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| Titel |
Filamentary Alfvénic structures excited at the edges of equatorial plasma bubbles |
| VerfasserIn |
R. Pottelette, M. Malingre, J. J. Berthelier, E. Seran, M. Parrot |
| 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 ; 25, no. 10 ; Nr. 25, no. 10 (2007-11-06), S.2159-2165 |
| Datensatznummer |
250015930
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| Publikation (Nr.) |
 copernicus.org/angeo-25-2159-2007.pdf |
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| Zusammenfassung |
| Recent observations performed by the French DEMETER satellite at altitudes
of about 710 km suggest that the generation of equatorial plasma bubbles
correlates with the presence of filamentary structures of field aligned
currents carried by Alfvén waves. These localized structures are located
at the bubble edges. We study the dynamics of the equatorial plasma bubbles,
taking into account that their motion is dictated by gravity driven and
displacement currents. Ion-polarization currents appear to be crucial for
the accurate description of the evolution of plasma bubbles in the high
altitude ionosphere. During their eastward/westward motion the bubbles
intersect gravity driven currents flowing transversely with respect to the
background magnetic field. The circulation of these currents is prohibited
by large density depressions located at the bubble edges acting as perfect
insulators. As a result, in these localized regions the transverse currents
have to be locally closed by field aligned currents. Such a physical process
generates kinetic Alfvén waves which appear to be stationary in the
plasma bubble reference frame. Using a two-dimensional model and "in situ"
wave measurements on board the DEMETER spacecraft, we give estimates for the
magnitude of the field aligned currents and the associated Alfvén
fields. |
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