用赝势方法计算五种简单金属的Hugoniot曲线

基于本文作者在文献[1]中所导出的冷压P_x,利用德拜固体模型并考虑电子的热压,得到了金属的高温高压状态方程。在与Hugoniot方程联立后,就能算出Hugoniot曲线。本文计算了五种简单金属的Hugoniot曲线。结果表明,在现有实验数据所能达到的范围内,理论计算与实验符合都比较好。 关键词：     

一种计算固体冷能、冷压和结合能的新方法

 给出了利用Hugoniot参数计算材料冷能、冷压和结合能的一种新方法，对52种纯元素单质固体材料的计算表明，该方法的计算误差较小，对计算碱金属等外层电子数较少的材料效果尤佳。利用文中给出的冷能、冷压公式，计算出的铝、铜、银和锌等材料的冲击绝热线与实验数据符合得非常好。     

凝聚态物质状态方程的一个数值模型

建立了凝聚态物质的一个三项式状态方程：以Faussurier平均原子模型为基础计算电子热压和电子热能;以Cowan模型为基础计算离子热压和离子热能;用基于实验数据的半经验拟合公式计算物质的冷压和冷能。用实验数据检验了用平均原子模型计算的平均电离度。将状态方程与Hugoniot关系式相结合,计算了Be和Al的冲击绝热曲线,结果充分地展现出电子在高温、高密度条件下的壳层结构效应。     

利用多层阻抗梯度飞片产生准等熵压缩的理论解析

基于冲击波理论对多层阻抗梯度飞片击靶过程波系的相互作用做了理论分析，计算表明在多层阻抗梯度飞片的撞击下，样品的压缩线是一组通过不同初始状态点的冲击压缩线的连线, 它位于冲击压缩(hugoniot)线与等熵压缩线之间. 所以通过飞片层数的设计,可获得介于冲击压缩线与等熵线之间的任意状态点,这就为以后偏冲击压缩(off-hugoniot)状态方程的实验研究提供了理论参考. 实验测量的样品/窗口界面速度与理论计算的一致性支持上述结论的可靠性与准确性. 关键词： 准等熵压缩 多层阻抗梯度飞片 理论解析     

石墨冲击压缩的理论研究

 用统一的排列模型研究石墨在高压下的状态方程。能量由冷能、晶格振动和电子的热贡献三部分组成。利用上述模型计算了石墨的膨胀曲线及石墨的冲击压缩Hugoniot曲线，当V₀＝5.29 cm³/mol时，计算结果与Morgan实验结果一致。     

A physically-based Mie–Grüneisen equation of state to determine hot spot temperature distributions

A physically-based form of the Mie–Grüneisen equation of state (EOS) is derived for calculating 1d planar shock temperatures, as well as hot spot temperature distributions from heterogeneous impact simulations. This form utilises a multi-term Einstein oscillator model for specific heat, and is completely algebraic in terms of temperature, volume, an integrating factor, and the cold curve energy. Moreover, any empirical relation for the reference pressure and energy may be substituted into the equations via the use of a generalised reference function. The complete EOS is then applied to calculations of the Hugoniot temperature and simulation of hydrodynamic pore collapse using data for the secondary explosive, hexanitrostilbene (HNS). From these results, it is shown that the choice of EOS is even more significant for determining hot spot temperature distributions than planar shock states. The complete EOS is also compared to an alternative derivation assuming that specific heat is a function of temperature alone, i.e. c_v(T). Temperature discrepancies on the order of 100–600 K were observed corresponding to the shock pressures required to initiate HNS (near 10 GPa). Overall, the results of this work will improve confidence in temperature predictions. By adopting this EOS, future work may be able to assign physical meaning to other thermally sensitive constitutive model parameters necessary to predict the shock initiation and detonation of heterogeneous explosives.     

Quasiisobaric approximation in combustion theory

Based on the laminar combustion of gases and the filtration combustion of porous condensed compounds, some general approaches to the study of their mathematical models are demonstrated that simplify their quantitative analysis. Processes in a wide circle of phenomena proceed under conditions of a weakly disturbed pressure field, though providing macroscopic convective transfer. Under conditions of the substantially changed temperature field, in contrast to condensed media, gaseous media change their specific volume and increase mobility, which should be considered in combustion processes. The suggested quasi-stationary consideration of reacting medium flows simplifies their computation and analysis.     

