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| Titel |
In situ evidence of breaking the ion frozen-in condition via the non-gyrotropic pressure effect in magnetic reconnection |
| VerfasserIn |
L. Dai, C. Wang, V. Angelopoulos, K.-H. Glassmeier |
| 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 ; 33, no. 9 ; Nr. 33, no. 9 (2015-09-17), S.1147-1153 |
| Datensatznummer |
250121247
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| Publikation (Nr.) |
 copernicus.org/angeo-33-1147-2015.pdf |
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| Zusammenfassung |
| For magnetic reconnection to proceed, the frozen-in condition for both ion
fluid and electron fluid in a localized diffusion region must be violated by
inertial effects, thermal pressure effects, or inter-species collisions. It
has been unclear which underlying effects unfreeze ion fluid in the diffusion
region. By analyzing in situ THEMIS (Time History of Events and Macroscale
Interactions during Substorms) spacecraft
measurements at the dayside magnetopause, we present clear evidence that the
off-diagonal components of the ion pressure tensor is mainly responsible for
breaking the ion frozen-in condition in reconnection. The off-diagonal
pressure tensor, which corresponds to a non-gyrotropic pressure effect in
this event, is a fluid manifestation of ion demagnetization in the diffusion
region. From the perspective of the ion momentum equation, the reported
non-gyrotropic ion pressure tensor is a fundamental aspect in specifying the
reconnection electric field that controls how quickly reconnection proceeds. |
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