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.     

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.     

稠密、冷铝等离子体的辐射不透明度研究

使用细致谱项模型、联合组态相互作用方法和R 矩阵方法计算了处于局域热动平衡条件下的稠密、冷铝等离子体的辐射不透明度 .组态相互作用方法用于获得束缚 束缚吸收截面所需要的偶极跃迁振子强度 ,R矩阵方法用于获得光电离截面 .对于温度在 6— 12eV、密度为 0 .36mg/cm3 的铝等离子体 ,计算得到的吸收系数在波长为 0 .35 1,0 .5 2 7和 1.0 5 4 μm处与实验结果符合较好 ,而温度在 3— 6eV时 ,理论计算比实验结果大. The radiative opacity has been investigated by using detailed term accounting approximation for dense, cold aluminum plasmas under local thermodynamic equilibrium. The configuration interaction scheme has been used to obtain the relevant atomic parameters for bound-bound absorption, such as excitation energies and oscillator strengths. R-matrix method has been used to obtain the photoionization cross sections. For aluminum plasmas of density 0.36 mg/cm 3, temperature of 6-12 eV, the...     

平均原子模型中谱线位置偏移对辐射不透明度的影响

使用平均原子(average atom,AA)模型计算了局域热动平衡近似下的Fe,Br等离子体的辐射不透明度.对AA模型中跃迁系的跃迁能量引入了统计修正，修正后的谱线位置与细致谱项模型的结果更接近，但仍然存在差距，进一步减小这种差距需要考虑等离子体的价态分布.研究了AA模型中这种谱线位置移动对平均不透明度的影响，计算了Fe等离子体等温度系列的平均不透明度，发现这种修正对于平均不透明度的影响是比较明显的.     

激光等离子体辐射不透明度的细致模型

细致谱线模型是等离子体辐射不透明度精确计算的理论方法,涉及到很多原子物理过程,需要计算大量的、精确的原子参数.在高温、稠密等离子体环境下,谱线展宽、组态相互作用、电离能下降等效应与不透明度的准确计算密切相关.文章重点介绍了目前作者在辐射不透明度细致谱线模型研究方面取得的进展情况,并且与国内外典型的实验和理论结果进行了对比.     

DTA模型计算高温Mg等离子体的辐射不透明度

使用DTA(detailedtermaccounting)模型计算了温度为 5 6eV、密度为 0 .0 1g/cm3 的Mg等离子体的辐射不透明度以及Rosseland和Planck平均不透明度 .对于处于局域热动平衡 (LTE)下的Mg等离子体 ,利用Saha方程计算出各价离子的丰度 .MCHF方法得到Mg各价离子的能级以及束缚 束缚跃迁的振子强度 ,考虑了Doppler展宽和碰撞展宽 ,谱线线型采用Voigt线型 .束缚 自由以及自由 自由吸收截面使用AA模型得到. The spectral resolved opacity of high temperature Mg plasma at a temperature of 56 eV and a density of 0.01 g/cm 3 is calculated by the detailed term accounting (DTA) model. Saha equation is applied to obtain the population distribution of the plasma in local thermodynamic equilibrium. Atom levels and bound-bound absorption oscillator strengths are obtained from a multi-configuration Hartree-Fock (MCHF) calculation that includes Breit-Pauli relativistic correction. After ...     

DTA模型计算高温Fe等离子体的辐射不透明度

使用DTA(detailed term accounting)模型计算了温度为20eV、密度为0.01g×cm^-3的Fe等离子体的辐射不透明度.对于处于局域热动平衡(local thermodynamic equilibrium,LTE)下的Fe等离子体,使用Saha方程计算出各价离子的丰度.使用MCHF方法得到了Fe离子的能级以及束缚-束缚跃迁的振子强度,考虑了Doppler展宽和碰撞展宽的谱线展宽机制,谱线线型采用Voigt线型.束缚-自由以及自由-自由吸收截面分别使用DCA及AA模型得到.所得的结果与美国Los Anamos National Laboratory(LANL)使用LEDCOP程序计算的结果进行了对比,两种结果符合很好.     

