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| Titel |
Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes |
| VerfasserIn |
H. Matsui, F. Darrouzet, J. Goldstein, P. A. Puhl-Quinn, Yu. V. Khotyaintsev, P.-A. Lindqvist, E. Georgescu, C. G. Mouikis, R. B. Torbert |
| 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 ; 30, no. 3 ; Nr. 30, no. 3 (2012-03-29), S.623-637 |
| Datensatznummer |
250017207
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| Publikation (Nr.) |
 copernicus.org/angeo-30-623-2012.pdf |
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| Zusammenfassung |
| In this event study, small-scale fluctuations in plasmaspheric plumes with time scales of
~10 s to minutes in the spacecraft frame are examined. In one event, plasmaspheric plumes are observed by
Cluster, while IMAGE measured density enhancement at a similar location.
Fluctuations in density exist in plumes as detected by Cluster and
are accompanied by
fluctuations in magnetic fields and electric fields. Magnetic fluctuations
are transverse and along the direction of the plumes. The E/B ratio is
smaller than the Alfvén velocity.
Another similar event is briefly presented. We then consider physical properties of
the fluctuations.
Alfvén mode modulated by the feedback
instability is one possibility, although non-local generation is likely.
It is hard to show that the fluctuations represent a fast mode.
Interchange motion is possible due to the consistency
between measurements and expectations. The energy source could be a
pressure or density gradient in plasmaspheric plumes. When more events are accumulated
so that statistical analysis becomes feasible, this type of study will be useful to understand the time evolution of plumes. |
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