Effect of Plasma Sheath on the Design of Electric Field Instrument Detecting Magnetosheath

Abstract

The distribution of plasma potential and density around spacecraft is affected by the coupling of spacecraft and plasma, resulting in disturbing the detection of space electric field. In this paper, Spacecraft Plasma Interaction Software (SPIS for short) is used to provide a reference to design the electric field instrument detecting magnetosheath on future missions. The interaction of plasma with the spacecraft platform and the probe is simulated to investigate the thickness of plasma sheath and the relationship between current and voltage drop under different plasma conditions. Our results indicate that the thickness of plasma sheath covered spacecraft is smaller than the Debye radius, and this difference is larger at higher temperature conditions caused by photoelectrons and secondary electrons. Moreover, the current collected by the probe at a different voltage drop is also simulated. The simulated results show that the influence of current disturbance on measuring potential can be reduced by the probe with a bias current. Furthermore, the estimated optimum bias current is also listed corresponding to the detected region.