Simulation of Plasma Interaction with Io’s Atmosphere

Abstract

One dimensional Direct Simulation Monte Carlo (DSMC) simulations are used to examine the interaction of the jovian plasma torus with Io’s sublimation atmosphere. The hot plasma sweeps past Io at ∼57 km/s due to the external Jovian magnetic and corotational electric fields and the resultant energetic collisions both heat and dissociate the neutral gas creating an inflated, mixed atmosphere of SO2 and its daughter products. The vertical structure and composition of the atmosphere is important for understanding Io’s mass loading of the plasma torus, electron excited aurora, and Io’s global gas dynamics. Our 1D simulations above a fixed location on the surface of Io allows the O+ and S+ ions to drift down into the domain where they then undergo elastic and charge exchange collisions with the neutral gas. Each electron’s position is determined by the motion of a corresponding ion; however, the electrons retain their own velocity components which are then used during elastic, ionization, and excitation collisio...