物质辐射不透明度对恒星结构与演化的影响及其计算

简要介绍了恒星结构与演化的理论模型，回顾了物质辐射不透明度计算的发展过程，详细讨论了物质辐射不透明度对恒星物理理论方面许多重要问题的影响以及发展现状。并介绍了利用改进的平均原子模型来进行恒星物质辐射不透明度的计算结果。     

He,Ne,Ar,Kr和Xe原子电子的动量密度分布研究

对He,Ne,Ar,Kr和Xe原子体系中电子在动量空间的性质进行了系统的理论计算研究.采用自洽场HFR方法计算了坐标空间He,Ne,Kr和Xe原子体系单电子径向波函数,动量空间的单电子波函数由坐标空间原子体系单电子径向波函数通过运用傅立叶变换计算得到.在冲量近似条件下,进一步计算研究了这些原子的单电子动量密度分布和原子体系总的Compton轮廓.计算结果与已有的实验实验值和其他文献的理论计算结果比较表明,本文计算的结果是准确的.     

The excitation temperature functions of some spectrum lines of He,Ne, Ar,Kr and Xe

The excitation temperature functions of 19 spectrum lines of 5 rare gases He, Ne, Ar, Kr, Xe have been calculated according to the method given by Fowler and Milne. The results make it possible to determine the radial plasma temperature distribution in the range of temperatures of 1.4 × 10⁴°K to 14 × 10⁴°K. Some examples are given for the determination of the plasma temperature distribution in space and time by using the Ar ecxitation temperature functions calculated.     

Differential cross sections for elastic scattering and positronium formation for positron collisions with Ne,Ar, Kr and Xe

Differential cross sections for elastic scattering and Ps(1s) formation are calculated in the truncated coupled-static (TCS) approximation. Comparison is made with the elastic scattering measurements of Dou et al. on Ar and Kr. There is no support from the TCS approximation for the view that structure seen in the experimental results for Ar in the energy range 55–60 eV may be due to a resonance associated with coupling to the positronium formation channel. Rather, we believe that Dou et al. are right in correlating this feature with the maximum in the ionization cross section. In the experiment on Kr structures are observed at 25 and 200 eV. It is tentatively suggested that the structure at 200 eV may be the resonance seen in the TCS calculation at 100 eV, but modified by polarization and absorption effects. It is also suggested that the feature at 25 eV could be associated with coupling to excited states of positronium. The TCS results for the Xe target predict some very pronounced behaviour which would be worth experimental investigation. TCS differential cross sections for Ps(1s) formation by capture of an electron from the outer p-shell of the atom are presented for impact energies up to 75 eV. A noticeable property of these cross sections is that they do not usually peak at the forward direction; this is consistent with an experimental observation by Laricchia et al. on He and Ar targets. The importance of also looking at electron capture from inner shells is emphasized and illustrated by the cross section for electron capture from the 3s shell of Ar.     

Transitions and level lifetimes in Ne II, III, Ar II, III, Kr II, III and Xe II

Beam-foil spectra of neon, argon, krypton, and xenon have been recorded photographically with a fast spectrograph. The particle energies ranged from 150 to 750 keV. Transitions in Ne II, III; Ar II, III; Kr II, III; and Xe II have been identified. In addition, new multiples were identified in Ne II and Xe II and a number of unidentified lines were observed in neon, argon, and krypton. Characteristic intensity decays of over 170 lines were measured, giving the mean lives of ≈ 80 levels, with an estimated error of 30 per cent. Tabulation of energy levels with similar electron configurations in neon, argon, krypton, and xenon shows a definite progression to larger mean lives as the nuclear change increases.     

