Falk K, McCoy C A, Fryer C L, Greeff C W, Hungerford A L, Montgomery D S, Schmidt D W, Sheppard D G, Williams J R, Boehly T R, Benage J F
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Sep;90(3):033107. doi: 10.1103/PhysRevE.90.033107. Epub 2014 Sep 12.
We present recent results of equation-of-state (EOS) measurements of shocked silica (SiO_{2}) aerogel foam at the OMEGA laser facility. Silica aerogel is an important low-density pressure standard used in many high energy density experiments, including the novel technique of shock and release. Due to its many applications, it has been a heavily studied material and has a well-known Hugoniot curve. This work then complements the velocity and pressure measurements with additional temperature data providing the full EOS information within the warm dense matter regime for the temperature interval of 1-15 eV and shock velocities between 10 and 40 km/s corresponding to shock pressures of 0.3-2 Mbar. The experimental results were compared with hydrodynamic simulations and EOS models. We found that the measured temperature was systematically lower than suggested by theoretical calculations. Simulations provide a possible explanation that the emission measured by optical pyrometry comes from a radiative precursor rather than from the shock front, which could have important implications for such measurements.
我们展示了在欧米茄激光装置上对冲击二氧化硅（SiO₂）气凝胶泡沫进行状态方程（EOS）测量的最新结果。二氧化硅气凝胶是许多高能量密度实验中使用的重要低密度压力标准，包括冲击与释放的新技术。由于其诸多应用，它一直是被大量研究的材料，并且有一条广为人知的雨贡纽曲线。这项工作通过额外的温度数据补充了速度和压力测量，在1 - 15电子伏特的温度区间以及对应0.3 - 2兆巴冲击压力的10至40千米/秒的冲击速度范围内，提供了热致密物质区域内完整的EOS信息。实验结果与流体动力学模拟和EOS模型进行了比较。我们发现测量到的温度系统地低于理论计算所表明的温度。模拟提供了一种可能的解释，即光学高温计测量到的发射来自辐射前驱体而非冲击前沿，这可能对此类测量有重要影响。
