Model of Io's Local Interaction: a Coupled Hall-MHD/Multi-Species Chemistry Model

Past studies have tackled the problem of the local interaction of Io's corona with the plasma in the torus using different complementary approaches, each providing new insights in the interaction but also involving some important simplifications. The MHD models employ a parameterization of the source of ionization, generally assuming a spherical symmetry and a single species, generally O and S (Linker et al., 1998; Combi et al., 1998, Khurana et al., 2011)). They thus by-pass the important effect of the cooling of electrons (Saur et al., 1999) and the multi-species chemistry. Others have taken a 2-fluid approach assuming a constant magnetic field (Saur et al., 1999), limiting the self-consistency of their approach or made a full hybrid simulation assuming an unrealistic ion mass to circumvent numerical limitations (Lipatov and Combi, 2006). We combine a multi-species chemistry model of the interaction that includes atomic and molecular species (Dols et al., 2008) with a self-consistent MHD-HALL calculation of the flow and magnetic perturbation to model as self-consistently as possible the plasma variables (plasma density, ion average temperature, composition, velocity, magnetic perturbation) along six different Galileo flybys of Io and compare to the observations.