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考虑到激光加热过程中电子和晶格之间的不平衡传热特性,将格子波尔兹曼方法(LBM)和双温度模型结合起来,建立了1个两步LBM方程,并用此方法对纳米薄膜在短脉冲激光照射过程中的热响应特性进行了模拟研究。分析了照射过程中薄膜内温度随时间及空间的变化规律;探讨了激光强度以及薄膜厚度对金属薄膜热响应的影响。研究结果表明,在照射过程中晶格温度的改变相对于电子温度的变化有明显的滞后效应,并且计算得到的电子温度响应及破坏阈值和实验结果吻合较好,说明所提出的两步LBM方程能够较好地描述激光照射过程中电子和晶格的不平衡传热现象。通过研究还发现,随着激光能量的增强以及薄膜厚度的减小,薄膜表面电子和晶格温度都有明显的升高,且电子和晶格温度达到稳定的时间均有所延迟。
Considering the unbalanced heat transfer characteristics between the electron and the crystal lattice during the laser heating process, a two-step LBM equation is established by combining the lattice Boltzmann method (LBM) and the dual-temperature model. By using this method, The thermal response of the thin film during short pulse laser irradiation was simulated. The variation of temperature in the film with time and space during irradiation was analyzed. The effect of laser intensity and film thickness on the thermal response of the metal thin film was also discussed. The results show that the change of lattice temperature has obvious hysteresis effect on the change of electron temperature during irradiation, and the calculated electron temperature response and failure threshold coincide well with the experimental results, indicating that the proposed two-step LBM equation It can describe the unbalanced heat transfer phenomena of electrons and lattices during laser irradiation. It is also found through research that with the increase of the laser energy and the decrease of the film thickness, the electron and lattice temperature of the film surface are obviously increased, and the time of the electron and lattice temperature stabilization is delayed.