金刚石膜的厚度及背表面过渡层对热导率的影响

 采用微波等离子体化学气相沉积（MWPCVD）方法制备金刚石膜，研究了金刚石膜的厚度以及生长初期的SiC过渡层对其热导率的影响，给出了膜厚和背表面SiC过渡层减薄厚度与金刚石膜热导率的关系。     

Equation of State for Shock Compressed Xenon in the Ionization Regime:ab Initio Study

Quantum molecular dynamic (QMD) simulations have been applied to study the thermophysical properties of liquid xenon under dynamic compressions. The equation of state (EOS) obtained from QMD calculations are corrected according to Saha equation, and contributions from atomic ionization, which are of predominance in determining the EOS at high temperature and pressure, are considered. For the pressures below 160 GPa, the necessity in accounting for the atomic ionization has been demonstrated by the Hugoniot curve, which shows excellent agreement with previous experimental measurements, and three levels of ionization have been proved to be sufficient at this stage.     

Equation of State for Shock Compressed Xenon in the Ionization Regime: ab Initio Study

Quantum molecular dynamic (QMD) simulations have been applied to study the thermophysical properties of liquid xenon under dynamic compressions. The equation of state (EOS) obtained from QMD calculations are corrected according to Saha equation, and contributions from atomic ionization, which are of predominance in determining the EOS at high temperature and pressure, are considered. For the pressures below 160 GPa, the necessity in accounting for the atomic ionization has been demonstrated by the Hugoniot curve, which shows excellent agreement with previous experimental measurements, and three levels of ionization have been proved to be sufficient at this stage.     

炸药爆轰产物Jones-Wilkins-Lee状态方程不确定参数

Jones-Wilkins-Lee (JWL)状态方程是一种不显含化学反应、由实验方法确定参数的半经验状态方程, 能比较精确地描述爆轰产物的膨胀驱动做功过程. 在JWL状态方程中有多个未知(不确定)参数需要确定. 传统的确定JWL状态方程参数的方法是“调参数”, 人为因素影响较大, 无法给出参数的不确定性信息. 本文利用贝叶斯分析方法研究了炸药的不确定参数, 该方法能够基于以往的认识、实验和模拟数据标定(calibration)不确定参数. 在本文结果中, 不确定参数的后验分布均值与文献结果相符合, 基于参数标定结果的数值模拟90%置信区间完全包含实验数据. 数值标定结果说明贝叶斯参数标定适用于确定样品炸药的JWL状态方程参数. 特别是, 在本文JWL状态方程参数标定过程中极大地减少了人为因素的影响.     

Effect of radiation on compressibility of hot dense sodium and iron plasma using improved screened hydrogenic model with l splitting

High pressure investigations of matter involve the study of strong shock wave dynamics within the materials which gives rise to many thermal effects leading to dissociation of molecules, ionization of atoms, and radiation emission, etc.The response of materials experiencing a strong shock can be determined by its shock Hugoniot calculations which are frequently applied in numerical and experimental studies in inertial confinement fusion, laboratory astrophysical plasma,etc. These studies involve high energy density plasmas in which the radiation plays an important role in determining the energy deposition and maximum compressibility achieved by the shock within material. In this study, we present an investigation for the effect of radiation pressure on the maximum compressibility of the material using shock Hugoniot calculations. In shock Hugoniot calculations, an equation of state(EOS) is developed in which electronic contributions for EOS calculations are taken from an improved screened hydrogenic model with-l splitting(I-SHML) [High Energy Density Physics(2018) 26 48] under local thermodynamic equilibrium(LTE) conditions. The thermal ionic part calculations are adopted from the state of the art Cowan model while the cold ionic contributions are adopted from the scaled binding energy model. The Shock Hugoniot calculations are carried out for sodium and iron plasmas and our calculated results show excellent agreement with published results obtained by using either sophisticated self-consistent models or the first principle study.     

用于预测疏松材料冲击压缩特性的热力学模型

 在一定的假设条件下，从基本的热力学关系出发，导出了一个新的物态方程表达式。利用这一新形式特态方程所建立的热力学模型，可预测疏松材料的冲击压缩行为。以低、中、高冲击阻抗的铝、铜和钨为示例，将本模型的理论计算曲线与实验冲击压缩数据比较，表明本模型的在宽广的压力范围内具有良好的普活性；对不同初妈密度，疏松材料的冲击压缩行为均显示出较为满意的理论经历测能力；与现有的其它疏松材料物态方程模型相比，本模型在理论上和实际应用中均具有较大的优越性。     

超压爆轰产物冲击绝热线的实验研究

炸药驱动高速飞片撞击基板和炸药,从而在炸药中产生超压爆轰状态。利用高速扫描相机测试了冲击波在炸药试样和铝标准试样中的传播速度,采用对比法得到了炸药爆轰产物的雨贡纽曲线。通过分析发现,通常的冲击波-粒子速度(D-u)关系式的线性拟合不适合CJ点附近的雨贡纽数据,对于炸药爆轰产物的冲击波-粒子速度关系式最好采用非线性关系式。利用冲击波前后物理量守恒关系式,将D-u数据转化为p-V数据,拟合得到了炸药爆轰产物的雨贡纽p-V关系。     

