烧蚀材料对辐射烧蚀驱动的Richtmyer-Meshkov不稳定性影响

Radiation-driven Richtmyer-Meshkov instability with different material ablators

在惯性约束聚变靶丸内爆过程中,辐射烧蚀所产生的冲击波经过带有扰动的界面时,会触发Richtmyer-Meshkov不稳定性。惯性约束聚变内爆靶丸一般使用掺杂的CH塑料或者掺杂的Be材料作为烧蚀层,为了探索Be和CH塑料烧蚀层对Richtmyer-Meshkov不稳定性抵抗能力,对界面预制单模正弦扰动的双层靶中Richtmyer-Meshkov不稳定性发展过程进行了理论分析与数值模拟。理论分析认为Richtmyer-Meshkov不稳定性线性增长率和X射线辐射温度、界面扰动波长、扰动振幅以及烧蚀层密度有较大关系。使用辐射流体力学程序对辐射温度高达100 eV的黑体谱X射线烧蚀界面带有扰动的双层靶进行了模拟。模拟结果表明,在相同的辐射烧蚀条件下,CH塑料/泡沫(CH/Foam)靶界面扰动增长比Be/Foam快,密度较大的Be对Richtmyer-Meshkov不稳定性具有更强的抵抗能力。该研究结果对惯性约束聚变内爆靶丸的设计具有重要的参考价值。

Fluid interface instability seriously affects the performance of ICF （inertial confinement fusion） capsule implosion, doped CH plastic or Be （Beryllium） ablator is generally employed in ICF capsule. The RM （ Richtmyer-Meshkov） instability occurs when the radiation-generated shock penetrates the rippled inner surface of ablator. In order to explore the resistance ability to RM instability with Be or CH plastic as ablator, theoretical analysis and numerical simulation were carried on the evolution of RM instability. Theoretical analysis indicates that the linear growth rate of RM instability depends on the radiation temperature, the wavelength, the initial amplitude of perturbation and the density of ablator. The hydrodynamics process of high temperature （above 100 eV） blackbody spectrum X-ray ablating rippled interface of Be/Foam and CH/Foam target is simulated by a radiation hydrodynamic code. Simulation results show that the Be ablator with higher density has stronger resistance ability to RM instability than CH plastic ablator. The results are useful for capsule design in inertial confinement fusion.