Investigation of the plasma wake of Titan from RPWS-LP observations and hybrid simulations

MODOLO, R.; WAHLUND, J.; CHANTEUR, G.; CANU, P.; KURTH, W.; BERTUCCI, C.; DOUGHERTY, M.

Congreso; AGU Fall Meeting 2006; 2006

Flybys of Titan by Cassini reveal a highly variable and complex structure of the ionised environment in the vicinity of Titan. The upstream plasma conditions and the orbital position of Titan, which changes the position of the ionisation sources (photoionisation and electronic impact ionisation), seem to significantly affect the plasma environment around Titan. We focus this study on the analysis of the Titan's plasma wake from the Radio and Plasma Wave Science (RPWS) data, and particularly the Langmuir Probe (LP) observations, and results from three-dimensionnal multi-species hybrid simulations. The electron density and the ion outflow measured by RPWS-LP are compared with hybrid simulation results performed using upstream parameters which are similar to those encountered by Cassini. The simulation model takes into account self-consistently the coupling between the ionised and neutral species. Ionisation of the neutral environment of Titan by solar photons, electron impacts and charge exchange reactions, between the co-rotating plasma and the neutral species, are included in this model. The hybrid model provides a full three-dimensional description of the interaction region and allows to set the observations back to a global context. Few flybys occurred in the wake of Titan, and mainly in the equatorial plane with different geometry encounters, are analyzed for this study.