Terragni Jacopo, Miotello Antonio
Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Italy.
Micromachines (Basel). 2021 Mar 12;12(3):300. doi: 10.3390/mi12030300.
The complexity of the phenomena simultaneously occurring, from the very first instants of high-power laser pulse interaction with the target up to the phase explosion, along with the strong changes in chemical-physical properties of matter, makes modeling laser ablation a hard task, especially near the thermodynamic critical regime. In this work, we report a computational model of an aluminum target irradiated in vacuum by a gaussian-shaped pulse of 20 ns duration, with a peak intensity of the order of GW/cm2. This continuum model covers laser energy deposition and temperature evolution in the irradiated target, along with the mass removal mechanism involved, and the vaporized material expansion. Aluminum was considered to be a case study due to the vast literature on the temperature dependence of its thermodynamic, optical, and transport properties that were used to estimate time-dependent values of surface-vapor quantities (vapor pressure, vapor density, vapor and surface temperature) and vapor gas-dynamical quantities (density, velocity, pressure) as it expands into vacuum. Very favorable agreement is reported with experimental data regarding: mass removal and crater depth due to vaporization, generated recoil momentum, and vapor flow velocity expansion.
从高功率激光脉冲与靶材相互作用的最初瞬间到相爆炸同时发生的现象的复杂性，以及物质化学物理性质的强烈变化，使得对激光烧蚀进行建模成为一项艰巨的任务，尤其是在热力学临界区域附近。在这项工作中，我们报告了一个计算模型，该模型用于模拟在真空中被持续时间为20 ns、峰值强度约为GW/cm²的高斯形脉冲辐照的铝靶。这个连续介质模型涵盖了辐照靶材中的激光能量沉积和温度演化，以及所涉及的质量去除机制和汽化材料的膨胀。由于有大量关于铝的热力学、光学和输运性质与温度相关性的文献，铝被选为一个案例研究对象，这些文献被用来估计铝在向真空中膨胀时表面蒸汽量（蒸汽压力、蒸汽密度、蒸汽和表面温度）和蒸汽气体动力学量（密度、速度、压力）的时间相关值。报告显示，在以下方面与实验数据有非常良好的一致性：由于汽化导致的质量去除和坑深、产生的反冲动量以及蒸汽流速膨胀。
