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| Titel |
A statistical study of field-aligned electron beams associated with ion conics events |
| VerfasserIn |
W. Miyake, T. Mukai, N. Kaya |
| 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 ; 16, no. 8 ; Nr. 16, no. 8, S.940-947 |
| Datensatznummer |
250013391
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| Publikation (Nr.) |
 copernicus.org/angeo-16-940-1998.pdf |
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| Zusammenfassung |
A statistical study of field-aligned electron
beams associated with upflowing ion conics is presented from Exos-D (Akebono)
observations below 10 000 km. The electron beams are narrowly collimated along
the field line and generally have energies of several tens of eV. They are
divided in the analysis into three types: upflowing, downflowing, and
counterstreaming. All the types of electron beams are almost equivalent in their
energy and pitch angle characteristics and their association rate with upflowing
ion events. About 50% of ion conics are found to be coincident with
field-aligned electron beams. There is also a correlation in energy between the
field-aligned electrons and ion conics. These show that the association is not a
mere coincidence but rather that the field-aligned acceleration of electrons is
related to the perpendicular energization of ions. The association rate of
upflowing electrons is high on the nightside, while that of downflowing
electrons is high on the dayside. The association rate of downflowing electrons
is high at low altitudes, and the rates of the three types of electron beams
become equivalent at high altitudes. Data indicate that the height of the
electron acceleration region is lower on the nightside. It is suggested that the
average height of the electron acceleration region is around the satellite
apogee (–10000 km), and the average thickness of the region is about thousands
km.
Key words. Ionosphere-magnetosphere interactions ·
Particle acceleration · Auroral phenomena |
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