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| Titel |
INTERBALL-Auroral observations of 0.1-12 keV ion gaps in the diffuse auroral zone |
| VerfasserIn |
R. A. Kovrazhkin, J.-A. Sauvaud, D. C. Delcourt |
| 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 ; 17, no. 6 ; Nr. 17, no. 6, S.734-742 |
| Datensatznummer |
250013771
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| Publikation (Nr.) |
 copernicus.org/angeo-17-734-1999.pdf |
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| Zusammenfassung |
We examine ion flux dropouts detected by
INTERBALL-Auroral upon traversal of the auroral zone at altitudes of \sim13 000
up to 20 000 km. These dropouts which we refer to as "gaps", are
frequently observed irrespectively of longitudinal sector and appear
characteristic of INTERBALL-Auroral ion spectrograms. Whereas some of these gaps
display a nearly monoenergetic character (~12 keV), others occur at energies of
a few hundreds of eV up to several keV. INTERBALL-Auroral data exhibit the
former monoenergetic gap variety essentially in the evening sector. As examined
in previous studies, these gaps appear related to transition from particle
orbits that are connected with the magnetotail plasma source to closed orbits
encircling the Earth. The latter gap variety, which spreads over several
hundreds of eV to a few keV is often observed in the dayside magnetosphere. It
is argued that such gaps are due to magnetospheric residence times well above
the ion lifetime. This interpretation is supported by numerical orbit
calculations which reveal extremely large (up to several tens of hours) times of
flight in a limited energy range as a result of conflicting E × B
and gradient-curvature drifts. The characteristic energies obtained numerically
depend upon both longitude and latitude and are quite consistent with those
measured in-situ.
Key words. Magnetospheric physics (auroral phenomena;
plasma convection) |
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