Grounding Method and Working Voltage Influence on Deep Dielectric Charging of Polyimide in GEO Environment

In order to guide the design of effective shielding layer to reduce the risk of dielectric electrostatic discharge in high-power and high-voltage spacecraft under GEO environment, it is necessary to explore the influence of grounding method and the joint action of high working voltage and deposited charge on the deep dielectric charging characteristics. In this article, based on the FLUMIC3 model, the electron flux of GEO environment is calculated, and an assessment method for the dielectric electrostatic discharge risk is established by combining Geant4 and a finite element method. Then, this method is used to calculate and analyze the influence of the grounding method and operating voltage on the electric field distribution of the polyimide under different shielding thicknesses. The results show that increasing the shielding thickness and grounding area can effectively reduce the polyimide internal electric field, and the aluminum shielding safety threshold required under the worst conditions is 2.920 mm; the influence of the working voltage mainly depends on the application method and the voltage value. During the working voltage increase from 100 to 5000 V, assume the working voltage ( $V_{s}$ ) is applied to one side of the polyimide sample, when the other side is suspended, namely, not grounded (B, $V_{s}$ -S; C, S- $V_{s}$ ), the maximum electric field depends on the deposited charge and it does not change with the working voltage; when the other side of the sample is grounded (A, $V_{s}$ -G; D, G- $V_{s}$ ), the maximum electric field and its distribution are determined by the working voltage and the deposited charge. Within this voltage range, the safety threshold of the aluminum shielding layer needs to reach 4–5 mm. In summary, under high working voltage, the grounding area of the sample can be increased, and the appropriate working conditions can be selected to determine the optimal shielding thickness that can suppress dielectric electrostatic discharge.