间接驱动惯性约束聚变六孔球腔辐射场特性研究

Hohlraum is crucial for the indirect drive inertial confinement fusion. It converts intense laser into soft x rays, These x rays are used to produce an ablation drive that compresses the D-T fuel capsule placed at the center of the hohlraum, driving it to ignition and burn. The experiments on the National Ignition Facility in U. S. indicated that the radiation asymmetry in the cylindrical hohlraum is one of the main obstacles in achieving ignition. Based on this understanding, Chinese scientists proposed the octahedral spherical hohlraum as the ignition hohlraum. The energetics and radiation field of octahedral spherical hohlraum have not been investigated since the octahedral spherical hohlraum is a new concept. In this project, we will study the characteristic of radiation field of the spherical hohlraum by using the ways of theory, numerical simulation and experiment. We will study how to obtain the radiation temperature of the spherical hohlraum by using the observed radiation flux and develop the diagnostic technique of the radiation field inside the hohlraum. Since the SGIII laser facility is designed for the cylindrical hohlraum, we will study how to arrange the laser beams of the SGIII in order to perform the energetics experiments on the SGIII laser facility.

黑腔在间接驱动惯性约束聚变中起着极其重要的作用，它将强激光转换成软X光，驱动靶丸内爆，最终实现点火。美国在国家点火装置上的实验表明，它们所采用的柱形黑腔在辐照均匀性的调控上遇到了难以克服的困难。基于这样的认识，我国的科研人员提出了六孔球腔的设计。作为一种新的腔型，ICF研究领域还从未开展过六孔球腔能量学方面的研究工作。在这个项目中，我们将深入开展六孔球腔辐射场特性的研究，通过理论、数值模拟和实验分析相结合的方法，研究获得六孔球腔辐射温度的方法；发展六孔球腔辐射场特性的诊断技术；针对SGIII激光器的光路排布，研究在SGIII主机上开展六孔球腔实验的光路排布；通过实验分析，给出六孔球腔的辐射场信息及激光X光转换效率。

在本项目中，我们深入分析了黑腔辐射场诊断中常用的软X光能谱仪(SXS)和平响应X光探测器(FXRD)测量两孔黑腔辐射温度的原理。对于六孔球腔，SXS/FXRD的视场中通常存在多个激光注入孔。这种情况下，必须按权重考虑从各个激光注入孔流出的辐射流对SXS/FXRD测到的总辐射流的贡献。假如六孔球腔为黑体辐射源，则由SXS/FXRD测到的总辐射流可获得六孔球腔的辐射温度。我们对冲击波测温技术的物理机制进行了全面分析，完成了利用冲击波测量技术诊断六孔球腔辐射场的理论设计，提出了利用多台阶样品获取黑腔辐射场在峰值时刻附近的时间行为的物理思想。通过分析为两端注入黑腔设计的某激光装置的光路排布，设计了在该激光装置上开展六孔球腔能量学实验的光路排布方案，进而开展并全面分析了首个六孔球腔能量学实验，实验中利用冲击波测温和FXRD两种诊断技术获得了六孔球腔的辐射场信息，理论分析给出了六孔球腔的激光X光转换效率。本项目所开展的研究工作为在该激光装置上建立六孔球腔惯性约束聚变研究平台打下了坚实的基础，并为未来的六孔球腔点火实验开创了良好的局面。