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| Titel |
Low-frequency linear waves and instabilities in uniform and stratified plasmas: the role of kinetic effects |
| VerfasserIn |
K. M. Ferrière |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 11, no. 5/6 ; Nr. 11, no. 5/6 (2004-12-23), S.731-743 |
| Datensatznummer |
250009001
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| Publikation (Nr.) |
 copernicus.org/npg-11-731-2004.pdf |
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| Zusammenfassung |
| We review the basic approximations underlying magnetohydrodynamic (MHD)
theory, with special emphasis on the closure approximations, i.e.
the approximations used in any fluid approach to close the hierarchy
of moment equations.
We then present the main closure models that have been constructed
for collisionless plasmas in the large-scale regime, and we describe
our own mixed MHD-kinetic model, which is designed to study low-frequency
linear waves and instabilities in collisionless plasmas.
We write down the full dispersion relation
in a new, general form, which gathers all the specific features
of our MHD-kinetic model into four polytropic indices, and
which can be applied to standard adiabatic MHD and to double-adiabatic MHD
through a simple change in the expressions of the polytropic indices.
We study the mode solutions and the stability properties of the full
dispersion relation in each of these three theories, first in the case
of a uniform plasma, and then in the case of a stratified plasma.
In both cases, we show how the results are affected by the collisionless
nature of the plasma. |
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