NEAR EQUALITY OF ION PHASE-SPACE DENSITIES AT EARTH, JUPITER, AND SATURN

Energetic ion phase space density profiles are strikingly similar in the inner magnetospheres of Earth, Jupiter, and Saturn for ions of first adiabatic invariant near 100 Mev/G and small mirror latitudes. Losses occur inside L approximately equals 7 for Jupiter and Saturn and inside L approximately equals 5 at Earth. At these L values there exist steep plasma density gradients at all three planets, associated with the Io plasma torus at Jupiter, the Rhea-Dione-Tethys torus at Saturn, and the plasmasphere at Earth. Measurements of ion flux tube contents at Jupiter and Saturn, by the low-energy charged particle experiment show that these are similar (for oxygen ions 5 APP 1STH L APP 1STH 9) to those at earth (protons 2 APP 1STH L APP 1STH 6). Furthermore, the thermal ion flux tube contents from Voyager plasma science data at Jupiter and Saturn are also very nearly equal, and again similar to those at Earth, differing by less than a factor of 3 at the respective L values.