1. Graduate School, Space Engineering University, Beijing 101416, China
2. Department of Aerospace Science and Technology, Space Engineering University, Beijing 101416, China
3. Aerospace Command College, Space Engineering University, Beijing 101416, China
Abstract：Solar cells are widely used as an efficient photo-converter in photovoltaic power generation systems. Laser, as a kind of high light source, will cause damage to the battery. The surface scattering spectrum characteristics of the battery can be used to determine the damage degree. This paper used the target surface scattering spectrum measurement system to measure the scattering spectrum of three junction GaAs cells irradiated by laser, and the bidirectional reflection distribution function (BRDF) was calculated. The measurement system comprised an FX 2000 and NIR 17 optical fiber spectrometer. Based on the strong mirror reflection characteristics of the battery surface, a geometric model of incident and reflection angle of 30° was adopted in the experiment.The structure of the original GaAs solar cells mainly consists of the antireflection film DAR layer, the top cell GaInP layer, the middle cell GaAs layer and the bottom cell Ge layer. The scattering spectrum characteristics of GaAs solar cells include absorption characteristics in the visible spectrum (500~900 nm) and period-like oscillation characteristics in the near-infrared spectrum (900~1 200 nm). When the cell was damaged by continuous laser irradiation, the change of the spectral BRDF of the damaged ones was obtained. The characteristics of the damaged film layer were analyzed.The results showed that the function of the DAR layer was to reduce the spectral reflection energy, and it had little effect on the characteristics of the spectral curve.The Ge layer had little effect on the change of the spectral curve, too.The scattering spectrum characteristics of the battery were mainly caused by the GaInP and GaAs layer. The GaInP layer mainly affected the absorption characteristics of the visible spectrum and modulated the interference characteristics of the near-infrared spectrum, while the GaAs layer mainly affected the interference characteristics of the near-infrared spectrum. As the damage of the GaInP layer reached a certain extent, it would lead tothe interference characteristics in the visible spectrum.Finally, based on the analysis of the experimental results, the influence of each layer of the battery on the scattering spectrum characteristics was studied according to the provided model, and the analysis of the battery damage based on the characteristics was discussed. The results can provide the basis for the damage degree determination of the battery.
