In order to study the surface thermal decomposition damage of millisecond pulse lasers irradiating GaAs at 0. 53 μm wavelength, a two-dimensional axisymmetric heat conduction model was established. Considering the temperature dependences of the thermophysical parameters, the transient temperature fields in the material were simulated by using the finite element method. The distributions of transient temperature fields and variation law with time have been obtained, and the curve of the thermal decomposition damage thresholds on the material surface was also given. Numerical results show that, heat conduction affects the whole process of millisecond pulsed laser interaction and its damage mechanism is mainly thermal effects. The temperature of the center is the highest on the irradiated surface, where it could be damaged by thermal decomposition first. With the increasing of laser energy density, the time of thermal decomposition damage's occurrence would be advancing.%针对波长0.53μm的毫秒脉冲激光辐照GaAs的表面热分解损伤问题,建立了二维轴对称热传导模型,在考虑材料的热物性参数随温度变化的基础上,采用有限元法模拟了材料的瞬态温度场,得到了温度场分布特征及其随时间的变化规律,给出了材料表面发生热分解损伤阈值曲线.数值结果表明:毫秒脉冲激光对GaAs作用时,热传导影响着激光作用全过程,对应的损伤机理主要为热损伤；在激光作用下,被作用表面中心处温度最高,并且首先发生热分解损伤；随着作用激光能量密度的增加,GaAs表面发生热分解损伤的时刻不断提前.
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