航天器高压太阳电池阵一次放电的诱发微观过程研究

In the low earth orbit (LEO) plasma environment, the solar array surface interacts with the plasma to form an inverse potential gradient, and primary discharge may be induced under the significant potential difference. It affects the insulation performance and normal operation, threatening the safe operation of the spacecraft. The previous research on the surface charging effect has only analyzed the macroscopic potential distribution characteristics, without examining the induced microscopic process on the primary discharge at the triple junction. The ideal tip breakdown mechanism cannot be used to explore the microscopic process of primary discharge, and the surface-plasma interaction under different working conditions needs to be considered. Therefore, by combining the surface charging effect and the vacuum tip breakdown mechanism, the primary discharge induction microscopic model is established to reveal the microscopic process. Firstly, based on the current balance equation, a three-dimensional surface charging effect model of the spacecraft is established by the particle in cell (PIC) method. Considering three typical potential points in the working process of spacecraft solar array, the distribution characteristics of surface charging potential and the distribution of surrounding plasma sheath under different working conditions are obtained, and the macroscopic electric field distribution at the triple junction is obtained by the finite element method. It is found that with the increase of the working voltage of the high voltage solar array, the surface charging potential is more negative, the equilibrium time is longer, and the local macroscopic electric field at the triple junction reaches 10⁷ V/m. The ion reduced wake phenomenon is formed at the tail of the spacecraft, which increases the local potential difference in the wake region. Secondly, based on the surface charging effect and the vacuum tip breakdown mechanism, the primary discharge induction microscopic model is established. The field emission current, tip physical characteristics, and microscopic particle distribution under different bias voltages are explored. When the thickness of the cover glass is 1mm, the bias voltage threshold for inducing primary discharge is -100 V. As the bias voltage decreases, the time required to induce discharge breakdown decreases. When the primary discharge breakdown occurs, the tip temperature and the number density of evaporated neutral particles increase sharply. The tip field emission current density is about 10¹² A/m², the local Fowler-Nordheim (F-N) electron density reaches 10¹⁷ m^-3, and the secondary electron on the side of the cover glass increases significantly, forming a positive feedback, which aggravates the electric field enhancement and field effect. Finally, the bias voltage threshold and current of primary discharge are measured by the ground simulation test system. According to the direction of the primary discharge current, the primary discharge process is that the silver interconnect emits electrons into space. It can be inferred that the silver interconnect, as the cathode, provides the primary electrons to induce primary discharge. The bias voltage thresholds of four samples with different cover glass thicknesses are -115, -115, -110, and -95 V, respectively. The simulation and experimental results are consistent. As the thickness of the cover glass increases, the absolute value of the bias voltage threshold decreases. This research has theoretical significance for revealing the microscopic mechanism and risk assessment of primary discharge on a spacecraft’s high-voltage solar array.