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| Titel |
Dual source populations of substorm-associated ring current ions |
| VerfasserIn |
M. Yamauchi, Y. Ebihara, I. Dandouras, H. Rème |
| 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 ; 27, no. 4 ; Nr. 27, no. 4 (2009-04-01), S.1431-1438 |
| Datensatznummer |
250016469
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| Publikation (Nr.) |
 copernicus.org/angeo-27-1431-2009.pdf |
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| Zusammenfassung |
| Sources of low-energy ring current ions in the early morning sector
(eastward drifting energy domain of about <5 keV) are examined using both
statistical analyses and numerical tracing methods (phase-space mapping and
simulation). In about 90% of Cluster perigee traversals at 02~07
local time, these low-energy ring current ions have dual ion populations:
one is wedge-like energy-dispersed ions, and the other is a band-like ions
over different latitudes in a narrow energy range at the upper energy
threshold of the wedge-like energy-dispersed ions. Both components are most
likely created during past substorm activities. Numerical tracing results
strongly suggest that these two components have different sources with
different temperatures and elapsed times. The band-like part most likely
comes from ions with plasma sheet temperature (~1 keV), and the
energy-dispersed part most likely comes from cold ions (temperature <0.1 keV).
The source density of the cold component (0.2~0.5×106/m3)
is slightly less than that of the hot component (0.5×106/m3), while Cluster observation shows slightly higher
density for the wedge-like part than the low-energy band-like part. The hot
source component also explains the observed high-energy (>10 keV) ions
drifting westward after adiabatic energization in the nightside under
time-varying electric field. The wedge-like part has much shorter elapsed
time, i.e., less charge-exchange loss, than the band-like part. |
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