3-DIMENSIONAL SIMULATION OF CURRENT COLLECTION IN-SPACE

A three-dimensional, time-dependent, two species (i.e. electron and io n) particle simulation model gis 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 (S UPS) model to study the plasma transient response and its asymptotic b ehavior around a three-dimensional, highly biased satellite. The SUPS model is developed because the plasma particles in LEGS are so abundan t that it is impossible to simulate each single particle in the study. Each simulation particle in this study represents a particle cloud. T he potential distribution and the electric field are dependent on the density distribution of the particles. The simulation could apply to t he spacecraft mission such as the first Tether Satellite System Re-fly (TSS-1R) mission for current collection analysis. Both positive and n egative charged particles are considered in the study. The potential d istribution surrounding the satellite is determined self-consistently by Poisson's equation. This study is both time dependent and space dep endent simultaneously. Results indicate that when the satellite is cha rged to a highly positive potential, a plasma torus is formed in the p lane perpendicular to the geomagnetic field. A dumbbell-shaped potenti al distribution is formed along the geomagnetic field lines and plasma oscillations are observed within the plasma sheath during the early s tage of simulation. The effect of the local geomagnetic held on curren t collection is also presented. (C) 1997 Elsevier Science Ltd.