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GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L04810, doi:10.1029/2003GL018899, 2004

Energetic ion composition in Saturn's magnetosphere revisited

C. Paranicas

Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland, USA


R. B. Decker

Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland, USA


B. H. Mauk

Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland, USA


S. M. Krimigis

Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland, USA


T. P. Armstrong

Fundamental Technology, Lawrence, Kansas, USA


S. Jurac

Massachusetts Institute of Technology, Cambridge, Massachusetts, USA


Abstract

We present a new analysis of the composition of energetic charged particles in Saturn's inner magnetosphere. This analysis is motivated by a discovery made after the Voyager 1 and 2 Saturn encounters of penetrating electrons in some total ion measurement channels of the Low Energy Charged Particle detectors. From this new analysis, we predict that there is no significant increase in the ratio of heavy energetic ions to protons inward of the orbit of the satellite Dione, as previously thought. This implies that energetic ion sputtering of the icy rings and satellites produces much less water vapor than has been assumed based on past composition estimates. For protons between about 500 keV and a few MeV, we observe a decrease in measured flux inward of about L = 6 and suggest the cause of this decrease is not well understood.

Received 22 October 2003; accepted 2 February 2004; published 28 February 2004.

Index Terms: 2720 Magnetospheric Physics: Energetic particles, trapped; 6275 Planetology: Solar System Objects: Saturn; 5780 Planetology: Fluid Planets: Tori and exospheres; 5737 Planetology: Fluid Planets: Magnetospheres (2756); 5704 Planetology: Fluid Planets: Atmospheres—composition and chemistry.

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 375285 bytes)

Citation: Paranicas, C., R. B. Decker, B. H. Mauk, S. M. Krimigis, T. P. Armstrong, and S. Jurac (2004), Energetic ion composition in Saturn's magnetosphere revisited, Geophys. Res. Lett., 31, L04810, doi:10.1029/2003GL018899.