强激光辐照下窗口材料靶传热及热应力破裂的解析分析

用有限Ｈａｎｋｅｌ积分变换法对轴对称强激光束辐照下平面薄靶（或薄膜）传热及热应力分布进行了解析推导，得到了随时间演变的温度场及相应的热应力场的解析解。对比有关实验，对强激光束辐照窗口材料（例如ＭｇＦ２晶体、Ｋ９玻璃）靶引起其脆性热应力破裂进行了分析，详细讨论了激光强度、激光－靶能量耦合系数、辐照时间及光斑尺寸等因素对靶的破坏的影响。

ANALYTICAL SOLUTION FOR LASER-INDUCED HEATING AND THERMAL STRESS CRACK OF OPTICAL MATERIAL TARGETS

An analytical model for laser –induced heating, heat conduction and thermal stress crack of a brittle thin target is proposed. The analytical expressions are induced for the temperature increment and thermal stress that varies with time, which can be described as h I0b2/Kh and a Eh I0b2/Kh , respectively, while their space –time distributions being expressed as a infinite series. The threshold laser parameters for thermal stress crack of K9 glass and MgF2 ploycrystal targets predicted by this model are in agreement with those obtained experimentally.