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研究了高能短脉冲激光薄膜制备的整个烧蚀过程.首先建立了基于超热理论的烧蚀模型,然后利用较为符合实际的高斯分布表示脉冲激光输入能量密度,给出了考虑蒸发效应不同阶段的烧蚀状态方程.结合适当的边界条件,以Si靶材为例,利用有限差分法得到了靶材在各个阶段温度随时间和烧蚀深度的演化分布规律及表面蒸发速度与烧蚀深度在不同激光辐照强度下随时间的演化规律.结果表明,在脉冲激光辐照阶段,靶材表面的蒸发效应使得靶材表面温度上升显著放缓;在激光辐照强度接近相爆炸能量阈值时,蒸发速度与蒸发厚度的变化由于逆流现象将显著放缓.还得到了考虑了熔融弛豫时间及蒸发效应的固-液界面随时间的演化方程,这一结论较先前工作更具有普适性.
The whole ablation process of high energy short pulse laser thin film was studied.First, an ablation model based on hypertherm theory was established, then the energy density of impulse laser input was represented by Gaussian distribution which was more realistic, Ablation equation of state.With the appropriate boundary conditions, taking the Si target as an example, the evolution and distribution rule of the target temperature and the ablation depth at different stages are obtained by the finite difference method, and the surface evaporation rate and ablation depth are different Laser irradiation intensity with time.The results show that the evaporation of the target surface causes a significant slowdown of the target surface temperature during the pulsed laser irradiation stage.When the laser irradiation intensity is close to the phase explosion energy threshold, The variation of velocity and evaporation thickness will be significantly slowed down due to the countercurrent phenomenon, and the evolution equation of solid-liquid interface with time taking into account the melting relaxation time and evaporation effect over time is obtained. This conclusion is more universal than previous work.