Energetic particles at Uranus.

This chapter reviews the energetic particle measurements by the Low Energy Charged Particles and Cosmic Ray instruments on the Voyager 2 spacecraft in the magnetosphere of Uranus. Upstream ion events were observed outside the Uranian bow shock, probably produced by ion escape from the magnetosphere. However, no energetic neutral particle fluxes were observed. The magnetospheric composition is totally dominated by protons, with only a trace abundance of H₂⁺ and no evidence for He or heavy ions; the Uranian atmosphere must be the principal plasma source. These results and plasma wave data suggest the existence of structures analogous to Earth's plasmasphere and plasmapause. The Uranian magnetosphere is the most Earth-like of the giant planet magnetospheres so far studied.