|
|
 |
|
|
Ann. Geophys., 22, 935-949, 2004
www.ann-geophys.net/22/935/2004/
© European Geosciences Union 2004
Influence of the Hall term on KH instability and reconnection inside KH vortices
K. Nykyri1 and A. Otto2
1The Blackett Laboratory, Imperial College, London, UK
2Geophysical Institute, University of Alaska, Fairbanks, USA
Abstract. 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.
Key words. Magnetospheric physics (magnetopause, cusp
and boundary layers; plasma waves and instabilities), Space
plasma physics (transport processes; magnetic reconnection;
numerical simulation studies; nonlinear phenomena; turbulence)
Full Article in PDF (1752 KB) |
|
|
