Reflected Protons and Sputtered Ions at the Moon: Hybrid Simulations

In recent years, it has become evident that the Moon plays a much more active role in its interaction with the solar wind than previously appreciated. Spacecraft observations have shown that a fraction of solar wind ions are reflected, likely both from the surface and in the fields of magnetic anomalies. In addition, several different ion species are expected to be sputtered from the surface material. Here we present hybrid (kinetic ions, electron fluid) simulations of reflected protons and sputtered ions under various solar wind conditions and field geometries. Some of the questions of interest are whether self-consistent interactions influence the paths of these ions and what their access is into the lunar wake. We demonstrate that for realistic reflection rates, instabilities can be generated with the incoming solar wind, and for certain field geometries the density of reflected protons can be sufficiently high to affect the solar wind flow upstream of the Moon