Kinetic aspects of wave propagation in the Io plasma torus

Abstract:

Io's motion in the Jovian magnetosphere generates plasma waves that propagate through the plasma torus and into Jupiter's ionosphere, which in turn generates aurora. This interaction is important in auroral physics because the power generated by Io can be predicted and compared to the power output of the Io-induced aurora. Since the power output of the aurora is significantly less than the input power, it is important to understand the transport of energy from Io to Jupiter. We utilize a hybrid plasma simulation to explore the propagation of plasma waves in the Io plasma torus generated by mass loading the flow. Mass loading creates MHD waves (e.g. Alfven and fast mode waves) through the pickup of new ions as well as electromagnetic ion cyclotron waves driven by unstable ring beam distributions. We analyze the propagation of this composite wave field through the Io plasma torus with a density gradient along the magnetic field. We also investigate the propagation of small-scale kinetic Alfven waves by including the electron pressure term.