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| Titel |
He2+ transport in the Martian upper atmosphere with an induced magnetic field |
| VerfasserIn |
Valery Shematovich, Dmitry Bisikalo, Gabriella Stenberg, Stas Barabash, Catherine Dieval, Jean-Claude Gérard |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250083280
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| Zusammenfassung |
| Solar wind helium may be a significant source of neutral helium in the Martian atmosphere.
The precipitating particles also transfer mass, energy and momentum. To investigate the
transport of He2+ in the upper atmosphere of Mars we have applied the Direct Simulation
Monte Carlo method to solve the kinetic equation. We calculate the upward He, He+ and
He2+ fluxes, resulting from energy spectra of the downgoing He2+ observed below 500 km
altitude by the ASPERA-3 instrument onboard Mars Express. The particle flux of the
downward moving He2+ ions was 1-2Ã106 cm-2 s-1, and the energy flux is equal to
9-10Ã10-3 erg cm-2 s-1. The calculations of the upward flux have been made for the
Martian atmosphere during solar minimum.
It was found, that if the induced magnetic field is not introduced in the simulations the
precipitating He2+ ions are not backscattered at all by the Martian upper atmosphere. If we
include a 20 nT horizontal magnetic field, a typical field measured by Mars Global Surveyor
(MGS) in the altitude range of 85 km – 500 km, we find that up to the 30% - 40% of the
energy flux of the precipitating He2+ ions is backscattered depending on the velocity
distribution of the precipitating particles. We thus conclude that the induced magnetic field
plays the crucial role in the transport of charged particles in the upper atmosphere of
Mars and, therefore, that it determines the energy deposition of the solar wind. |
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