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| Titel |
Current-voltage relationship in the auroral particle acceleration region |
| VerfasserIn |
M. Morooka, T. Mukai, H. Fukunishi |
| 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 ; 22, no. 10 ; Nr. 22, no. 10 (2004-11-03), S.3641-3655 |
| Datensatznummer |
250015037
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| Publikation (Nr.) |
 copernicus.org/angeo-22-3641-2004.pdf |
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| Zusammenfassung |
| The current-voltage relationship in the auroral particle acceleration region
has been studied statistically by the Akebono (EXOS-D) satellite in terms of
the charge carriers of the upward field-aligned current. The Akebono
satellite often observed field-aligned currents which were significantly
larger than the model value predicted by Knight (1973). We compared the
upward field-aligned current estimated by three different methods, and found
that low-energy electrons often play an important role as additional current
carriers, together with the high-energy primary electrons which are expected
from Knight's relation. Such additional currents have been observed
especially at high and middle altitudes of the particle acceleration region.
Some particular features of electron distribution functions, such as
"cylindrical distribution functions" and "electron conics", have often been
observed coinciding with the additional currents. They indicated time
variability of the particle acceleration region. Therefore, we have concluded
that the low-energy electrons within the "forbidden" region of electron
phase space in the stationary model often contribute to charge carriers of
the current because of the rapid time variability of the particle
acceleration region. "Cylindrical distribution functions" are expected to be
found below the time-varying potential difference. We statistically examined the
locations of "cylindrical distribution function", and found that their
altitudes are related to the location where the additional currents have been
observed. This result is consistent with the idea that the low-energy
electrons can also carry significant current when the acceleration region
changes in time. |
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