超快脉冲激光辐照金属薄膜热-力效应的模拟研究

基于双曲双温两步热传导和热电子崩力模型,考虑到超快脉冲激光辐照金属薄膜材料过程中的热-力耦合效应,得到了完全耦合的、非线性的超快热弹性模型.运用具有人工粘性和自适应步长的有限差分算法,以脉宽为100 fs的脉冲激光辐照200 nm厚金膜为例,对薄膜体内的电子-晶格温度及温度梯度、热应力和电子热流进行了数值模拟研究.结果表明：脉冲辐照早期为明显的非平衡加热阶段,同时形成较大的热电子崩力；电子热流出现双峰现象；超快加热引起的热应力是导致薄膜力学损伤的主要原因.

Simulation Study of Thermal and Mechanical Effect on Metal Film Irradiated by Ultra-fast Laser Pulse

Based on the dual-temperature hyperbolic two-step heat conduction and hot- electron blast models,a new set of fully coupled and nonlinear ultra-fast thermo-elasticity model was derived to investigate the thermo-mechanical coupling effect of metal films caused by ultra-fast pulsed laser.Taking the 200nm gold film irradiated by a 100fs laser pulse as a typical example,thermal stress development in the lattice sub-system,temperature along with temperature gradient and electron heat flux were modeled by using artificial viscosity and the adaptive step finite-difference algorithm.It is shown that the early period of laser heating is a non-equilibrium process and forming large hot-electron blast force.It is also found that electron heat flow presents bimodal phenomenon.In addition,thermal stress induced by ultra-fast laser heating could be the main reason for mechanical damage.