H_2+He流体混合物在部分离解区的物态方程

H2+He流体混合物在高温高压下由于氢的离解化学反应形成由H2,H,He三种粒子构成的混合体系,此时粒子间的相互作用较为复杂,离解能也会由于粒子间的这种复杂相互作用而降低.本文利用自洽流体变分理论来研究部分离解区H2+He流体混合物的高温高压物态方程,模型考虑了各种粒子间的相互作用及由温致和压致效应引起的离解能降低的自洽变分修正,并通过自洽流体变分过程对非理想的离解平衡方程求解得到粒子数密度分布,进而对自由能求导获得体系的热力学状态参量.计算结果与已有的冲击波实验数据、蒙特卡罗模拟及其他理论计算进行了比较.     

低能电子碰撞He+(e,2e)反应绝对三重微分截面的理论研究

利用Berakdar和Briggs对BBK波函数Sommerfeld参数的修正结果，即考虑第三个粒子存在对两个粒子间相互作用的影响，考虑了入射道的库仑相互作用及出射粒子的交换对称性，计算了在共面等能分配几何情况下低能电子碰撞He⁺(e,2e)反应绝对三重微分截面.结果表明，入射道库仑场对较低的入射能量及小的碰撞参数的三重微分截面影响较大. 关键词：     

温稠密铝等离子体物态方程及其电离平衡研究

温稠密物质的物性参数在惯性约束聚变能源、Z箍缩等高能量密度物理领域的实验结果分析和物理过程数值模拟等方面有着重要的应用价值.本文应用部分电离等离子体模型,在理想自由能的基础上考虑了库仑相互作用、排斥体积作用和极化作用等非理想特性,开展了温稠密等离子体物态方程和电离平衡的研究.计算了温稠密铝等离子体的压强等物态方程数据和在密度为1.0×10^-4-3.0 g/cm^3,温度为1.0×10^4-3.0×10^4 K范围内的粒子组分.计算结果显示,铝等离子体的平均电离度在临界密度区域内随着密度的增加而突然增大.根据非理想Saha方程中有效电离能这一关键参数,分析了铝等离子体平均电离度在临界密度区域内随密度迅速增大的现象.     

氦原子和类氦离子基态能量的变分计算及相对论修正

采用一个包含坐标伸缩系数的简单有效的变分波函数,同时考虑到核的运动,利用Mathematic a语言开发了一个用变分法计算三体问题的程序,对氦原子和类氦离子(H^-,He,Li ⁺,Be⁺⁺,B³⁺,C⁴⁺,N⁵⁺,O ⁶⁺)的非相对论基态能量和解析波 函数进行了变分计算.在此基础上,对非相对论哈密顿量进行相对论和辐射修正,并考虑到有 限核电荷半径的影响,得到了氦原子和类氦离子高精度的基态能量值. 关键词： 氦原子 类氦离子 变分法 基态能量 相对论修正     

双色场中高次谐波转化效率提高的数值研究

采用渐近边界条件和辛算法数值求解了双色激光场分别与模型Pschl-Teller势和模型He⁺相互作用的含时Schrdinger方程的无穷空间初值问题,计算了电离概率、电子平均位移、高次谐波与跃迁概率;数值结果显示,添加适当的倍频光的双色激光场使高次谐波转化效率极大提高,并给出定性与定量分析. 关键词： 辛算法 双色激光场 高次谐波 定量分析     

类锂体系(Z=21—30)基态1s22s电离能和相对论项能的理论计算

使用全实加关联方法和里兹(Ritz)变分方法计算了类锂体系(Z=21—30)基态1s²2s的非相对论能量和波函数；包括动能修正、电子-电子接触项、轨道-轨道相互作用项以及Darwin项的相对论修正和质量极化项由全实加关联波函数的一阶微扰给出，量子电动力学修正QED(quantum electronic dynamic)由有效核电荷方法和类氢公式计算；给出了中等核电荷的高电离类锂体系基态的电离能、相对论效应的项能(term energy)，并将计算结果与实验数据进行了比较，表明FCPC 关键词： 类锂体系 全实加关联 电离能 项能     

(e,2e)反应三重微分截面的计算

给出了利用BBK模型计算电子碰撞电离H,He⁺,He和Li⁺三重微分截面的通用方法,适用于中、高入射能量下的各种几何条件。计算结果与其它理论结果和实验数据进行了比较,符合得很好。     

