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| Titel |
Vlasov simulations of parallel potential drops |
| VerfasserIn |
H. Gunell, J. Keyser, E. Gamby, I. Mann |
| 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 ; 31, no. 7 ; Nr. 31, no. 7 (2013-07-18), S.1227-1240 |
| Datensatznummer |
250019067
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| Publikation (Nr.) |
 copernicus.org/angeo-31-1227-2013.pdf |
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| Zusammenfassung |
| An auroral flux tube is modelled from the magnetospheric equator to the
ionosphere using Vlasov simulations.
Starting from an initial state, the evolution of the
plasma on the flux tube is followed in time.
It is found that when applying a voltage between the ends of the flux tube,
about two thirds of the potential drop is
concentrated in a thin double layer at approximately one Earth radius altitude.
The remaining part is situated in an extended
region 1–2 Earth radii above the double layer.
Waves on the ion timescale develop above the double layer, and they move
toward higher altitude at approximately the
ion acoustic speed. These waves are seen both in the electric field and as
perturbations of the ion and electron distributions, indicative of
an instability.
Electrons of magnetospheric origin become trapped between the
magnetic mirror and the double layer during its formation. At low altitude,
waves on electron timescales appear and are seen to be non-uniformly
distributed in space.
The temporal evolution of the potential profile and the total voltage
affect the double layer altitude, which decreases with an increasing
field aligned potential drop. A current–voltage relationship is found
by running several simulations with different voltages over the system,
and it agrees with the Knight relation reasonably well. |
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