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Ann. Geophys., 17, 595-603, 1999
www.ann-geophys.net/17/595/1999/
© European Geosciences Union 1999
New aspects of plasma sheet dynamics - MHD and kinetic theory
H. Wiechen
Institut für Astronomie und Astrophysik, Ludwig-Maximilians-Universität München, Scheinerstr. 1, D-81679 Munich, Germany
Abstract. Magnetic reconnection is a process of
fundamental importance for the dynamics of the Earth's plasma sheet. In this
context, the development of thin current sheets in the near-Earth plasma sheet
is a topic of special interest because they could be a possible cause of
microscopic fluctuations acting as collective non-idealness from a macroscopic
point of view. Simulations of the near-Earth plasma sheet including boundary
perturbations due to localized inflow through the northern (or southern) plasma
sheet boundary show developing thin current sheets in the near-Earth plasma
sheet about 810 RE tailwards of the Earth. This location is
largely independent from the localization of the perturbation. The second part
of the paper deals with the problem of the macroscopic non-ideal consequences of
microscopic fluctuations. A new model is presented that allows the quantitative
calculation of macroscopic non-idealness without considering details of
microscopic instabilities or turbulence. This model is only based on the
assumption of a strongly fluctuating, mixing dynamics on microscopic scales in
phase space. The result of this approach is an expression for anomalous
non-idealness formally similar to the Krook resistivity but now describing the
macroscopic consequences of collective microscopic fluctuations, not of
collisions.
Key words. Magnetospheric physics (plasma sheet) ·
Space plasma physics (kinetic and MHD theory; magnetic reconnection)
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