摘要
为研究Al膜受短脉冲激光作用时的能量传输过程,建立了一维半经典双温热传导模型。根据材料加工过程的熔化现象,对模型的相变区域进行有效设置。通过有限元法求解,得到晶格温度随时间分布的规律。根据自由电子气理论优化了模型,得到Al膜表面反射率和热吸收系数随时间的分布图。得到了激光辐照所产生热电场的分布规律,并分析了电子温度梯度对其影响。描绘出电子漂移运动速度的分布规律,证实激光作用产生的热电场是电子漂移运动的主导因素,发现最大漂移速度位置随时间的延长而加深。对激光作用后的晶格温度进行了区域性分析,定义了过热加热区,并得到激光烧蚀深度随时间的变化关系。实验结果表明,不同功率皮秒激光烧蚀Al膜的深度接近于理论计算结果。
In order to investigate the energy transport process in Al film irradiated by 10 ps lasers, a semi-classical two temperature model (TTM) was applied, and a 1D finite element calculation model was constructed with finite element software. Considering phase change region of material during laser ablation, reasonable expression was added to the TTM. According to the calculation, the surface lattice temperature evolutions along with time for single pulse lasers with different powers were presented. In order to investigate the surface plasma reflectivity and the heat absorption coefficient changing with lattice temperature during laser irradiation, the free-electron gas theory was applied. Moreover, the laser generated thermoelectric field and the electron drift velocity distribution map were depicted. The results verify that the thermoelectric field is the major reason for the electron drift movement, and the location of maximum velocity is changed with time. The spatial and temporal lattice temperature distribution map of Al film irradiated by 0.12 W picosecond laser was depicted. According to the calculation, the phase explosion is the reason for ablation, and it occurs during the process of laser energy deposition. The over-heated zone (OHZ) was defined, and the relationship between ablated depths and time was found. The calculated ablation depths of single pulses coincide with the experiment for 10 ps laser.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2014年第6期754-760,共7页
Chinese Journal of Luminescence
基金
国家自然科学基金(10878004/A03)资助项目
关键词
激光技术
半经典双温方程
有限元方法
自由电子气理论
热电场
Aluminum
Electron gas
Experiments
Finite element method
Laser ablation
Laser theory
Metallic films
Truck trailers
