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利用SHML模型计算了密度为ρ=1g·cm-3、温度为150eV、200eV、250eV、300eV、400eV的Sn等离子体的随光子能量变化的辐射不透明度及Rosseland平均不透明度.分析了不透明度随光子能量变化曲线的吸收峰值(不透明度峰值)与能级跃迁的对应关系.还将Sn的Rosseland平均不透明度与DCA/UTA及STA模型计算结果作了比较,吻合较好.     

Ne、Ar、Kr、Xe等离子体Planck和Rosseland平均不透明度的近似计算

根据平均原子模型和类氢光吸收系数，近似地计算了Ne、Ar、Kr、Xe等惰性元素高温、高密度等离子体的Planck和Rosseland不透明度。在计算线谱吸收过程中，采用了唯象方法处理线谱演化成谱带时的加宽效应及谱带重叠效应。将不透明度数据拟合成温度和密度的幂函数形式，它能够用于辐射体的数值拟合。     

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利用l能级分裂的屏蔽氢模型(SHML)，计算了不同混合比例的Au-Gd混合物在温度为250eV、密度为1g•cm–3的Rosseland平均不透明度。计算值与实验值和理论值吻合得较好。     

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利用考虑l能级分裂的屏蔽氢离子模型(SHML),计算高温(T=200~300eV)、高密度(ρ=1g.cm-3)下纯元素Au、Ho、Gd、Sm、Nd、Sn、Ag的Rosseland平均不透明度,以及Au与这些元素混合后的Rosseland平均不透明度,其结果与DCA/UTA及STA模型计算结果吻合较好。     

利用混合介质降低黑腔壁辐射能耗的理论研究

 采用Au-Gd混合介质作腔壁，增大腔壁Rosseland不透明度，降低其辐射能耗是提高黑腔辐射温度的途径之一。利用纯Au和Au-Gd混合介质的Rosseland平均辐射不透明度数据库和多次电离区物态方程加入一维辐射流体力学程序，计算分析了在神光 Ⅱ激光装置产生的黑腔X光辐射能源条件下， Au-Gd混合介质作腔壁对提高黑腔辐射温度的影响，得到了Au-Gd混合介质作腔壁可使黑腔辐射温度提高0.1~0.2MK的结论。     

稠密Ar等离子体不透明度的计算

用屏蔽氢离子模型计算了冲击压缩产生的温度T～1.8 eV,密度ρ～0.0044 g/cm3稠密氩等离子体随光子能量变化的辐射不透明度,并与实验作了比较,探讨了冲击压缩产生的稠密等离子体中自由-自由吸收、束缚-自由吸收和束缚-束缚吸收对不透明度的贡献.计算结果表明,对冲击压缩产生的稠密等离子体,自由-自由吸收对不透明度的贡献非常大,特别当光子能量较低时(hv～2.0 eV )自由-自由吸收为不透明的主要部分,因此较好地计算自由-自由吸收项对冲击压缩产生的稠密等离子体不透明度的研究是非常重要的.     

DTA模型计算高温氟化钠等离子体的辐射不透明度

使用细致谱项模型(detailed term accounting,DTA)计算了局域热动平衡(local thermodynamic equilibrium,LTE)近似下氟化钠等离子体密度为0.01?g/cm3的等密度系列的谱分辨不透明度以及Rosseland和Planck平均不透明度,分析了钠和氟离子L→M跃迁对不透明度的贡献以及温度的升高对于两种元素的L→M跃迁吸收峰的影响.     

DTA模型计算高温氟化钠等离子体的辐射不透明度

使用细致谱项模型(detailed term accounting，DTA)计算了局域热动平衡(local thermodynamic equilibrium，LTE)近似下氟化钠等离子体密度为0．01g／cm^3的等密度系列的谱分辨不透明度以及Rosseland和Planck平均不透明度，分析了钠和氟离子L→M跃迁对不透明度的贡献以及温度的升高对于两种元素的L→M跃迁吸收峰的影响。     

Pt等离子体不透明度的理论计算

利用考虑l能级分裂的屏蔽氢离子模型SHML,计算了重核等离子体Pt在密度温度分别为时束缚—束缚、束缚—自由、自由—自由的吸收系数,并由此计算了Pt等离子体随光子能量变化的辐射不透明度.SHML模型计算的辐射不透明度好于SHM模型的计算结果这是肯定无疑的.     

