In inertial confinement fusion (ICF), polycrystalline diamond—referred to as high density carbon (HDC)—has become a promising ablator candidate. However, with smaller grain size and lower initial density, the equation of state (EOS) for HDC can deviate from that for single-crystal diamond, which could be a concern for ICF designs, but current experimental EOS studies for HDC are far from sufficient to clarify how initial density affects target compressibility. Presented here are measurements of the Hugoniot for HDC with an initial density of 3.23 g/cm³ at pressures of 17–26 Mbar. Combined with experimental data reported for nanocrystalline diamond (NCD), a stiffer compressibility of NCD due to lower initial density is confirmed. Two porous models are used for comparison and seem to offer better agreement compared with SESAME databases. Also, the effect of temperature on the Grüneisen parameter, which is usually neglected, might need to be considered for NCD under these conditions. The present data offer important support for EOS studies relevant to ICF and constrain the construction of wide-range EOS.

中文翻译：

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在与ICF有关的压力下，多晶金刚石的密度依赖性冲击休格尼奥特

在惯性约束聚变（ICF）中，被称为高密度碳（HDC）的多晶金刚石已成为一种有前途的烧蚀候选材料。但是，由于晶粒尺寸较小且初始密度较低，因此HDC的状态方程（EOS）可能与单晶金刚石的状态方程有所不同，这可能是ICF设计所关注的问题，但是目前对HDC进行的实验EOS研究远远不够阐明初始密度如何影响目标可压缩性。此处显示的是用于HDC的Hugoniot的测量，初始密度为3.23 g / cm ³在17–26 Mbar的压力下。结合报道的纳米晶金刚石（NCD）的实验数据，证实了由于较低的初始密度，NCD的可压缩性更高。使用了两个多孔模型进行比较，与SESAME数据库相比，它们似乎提供了更好的一致性。同样，在这些条件下，对于NCD可能需要考虑温度通常对Grüneisen参数的影响。目前的数据为与ICF有关的EOS研究提供了重要的支持，并限制了大范围EOS的建设。