激光驱动黑腔中的激光镜面反射诊断技术及时空特性研究

In indirect-drive laser inertial confinement fusion, glint will causes loses of energy and adds seeds of hydrodynamic instability on the target, which destroy thesubsequent implosion and fusion ignition. When driven by multi-beams, glint will also interaction with other laser beams, exciting laser and plasma instability mechanisms beyond anticipation, which contain new scientific discoveries. However, at present, the radiation fluid simulation programs used in the study of laser fusion still can not calculate the process self-consistently. And it also lacks diagnosis technologies with high spatial and temporal resolution to study this progress. This project intends to develop optical imaging technology with high temporal resolution provided by optical fiber bundle coupling with streak camera. Then, combining Near backscatter diagnostic system, glint diagnosis technology will be established and used to obtain the temporal and spatial distribution of glint by experiments. Furthermore, by designing experiments with different conditions, researching on the micro mechanism and influencing factor of secondary LPI will be carried out. By this project, understanding of physical problems for glint will be promoted and some speculative physical analysis which constraint laser fusion development will be clarified.

激光间接驱动惯性约束聚变中，激光在黑腔壁的镜面反射既会造成能量的亏损，又可能对靶丸附加流体力学不稳定性的种子，破坏后续内爆压缩和聚变点火。在多环多光束作用下，镜面反射光还有可能与其他光束耦合激发超出预期的激光等离子体不稳定性机制，蕴含了新的科学发现。然而，目前用于激光聚变研究的辐射流体模拟程序还不能自洽计算该过程，实验上也缺乏全空间高时空分辨的诊断技术对其进行研究。本项目拟发展基于光纤传像束配条纹相机的高时间分辨光学成像技术，结合神光Ⅲ装置具有较大立体角的近背向散射光诊断系统，建立镜面反射激光诊断技术，通过实验直接获得镜面反射激光的时空分布特性，并通过设计不同条件的实验，研究镜面反射激光的微观机制及其影响因素和规律，推进对激光镜面反射相关物理问题的理解，澄清制约目前激光聚变进展的一些推测性物理分析。

本项目围绕背向散射光时空分布图像测量需求，开展高时间分辨光学成像技术研究，设计并制备核心器件异型传像束，并对其时空非均匀性进行了检测和校正，开发相应的数据处理方法，形成高时间分辨光学成像诊断能力。同时基于大型激光装置近背向散射光诊断系统，构建了散射光时空分布诊断模块，测量获得了近背向散射光时空分布演化过程，具备了镜面反射激光时空演化特性的诊断能力。该项目形成的高时间分辨光学成像能力，能够适用于高能量密度物理等领域的光学图像时空演化过程诊断，具备广泛的应用前景。建立的近背向散射光时空分辨演化过程诊断能力，能够移植于同类的大型激光装置，为LPI物理过程精细研究提供更为丰富的数据。