高压温稠密物质X射线吸收光谱的环境密度效应实验研究

The high pressure warm dense matter is generated through strong shock compression of solid matter. The atomic structure and the X–ray radiation characters of high pressure warm dense matter are different from the condensed matter and hot plasma. The study of environmental density effect on X-ray absorption spectra has the characteristics of interdiscipline and multi-dimension, and is an extremely challenging area in the research field of high energy density physics (HEDP). The present project will adopt high temperature plank radiation, which is generated by the interaction of Shenguang high power laser with high Z hohlraum, to ablate sandwiches target and take colliding shock compression. The compressed sample could reach a high pressure from million to tens of millions atmospheric pressure. By developing high spectral and high temporal resolved quantitative diagnostics of X-ray absorption spectra, the different environmental density effects on X-ray absorption spectra could be studied by the comparison with theoretical simulations. This work will improve the understanding of the atomic structure and radiation feature in WDM under extreme state, lay the foundation of theoretical model, and promote the development of related fields such as inertial fusion science and astrophysics.

固体物质在强冲击压缩下将会处于特殊的高压温稠密状态，其微观原子结构和X光辐射特性不同于凝聚态物质与热等离子体，具有独特的性质，X射线吸收光谱的环境密度效应研究具有跨学科、多尺度的特点，是当前高能量密度物理研究中最具挑战性的研究对象之一。本项目提出利用神光高功率大能量激光与特殊高Z黑腔作用所产生的近Plank辐射场为驱动源，通过辐射驱动冲击波对撞压缩方式产生均匀的高压（百万到数千万大气压）温稠密物质。通过发展高谱分辨与高时间分辨的X射线吸收光谱定量测量技术，获得可控压缩密度和离子环境下的X射线吸收特征光谱，结合理论计算模型分析光谱特征量随环境密度的变化规律与定量关系。本项研究将有助于提高人们对温稠密物质在极端状态下原子结构和辐射特性的物理认识，为新的物理模型建立和已有模型的验证提供重要参考，促进惯性约束聚变、XX物理以及实验室天体等极端条件物理研究的发展。

高密度温稠密物质广泛存在于惯性约束聚变和天体物理等系统中。开展更宽温度密度状态下的温稠密物质Ｘ射线吸收光谱研究对深入理解稠密等离子体中的电子结构，发展新的状态诊断方法具有重要意义。本项目基于神光系列激光装置，通过辐射驱动冲击波对撞压缩方式产生了最高超过4倍固体密度的温稠密Al等离子体；针对环境等离子体效应引起的吸收边移动和展宽等细致光谱结构的变化建立了高谱分辨的X射线光谱测量技术；开展了不同加载条件下时间分辨温稠密Al等离子体的X射线吸收光谱测量，获得了不同密度下的光谱特征，最后结合理论计算模型分析了X射线吸收光谱特征量随密度变化的规律，提高了对温稠密物质在极端状态下原子结构和辐射特性的物理认识。