ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-22-935-2004 Influence of the Hall term on KH instability and reconnection inside KH vortices Nykyri K. 1 Otto A. 2 The Blackett Laboratory, Imperial College, London, UK Geophysical Institute, University of Alaska, Fairbanks, USA 19 03 2004 22 3 935 949 Copyright: © 2004 K. Nykyri 2004 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/22/935/2004/angeo-22-935-2004.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/22/935/2004/angeo-22-935-2004.pdf

The Kelvin-Helmholtz instability (KHI) in its nonlinear stage can develop small-scale filamentary field and current structures at the flank boundaries of the magnetosphere. It has been shown previously with MHD simulations that magnetic reconnection can occur inside these narrow current layers, resulting in plasma transport from the solar wind into the magnetosphere. During periods of northward IMF, this transport is sufficient to generate a cold, dense plasma sheet on time scales consistent with satellite observations. However, when the length scales of these narrow current layers approach the ion inertia scale, the MHD approximation is not valid anymore and the Hall term in the Ohm's law must be included. We will study the influence of the Hall term on the KHI with 2-D Hall-MHD simulations and compare our results with corresponding MHD simulations. We estimate plasma transport velocities of the order of ~1.5km/s, thus confirming the results of the MHD approximation. However, the fine structure and the growth rates differ from the MHD approximation in an interesting way.<br><br> <b>Key words.</b> Magnetospheric physics (magnetopause, cusp and boundary layers; plasma waves and instabilities), Space plasma physics (transport processes; magnetic reconnection; numerical simulation studies; nonlinear phenomena; turbulence)