高温稠密金等离子体辐射不透明度的多极效应

使用平均原子模型研究了电四极及更高阶跃迁对高温稠密金等离子体辐射不透明度的贡献.计算并讨论了在不同温度密度条件下,电四极,电八极,电十六极跃迁对束缚-束缚跃迁的影响.计算了密度为96.405 g/cm3时,不同温度条件下,电四极,电八极跃迁对Rosseland平均不透明度的贡献.考虑了电四极、电八极跃迁后金等离子体不透明度的相对改变最大分别为4.67%和1.5%,并和其它文献的理论结果进行了比较.     

Radiative properties of matter based on quantum statistical method

We present the preliminary results of our code OPAQS(opacity calculation using quantum statistical model) that is based on the self consistent Hartree-Fock-Slater model for the average atom. The code is capable of performing robust calculations of average charge state, frequency-dependent and mean opacities. The accuracy of the atomic model is verified by comparing the calculations of average charge state with various published results. The monochromatic opacities for iron computed at different sets of temperatures and densities are compared with LEDCOP. The Rosseland and Planck opacities for iron and aluminum are validated with some state-of-the-art codes. The results are in good agreement with the published data.     

Radiative opacity of plasmas studied by detailed term (level) accounting approaches

Detailed term and level accounting (DTA and DLA) schemes have been developed to calculate the spectrally resolved and Rosseland and Planck mean opacities of plasmas in local thermodynamic equilibrium. Various physical effects, such as configuration interaction effect (including core-valence electron correlations effect and relativistic effect), detailed line width effect (including the line saturation effect), etc., on the opacity of plasmas have been investigated in detail. Some of these physical effects are less capable or even impossible to be taken into account by statistical models such as unresolved transition arrays, super-transition-array or average atom models. Our detailed model can obtain accurate opacity of plasmas. Using this model, we have systematically investigated the radiative opacities of low, medium and high-Z plasmas under different conditions of temperature and density. For example, for aluminum plasma, in the X-ray region, we demonstrated the effects of autoionization resonance broadening on the opacity for the first time. Furthermore, the relativistic effects play an important role on the opacity as well. Our results are in good agreement with other theoretical ones although better agreement can be obtained after the effects of autoionization resonance broadening and relativity have been considered. Our results also show that the modelling of the opacity is very complicated, since too many physical effects influence the accuracy of opacity. For medium and high-Z plasmas, however, there are systematic discrepancies unexplained so far between the theoretical and experimental opacities. Here, the theoretical opacities are mainly obtained by statistical models. To clarify the discrepancies, efforts from both sides are needed. From the view-point of theory, however, a DLA method, in which various physical effects can be taken into account, should be useful in resolving the difference. Taking gold plasma as an example, we studied in detail the effects of core-valence electron correlation and line width on the opacity. Our DLA results correctly explained, for the first time, the relative intensity of the two strong absorption peaks located near the photon energy of 70 and 80 eV, which was experimentally observed by Eidmann et al. [Europhys. Lett., 1998, 44: 459].     

Radiative opacity of low-Z plasma using screened hydrogenic model including l-splitting

Radiative opacities of low-Z plasma are computed using average atom model. Screened Hydrogenic Model including l-splitting (SHML) is used as the atomic model to obtain the internal structure of ions embedded in plasma. The phenomenon of pressure ionization of levels is described by a Gaussian density dependent degeneracy function. Use of the most recent compilation of the screening constants makes it possible to include l-splitting in a direct manner. The average ionization in the plasma is obtained by self-consistently solving the non-linear set of coupled SHML equations along with the charge neutrality condition of Wigner–Seitz cell. The frequency dependent opacity of Aluminum plasma is compared with the data obtained from Los Alamos (LANL) opacity library and a reasonable agreement is seen. The computed values of Rosseland and Planck opacity of C, Al and Fe plasma are also in good agreement with the LANL opacity database value for different plasma density and temperature.     

Enhancement of extreme ultraviolet radiations from a laser-produced plasma using copper–tungsten alloy

Continuous extreme ultraviolet (EUV) emission intensity from a laser-produced plasma in the wavelength between 40 and 200 nm for a copper–tungsten alloy target was observed to be 1.3 times higher than that for a tungsten target. Using the alloy target, low-opacity regions of one material were filled with high-opacity regions of another material. This opacity effect resulted in the increase of a calculated Rosseland mean opacity compared with either of the constituents, which may explain the increase of the EUV emission intensity.