Amendt Peter, Bellei Claudio, Ross J Steven, Salmonson Jay
Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Feb;91(2):023103. doi: 10.1103/PhysRevE.91.023103. Epub 2015 Feb 6.
Recent efforts to demonstrate significant self-heating of the fuel and eventual ignition at the National Ignition Facility make use of plastic (CH) ablators [O. A. Hurricane et al., Phys. Plasmas 21, 056314 (2014)]. Mainline simulation techniques for modeling CH capsule implosions treat the ablator as an average-atom fluid and neglect potential species separation phenomena. The mass-ablation process for a mixture is shown to lead to the potential for species separation, parasitic energy loss according to thermodynamic arguments, and reduced rocket efficiency. A generalized plasma barometric formula for a multispecies concentration gradient that includes collisionality and steady flows in spherical geometry is presented. A model based on plasma expansion into a vacuum is used to interpret reported experimental evidence for ablator species separation in an inertial-confinement-fusion target [J. S. Ross et al., Rev. Sci. Instrum. 83, 10E323 (2012)]. The possibility of "runaway" hydrogen ions in the thermoelectric field of the ablation front is conjectured.
近期在国家点火装置上为证明燃料显著的自热及最终点火所做的努力利用了塑料（CH）烧蚀层[O. A. 赫里克森等人，《物理等离子体》21，056314（2014）]。用于模拟CH胶囊内爆的主流模拟技术将烧蚀层视为平均原子流体，而忽略了潜在的物种分离现象。混合物的质量烧蚀过程显示出会导致物种分离的可能性、根据热力学观点的寄生能量损失以及火箭效率降低。本文给出了一个适用于多物种浓度梯度的广义等离子体气压公式，该公式包括球形几何结构中的碰撞性和稳定流。基于等离子体向真空中膨胀的模型被用于解释惯性约束聚变靶中烧蚀层物种分离的已报道实验证据[J. S. 罗斯等人，《科学仪器评论》83，10E323（2012）]。推测了在烧蚀前沿的热电场中“逃逸”氢离子的可能性。
