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| Titel |
Conditions for substorm onset by the fast reconnection mechanism |
| VerfasserIn |
M. Ugai |
| 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 ; 26, no. 12 ; Nr. 26, no. 12 (2008-12-02), S.3875-3883 |
| Datensatznummer |
250016316
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| Publikation (Nr.) |
 copernicus.org/angeo-26-3875-2008.pdf |
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| Zusammenfassung |
| The fast reconnection mechanism,
involving slow shocks and Alfvénic fast
plasma jets, is most responsible for the
explosive conversion of magnetic energy associated
with geomagnetic substorms
and solar flares. In this paper,
the spontaneous fast reconnection
model is applied to well-known phenomena of
substorms. When the east-west width of the tail
current sheet becomes 3–4 times larger than its
north-south thickness, the fast
reconnection mechanism can fully be established, which
may lead to substorm onset. The resulting Alfvénic
jet can exactly explain, both qualitatively
and quantitatively, the in-situ satellite
observations of the traveling
compression regions (TCRs) associated with
large-scale plasmoids propagating down the tail.
Also, the earthward fast reconnection jet causes drastic
magnetic field dipolarization, so that the sheet
current ahead of the magnetic loop of closed field
lines suddenly turns its direction toward the
loop footpoint and a large-scale current wedge is
formed according to the growth of
field-aligned currents. It is demonstrated
that an MHD generator arises ahead
of the magnetic loop and drives the
current wedge to distinctly enhance the
current density in a pair of thin layers of the
loop footpoint, giving rise to drastic
heating in the form of two ribbons. |
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