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| Titel |
Magnetic field aligned potential drops in the magnetosphere, in the laboratory, and in Vlasov simulations |
| VerfasserIn |
Herbert Gunell, Johan De Keyser, Emmanuel Gamby |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037140
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| Zusammenfassung |
| Electric fields parallel to the magnetic fields are known to exist in the auroral zone, and they
are known to contribute to the acceleration of auroral electrons. Magnetic field aligned
electric fields can be supported by the magnetic mirror field, giving rise to a quasi-neutral
potential drop that extends over great distances in space (Alfvén and Fälthammar, Cosmical
Electrodynamics, 2nd edition, 1963).
Early theory included stationary kinetic models of the potential profile and the
relationship between the field aligned current and the total potential drop along the field line
(Knight, Planetary and Space Science, vol. 21, 741-750, 1973). Later fluid models have been
used to study Alfvén waves, and buildup of the electrostatic field (e.g. Rönnmark and
Hamrin, JGR, vol. 105, 25333–25344, 2000). Recently, combined approaches have
also been used where particle simulations have been used to provide non-local
kinetic closure of the fluid equations (Vedin and Rönnmark, JGR, vol. 111, 12201,
2006).
Recent observations have shown that electric double layers play an important role in
auroral physics (e.g. Ergun, et al., Physics of Plasmas, vol. 9, 3685-3694, 2002). These are
space charge layers embedded in the plasma, and constitute local violations to the assumption
of quasi-neutrality.
We present results from Vlasov simulations of magnetic field aligned potential drops in a
model that is one-dimensional in configuration space and two-dimensional in velocity space.
The model is verified by comparison with a double layer experiment in the laboratory, and it
is then applied to the auroral field lines. |
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