基于MHD的双特征平面内X箍缩内爆动力学过程的二维数值模拟研究

X-pinch is very suitable for X-ray backlighting of a rapidly changing field of high-density, such as Z-pinches as x-ray sources for inertial confinement fusion. Thus, studying X-pinch has important significance and broad application prospects. Based on a large number of X-pinch diagnosis experiments and two-dimensional radiative MHD (Magnetohydrodynamics) with three-temperature simulations of X-pinch implosion were already built, this project will carry out corresponding numerical simulation analysis in two-dimensional MHD simulations of X-pinch implosion. The simulations will perform in the (r, z) and (x, y) geometries for homogeneous and heterogeneous loads to get implosion plasma various parameters of two-dimensional space-time distribution. The formation of a minidiode in X-pinch, the development of a neck and an X-radiating hot spot, and the influence of the plasma corona on the implosion dynamics of the dense X-pinch plasma will be investigated. These simulations will confirm the previous experimental and numerical results on the cascade character of implosion. And necessary theoretical guidance can be provided to the optimized design for experimental parameters involved in the key problems of X-pinch experiments.The research achievements of this project is expected to enrich the fundamental theory, analyzing methodology and innovation technology of X-pinch research field, which are of unique significance in both theoretical development and practical applications.

X箍缩（X-pinch）等离子体是高质量的X射线辐射点源，其研究具有重要的意义和广阔的应用前景。基于已开展的X-pinch诊断实验工作，以及预研工作所建立的描述X-pinch内爆动力学行为的磁流体动力学（Magnetohydrodynamic，MHD）模型，本项目将深入开展在二维（r, z）和（x, y）空间内针对X-pinch二维MHD模型的数值模拟研究，得到内爆等离子体在两个相互垂直特征平面内的二维时空分布，研究箍缩区域内小型二极管的形成、箍缩瓶颈和X射线热点的发展、等离子体晕层对高密度X箍缩等离子体内爆过程的影响等复杂动力学特性，并与X-pinch实验所获得背光照相图像及相关诊断数据相互印证，从而对X-pinch实验参数优化设计等X-pinch应用中涉及的关键问题提供必要的理论指导。本项目研究结果将丰富X-pinch数值模拟研究领域的基础理论和分析方法，具有重要的理论意义和应用价值。

X 箍缩（X-pinch）等离子体是高质量的X 射线辐射点源，非常适合作为X 射线背光光源用来研究高密度材料中的瞬态现象，如应用于与受控核聚变相关的Z 箍缩（Z-pinch）内爆等离子体的背光成像研究，因此X-pinch 的研究具有重要的意义和广阔的应用前景。本项目利用X-pinch辐射点源对X-pinch自身发展过程及丝阵Z-pinch的早期发展过程开展了背光照相的实验研究，获得了X-pinch发展过程不同时刻的时间序列图像，在背光照相的图像中可以清晰观察到X-pinch交叉点处等离子体的外爆、箍缩以及最终的崩溃阶段。基于大量的X-pinch 实验工作，针对X-pinch内爆基本物理过程，本项目建立了能模拟X-pinch内爆动力学整个箍缩演变过程（包括稠密等离子体的形成、压缩，热点的生成，X射线脉冲辐射）的二维MHD模型，确定了数值模拟研究的对象区域、计算初始时刻以及等离子体初始状态。针对均质、非均质模型和不同阶段的圆锥模型和抛物线模型确定明确解条件，运用改进拉格朗日－欧拉法进行数值模拟计算，以求再现X-pinch内爆动力学的演化过程，从而研究X-pinch内爆动力学过程的物理特性。本项目的研究成果将丰富X-pinch研究领域的基础理论和分析方法，具有重要的理论意义和应用价值。