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.     

The energies of ions calculated by the improved screened hydrogenic ionization model

:用改进的屏蔽氢离子模型[1]计算了离子的电离势和次壳层能量。大量计算数据表明,改进模型计算的结果在低Z低离化时与实验相符;在高Z高离化时与MCDF的结果相符,从而弥补了R.M.More屏蔽氢离子模型、Slater单电子模型、WBEPM模型的不足。     

用改进的屏蔽氢离子模型计算离子的能量

:用改进的屏蔽氢离子模型[1]计算了离子的电离势和次壳层能量。大量计算数据表明,改进模型计算的结果在低Z低离化时与实验相符;在高Z高离化时与MCDF的结果相符,从而弥补了R.M.More屏蔽氢离子模型、Slater单电子模型、WBEPM模型的不足。     

A screened hydrogenic model using analytical potentials

The screened hydrogenic model and analytical potentials are tools widely used for atomic calculation of dense plasma physics. In this paper, we present a simple method to obtain screened hydrogenic energy levels and wave functions from analytical potentials for ions. Atomic data obtained using this model are compared satisfactorily with results of similar models and of more sophisticated self-consistent codes.     

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.     

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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。     

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利用试验势法和平均半径-屏蔽电荷迭代法研究基于解析势的相对论和非相对论屏蔽类氢模型。通过对屏蔽电荷的计算和比较,证实平均半径-屏蔽电荷迭代法无论在效率上还是计算精度上优于试验势法。与More和Faussurier屏蔽类氢模型比较,在电子电离能、离子总能量和电子跃迁能量的计算结果精度方面,基于解析势的相对论性屏蔽类氢模型占有优势。     

激光靶耦合中的部分角量子数平均原子模型

在一维平面非平衡多群辐射输运激光靶耦合总体程序RDMG角量子数平均原子模型的基础上,针对程序在计算如Au等高Z元素时,所需计算能级太多,计算量大的问题,合理的提出了只在部分能级考虑角量子数,其它能级考虑主量子数的部分角量子数平均原子模型.对比了新旧模型的数值模拟结果,结果显示,新模型得到了与原模型符合的很好的物理图像,同时计算时间由于计算能级数的减少而大大降低.     

Simple models of correlation in atoms

Brillouin's theorem, together with a power series expansion method, is used to explain the result (obtained by the numerical calculations of other workers) that the use of a Hartree-Fock 1s orbital in the correlation splitting approach to two-electron atoms is less satisfactory than the use of a screened hydrogenic orbital.     

Average-ion model for calculating the state of a multicomponent transient nonequilibrium highly charged ion plasma

The ionization kinetics of a transient nonequilibrium highly charged ion plasma are investigated in the average-ion approximation. Approximations of a hydrogenic ion, whose energy levels depend either on the principal quantum number alone or on the principal and orbital angular momentum quantum numbers, are considered as atom models. The results of calculations of various plasma characteristics performed within this model are presented, and a comparison with previously published data, as well as with calculations in the chemical-bond approximation, is performed. It is shown that the average-ion model satisfactorily describes the spectral characteristics of a nonideal plasma. Zh. éksp. Teor. Fiz. 111, 496–513 (February 1997)     

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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。     

Study of theK α satellites and hypersatellites in the x-ray and Auger spectra of neon

We report in this paper our calculations of the energies of the satellite and hypersatellite lines in the x-ray and Auger spectra of neon, using screened hydrogenic wavefunctions. Our calculations have enabled us to draw an energy level diagram for the neon atom in various defect-electron configurations. It is possible to show the transitions giving rise to the various x-ray and Auger satellites and hypersatellites using this diagram. The authors felicitate Prof. D S Kothari on his eightieth birthday and dedicate this paper to him on this occasion     

Calculation of the radiative opacity of laser-produced plasmas using a relativistic-screened hydrogenic model

In this work, we use a relativistic-screened hydrogenic model to compute the radiative opacity of laser-produced plasmas. The model is based on a set of screening charges which allow one to easily calculate atomic properties of isolated ions. These screened charges have been fitted to a fourth-order polynomial depending on the nuclear charge Z for ground and single excited states of ions belonging to the isoelectronic sequences comprised between He-like to U-like. In the opacity model used, ionic populations are obtained by solving the Saha equation including degeneracy corrections. Bound-bound transitions are determined using a Voigt profile for line shape, which includes natural, collisional, Doppler and UTA widths. Bound-free and free-free opacities are evaluated using the Kramer cross-sections with appropriate corrections. Scattering processes are computed through the use of the Thomson formula with corrections. The results are compared with other screened hydrogenic models and more sophisticated self-consistent codes.     

Validity of formulae for nuclear widths used in pion cascade codes

Cascade codes used for pionic X-ray calculations use formulae for nuclear absorption widths derived from perturbation theory using hydrogenic wavefunctions. Comparison with exact calculations shows that these formulae are very accurate for orbitals with l 2 but large errors can arise for l = 0, 1. An improved formula for s and p states is derived.     

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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.     

Quantum well excitons in an electric field: two versus three dimensional behavior

Previous calculations have shown a transition between two dimensional and three dimensional behavior of excitons confined in a semiconducting quantum well structure as a function of electric field. We here present calculations of the exciton binding energy as a function of electric field using a two parameter variational wave function of the form used in the absence of the electric field by Matsuura and Shinozuka. Our calculations were performed using a finite potential barrier model for the confinement of the exciton in the quantum well. The results of our calculations confirm the validity of the conclusion that the variational exciton wave function goes from being of a purely 2D hydrogenic type at small well widths and/or low electric fields to a 3D hydrogenic type in wide wells and/or high electric fields.     

Breit and Quantum Electrodynamics Energy Contributions in Multielectron Atoms from the Relativistic Screened Hydrogenic Model

The correction to the Coulomb repulsion between two electrons due to the exchange of a transverse photon, referred to as the Breit interaction, as well as the main quantum electrodynamics contributions to the atomic energies (self-energy and vacuum polarization), are calculated using the recently formulated relativistic screened hydrogenic model. Comparison with the results of multiconfiguration Dirac-Hartree-Fock calculations and experimental X-ray energies is made.     

高密度氩等离子体电子密度的计算

用屏蔽氢离子模型计算了冲击压缩产生的温度T～2.0eV、密度ρ～0.01g/cm3～0.49g/cm3范围内氩等离子体的电子密度,探讨了不同温度、密度范围内的高密度氩等离子体中粒子之间相互作用对电子密度的影响.     

Theoretical calculations of the energies of the ∝ satellite and hypersatellite lines of magnesium

The satellite and hypersatellite x-ray lines which lie on the high energy side of the dipole ∝_1,2 lines are generally attributed to multiple ionization. In this paper, an attempt is made to calculate the energies of these lines in the x-ray spectrum of the magnesium atom using screened hydrogenic wavefunctions. Besides the good agreement found between our calculated values and the experimental results, our calculations give some additional lines not reported earlier.