Hall MHD effects on the 2D Kelvin-Helmholtz/tearing instability

The Kelvin-Helmholtz (KHI)/tearing (TMI) instability is studied with a 2D incompressible Hall MHD model. In the equilibrium configuration of interest, the magnetic and ion velocity fields are parallel and identically sheared. While in resistive MHD simultaneous growth of a TMI and a KHI is precluded, Hall physics, by decoupling electrons and ions, destabilizes both modes, leading to a more complex interaction. Nonlinearly, saturation occurs with the formation of a magnetic island and an ion flow vortex in both sub- and super-Alfvenic regimes. For moderately large c/w(pi), the electron flow shows good aligment with the magnetic field, while demagnetized ions still show KH activity. (C) 2003 Elsevier Science B.V. All rights reserved.