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| Titel |
Cluster and TC-1 observation of magnetic holes in the plasma sheet |
| VerfasserIn |
W. J. Sun, Q. Q. Shi, S. Y. Fu, Z. Y. Pu, M. W. Dunlop, A. P. Walsh, Q. G. Zong, T. Xiao, C. L. Tang, H. Rème, C. Carr, E. Lucek, A. Fazakerley |
| 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 (2012-03-26), S.583-595 |
| Datensatznummer |
250017204
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| Publikation (Nr.) |
 copernicus.org/angeo-30-583-2012.pdf |
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| Zusammenfassung |
| Magnetic holes with relatively small scale sizes, detected by
Cluster and TC-1 in the magnetotail plasma sheet, are studied in
this paper. It is found that these magnetic holes are spatial
structures and they are not magnetic depressions generated by the
flapping movement of the magnetotail current sheet. Most of the
magnetic holes (93%) were observed during intervals with
Bz larger than Bx, i.e. they are more likely to
occur in a dipolarized magnetic field topology. Our results also
suggest that the occurrence of these magnetic holes might have a
close relationship with the dipolarization process. The magnetic
holes typically have a scale size comparable to the local proton
Larmor radius and are accompanied by an electron energy flux
enhancement at a 90° pitch angle, which is quite different
from the previously observed isotropic electron distributions
inside magnetic holes in the plasma sheet. It is also shown that
most of the magnetic holes occur in marginally mirror-stable
environments. Whether the plasma sheet magnetic holes are
generated by the mirror instability related to ions or not,
however, is unknown. Comparison of ratios, scale sizes and
propagation direction of magnetic holes detected by Cluster and
TC-1, suggests that magnetic holes observed in the vicinity of the
TC-1 orbit (~7–12 RE) are likely to be further
developed than those observed by Cluster (~7–18 RE). |
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