Mean-field potential calculations of high-pressure equation of state for BeO

A systematic study of the Hugoniot equation of state, phase transition, and the other thermodynamic properties including the Hugoniot temperature, the electronic and ionic heat capacities, and the Gruneisen parameter for shockcompressed BeO, has been carried out by calculating the total free energy. The method of calculations combines first-principles treatment for 0 K and finite-T electronic contribution and the mean-field-potential approach for the vibrational contribution of the lattice ion to the total energy. Our calculated Hugoniot is in good agreement with the experimental data.     

Release Behaviour of Shock Loaded LY12 Aluminium Alloy

By making use of a light gas gun, a specially designed target is impacted by the LY12 flyer, and the pressure is taken in the range of 0.6-3 GPa. Based on the stress profiles measured in the buffer materials by manganese gauges, the Hugoniot curve and release curves of LY12 aluminium alloy are obtained. Meanwhile, the release curves from different initial shocked states are described in both the pressure-particle velocity plane and the pressure-specific volume plane.     

计算零温物态方程的一种方法

本文利用Gruneisen系数的冷压微分关系式和经验内插公式,给出物质的冷压和冷能,在1≤ρ/ρ_o≤1.5范围内与Born-Mayer势和改进的Morse势形式的冷压相符得很好。我们计算Pb、W、Mo、Cu、Fe、Al等物质的Hugonit曲线(直至几TPa),与其实验结果比较,符合程度也是令人满意的。本文提供了两个积分表(I_p、I_e),可以利用它方便地计算出物质的冷压和冷能。     

Equation of state of fluid helium at high temperatures and densities

Hugoniot curves and shock temperatures of gas helium with initial temperature 293 K and three initial pressures 0.6, 1.2, and 5.0 MPa were measured up to 15000 K using a two-stage light-gas gun and transient radiation pyrometer. It was found that the calculated Hugoniot EOS of gas helium at the same initial pressure using Saha equation with Debye-Hückel correction was in good agreement with the experimental data. The curve of the calculated shock wave velocity with the particle velocity of gas helium which is shocked from the initial pressure 5 MPa and temperature 293 K, i.e., theD ≈u relation,D=C ₀+λu (u<10 km/s, λ=1.32) in a low pressure region, is approximately parallel with the fittedD ≈u (λ=1.36) of liquid helium from the experimental data of Nellis et al. Our calculations show that the Hugoniot parameter λ is independent of the initial density p{in0}. TheD≈u curves of gas helium will transfer to another one and approach a limiting value of compression when their temperature elevates to about 18000 K and the ionization degree of the shocked gas helium reaches 10⁻³.     

固体炸药爆轰的一种考虑热学非平衡的反应流动模型

基于固体炸药爆轰过程中化学反应混合区内的固相反应物与气相生成物处于力学平衡状态及热学非平衡状态的事实,提出一种考虑热学非平衡效应的反应流动模型来描述固体炸药的爆轰流动现象.该爆轰流动模型的主要特点是,在反应混合物Euler方程和固相反应物质量守恒方程的基础上,通过附加一套关于固相反应物的组分物理量的流动控制方程来表达固相反应物与气相生成物之间的热学非平衡效应.根据反应混合区内固相反应物与气相生成物这两种化学组分保持各自内能守恒的混合规则,并借助它们具有压力相等的性质以及满足体积分数总和为1的条件,推导获得的附加方程有：固相反应物的内能演化方程、体积分数演化方程及反应混合物的压力演化方程.这样,建立的爆轰模型包括：反应混合物的质量守恒方程、动量守恒方程、总能量守恒方程、压力演化方程,以及固相反应物的质量守恒方程、内能演化方程、体积分数演化方程.对所获得的爆轰模型方程组采用一个时空二阶精度的有限体积法进行数值求解,典型爆轰问题算例结果表明本文提出的固体炸药爆轰模型是合理的.     

冲击载荷下Al2O3陶瓷的动态响应

 通过平面飞片碰撞实验，研究了质量分数为90%的Al₂O₃陶瓷在0～11.0 GPa的动态响应行为，给出了该材料的Hugoniot弹性极限（σ_HEL）、动态屈服强度、高压声速和Hugoniot曲线。结果表明：当冲击应力在σ_HEL≈11.0 GPa的范围内，Al₂O₃陶瓷的塑性区压缩特性表现出较明显的弥散行为；在远低于σ_HEL的应力区，Al₂O₃陶瓷已表现出明显的压缩损伤效应，即出现所谓的破坏波效应。