Analysis of Electric Transmission Failure Induced by Electrostatic Migration and Deposition of Abrasive Dusts in SADA

Abstract

The electric transmission failure induced by the electrostatic migration and deposition of the friction-pair-produced abrasive dusts in the Solar Array Drive Assembly (SADA) is studied for the first time by integrating experiments and Finite Element Method (FEM) simulation. Particle morphology and composition are characterized by SEM and X-ray EDS, respectively. The size, distribution and average charge of the abrasive dusts are characterized by PSDA as well as the home-made particle charge measurement device. The results show that the dusts’ sizes are in the range of 10–40 μm, and the dusts are primarily composed of Ag and a small amount of Cu and S. Sliced abrasive dusts with an average diameter of 30 μm and a charge of 85 e are used for the FEM prediction of particle trajectory, which is consistent with the theoretical calculation results. The electromagnetic field distribution in the SADA and the electrostatic migration and deposition of abrasive dusts are predicted and analyzed by adopting the FEM method. The experimentally observed dusts’ trajectories in a vacuum chamber with 0.02 Pa vacuum degree are consistent with the simulation results, which qualitatively verifies the accuracy of the FEM model. The predicted results show that the irradiation-induced conductivity increase in polyimide material has little influence on the electric field distribution and the migration and deposition of the abrasive dusts but has great influence on the local current density. Both the potential differences between the two adjacent conducting rings and the loose contact between the electric brush and the conducting rings have significant influence on the migration and deposition of the abrasive dusts, which may greatly increase the surface discharge risk and the electrical transmission instability in the SADA. This study is conducive to the safe and stable operation of the on-orbit spacecrafts.