Magnetospheric plasma sputtering of Io's atmosphere

Neutral coronae due to magnetospheric ion sputtering from the exobase are generated, and ion and neutral injection into the plasma torus are calculated, on the assumption of the existence of an atmosphere on Io and a consideration of that atmosphere's various possible characteristics. Through the inclusion of the sputtered atmospheric corona that emerges from an assumed unattenuated incident ion flux, it becomes possible to satisfy the supply rate to the torus with an exobase that is close to the surface; such an exobase would imply that the Io atmosphere is insufficiently robust to support a fully dissociated corona, and that a significant fraction of the incident plasma ions can penetrate to the surface to furnish a sputter source of atmospheric gas.