Three-dimensional simulation of current collection in space

A three-dimensional, time-dependent, two species (i.e. electron and ion) particle simulation model is developed for a better understanding of current collection by a charged body in space. The Low Earth Orbit (LEO) space environment is simulated by a super-particle simulation (SUPS) model to study the plasma transient response and its asymptotic behavior around a three-dimensional, highly biased satellite. The SUPS model is developed because the plasma particles in LEO are so abundant that it is impossible to simulate each single particle in the study. Each simulation particle in this study represents a particle cloud. The potential distribution and the electric field are dependent on the density distribution of the particles. The simulation could apply to the spacecraft mission such as the first Tether Satellite System Re-fly (TSS-1R) mission for current collection analysis. Both positive and negative charged particles are considered in the study. The potential distribution surrounding the satellite is determined self-consistently by Poissonʹs equation. This study is both time dependent and space dependent simultaneously. Results indicate that when the satellite is charged to a highly positive potential, a plasma torus is formed in the plane perpendicular to the geomagnetic field. A dumbbell-shaped potential distribution is formed along the geomagnetic field lines and plasma oscillations are observed within the plasma sheath during the early stage of simulation. The effect of the local geomagnetic field on current collection is also presented.