Energetic ion dynamics in Jupiter's plasma sheet

A systematic study of energetic ion trajectories in Jupiter's plasma sheet region predicts a significant role for both regular and stochastic types of motion and reveals several aspects of the ion dynamics that aid in the int erpretation of Galileo observations. The motion is generally confined to th e vicinity of the current sheet in a way that is proportional to the variab le current sheet thickness as seen in the particle and field data. The radi al extent of the trajectories increases with rigidity and initial radial di stance from the planet, explaining the corresponding lack of high-rigidity ions and decreasing radial gradients at lower rigidity. Ion intensity incre ases associated with changes in current sheet thickness suggest an accelera tion region at similar to 25 to 30 R-J. Energy dispersion in ion events at larger radial distances can be explained by such a source combined with ela stic ion scattering.