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| Titel |
Kinetic Ballooning/Interchange Instability in a Bent Plasma Sheet |
| VerfasserIn |
E. V. Panov, R. Nakamura, W. Baumjohann, M. G. Kubyshkina, A. V. Artemyev, V. A. Sergeev, A. A. Petrukovich, V. Angelopoulos, K.-H. Glassmeier, J. P. McFadden, D. Larson |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062575
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| Zusammenfassung |
| We use THEMIS and GOES observations to investigate the plasma sheet evolution on 28
February 2008 between 6:50 and 7:50 UT, when there developed strong magnetic field
oscillations with period of 100 s. Using multi-spacecraft analysis of the plasma sheet
observations and an empirical plasma sheet model, we determine both the large-scale
evolution of the plasma sheet and the properties of the oscillations. We found that the
oscillations exhibited signatures of kinetic ballooning/interchange instability fingers that
developed in a bent current sheet. The interchange oscillations had a sausage structure,
propagated duskward at a velocity of about 100 km/s, and were associated with periodical
radial electron flows. We suggest that the observed negative gradient of the ZGSM magnetic
field component (-BZ--X) was a free energy source for the kinetic ballooning/interchange
instability. Tens of minutes later a fast elongation of ballooning/interchange fingers was
detected between 6 and 16Â RE downtail with the legnth-to-width ratio exceeding
20. The finger elongation ended with signatures of reconnection in an embedded
current sheet near the bending point. These observations suggest a complex interplay
between the midtail and near-Earth plasma sheet dynamics, involving localized
fluctuations both in cross-tail and radial directions before current sheet reconnection. |
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