HR: 1400h
AN: P33A-06    [Abstracts]
TI: Dusty plasma of E-ring and Enceladus observed by Cassini Langmuir probe
AU: * Morooka, M W
EM: morooka@irfu.se
AF: Swedish Institute of Space Physics Uppsala, Box 537, SE-751 21, Uppsala, Sweden
AU: Wahlund, J
EM: jwe@irfu.se
AF: Swedish Institute of Space Physics Uppsala, Box 537, SE-751 21, Uppsala, Sweden
AU: Shafiq, M
EM: muhammad.shafiq@irfu.se
AF: Swedish Institute of Space Physics Uppsala, Box 537, SE-751 21, Uppsala, Sweden
AU: Gurnett, D A
EM: donald-gurnett@uiowa.edu
AF: Department of Physics and Astronomy, University of Iowa, 52242-1479, 203 Van Allen Hall, Iowa City, IA , United States
AU: Kurth, W S
EM: william-kurth@uiowa.edu
AF: Department of Physics and Astronomy, University of Iowa, 52242-1479, 203 Van Allen Hall, Iowa City, IA , United States
AU: Farrell, W M
EM: william.m.farrell@gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Science and Exploration Directorate, NASA/GSFC, Code 695, Greenbelt, MD, United States
AB: During the three Enceladus plume and associated E-ring encounter of the Cassini spacecraft, the ion/electron number densities and the temperature data are obtained by the RPWS Langmuir probe (LP). We found that the electron/ion densities increase as Cassini approaches the E-ring. As Cassini encounters the E-ring within the distance from the equator Z = ∼ ± 20,000 km, the electron density gradually decrease while the ion density is still increasing. This signature seems to be due to the negatively charged dust as recently reported by Wahlund et al. (2005, 2009). Furthermore, in this region the ion velocity is close to the Keplarian speed. Such observed signatures have been detected throughout the plasma disk near the E-ring. There are no Langmuir probe observations indicating an ionosphere around Enceladus. In the Enceladus plume, on the other hand, both the ion and electron density became very large (up to a few 10⁵ cm^-3 for the ions and at least few 10⁴ cm^-3 for the electrons). However, the number densities of the electrons are still significantly lower than the ion number densities, except possibly in the densest parts. That is, the charged dusts are still important in the plume region. The ion speed is departed from the Keplarian speed, which seems to be consistent with the plasma flow in the plume region. We discuss the dust-plasma interaction and electrodynamics in the plasma disk near the E-ring and in the Enceladus plume region.
DE: 6213 Dust
DE: 6265 Planetary rings
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: 2009 Joint Assembly