The density, temperature, and velocity of plasma in the inner magnetosphere (L<12) of Saturn are well determined from observations by the Voyager plasma science experiment. We combine the ion and electron data sets from both Voyager flybys to produce an overview of the Saturnian plasma environment. A small spacecraft potential of -10 to -20 V is found to to a plausible mechanism for reconciling differences between the observed ion and electron densities. Electron and ion measurements from the Voyager 1 and 2 encounters are combined to produce a map of density contours inside L=12. This contour map incorporates all the available Voyager thermal plasma data in this region under the assumption that the inner magnetosphere was stable during the nine months between encounters. In the model, heavy ions are confined to a narrow region near the equator because of their large temperature anisotropy and their low thermal velocity parallel to the magnetic field. The protons are spread much more widely in latitude. The model does not satisfactorily reproduce the densities of the suprathermal electrons observed inside L=7, but these constitute only a few precent of the total electron density. The oxygen flux tube content decreases rapidly inside L=5, indicating that losses occur in this region. The lifetime of neutral atoms in the inner magnetosphere is a strong function of latitude, with lifetimes varying from weeks to years. ¿ American Geophysical Union 1990 |