Internal Charging Characteristics in Typical Navigation Satellite Orbits

Internal charging is an important hazard for navigation satellites, which operate in outer electron radiation belt and experience a very variable radiation environment because of the inclination of orbits. A rapid analysis method of internal charging is introduced, including physical model, conductivity model, shielding and electron transportation algorithm, and charging calculation method. Using this method, we calculate the charging processes of dielectric in medium earth orbit (MEO), geostationary earth orbit (GEO), and inclined geosynchronous orbit (IGSO). The results show that charging field fluctuates a lot in orbit and variation rate of field is proportional to electron flux. The saturated charging field in MEO is higher than that in GEO, and the field in GEO is higher than that in IGSO. So, the internal electrostatic discharging risk in MEO, GEO, and IGSO decreases in turn. If conductivity of dielectric is smaller, saturated field is larger and the difference of field in MEO, GEO, and IGSO is smaller. The dark and radiation-induced conductivity (RIC) of dielectric are important parameters in simulation, so we study the impact of conductivity in charging processes. In IGSO and MEO, when dark conductivity-induced time constant of charging is greater than orbital period and RIC is not large, the deposited electrons between different orbits accumulate and the charging field increase constantly. In this situation, the dark conductivity has a big influence on internal charging and it is important to measure it accurately.