纳秒激光熔石英损伤颗粒喷溅的瞬态参量表征与物理机制研究

Fused silica is one of the most important optical materials which is widely used in high power laser device. However, it is also susceptible to damage under high UV nanosecond laser fluence, and fused silica damage restricts the output ability of laser device seriously. Particle ejection is part of fused silica damage, closely related to the damage mechanism. Due to the ultra short duration and complex impact factors of particle ejection process, the transient parameter measurement is rather difficult and its mechanism is not well explained. In this research subject, we study the dynamic mechanism of the particle ejection process. A parametric model is built to reveal the rule of phase transition process, shock wave propagation and transient dynamics feature of ejected particles. Based on the static distribution of ejected particles, the mechanism of physical dimension, chemical composition and morphology feature distribution function on the ejecting process will be theoretical analyzed. Finally, time-resolved pump and probe technique will be employed to identify the transient parameter of damage process to verify and modify the particle ejecting model. In this project, we will originally build the particle ejection mathematical model and realize full parametrical characterization of particle ejecting process. Benefited from this model, the theoretical knowledge of nanosecond laser induced damage of fused silica will be greatly improved.

熔石英是一种广泛应用于强激光装置中的重要光学材料，在高通量紫外纳秒激光作用下容易发生损伤，严重制约着高功率固体激光器的负载能力。颗粒喷溅作为熔石英激光损伤过程中能量释放的重要环节，与损伤机制密切相关。由于颗粒喷溅时间极短，瞬态参量表征难度较大，其喷溅过程的物理机制尚未得到较好解释。本课题拟开展喷溅颗粒的动力学机理研究，建立颗粒喷溅的数学参量模型，掌握喷溅物理过程中的材料相变、冲击波传输以及颗粒运动的演化规律，深入揭示熔石英损伤能量释放过程的物理机制；研究喷溅颗粒的静态特性分布规律，理论解析几何形状、化学成分和形貌特征的分布函数与颗粒喷溅过程的内在联系；利用时间分辨泵浦探测技术对熔石英损伤后期的瞬态动力学参数进行辨识，完成颗粒喷溅参量模型的实验验证和参数修正。本课题创新性地建立损伤颗粒喷溅的数学模型，实现颗粒喷溅过程的全参量化表征，为深入揭示熔石英损伤机制提供了理论基础。

高功率激光装置中的熔石英元件，在高通量紫外纳秒激光作用下容易发生损伤，严重制约着高功率固体激光器的负载能力。而损伤后期的颗粒喷溅是激光与物质相互作用能量释放的重要环节，与损伤机制密切相关。由于颗粒喷溅时间极短，瞬态参量表征难度较大，其喷溅过程的物理 机制尚未得到较好解释。本课题针对紫外纳秒激光熔石英损伤后期的颗粒喷溅过程开展研究，实验研究了损伤后期的超热材料相变演化、冲击波传输以及颗粒运动等瞬态物理过程，获得了离化区域演化、冲击波传播、喷溅颗粒特性分布的特征，揭示颗粒喷溅的动力学机制，本课题重点开展颗粒喷溅瞬态动力学参数的辨识和相关参量测量实验研究，成果能够全面而深入地揭示损伤颗粒喷溅机理，为加深熔石英损伤机制的认识提供理论支撑。