Journal article
Ion Heating in the Martian Ionosphere
Journal of geophysical research. Space physics, Vol.122(10), pp.10,612-10,625
10/2017
DOI: 10.1002/2017JA024578
Abstract
Energetic O+ and O
2+ ions with energies of up to a few hundred eV are observed in the Martian ionosphere. Corresponding ion velocity distributions show ion conics, suggesting that the observed ion populations have been heated perpendicular to the local magnetic field before experiencing a magnetic mirror force. Magnetic field observations support these interpretations: wave power at the local O+ and O
2+ gyrofrequencies in the spacecraft frame is observed coincident with the energetic ions, within an apparent magnetic field bottle‐like topology. Analysis of the observed ion conics leads to estimates of ion temperatures of 10–30 eV. We suggest that the ion populations are initially heated perpendicular to the local magnetic field by wave power propagating inward from the Mars‐solar wind interaction. The local magnetic field “balloons out” in response to these enhanced ion temperatures and pressures. The resultant magnetic field topology is bottle like; the transversely heated ions would subsequently experience a magnetic mirror force in the converging field regions, agreeing with the reported observations. Such strong heating events that significantly increase the ion temperature and pressure, thereby decreasing the net magnetic field, are rare and seem to occur under specific interplanetary magnetic field orientations. Events were observed to span the upper exobase region and just above, a region characterized by significant ion densities in an increasingly collisionless domain. Ion heating in this region has the potential to drive significant ion outflows, thus contributing to atmospheric loss from the planet.
Key Points
Energetic ions of up to a few hundred eV are observed in the Martian ionosphere
Ion velocity distributions show ion conics, suggesting ions have been heated and experienced a magnetic mirror force
Heating events occur primarily on the dayside, suggesting that the Mars‐solar wind interaction influences the occurrence of such events
Details
- Title: Subtitle
- Ion Heating in the Martian Ionosphere
- Creators
- C. M Fowler - University of Colorado BoulderR. E Ergun - University of Colorado BoulderL Andersson - University of Colorado BoulderW. K Peterson - University of Colorado BoulderT Hara - University of California, BerkeleyJ Mcfadden - University of California, BerkeleyJ Espley - Goddard Space Flight CenterJ Halekas - University of IowaD. L Mitchell - University of California, BerkeleyC Mazelle - Université de ToulouseB. M Jakosky - University of Colorado Boulder
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.122(10), pp.10,612-10,625
- DOI
- 10.1002/2017JA024578
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 14
- Grant note
- NASA (NNH10CC04C)
- Language
- English
- Date published
- 10/2017
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199754902771
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