HYBRID MODELING OF THE FORMATION OF THIN CURRENT SHEETS IN MAGNETOTAIL CONFIGURATIONS

Hybrid simulations are used to investigate the formation of a thin cur rent sheet inside the plasma sheet of a magnetotail-like configuration . The initial equilibrium is subjected to a driving electric field qua litatively similar to what would be expected from solar wind driving. As a result, we find the formation of a new current sheet, with a thic kness of approximately the ion inertial length. The current density in side the current sheet region is supplied largely by the electrons. Io n acceleration in the cross-tail direction is absent due since the dri ving electric field fails to penetrate into the equatorial region. The ions in the thin current sheet region exhibit anisotropies which appe ar to be driven by the bounce motion in the z direction between the in ward moving plasma sheet-lobe boundary.