Ablation damage in solar cells under high-power-density laser irradiation

High-power-density lasers (HPDLs) irradiation can cause severe ablation in spacecraft-mounted solar cells within extremely short timescales, leading to functional degradation and posing a potential threat to spacecraft reliability. Understanding the thermal damage mechanisms in such systems is crucial for protection design. In this study, a staged simulation strategy based on the level-set method is proposed to investigate ablation evolution. A simplified multiphysics model coupling with heat transfer, fluid dynamics, and phase change is developed to simulate laser-material interactions at the millisecond scale for the complex multilayer structure of solar cell. First, compared with low-power-density lasers (LPDLs), HPDLs induce transient thermal localization due to suppressed heat conduction, resulting in irreversible vaporization damage to the cell components of epoxy resin, germanium and aluminum under a single-pulse. The ablation diameter and depth continuously increase over time, eventually resulting in through-structure ablation. In contrast, the coverglass remains largely unaffected due to its high melting point and low optical absorptivity. Furthermore, the rapid accumulation of vaporized products within the confined cavity leads to a significant pressure increase, especially during the initial vaporization of the epoxy resin. To mitigate ablation damage and evaluate the heat dissipation performance of the substrate, a dimensionless thermal diffusion number is introduced. Parametric analyses show that increasing the thermal conductivity of substrate is the most effective approach for reducing the ablation depth, followed by the specific heat capacity and the thickness. The damage diagrams of ablation depth with respect to the substrate thickness, irradiation duration and power density are further illustrated. The results show that increasing the substrate thickness effectively reduces the ablation depth under multipulse irradiation. However, owing to insufficient heat diffusion during single-pulse irradiation, increasing the substrate thickness has limited effect on ablation damage. These findings offer theoretical insights and practical guidance for the protective design of solar cells.