Ambient ion distributions in Saturnʹs magnetosphere near Titan during a non-Voyager type interaction Original Research Article

The interaction of Titanʹs ionosphere with the Saturnʹs magnetospheric plasma was found to be subsonic, superAlfvénic and submagnetosonic. However, the plasma conditions along Titanʹs orbit are highly variable [cf. J. Geophys. Res., 87 (1982) 881; Ph.D Dissertation, University of Michigan, Ann Arbor, 2001] resulting in a wide range of possible Mach numbers for the interaction. We consider the effect Titan would have on the ambient (or magnetospheric) ion population during a supermagnetosonic interaction, which might occur in the outer magnetosphere. The trajectories of several thousand ions in the vicinity of Titan are calculated using the fields from the output of a three-dimensional MHD model of Titanʹs plasma interaction. We have simulated the Voyager Plasma Spectrometer (PLS) response to the ambient ions using the determined ion trajectories. These results are compared with the Voyager distribution functions in order to illustrate how upstream conditions might affect the observed distributions, as will likely be observed during the Cassini mission Titan flybys.