Oxygen ion energization observed at high altitudes
We present a case study of significant heating (up to 8 keV) perpendicular to the geomagnetic field of outflowing oxygen ions at high altitude (12 <I>R</I><sub>E</sub>) above the polar cap. The shape of the distribution functions indicates that most of the heating occurs l...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2010-04-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/28/907/2010/angeo-28-907-2010.pdf |
| Summary: | We present a case study of significant heating (up to 8 keV) perpendicular to
the geomagnetic field of outflowing oxygen ions at high altitude (12 <I>R</I><sub>E</sub>)
above the polar cap. The shape of the distribution functions indicates that
most of the heating occurs locally (within 0.2–0.4 <I>R</I><sub>E</sub> in altitude). This
is a clear example of local ion energization at much higher altitude than
usually reported. In contrast to many events at lower altitudes, it is not
likely that the locally observed wave fields can cause the observed ion
energization. Also, it is not likely that the ions have drifted from some
nearby energization region to the point of observation. This suggests that
additional fundamentally different ion energization mechanisms are present at
high altitudes. One possibility is that the magnetic moment of the ions is
not conserved, resulting in slower outflow velocities and longer time for ion
energization. |
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| ISSN: | 0992-7689 1432-0576 |