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| Titel |
On MHD waves, fire-hose and mirror instabilities in anisotropic plasmas |
| VerfasserIn |
L.-N. Hau, B.-J. Wang |
| 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 ; 14, no. 5 ; Nr. 14, no. 5 (2007-09-03), S.557-568 |
| Datensatznummer |
250012272
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| Publikation (Nr.) |
 copernicus.org/npg-14-557-2007.pdf |
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| Zusammenfassung |
| Temperature or pressure anisotropies are characteristic of space plasmas,
standard magnetohydrodynamic (MHD) model for describing large-scale plasma
phenomena however usually assumes isotropic pressure. In this paper we
examine the characteristics of MHD waves, fire-hose and mirror instabilities
in anisotropic homogeneous magnetized plasmas. The model equations are a set
of gyrotropic MHD equations closed by the generalized Chew-Goldberger-Low
(CGL) laws with two polytropic exponents representing various thermodynamic
conditions. Both ions and electrons are allowed to have separate plasma
beta, pressure anisotropy and energy equations. The properties of linear MHD
waves and instability criteria are examined and numerical examples for the
nonlinear evolutions of slow waves, fire-hose and mirror instabilities are
shown. One significant result is that slow waves may develop not only mirror
instability but also a new type of compressible fire-hose instability. Their
corresponding nonlinear structures thus may exhibit anticorrelated density
and magnetic field perturbations, a property used for identifying slow and
mirror mode structures in the space plasma environment. The
conditions for nonlinear saturation of both fire-hose and mirror
instabilities are examined. |
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