Numerical Simulation for generation of Carbon Simple Cubic by Dynamic Compression of flyer impact

数值研究表明，在激光烧蚀压力的作用下，靶板与飞片碰撞过程中碰撞的动态压缩能够在热力学上产生碳简单立方体。碳素立方体有望在大于2TPA的压力下出现，但在高于几千K的温度下可能会熔化。为了实现从钻石开始的低熵动态压缩，提出了一种层状结构的板靶和飞片的撞击方案。利用一维拉格朗日流体力学程序和表格化状态方程库SESAME研究了金刚石在压缩过程中的热力学状态。冲击界面使用具有小冲击阻抗的材料会显著降低主冲击波的强度。研究发现，激波阻抗沿飞片厚度的梯度会产生小的多个冲击波进入钻石，对低熵压缩是有效的。得到了碳简单立方低熵动态压缩所需的热力学条件。

This research numerically makes it clear that Carbon Simple Cubic is able to be generated thermodynamically by the dynamic compression of the impact at the collision between the target and flyer which is accelerated by the laser ablation pressure. The Carbon Simple Cubic is expected to appear at the pressure more than 2 Tpa, however it may melt with the temperature of more than several 1000 K. An impact scheme of a slab target and flyer with a layered structure is proposed to achieve low-entropy dynamic compression starting from diamond. The thermodynamic state of diamond during compression is examined using one-dimensional Lagrangian hydrodynamic code and the tabulated equation of state library SESAME. The use of a material with a small shock impedance for the impact interfaces markedly decreases the strength of the primary shock wave. It is found that a gradient of shock impedance across the thickness of the flyer generates small multiple shock waves into the diamond and effective for low-entropy compression. The thermodynamic conditions required for Carbon Simple Cubic and low-entropy dynamic compression is achived.