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| Titel |
Foreshock-like density cavity in the outflow region of magnetotail reconnection |
| VerfasserIn |
C. L. Cai, I. Dandouras, H. Rème, J. B. Cao, G. C. Zhou, G. K. Parks, D. Fontaine |
| 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. 8 ; Nr. 27, no. 8 (2009-08-05), S.3043-3053 |
| Datensatznummer |
250016612
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3043-2009.pdf |
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| Zusammenfassung |
| During Cluster spacecraft crossing of the magnetotail, a
novel density depleted cavity in association with magnetic compressions in
the outflow region of reconnection was observed. It contains intense
reflected field-aligned particles, which are produced by a generation
mechanism similar to that of the terrestrial foreshock, and hence manifests
a foreshock-like morphology. In this cavity, reflected field-aligned proton
beams were observed and simultaneously the feature of magnetic-mirror
loss-cone proton distributions were found. Magnetic field fluctuations,
especially quasi-monochromatic oscillations, were recorded. Both the leading
egde and the ULF wave boundary of the ion foreshock are identified from the
time sequence of proton and magnetic field observations. Just upstream of
the leading egde of the ion foreshock, reflected field-aligned electrons
were detected, whose distribution has a narrow bump-on-tail pattern.
However, close to the shock front, reflected electrons with a broad
bump-on-tail pattern was measured. These two different manifestations of
reflected electrons reveal the differences in their microscopic physics of
the reflecting process. Moreover, a part of incident ions was further
accelerated in the cavity due to trans-time magnetic pumping which provides
another possible mechanism in the multi-step acceleration processes in
reconnection. |
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