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| Titel |
Mirror structures above and below the linear instability threshold: Cluster observations, fluid model and hybrid simulations |
| VerfasserIn |
V. Génot, E. Budnik, P. Hellinger, T. Passot, G. Belmont, P. M. Trávníček, P.-L. Sulem, E. Lucek, I. Dandouras |
| 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 ; 27, no. 2 ; Nr. 27, no. 2 (2009-02-06), S.601-615 |
| Datensatznummer |
250016399
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| Publikation (Nr.) |
 copernicus.org/angeo-27-601-2009.pdf |
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| Zusammenfassung |
| Using 5 years of Cluster data, we present a detailed statistical analysis of
magnetic fluctuations associated with mirror structures in the magnetosheath.
We especially focus on the shape of these fluctuations which, in addition to
quasi-sinusoidal forms, also display deep holes and high peaks. The
occurrence frequency and the most probable location of the various types of
structures is discussed, together with their relation to local plasma
parameters. While these properties have previously been correlated to the
β of the plasma, we emphasize here the influence of the distance to the
linear mirror instability threshold. This enables us to interpret the
observations of mirror structures in a stable plasma in terms of bistability
and subcritical bifurcation. The data analysis is supplemented by the
prediction of a quasi-static anisotropic MHD model and hybrid numerical
simulations in an expanding box aimed at mimicking the magnetosheath plasma.
This leads us to suggest a scenario for the formation and evolution of mirror
structures. |
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