纳秒激光烧蚀冲量耦合数值模拟

摘要

To investigate the process and mechanism of the impulse generation of laser ablation target, a comprehensive model including one-dimensional heat conduction and fluid dynamics is developed. The target Al, the most common space debris material, is used based on the proposed numerical model in the calculation of ns laser pulse ablation impulse and impulse coupling coefficient as a function of time. Numerical results agree well with experimental data available. Numerical simulations show that, during the laser pulse the impulse the target gained increases greatly with time; after the laser pulse terminates, the impulse tends to be stable with time. In the process of laser impulse coupling, the laser ablation plasma expands into vacuum and its size also gradually increases;meanwhile the plasma plume absorbs the incident laser energy and leads to the reduction in the laser energy deposited onto the target.%为研究激光烧蚀靶产生冲量过程和机理，建立了一个复杂的一维热传导和流体动力学模型。以空间碎片常见材料Al为例，用建立的模型数值计算了纳秒脉宽激光烧蚀靶产生的冲量及冲量耦合系数随时间变化情况。数值结果和已有的实验数据符合的较好。数值计算表明：激光脉冲时间内，靶获得的冲量随时间迅速增加，在脉冲时间结束后，冲量变化随时间趋于稳定；在冲量耦合过程中，烧蚀等离子体向真空膨胀，羽流尺度逐渐增大，同时吸收入射激光能量，导致激光与靶耦合的能量降低。