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The nonlinear breakup of a magnetic layer: instability to interchange modes

Published online by Cambridge University Press:  21 April 2006

F. Cattaneo  and
D. W. Hughes
F. Cattaneo
Affiliation:
Institute for Laboratory Astrophysics, University of Colorado, Boulder. CO 80309. USA Present address: Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW, U.K.
D. W. Hughes
Affiliation:
Institute for Laboratory Astrophysics, University of Colorado, Boulder. CO 80309. USA
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Abstract

Motivated by considerations of the solar toroidal magnetic field we have studied the behaviour of a layer of uniform magnetic field embedded in a convectively stable atmosphere. Since the field can support extra mass, such a configuration is top-heavy and thus instabilities of the Rayleigh-Taylor type can occur. For both static and rotating basic states we have followed the evolution of the interchange modes (no bending of the field lines) by integrating numerically the nonlinear compressible MHD equations. The initial Rayleigh-Taylor instability of the magnetic field gives instabilities to strong shearing motions, thereby exciting secondary Kelvin-Helmholtz instabilities which wrap the gas into regions of intense vorticity. The subsequent motions are determined primarily by the strong interactions between vortices which are responsible for the rapid disruption of the magnetic layer.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 196 , November 1988 , pp. 323 - 344
Copyright
© 1988 Cambridge University Press

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