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| Titel |
Outflow of low-energy O+ ion beams observed during periods without substorms |
| VerfasserIn |
G. K. Parks, E. Lee, S. Y. Fu, M. Fillingim, I. Dandouras, Y. B. Cui, J. Hong, 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 ; 33, no. 3 ; Nr. 33, no. 3 (2015-03-17), S.333-344 |
| Datensatznummer |
250121176
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| Publikation (Nr.) |
 copernicus.org/angeo-33-333-2015.pdf |
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| Zusammenfassung |
| Numerous observations have shown that ions flow out of the ionosphere
during substorms with more fluxes leaving as the substorm intensity increases
(Wilson et al., 2004). In this article we show observations of low-energy (few
tens of electron volts) ionospheric ions flowing out periods without substorms,
determined using the Wideband Imaging Camera (WIC) and Auroral Electrojet (AE) indices. We use
Cluster ion composition data and show the outflowing ions are field-aligned H+,
He+ and O+ beams accelerated to energies of ~40–80 eV, after
correcting for spacecraft potential. The estimated fluxes of the low-energy
O+ ions measured at ~20 000 km altitude are >103–105 cm−2 s.
Assuming the auroral oval is the source of the escaping ions, the measured
fluxes correspond to a flow rate of ~1019–1021 ions s−1
leaving the ionosphere. However, periods without substorms can persist for hours
suggesting the low-energy ions flowing out during these times could be
a major source of the heavy ion population in the plasma sheet and lobe. |
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