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| Titel |
On the propagation of MHD eigenmodes in a 2-D-magnetotail |
| VerfasserIn |
G. Fruit, P. Louarn |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 29, no. 1 ; Nr. 29, no. 1 (2011-01-05), S.19-30 |
| Datensatznummer |
250016944
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| Publikation (Nr.) |
 copernicus.org/angeo-29-19-2011.pdf |
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| Zusammenfassung |
| The propagation of MHD kink/sausage low frequency waves in the magnetotail with a finite normal
Bz component is addressed. The general idea is to investigate how a finite Bz may affect the
propagation of MHD eigenmodes in the plasma sheet. The standard MHD equations are linearized and
solved numerically in a modified Harris sheet. Boundary conditions are chosen such that energy
flows outward of the frame box (free propagating system). An initial perturbation is set up in the
pressure gradient term and the wave energy is then traced in the system. While a pure 1-D-Harris
sheet constitutes an efficient wave guide for MHD eigenmodes, the introduction of a finite Bz in
the zero-order geometry changes significantly the propagation of MHD fluctuations: the eigenmodes
propagate much more slowly and carry little energy whereas a pure sound wave is excited and
propagates isotropically in the system. The presence of a finite Bz thus tends to inhibit the
MHD propagation of energy along the plasma sheet. It tends rather to spread the energy throughout
the magnetotail. As an application of the above study, the role of a permanent X-point structure on
MHD propagation in the plasma sheet is also explored. |
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