Simulations of the Spacecraft Charging and Wake Effects in the Solar Wind

Surface charging and wake effects can disturb the plasma around the spacecraft and affect the measurements of spacecraft payloads. In this paper the Spacecraft Plasma Interaction Software (SPIS) is used to simulate the interaction between the solar wind and the spacecraft, in order to reveal the ion, electron, photoelectron, and electric potential distributions around the spacecraft. The results show that, since the plasma is tenuous, the electrons collected by the spacecraft give a much smaller current than the photoemission current, and the spacecraft could be charged to positive potential. A negatively charged wake will form downstream the spacecraft. It is demonstrated that the wake features can be altered by the photoemission. The scale of the wake can be larger due to the surface photoemission. It is also concluded that, since the bulk flow kinetic energy is much larger than the spacecraft potential energy, the size of the wake depends on the dimension of spacecraft. The wake can be substantially larger behind a larger spacecraft with the same parameters in the solar wind.