Stratification-driven instabilities with bi-kappa distribution functions in the Io plasma torus

Abstract

We extend our previous studies on plasma transport in the fast rotating magnetosphere of Jupiter. The present study uses a new kinetic Io plasma torus model in order to test the local stability criteria against stratification-driven low-frequency modes in this environment. Compared to the model used in our previous application, the new model introduces bi-kappa velocity distributions and plasma pressure anisotropies in order to reproduce most of the available observational data obtained in the torus. This generates radial profiles of plasma densities and temperatures that slightly differ from those used previously. Here we examine the implications of non bi-Maxwellian velocity distributions and of pressure anisotropies for the centrifugal interchange instability and for the resulting transport of plasma in the Io torus and further demonstrate how our theoretical findings can be applied to realistic environments.