Energetic particle injections in Saturn's magnetosphere

Abstract

Measurements from the Cassini Magnetospheric Imaging Instrument (MIMI) beginning in July 2004 reveal that sudden planetward injections of energetic ions (5–200 keV) and electrons (20–200 keV) over confined regions of azimuth are pervasive events in Saturn's magnetosphere over the radial range of 3.8 to 11.2 Saturn radii (R S ). Saturn is thus similar to both Earth and Jupiter in the pervasiveness of such injections. At Saturn with Cassini, unlike Jupiter with Galileo, effects of the large radial gradients in the global azimuthal rotational flow pattern often dominates the dispersive particle injection signatures. Accurate knowledge of rotational flow patterns is required to calculate the age and formation positions of injections that are more than several hours old. Here we develop procedures to derive the needed flow profiles from the injections themselves.