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| Titel |
The current-voltage relationship revisited: exact and approximate formulas with almost general validity for hot magnetospheric electrons for bi-Maxwellian and kappa distributions |
| VerfasserIn |
P. Janhunen  , A. Olsson |
| 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 ; 16, no. 3 ; Nr. 16, no. 3, S.292-297 |
| Datensatznummer |
250013196
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| Publikation (Nr.) |
 copernicus.org/angeo-16-292-1998.pdf |
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| Zusammenfassung |
We derive the current-voltage relationship in
the auroral region taking into account magnetospheric electrons for the
bi-Maxwellian and kappa source plasma distribution functions. The
current-voltage formulas have in principle been well known for a long time, but
the kappa energy flux formulas have not appeared in the literature before. We
give a unified treatment of the bi-Maxwellian and kappa distributions,
correcting some errors in previous work. We give both exact results and two
kinds of approximate formulas for the current density and the energy flux. The
first approximation is almost generally valid and is practical to compute. The
first approximation formulas are therefore suitable for use in simulations. In
the second approximation we assume in addition that the thermal energy is small
compared to the potential drop. This yields even simpler linear formulas which
are suitable for many types of event studies and which have a more transparent
physical interpretation than the first approximation formulas. We also show how
it is possible to derive the first approximation formulas even for those
distributions for which the exact results can not be computed analytically. The
kappa field-aligned conductance value turns out always to be smaller than the
corresponding Maxwellian conductance. We also verify that the obtained kappa
current density and energy flux formulas go to Maxwellian results when
κ→∞.
Key words. Current-voltage relationship ·
Bi-Maxwellian distributions · Kappa distribution |
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