In Situ Plasma Diagnostics from RPI Experiment on IMAGE Using the Thermal
Noise Spectroscopy Method

Issautier, K., P. Fˇdou, J.-L. Bougeret, R. Manning

Radio sounding can be used to obtain accurate remote sensing as well as in
situ measurements in space plasmas. The IMAGE spacecraft, launched in March
2000, is dedicated to imaging the Earth's magnetosphere. 

We analyse the power spectra measured by the Radio Plasma Imager (RPI) in
the passive mode, using the 20-m long dipole antenna on IMAGE, during its
passages through the Earth's plasmasphere. 

Below the upper hybrid frequency, fUH, the spectra are weakly banded between
gyroharmonics. These observations were interpreted by Meyer-Vernet [1993] in
magnetized space plasmas as quasi-thermal fluctuations in Bernstein waves.
It was already applied in the Io plasma torus using the ULYSSES radio
observations and in the Earth's plasmasphere with the WIND/TNR experiment.
From the gyroharmonic frequencies, we will obtain an independent measure of
the magnetic field magnitude. From fUH, the local electron density will be
derived and we will finally give a preliminary estimation of the local
electron temperature.

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To be presented at the Magnetospheric Imaging Workshop, 
Yosemite National Park, California, U.S.A., Feb. 5-8, 2002.