Cassini observations of the thermal plasma in the vicinity of Saturn's main rings and the F and G rings
Article first published online: 11 JUN 2005
Copyright 2005 by the American Geophysical Union.
Geophysical Research Letters
Volume 32, Issue 14, 28 July 2005
How to Cite
2005), Cassini observations of the thermal plasma in the vicinity of Saturn's main rings and the F and G rings, Geophys. Res. Lett., 32, L14S04, doi:10.1029/2005GL022690., et al. (
- Issue published online: 11 JUN 2005
- Article first published online: 11 JUN 2005
- Manuscript Accepted: 16 MAY 2005
- Manuscript Revised: 3 MAY 2005
- Manuscript Received: 11 FEB 2005
 The ion mass spectrometer on Cassini detected enhanced ion flux near Saturn's main rings that is consistent with the presence of atomic and molecular oxygen ions in the thermal plasma. The ring “atmosphere” and “ionosphere” are likely produced by UV photosputtering of the icy rings and subsequent photoionization of O2. The identification of the O+ and O2+ ions is made using time-of-flight analysis and densities and temperatures are derived from the ion counting data. The ion temperatures over the main rings are a minimum near synchronous orbit and increase with radial distance from Saturn as expected from ion pick up in Saturn's magnetic field. The O2+ temperatures provide an estimate of the neutral O2 temperature over the main rings. The ion mass spectrometer also detected significant O2+ outside of the main rings, near the F ring. It is concluded that between the F and G rings, the heavy ion population most likely consists of an admixture of O2+ and water group ions O+, OH+, and H2O+.