HR: 09:45h
AN: P51E-07    [Abstracts]
TI: Ion Production and Loss within Saturn's Inner Magnetosphere: Cassini Results
AU: * Sittler, E C
EM: edward.c.sittler@nasa.gov
AF: Goddard Space Flight Center, 8800 Greenbelt Road Code 612.2, Greenbelt, MD 20771 United States
AU: Andre, N
EM: Nicolas.Andre@cesr.fr
AF: CESR, 9 Avenue Colonel Roche, Toulouse, 31500 France
AU: Blanc, M
EM: michel.blanc@cesr.fr
AF: CESR, 9 Avenue Colonel Roche, Toulouse, 31500 France
AU: Coates, A J
EM: ajc@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, RH5 6NT United Kingdom
AU: Johnson, R E
EM: rej@virginia.edu
AF: University of Virginia, Engineering Physics, Thornton Hall, Charlottesville, VA 22904 United States
AU: Baragiola, R A
EM: rb9a@virginia.edu
AF: University of Virginia, Engineering Physics, Thornton Hall, Charlottesville, VA 22904 United States
AU: Hartle, R E
EM: Richard.E.Hartle@nasa.gov
AF: Goddard Space Flight Center, 8800 Greenbelt Road Code 612.2, Greenbelt, MD 20771 United States
AU: Reisenfeld, D
EM: dan.reisenfeld@umontana.edu
AF: University of Montana, Department of Physics and Astronomy, 32 Campus Drive, Missoula, MT 59812 United States
AU: Thomsen, M F
EM: mthomsen@lanl.gov
AF: Los Alamos National Laboratory, Space and Atmospheric Science Group, D-466, Los Alamos, NM 87545 United States
AU: Chornay, D
EM: dennis.chornay@gsfc.nasa.gov
AF: Goddard Space Flight Center, 8800 Greenbelt Road Code 612.2, Greenbelt, MD 20771 United States
AU: Shappirio, M D
EM: Mark.D.Shappirio@nasa.gov
AF: Goddard Space Flight Center, 8800 Greenbelt Road Code 612.2, Greenbelt, MD 20771 United States
AU: Simpson, D G
EM: David.G.Simpson@nasa.gov
AF: Goddard Space Flight Center, 8800 Greenbelt Road Code 612.2, Greenbelt, MD 20771 United States
AU: Dougherty, M
EM: m.dougherty@ic.ac.uk
AF: Imperial College London, Blackett Laboratory, London, SW7 2AZ United Kingdom
AU: Crary, F
EM: fcrary@swri.edu
AF: Southwest Research Institute, Division of Space Science and Engineering, 6220 Culebra Road, San Antonio, TX 78228-0510 United States
AU: McComas, D J
EM: dmccomas@swri.edu
AF: Southwest Research Institute, Division of Space Science and Engineering, 6220 Culebra Road, San Antonio, TX 78228-0510 United States
AU: Young, D T
EM: dyoung@swri.edu
AF: Southwest Research Institute, Division of Space Science and Engineering, 6220 Culebra Road, San Antonio, TX 78228-0510 United States
AB: We will present fluid parameters derived from Cassini Plasma Spectrometer (CAPS) observations of ions and electrons within Saturn's inner magnetosphere as presented in Sittler et al. [2005]. From these parameters one can estimate the ion total flux tube content per L shell, NL², for protons and water group ions as a function of radial distance or L shell. When we do this, the calculation shows that the dominant ion production peaks at Dione's L shell and not within the vicinity of Enceladus' L shell, L ~ 4, where most of the neutral oxygen and OH have been observed by Cassini (Esposito et al., 2005) and HST (Shemansky et al., 1993; Richardson et al., 1998), respectively. Our calculations also show that the ion abundance for H⁺ and W⁺ are nearly identical for all L. Our calculations self-consistently solve for the ambipolar electric field and the ion distribution along the field lines. Pressure anisotropies from Richardson and Sittler, [1990] for the ions are used. We assumed the pressure anisotropies for electrons to be the same as protons. Future analysis of the CAPS data during later orbits with actuator motion should allow us to measure the pressure anisotropies of the ions and electrons. In the vicinity of Dione the electron population is relatively hot, so that ion production via electron impact ionization is high at Dione. In contrast, within the inner most regions of the magnetosphere, the plasma is very cold and ionization rates due to electron impact are small so that photoionization may be the only important mechanism for ion production in the vicinity of Enceladus. We would argue that the primary sink for the neutral clouds at Enceladus is charge exchange, which just replaces one ion with another, and therefore does not contribute to ion production. However, it can contribute to compositional changes in the plasma with radial distance and redistribution of the plasma in energy space. We will explore the relative importance of Dione and Enceladus with regard to the source of neutrals within Saturn's inner magnetosphere. References: Sittler et al., GRL, 32, L14S07, 2005. Esposito et al., Science, 307, 1251, 2005. Shemansky et al., Nature, 363, 329, 1993. Richardson et al., J. Geophys. Res., 103, 20245, 1998. Richardson and Sittler, J. Geophys. Res., 95, 12019, 1990.
DE: 2732 Magnetosphere interactions with satellites and rings
DE: 2756 Planetary magnetospheres (5443, 5737, 6033)
DE: 2768 Plasmasphere
DE: 6275 Saturn
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: Fall Meeting 2005