The role of ambipolar diffusion has been studied analytically in the context of magnetic reconnection. It has been found that in a Sweet-Parker geometry, the ambipolar diffusion increases the reconnection rate (Vishniac & Lazarian 1999;Krishan 2009). Some of the observations of magnetic field in the solar chromosphere suggest that reconnection can occur at speeds ∼ 0.1 VA (Dere 1996).…”