Ray tracing studies for the plasmapause sounding from a geostationary satellite

The transmission of VLF/LF waves from a geostationary satellite toward the plasmasphere is simulated numerically by a ray tracing technique in order to assess the feasibility of designing a plasmasphere sounder to be installed aboard such a satellite. Ray paths and relationships of virtual echo range vs sounding frequency (so-called plasmagrams) are computed for various plasmapause positions and various steepnesses of the electron density gradient in the plasmasphere. Computed ray paths were found to deviate in general from the mirror reflection case. The general features of computed plasmagrams are very similar to those of topside ionograms, although the distance of propagation is very different.