温稠密氢氘混合物热力学、光学和电子输运特性理论研究

Theoretical study on the thermodynamic, optical, and electronic transport properties of warm dense hydrogen-deuterium mixtures

摘要:

温稠密状态下的氘氚混合物是惯性约束聚变必然要经历的中间物质状态. 其在温稠密状态下的热力学特性和输运参数在聚变实验设计研究中起着重要作用. 但由于氚具有放射性, 实验中可以用氢氘混合物来模拟替代研究氘氚混合物. 本文采用了密度泛函理论分子动力学模拟和基于自洽流体变分理论的化学模型, 构建了氢氘混合物在0~200 GPa和300~10 000 K宽范围状态方程和声速数据库. 此外, 结合Kubo–Greenwood公式计算得到了氢氘混合物电子电导率以及光学反射率和折射率, 建立起混合物绝缘–金属化相变与实验上易探测的光学物理量反射率和折射率之间的联系, 为从实验角度探索氢及其同位素的金属化提供了理论指导.

Abstract:

The deuterium-tritium mixture under warm dense state is an intermediate material state that is inevitably encountered in inertial confinement fusion. The thermodynamic properties and transport parameters of this mixture play a significant role in the design of fusion experiments. However, due to the radioactivity of tritium, hydrogen-deuterium mixtures can be used as a substitute in experiments to simulate and study deuterium-tritium mixtures. In this study, density functional theory molecular dynamics simulations and a chemical model based on self-consistent fluid variational theory were employed to construct the equation of state and sound velocity database for hydrogen-deuterium mixtures in the range of 0~200 GPa and 300~10 000 K. Additionally, using the Kubo-Greenwood formula, the electronic conductivity, optical reflectivity, and refractive index of hydrogen-deuterium mixtures were calculated. The relationship between the insulator-to-metal phase transition in the mixture and the experimentally detectable optical physical quantities including optical reflectivity and refractive index was established. This theoretical guidance helps in exploring the metalization of hydrogen and its isotopes from an experimental perspective.