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| Titel |
Warm trapped plasmaspheric plume at keV energy confined near the equator |
| VerfasserIn |
M. Yamauchi, I. Dandouras, F. Mazouz, H. Rème, S. Grimald, J. Pickett, H. Nilsson |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250058589
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| Zusammenfassung |
| Cluster perigee observation (at about 4 Earth radius) revealed that the trapped plasmaspheric
plasma in a very limited region near the magnetic equator, that was reported by Olsen et al.Ë(
1987) at tens eV range, are sometimes heated to more than hundred eV and up to keV, a much
higher energy than plasmaspheric ions. Yet, the composition data confirms the plasmaspheric
origin, with domination by H+ and existence of some amount of He+ without He++ or O+.
The pitch angle of this warm plasma plume is nearly 90° and is consistent with the
confinement within a few degrees latitude of the equator. In the energy-time domain, this
warm plasma plume is structureless although various forms of energy-time (or
energy-latitude) dispersion, including signatures of energy-dependent magnetic drift, are
sometimes recognized.
Together with this equatorially trapped warm plasma plume, electrostatic wave above the
upper hybrid frequency at (n + 1
2)fce (Jones et al., 1987) are observed, indicating that the
wave is directly related to this plume. The time scales of the plume formation and its decay
are both about 1-2 hours, and the wave activity follows the change in the warm
trapped plasma. The local time dependence and non-correlation to the substorm
activity indicate that this phenomenon is different from the plasmaspheric drain.
This phenomenon indicates the specialty of the equator even for hundreds eV ions. |
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