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Instability of the magnetopause with a finite curvature radius and velocity shear
Arshukova I. L., Erkaev N. V., Biernat H. K.
Int. J. of Geomagnetism and Aeronomy. — 2002. — Vol. 3. — P. 27-34.
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Full text of the article [pdf, 238 Kb, in english]
Abstract
This article deals with the magnetohydrodynamic instability of the high
magnetic shear magnetopause, which is considered to be a thin layer with a constant
curvature radius and plasma velocity shear. In our model, the magnetic field and plasma
density are assumed to be piecewise constant in three regions: in the magnetosphere adjacent
to the magnetopause, in the magnetosheath, and inside a thin layer associated with the magnetopause. The plasma parameters and the magnetic field are assumed to obey the ideal incompressible magnetohydrodynamics. A Fourier analysis is used to calculate small
perturbations of magnetic field and plasma parameters near the magnetopause in a linear
approximation. The instability growth rate is obtained as a function of the angle between
the velocity vector and the geomagnetic field direction for different plasma bulk speeds,
wave numbers and curvature radii. The resulting instability is a mixture of interchange
and Kelvin-Helmholtz instabilities on a surface with a nonzero curvature. The instability
growth rate is an increasing function of the tangential velocity component perpendicular
to the magnetic field. On the other hand, the growth rate is a decreasing function of the
velocity component along the magnetic field.
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