HR: 1340h
AN: P53A-1450    [Abstracts]
TI: Wave Activity Above the Ionosphere of Titan - Predictions for the Cassini Mission
AU: Dobe, Z
EM: Zoltan.Dobe@lighting.ge.com
AF: KFKI Research Institute for Particle and Nuclear Physics, POBox 49, Budapest, H-1525 Hungary
AU: Szego, K
EM: szego@rmki.kfki.hu
AF: KFKI Research Institute for Particle and Nuclear Physics, POBox 49, Budapest, H-1525 Hungary
AU: * Erdos, G
EM: erdos@rmki.kfki.hu
AF: KFKI Research Institute for Particle and Nuclear Physics, POBox 49, Budapest, H-1525 Hungary
AU: Kurth, W
EM: william-kurth@uiowa.edu
AF: University of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AB: Beam driven wave generation mechanisms are investigated in linear approximation, which are viable in the flowside plasma mantle of Titan. The flowside plasma mantle is defined - by analogy with the dayside plasma mantle of the planet Venus and Mars - as being the interaction region between the "cold" ionospheric plasma and the "hot" streaming plasma of magnetospheric or solar wind origin, with both types of plasma being present in comparable densities. In order to match the various plasma and field parameters expected to be measured by Cassini during its numerous encounters with Titan, we have performed our model calculations in a broad parameter space encompassing the plasma characteristics determined by Voyager 1 in Titan's wake, and also making use of the results of available MHD model calculations concerning the plasma environment of Titan. Two types of beam-instability modes were found to be dominant: a fluid-like (non-resonant) modified two stream instability (MTSI) and the kinetic (beam resonant) ion-ion acoustic instability (IIAI). The two instability modes are characterized by distinct frequency ranges (an order or below the lower hybrid frequency for the MTSI, and a few times the lower hybrid frequency for the IIAI), and are found to be dominant in well separated spatial regions determined by the presence/absence of cold ionospheric electrons. Giving a global rather than a specific description of the instability types expected to be the most important growing modes within Titan's flowside mantle we make predictions concerning the wave characteristics and the spatial location of the dominant wave modes measurable by the plasma wave instrument onboard Cassini. In particular, the extension of the waves towards the flanks is investigated, with comparisons to the observations by Cassini during its first Titan encounter.
DE: 2772 Plasma waves and instabilities
DE: 2780 Solar wind interactions with unmagnetized bodies
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting