Aerodynamic ablation of dust grains in ambient gas under hypervelocity impact

During hypervelocity impacts, the ablation of dust grains constitutes a significant source of impact flash and electromagnetic radiation. This study presents, for the first time, an investigation into the coupled mechanisms of dust grain ablation and ionization under hypervelocity impact conditions, employing the electrostatic parallel particle-in-cell (EPPIC) method in conjunction with a Monte Carlo collision model. The analysis evaluates the spatial and temporal characteristics of potential distributions arising from charge separation. Our findings reveal that, in hypervelocity impact conditions, the ablation of dust grains releases high-temperature atoms, which undergo rapid ionization due to gasdynamic effects, resulting in plasma formation. The ions and electrons generated through ablation ionization exhibit pronounced directionality and spatial-temporal inhomogeneity, forming a distinctive trail structure behind the dust grains. The rapid diffusion of electrons induces charge separation, creating distinct regions of positive potential surrounding the dust grains. Variations in field boundary conditions, ablation rates, and ambient gas pressure influence the distribution of ionization products and the evolution of the electric potential. Furthermore, the differences between ablation-induced ionization and impact ionization were analyzed, and the potential electromagnetic radiation from ablation-induced ionization was estimated. This study provides theoretical insights into the physical mechanisms governing dust grain ablation and ionization in hypervelocity impact environments, while also offering valuable guidance for the design of related experimental investigations.