Study of Deep Dielectric Charging Characteristics and Suppression Method Under Space Irradiation Environment

With the rapid increasing interest on the space exploration, the reliability of the spacecraft becomes a very important problem. The space solar power station (SSPS) is inevitably exposed to space plasma, energetic particles radiation, extreme temperature, cosmic rays, etc. Energetic electrons can penetrate through the aluminum shield and deposit in the deep-layer of insulating materials, leading to partial accumulation of space charges and high electric field. Electrostatic discharge (ESD) occurs when the maximum electric field of insulating materials exceeds a certain threshold, resulting in deterioration of the insulating material and even the failure of the entire electronic equipment. Deep-layer dielectric charging has been the key scientific issue for developing high-voltage and high-power spacecraft technology. In this paper, a physical model is established to simulate the deep-layer charging characteristics of ethylene-tetrafluoro-ethylene (ETFE) under FLUMIC spectrum electron irradiation, based on the processes of carriers' transport and deposition of charge and energy. Two operating conditions, i.e. typical GEO condition and extreme GEO condition with varied flux enhancement, are studied. In addition, the possibility of suppressing the deep dielectric charging properties of ETFE by the addition of nano-boroncarbide (nano-B4C) is also investigated. The calculation results show that the maximum electric field in the deep-layer of ETFE rapidly reaches 108 V/m under extreme GEO space environment. Electrostatic discharge is easily to take place as it exceeds the breakdown threshold. It is found that the time spent to reach the maximum value of potential and electric field is less than one minute under extreme space radiation environment. Furthermore, the addition of nano-B4C can suppress the deep dielectric charging properties of ETFE to a large extent by introducing more shallow traps. This provides a potential approach on suppressing the deep dielectric charge accumulation.