HR: 0800h
AN: SM11A-1168    [Abstracts]
TI: Magnetotail thin currents sheet equilibrium: Influence of electron pressure anisotropy
AU: Malova, H V
EM: mlv@dec1.sinp.msu.ru
AF: Space Research Institute, RAS, Moscow, 117810 Russian Federation
AU: * Sharma, A S
EM: ssh@umd.edu
AF: University of Maryland, Department of Astronomy, College Park, MD 20742 United States
AU: Zelenyi, L M
EM: lzelenyi@iki.rssi.ru
AF: Space Research Institute, RAS, Moscow, 117810 Russian Federation
AU: Popov, V Y
AF: Moscow State University, Faculty of Physics, Moscow, 119899 Russian Federation
AU: Delcourt, D
AF: Centre d'Etude des Environnements Terrestre et Planetaires, CNRS, Saint Maur des Fosse, 8679 France
AB: The magnetotail current sheet is the site of magnetic energy storage and subsequent release during substorms, and thus plays a key role in the evolution of the magnetosphere. Recent multi-spacecraft measurements, especially by CLUSTER, have motivated many studies, in particular their small scale and multi-dimensional structure. A self-consistent 1D analytical model of thin current sheets in which the tension of the magnetic field lines is balanced by the ion inertia rather than by the plasma pressure gradients was developed earlier and this model is used to study the effect of electron anisotropy and the electrostatic field that ensures quasi-neutrality. It is assumed that the electron motion is fluid-like in the direction perpendicular to the magnetic field and fast enough to support quasi-equilibrium Boltzmann distribution along the field lines. Electrostatic effects lead to a narrow but sharp peak of electron current in the very center of the sheet due to fast curvature drift of the particles in this region. The corresponding magnetic field profile becomes much steeper near the neutral plane although the total cross-tail current is dominated by the ion contribution. The dependence of electrostatic effect on the ion to electron temperature ratio, the curvature of the magnetic field lines, and the average electron magnetic moment are also analyzed. The implications of these effects on the fine structure of thin current sheets and their impact on substorm dynamics will be presented.
DE: 7827 Kinetic and MHD theory
DE: 7835 Magnetic reconnection
DE: 2744 Magnetotail
DE: 2764 Plasma sheet
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting