Martin Waara (IRF)Date:
AniaraOxygen ion energization observed at high altitudes
Swedish Institute of Space Physics
We present three studies of heating perpendicular to the geomagnetic field of outflowing oxygen ions in the high altitude cusp/mantle region.
In the first study we present a clear example of local ion energization at much higher altitude than usually reported (12RE). In contrast to many events at lower altitudes, it is not likely that the locally observed wave fields can cause the observed ion energization.
The second study is a statistical study of the low (< 1 Hz) frequency electric and magnetic field spectral densities. In this study we provide average values of a coefficient describing diffusion in ion velocity space at different altitudes, which can be used in studies of ion energization and outflow. The observed average waves can explain the average O+ energies measured in the high altitude (8-15 RE) cusp/mantle region of the terrestrial magnetosphere according to our test particle calculations.
In the last study we show a clear correlation between temperature and wave intensity at the gyrofrequency at each measurement point. This correlation agrees approximately with the predictions of the mean-particle theory.Created 2011-01-14 14:12:39 by Mats HolmströmLast changed 2011-01-20 22:52:26 by Mats Holmström