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Electron Temperature and Density at High Latitude

C. A. Kletzing

Department of Physics and Astronomy,University of Iowa, Iowa City, IA, USA

F. S. Mozer

Space Science Laboratory, University of California, Berkeley, CA, USA

R. B. Torbert

Department of Physics and Institute for Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA

Abstract: The background electron temperature and density at altitudes between 1000 and 8000 km at latitudes greater than 60$^\circ$ invariant latitude have been determined from swept Langmuir probe measurements from the S3-3 satellite. These plasma parameters are determined by fitting the measured probe current-voltage relation to the expected theoretical response. Statistically acceptable fits are found for approximately 20% of the measurements and do not include measurements within the auroral density cavity. The derived parameters show a density dependence which is an inverse a power law with increasing altitude and with a typical density of 10 cm-3 at 8000 km in altitude. The electron temperature shows a slight increase with altitude but is less than 5 eV for almost all measurements. These results suggest that the background plasma outside of density cavities on high latitude field lines below 8000 km is dominated by cold plasma of ionospheric origin which is at least an order of magnitude more dense than hotter magnetospheric components.


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Craig A. Kletzing