丝阵Z箍缩早期消融等离子体动力学的二维数值模拟研究

Two-dimensional numerical studies of ablated-plasma dynamics of wire-array Z-pinches

采用理想磁流体力学模型,给出合理的二维(r,θ)质量注入边界条件,对丝阵Z箍缩早期消融等离子体的动力学过程进行了二维(r,θ)数值模拟研究,得到消融等离子体各参量以及磁场的二维时空分布.模拟结果表明,消融等离子体的运动包括四个主要阶段:首先向轴漂移,然后在轴线处滞止并形成先驱等离子体柱,随后先驱等离子体柱被压缩,最后缓慢膨胀.计算了不同丝阵半径和丝间距情况下消融等离子体到轴速度以及消融质量占丝阵总质量的份额,它们的变化规律与实验结果基本符合.通过比较不同丝间距情况下的二维磁场结构及其对消融等离子体的加速情况,可以为丝阵负载优化设计提供有价值的参考.

The dynamics of ablated plasma of wire-array Z-pinches are studied numerically in （r,θ） geometry by using 2D MHD simulation model,in which plausible mass injection boundary conditions are incorporated,and 2D spatio-temporal distribution of plasma parameters and magnetic field are obtained. The ablated-plasma dynamics involves 4 stages： drifting towards the axis,arriving at the axis and forming the precursor column,contraction and expansion of the precursor column,which is essentially reasonable. The relationships between the ablation velocity,the ratio of ablated plasmas to the total wire-array mass and the initial array load parameters are analyzed,and the results are in reasonablly good agreement with the experiment. The effects of the initial inter-wire separation on the structure of magnetic field are investigated and the results can give valuable suggestions to designing the wire array Z-pinch loads.