Internal Charging Issues Met During Electric Orbit Raising and in GPS-Like MEO Environment

Abstract

This paper was dedicated to the experimental characterization and numerical assessment of the possible risk of charging during the electric orbit raising (EOR). Different elements [printed circuit board (PCB), ethylene tetrafluoroethylene wires (ETFE)] considered at risk in representative electron environment have been tested to assess their charging behavior and any risks of electrostatic discharges in this environment. This task has been performed in the GEODUR irradiation test facility installed at Office National d’Etudes et de Recherches Aerospatiales (Toulouse, France) and equipped with a 2.5-MeV electron accelerator. The samples have been irradiated with an electron spectrum representative of the maximum spectrum (in regard of electron flux) met during the EOR behind 1-mm shielding. This experimental study revealed high charging kinetics on the different elements over successive cycles that led to the initiation of several electrostatic discharges on PCB, located on metallic floating parts. This paper demonstrated the risk of high charging and electrostatic discharge (ESD) risks during EOR on sensitive components. These discharges could affect the electronics operation and damage the insulators. The final step of this paper was to perform numerical simulation for internal charging assessment in global positioning system (GPS)-type orbit on different space used materials with a dedicated tool that takes into account the temporal evolution of high energy electron fluxes. Then we demonstrated a strong evolution of internal charging with the radiation environment, which has been ascribed to the influence of radiation-induced conductivity (RIC). Strong discrepancies from one material to the other have been observed later on the temporal evolution of the surface potential.