Assessment of Jovian radiation belt electron-induced internal dielectric charging

The Jovian radiation environment experienced by spacecraft such as the proposed Jupiter Ganymede Orbiter (JGO) is intense and characterized by a harder electron spectrum than typical of the terrestrial radiation belts. The DICTAT code is a 1-d analytical tool that is widely used for the assessment of electron-induced internal charging effects in terrestrial orbit. This code has been modified to extend the validity of the code to higher electron energies. In addition, the current deposition algorithm has been made material-specific, so that high atomic number materials used as shielding can be modelled. These changes are to enable the more energetic Jovian environment to be simulated and to allow the effects of Tantalum shielding to be modelled. Tantalum is expected to be widely used to control radiation levels on the JGO spacecraft. Simulations using the modified code indicate that the Jovian environment is more severe in terms of internal charging than the terrestrial geostationary environment and that shielding mass can be saved by using Tantalum instead of Aluminium.