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| Titel |
Alfvèn wave ion acceleration at Mars |
| VerfasserIn |
Rickard Lundin, Anatol Guglielmi |
| 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 |
250034501
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| Zusammenfassung |
| Intense ULF wave activity characterizes the Martian plasma environment. The waves appear
to be generated by the shocked solar wind plasma (sheath), subsequently propagating into the
Martian induced magnetosphere. ULF waves are omnipresent in the Martian magnetosphere.
Even the ionosphere down to 300 km altitude (pericenter of Mars Express) is characterized
by strong density modulations in the ULF frequency range. Coincident with density
modulations is ion energization. At times ions are energized to the same velocity, i.e. the
energized ions has energies proportional to their mass, but the general feature is a
mix of energy- and velocity-dependent energization. We consider the multispecies
acceleration of ionospheric ions above Mars, comparing ion data from the ASPERA ion
instrument on Mars Express with the wave activity inferred from the ion and electron
modulation in the ULF frequency range. Due to the lack of magnetometer data we are
unable to determine the wave mode, but the coincident modulation of ions and
electrons implies MHD waves. We use ponderomotive force theory to compute ion
energization by MHD waves, and compare with observions. We also consider wave
focussing onto the plasma sheet as a means of further ion energization in the tail. |
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