Plasma Wake Simulation for Charged Space Platforms: Fully Kinetic PIC Versus Hybrid PIC

A comparative study using both electrostatic hybrid particle-in-cell (PIC) and fully kinetic PIC simulations is carried out to study collisionless, mesothermal plasma flow over large, negatively charged plates. The surface potential considered covers plasma wakes under the “quasi-neutral,” the thin sheath, and the “thick sheath” regimes. It is shown that both approaches produce qualitatively similar plasma wake features. The hybrid-PIC approach is accurate in the sheath region around the plate and in the expansion fan region. The full-PIC simulations also confirm the presence of the embedded sheath in the wake generated by a charged plate. However, the hybrid-PIC model is quantitatively inaccurate in the deep wake region where the electrons are nonequilibrium. It is also found that, for high-voltage plates, the ratio of the ram side ion current collection to the backside one scales linearly with the logarithm of the surface potential.