3D Physical Chemistry and Emission Simulations of the Io Plasma Torus

ESA's JUICE mission and NASA's Europa Clipper are sending UVS instruments to the Jupiter system that will view the Io plasma torus. In anticipation of these missions, we have built a 3D Io plasma torus emission model in order to simulate what we would expect to see from both UVS instruments looking at the Io plasma torus. The Colorado Io Torus Emission Package 2 (CITEP 2) calculates the line of sight given the position of each spatial pixel and pointing of the spacecraft and produces a synthetic spectrum given plasma densities and temperatures along the line of sight using the CHIANTI atomic database (version 10) to compute volume emission rates. We compare our model with Cassini UVIS and Hisaki UV observations as well as ground based optical observations of the Io plasma torus. In addition, we use a 3D model of the physical chemistry while varying the neutral source rate and diffusion coefficient in order to model the warm torus, ribbon, and cold torus self-consistently. We investigate the tipping point of inflow versus outflow of mass and energy and quantify the transport timescales given the diffusion coefficient profile and flux tube content radial profiles. The output of our 3D physical chemistry model produces a 3D model of densities and temperatures which we use in conjunction with CITEP 2 to simulate corresponding emission profiles for a given viewing geometry.