Contribution of relaxation sounding experiments to the understanding of magnetospheric processes.

Relaxation Sounding (RS) experiments onboard GEOS and ISEE provided a reliable and permanent determination of the plasma density during the whole lives of the spacecraft. Plasmaspheric bulge location and the role of equatorial density in Pc5 events were studied. Accurate determination of the plasma characteristic frequencies and the very good frequency resolution of the receiver were used to investigate banded electron cylotron harmonic waves, and natural waves upstream of the Earth's bow shock. The good time resolution of the RS allowed measurements of fast density variations, for compressible MHD waves and magnetospheric boundaries.-from STAR, 23(14), 1985