Potential structure around the Cassini spacecraft near the orbit of Enceladus

We present the results of numerical simulations of the potential structure around an object in a streaming plasma with parameters relevant for the Cassini spacecraft passing through Saturn's plasma disk near the orbit of Enceladus. Two- and three-dimensional particle-in-cell codes have been used allowing the potential of the simulated spacecraft body to develop self-consistently through the collection of charge by its surface. The dependence of the density and potential profiles on ambient plasma density, electron temperature, and ion drift speed is discussed. The spacecraft floating potential values, found in the simulations, are compared to those deduced from the analysis of Cassini Langmuir probe characteristics.