He2+离子与H原子的重粒子碰撞电离过程

利用初态程函近似的连续扭曲波方法研究了He²⁺离子与Ｈ原子的碰撞电离过程. 计 算得到了入射离子能量从30keV/u到2000keV/u的碰撞电离总截面、随电离电子能量和角度变 化的一阶和二阶微分散射截面，及随入射离子能量变化的电离电子平均能量.计算的总电离 截面与其他理论和实验结果进行了比较，在入射离子能量大于100keV／u的能区，计算结果 与实验符合得很好；在较低的能区，各种理论结果之间有较大差别，计算结果比实验约小50 ％.利用计算的二阶微分散射截面讨论了软碰撞、电子俘获到入射离子连续态、两体相遇碰 撞等碰撞电离机理. 关键词： 重粒子碰撞电离 初态程函近似 总截面 一阶和二阶微分散射截面     

部分电离金属钛和银等离子体输运性质的计算

金属等离子体的组分为计算热力学、光学和辐射输运特性研究提供了基本的输入参数.为获得此参数,本文用部分电离等离子体模型,在考虑金属发生三次电离,以及电子与中性粒子的极化作用、离子与离子之间、电子与离子之间、电子与电子之间库仑相互作用下,计算得到了等离子体组分,进而用线性响应理论计算了金属钛和银的电导率.并与已有的实验数据进行了比较,验证了模型的可靠性.在此基础上进一步预测了密度在0.001—2.0 g/cm³、温度在1.5×10⁴—2.5×10^{4关键词： 等离子体 线性响应理论 电离度 输运系数}     

氦原子Rydberg态10G—10M磁精细结构的计算

通过自洽迭代求解Hartree方程，得到了氦原子1snl组态下的严格数值解波函数，以此构造LS耦合谱项(支项)波函数作为基矢.采用线性变分法，同时考虑交换作用和Breit-Bethe近似下的磁相互作用项，计算了氦Rydberg态10G—10M系列能级的磁精细结构，计算结果很好地符合已有的实验值.对计算方法的进一步改进提出了设想和讨论. 关键词： 氦原子 Rydberg态 磁精细结构 自洽迭代     

Influence of atom-atom collisions on the collisional-radiative ionization and recombination coefficients of helium plasmas

Coefficients for volume recombination and ionization have been calculated for a dense helium plasma of low degree of ionization. The calculations are based on a collisional-radiative model in which electron-atom, electron-electron-ion, atom-atom, and electron-atom-ion collisions intervene. Molecular species such as He ₂ ^* and He ₂ ⁺ have not been taken into account. The essential results are: At low temperatures and high neutral gas densities the recombination coefficient is proportional to the number density of neutral helium atoms. At high temperatures the presence of neutral particles practically does not influence the recombination process compared to pure ion-electron-electron recombination. At high neutral particle densities, high atom temperatures and low electron densities the ionization process is mainly due to atom-atom collisions. In this point our calculations are in relatively good agreement with recent shock tube measurements of Kalra and Measures (Phys. Fluids14, 2544 (1971)). It is emphasized that the simple two-step model for ionization by shock waves in the noble gases should be replaced by a more general collisional-radiative model in which the atomic level structure intervenes in more detail.     

The Hyperfine Structure of the Ground State in the Muonic Helium Atoms

Non-relativistic ionization energies ³He²⁺μ^?e^? and ⁴He²⁺μ^?e^? of helium-muonic atoms are calculated for ground states. The calculations are based on the variational method of the exponential expansion. Convergence of the variational energies is studied by an increasing of a number of the basis functions N. This allows to claim that the obtained energy values have 26 significant digits for ground states. With the obtained results we calculate hyperfine splitting of the muonic helium atoms.     

Collision-energy-resolved Penning ionization electron spectroscopy of toluene and chlorotoluenes

Stereodynamics in ionization of toluene and o-, p-chlorotoluenes by collision with He^*(2³S) metastable atoms were investigated by two-dimensional collision-energy/electron-energy-resolved Penning ionization electron spectroscopy. Anisotropic interactions around the molecule were studied by the collision energy dependence of partial ionization cross-sections (CEDPICS) as well as model potential calculations, and shielding effect by the methyl group was observed in CEDPICS for ionization from Cl lone-pair orbitals of o- chlorotoluene. Attractive interaction with He^*(2³S) around the π orbital region was found to be larger for toluene rather than o-, p- chlorotoluenes. Exterior electron density (EED) calculation of partial ionization cross-sections in Penning ionization and negative CEDPICS for ionization band observed in ca. 4 eV in electron energy indicated that π^-2π⁺¹ shake-up state was observed in Penning ionization electron spectroscopy of toluene.     