The empirical Kestin model and the second order transport properties of binary mixtures of Ne,Ar, Kr and Xe

It is showed from the experimental α_T data for the dilute binary mixtures of Ne, Ar, Kr and Xe at 340 K that the law of corresponding states proposed by Kestin, Ro and Wakeham is able to predict the mentioned second order kinetic property altogether with the first order transport and thermodynamic properties of the examined mixtures.     

Long range dispersion interactions of the low lying states of Mg with H,He, Ne,Ar, Kr and Xe

The dispersion coefficients for the van der Waals interactions for the low lying states of magnesium (3s² ¹S ^e , 3s3p ³P ^o , 3s3p¹P ^o , 3s4s ³S ^e , 3s4s ¹S ^e , 3s3d ³D ^e and 3s3d ¹D ^e ) interacting with H, He, Ne, Ar, Kr and Xe are determined using sum rules of reduced matrix elements over pseudo-state representations of the atomic excitation spectra. The sets of transition matrix elements were taken from previous investigations of the van der Waals interactions of the Mg₂ dimer and an investigation of the van der Waals interaction for alkali atoms interacting with rare gases.     

Cooling efficiency in collisions between Pd and He,Ne, Ar and Kr

The cooling of the metal cluster Pd₁₃ in an atmosphere of rare gas has been studied by means of computer simulation. By simulation, the average energy transfer in collisions between one cluster and one gas atom has been obtained. Emphasis has been placed on conditions when the temperatures of the colliding species are almost equal. All modes of motion, inclusive the translation, must be considered in order to obtain vanishing energy transfer at equilibrium. A simulation scheme is presented by which the energy transfer is zero to the cluster when the gas and the cluster temperatures are equal. At equilibrium the energy transfer does however not vanish for all impact parameters. In the collisions with Pd₁₃, the cluster is heated by collisions with a small impact parameter but equally cooled by collisions with a large impact parameter. Argon and krypton are found to cool Pd₁₃ equally efficiently while neon and helium are less efficient cooling agents. Received 28 September 2001 / Received in final form 8 August 2002 Published online 12 November 2002 RID="a" ID="a"e-mail: JanW@phc.gu.se     

氖,硅和钛元素的类锂离子激发态参数的计算

为利用本所重离子加速器原子物理实验装置进行高电离态离子物理实验研究，本文采用郑能武等人＾［＾１＾］提出的最弱受约束电子势模型理论的波函数和Ｈ．Ａ．Ｂｅｔｈｅ等入＾［＾２＾］的量子力学理论，估算了Ｎｅ，Ｓｉ和Ｔｉ离子的类锂等电子序２Ｓ－２Ｐ态的跃迁几率和振子强度，并把计算结果与文献结果作了比较。     

Calculations of total ionization cross sections of Ne,Ar, Kr,and Xe atoms in the born approximation allowing for electron perturbations in the continuous spectrum

Electron impact ionization cross sections of Ne, Ar, Kr, and Xe atoms are numerically calculated. The electron perturbation in the continuous spectrum in the target field is taken into account. The matrix elements are calculated in many-electron, nonrelativistic approximation with allowance for the superposition of configurations and relaxation effect. The radial part of the electron wave function in the continuum is calculated by solving the single-configuration Hartree-Fock equation. The wave functions of electrons in the continuum are orthogonalized with respect to the core orbital functions. The calculated cross sections are compared to the experimental data and calculations made using the plane-wave Born approximation and that involving generalized oscillator strengths.     

Totale Streuquerschnitte für den Stoß von H2, D2 und He an den Edelgasen Ne,Ar, Kr und Xe im thermischen Energiebereich

The velocity dependence of the total elastic cross section has been measured for the scattering of H₂, D₂, and He beams by Ne, Ar, Kr, and Xe gases. Velocity-selected beams were attenuated by gas in a scattering chamber. A universal detector, with a magnetic mass separator, was used in conjunction with lock-in techniques. The results are compared with quantum mechanical calculations using a Lennard-Jones-(12.6)-potential, and employing suitable averaging over experimental velocity distributions. Potential parameters are presented. These are in good agreement with those expected from other methods of measurement.