Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA.
Phys Rev E. 2018 Aug;98(2-1):023205. doi: 10.1103/PhysRevE.98.023205.
We report a theoretical equation of state (EOS) table for boron across a wide range of temperatures (5.1×10^{4}-5.2×10^{8} K) and densities (0.25-49 g/cm^{3}) and experimental shock Hugoniot data at unprecedented high pressures (5608±118 GPa). The calculations are performed with first-principles methods combining path-integral Monte Carlo (PIMC) at high temperatures and density-functional-theory molecular-dynamics (DFT-MD) methods at lower temperatures. PIMC and DFT-MD cross-validate each other by providing coherent EOS (difference <1.5 Hartree/boron in energy and <5% in pressure) at 5.1×10^{5} K. The Hugoniot measurement is conducted at the National Ignition Facility using a planar shock platform. The pressure-density relation found in our shock experiment is on top of the shock Hugoniot profile predicted with our first-principles EOS and a semiempirical EOS table (LEOS 50). We investigate the self-diffusivity and the effect of thermal and pressure-driven ionization on the EOS and shock compression behavior in high-pressure and -temperature conditions. We also study the sensitivity of a polar direct-drive exploding pusher platform to pressure variations based on applying pressure multipliers to LEOS 50 and by utilizing a new EOS model based on our ab initio simulations via one-dimensional radiation-hydrodynamic calculations. The results are valuable for future theoretical and experimental studies and engineering design in high-energy density research.
我们报告了一个硼的宽温区（5.1×10^{4}-5.2×10^{8} K）和密度区（0.25-49 g/cm^{3}）的理论状态方程（EOS）表以及前所未有的高压（5608±118 GPa）下的实验冲击 Hugoniot 数据。这些计算是通过将路径积分蒙特卡罗（PIMC）与第一性原理方法相结合，在高温下进行的，在较低温度下则使用密度泛函理论分子动力学（DFT-MD）方法进行的。PIMC 和 DFT-MD 通过在 5.1×10^{5} K 下提供一致的 EOS（能量差<1.5 哈特利/硼，压力差<5%）相互验证。Hugoniot 测量是在国家点火装置上使用平面冲击平台进行的。我们的冲击实验中发现的压力-密度关系位于我们的第一性原理 EOS 和半经验 EOS 表（LEOS 50）预测的冲击 Hugoniot 轮廓之上。我们研究了自扩散以及热和压力驱动的离化对 EOS 和在高温高压条件下的冲击压缩行为的影响。我们还研究了基于向 LEOS 50 应用压力倍增器以及通过利用基于我们从头算模拟的新 EOS 模型通过一维辐射流体动力学计算来研究极性直接驱动爆炸推进器平台对压力变化的敏感性。这些结果对于未来的高能密度研究中的理论和实验研究以及工程设计都具有重要价值。