Ionization of helium in positron collisions

A new Coulomb distorted-wave method with coupled-channel target functions is used to calculate total ionization cross-sections for helium in positron collisions. Besides Slater-like orbitals we use regular Coulomb wave packets in our configurational interaction basis to describe the target continuum. The incident positron energy was varied between the ionization threshold and 500 a.u. The results are in good agreement with experimental data and other theoretical calculations. Comparing to other sophisticated distorted wave methods our model is much easier to implement and gives accurate results. As a new feature we present ionization cross-sections where the He ⁺ ion remains in the 1s ground state or excited to the 2s or 2p state. As we know there are no experimental work done to determine such cross-sections. In the case of ionization followed by 2s or 2p excitation we compared our results with other calculations.Received: 18 February 2004, Published online: 15 April 2004PACS: 34.85. + x Positron scattering     

Metastable states of antiprotonic helium atoms

We discuss the latest theoretical achievements in calculations of energy transitions in the antiprotonic helium He⁺ p-0304; atoms. New variational calculations of the nonrelativistic energies with precision of ∼10^-10 a.u. and relativistic and QED corrections to the energy levels of mα ⁵ order are presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

Charged cores in ionized He clusters

Experimental and theoretical studies in large ionic helium clusters have suggested the presence of a diatomic (and occasionally triatomic) charged molecular core surrounded by the other atoms which are bound to it by weaker interactions [1-3]. The understanding of the interactions between the system He ₂ ⁺ and an additional He atom of the cluster is therefore important in order to start modelling the full cluster interaction potential. In the present work we carry out a new set of calculations on the full potential and on the bound states supported by the He ₂ ⁺ isolated ion and further extend them to generate a Rigid Rotor (RR) potential energy surface (PES) for the triatomic system with He ₂ ⁺ kept at its equilibrium geometry (2.0 a.u.). The 13 bound states which were found and the overall angular anisotropy that exists for this Potential Energy Surface (PES) are discussed in detail. We additionally show results of calculations on the surface vibrational extension to nine different values of the He ₂ ⁺ interatomic distance, thereby generating a fuller, three-dimensional interaction potential. A simpler modelling of the latter via “Pseudo Rigid Rotor” calculations for the bound states with a vibrationally excited core is also presented and discussed.     

H<Superscript>+</Superscript><Emphasis Type="Bold">and He</Emphasis><Superscript>2+</Superscript> impact single and double ionization of lead

H⁺ and He²⁺ impact single and double ionization cross sections of ground state lead atoms have been calculated in the binary encounter approximation. Calculations of direct double ionization cross sections have been performed in the modified double binary encounter model. The accurate expressions of σ_ΔE (cross-section for energy transfer ΔE) and Hartree-Fock velocity distributions for the target electrons have been used throughout the calculations. Contributions to double ionization from Auger effect following ionization of inner shells have been considered in the present work. Our H⁺ impact single and double ionization cross sections are in good agreement with the experimental observations. In calculations of He²⁺ impact cross sections, the present theoretical approach shows limited success in the experimentally investigated region (50–350 keV amu^-1).     

Two-dimensional Penning ionization electron spectroscopic study on outer characteristics of molecules

Collision-energy/electron-energy-resolved two-dimensional Penning ionization electron spectroscopy (2D-PIES) has been used to study outer characteristics of molecules. Anisotropic potential energy surfaces for collisional ionization of molecules with a metastable helium atom He*(2³S) have been determined starting from ab initio model potentials via optimization based on trajectory calculations. Since ionization widths in the theoretical model of Penning ionization are functionals of target molecular orbitals, outer electron distributions of molecular orbitals can be determined via optimization procedures of calculated ionization cross-sections by trajectory calculations with respect to observed 2D-PIES data.     

双力程核子力的讨论

The binding energies of nuclei H³. He³, He⁴, the low energy n-p scattering length and effective range are calculated by using the standard variational methods. A two-range central Yukawa potential is considered in the first two sections. The longer range corresponds to the π meson mass. The smaller range corresponds either to the heavier meson or to the higher order field interactions. No repulsive core appears, when the force parameters are chosen to fit the low energy scattering and deuteron data. The calculated binding energies of nuclei H³, He³ and He⁴ are too high. This result is in agreement with most of the previous calculations. Tensor force of the Schwinger mixed type is considered in the third and fourth sections. The force parameters are chosen to fit the low energy two body data. They are not uniquely determined and are given for a set of possible D-percentage values. The adding of the tensor force reduces considerably the calculated binding energies of nuclei H³, He³, He⁴. But still, the calculated values increase too fast with the mass number. It does not fit the triton and helium binding energies simultaneously. The possibility of adding many body forces is discussed at the end of the paper.