KDP晶体缺陷纳秒激光损伤的瞬态动力学参量表征与演化机制研究

Potassium Dihydrogen Phosphate (KDP) crystal is a widely applied nonlinear optical material. It's likely to be damaged during the interaction with high-power laser pulses. Owing to the specifics in preparation technologies and mechanical properties, the damage behavior of KDP is different from standard optical glass, and the key process and mechanism haven't been clearly explained. As the laser fusion research of China is in great progress, the damage threshold of KDP crystal requires to achieve a higher level. Under this condition, we propose this research topic to make effort for the understanding of KDP damage mechanism. We novelly put eyes on the transient kinetics of damage process, including thermal strain and stress propagation. First, we will build a simplified model of damage kinetics, and the thermal absorption, stress propagation and strain fracture could be simulated. Second, we will carry out the Time-Resolved Pump and Probe (TRPP) experiment to characterize the transient process in damage generation. The morphological and kinematical information during damage evolution could be acquired. The experimental results are beneficial for the verification of theoretical model, and furthermore, the mechanisms in damage initiation, growth and form could be well explained based on the modeling of kinetics parameters. This research is helpful for the improvement of preparation, fabrication and maintenance of KDP crystal optics.

在强激光装置中，磷酸二氢钾（KDP）晶体是一种重要的非线性光学材料，在高功率纳秒脉冲激光负载条件下容易发生损伤。由于KDP晶体具有独特的生长加工方法，复杂的杂质缺陷因素使其损伤特性较为特殊，关于缺陷向损伤转化的过程机制尚未得到较好解释。本课题针对此研究现状，着眼于缺陷在激光作用下发生的热应变与力学传导过程，开展晶体损伤的动力学机制研究：建立KDP缺陷在激光作用下形成热吸收、等离子体爆炸、应力传导与应变断裂等阶段的理论模型，结合时间分辨泵浦探测（TRPP）技术与缺陷表征技术，完成瞬态动力学相关缺陷参数和力学参数测量，探寻损伤的预测数学模型，并通过激光辐照实验，对模型进行验证和修正。本课题将深入揭示KDP晶体缺陷向损伤演化过程中包含的光热诱导、应变建立与断裂形成机制，创新地从动力学参量角度出发建立缺陷的损伤模型，预期成果将有助于指导现有缺陷控制工艺的优化和改进，评估晶体的负载能力与使用寿命。

本课题针对 KDP 晶体缺陷在纳秒激光作用下经历的瞬态过程进行研究，深入揭示了 KDP 晶体激光损伤的光热诱导、应变建立和断裂形成机制。研究方法主要采用 TRPP 瞬态表征技术，对损伤演化周期中包含的缺陷热吸收、等离子体爆炸、应力传导与应变断裂等瞬态过程进行实验观察和测量，并结合缺陷的热学模型和材料的力学模型，探寻损伤的预测数学模型。本课题首次针对 KDP损伤瞬态过程开展动力学参数表征和演化机制描述，预期为晶体生长、加工、预处理和使用环节的工艺优化提供理论参考。