Abstract
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 113,
A12218,
11 PP., 2008
doi:10.1029/2008JA013486
Cassini plasma spectrometer thermal ion measurements in Saturn's inner magnetosphere
Space and Atmospheric Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
Space and Atmospheric Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
Space and Atmospheric Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
Department of Physics and Astronomy, Rice University, Houston, Texas, USA
Space and Atmospheric Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
Physics Department, Birmingham-Southern College, Birmingham, Alabama, USA
Plasma data from the Cassini Plasma Spectrometer experiment are analyzed using a robust forward modeling technique for dayside
equatorial orbits within the range 5.5 to 11 Saturn radii (1 RS = 60,268 km). It is assumed the measured ion data may be represented by two anisotropic Maxwellian distributed species, H+ and a water group ion, W+. Saturn's magnetospheric plasma is shown to subcorotate by 15–30% below rigid corotation within this region, with a minimum
in fractional lag between 7 and 9 RS. There is a suggestion of a small radial outflow, but the selection of data for this study precluded the inclusion of interchange
injection events. Ion densities are in excellent agreement with the Cassini plasma wave instrument, giving confidence in the
forward modeling technique. Plasma moments including density, temperatures, and velocities are presented, along with empirical
models for density and azimuthal velocity. Water group temperature anisotropies T
Received 12 June 2008; accepted 17 September 2008; published 31 December 2008.
Citation: (2008), Cassini plasma spectrometer thermal ion measurements in Saturn's inner magnetosphere, J. Geophys. Res., 113, A12218, doi:10.1029/2008JA013486.
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