Au~(34+)离子双电子复合过程的理论研究

复杂结构离子的双电子复合(DR)速率系数在核聚变、极紫外光刻光源等应用研究的等离子体谱模拟中具有重要的价值.利用基于全相对论组态相互作用理论的FAC程序包,详细计算了Au~(34+)离子的双电子复合速率系数.研究分析了激发、辐射通道,组态相互作用,级联退激对DR速率系数的影响.其中,级联退激对DR速率系数的贡献必须予以考虑.对双电子复合、辐射复合以及三体复合速率系数做了比较,在温度大于1 eV范围,双电子复合都大于辐射复合以及三体复合速率系数,相应的DR过程对于等离子体离化态分布和能级布居以及光谱模拟都极为重要.对基态和第一激发态的DR速率系数进行了参数拟合,拟合值与计算值的偏差小于1.73%.研究结果将为复杂结构离子双电子复合过程的进一步研究提供参考.     

高离化态Cu18+离子的双电子复合及共振转移激发过程的理论研究

在准相对论理论框架下计算了Cu18+离子的双电子复合截面,分析了组态相互作用对截面的影响.基于这些数据,在冲量近似下,通过对靶原子中电子动量分布的卷积,进一步得到了Cu18+与H2碰撞过程中的共振转移激发截面,并与已有的实验结果作了比较,符合得很好.     

高离化态Hg和U离子的双电子复合过程的理论研究

在相对论多组态Dirac-Fock理论基础上,利用近期发展的计算双电子复合截面的程序,系统研究了高离化态类氦到类硼Hg和U离子的KLL双电子复合过程. 讨论了Breit效应和量子电动力学(QED)效应对Hg离子共振双激发态能级的贡献,得到了双激发态的共振能、总线宽和相应的双电子复合共振强度,所得结果与其他理论和实验结果都符合得很好. 在此基础上进一步研究了高离化态U离子的KLL双电子复合过程,并与已有的实验和理论结果作了比较. 关键词： 双电子复合 MCDF     

高离化态Hg和U离子的双电子复合过程的理论研究

在相对论多组态Dirac-Fock理论基础上，利用近期发展的计算双电子复合截面的程序，系统研究了高离化态类氦到类硼Hg和U离子的KLL双电子复合过程. 讨论了Breit效应和量子电动力学(QED)效应对Hg离子共振双激发态能级的贡献，得到了双激发态的共振能、总线宽和相应的双电子复合共振强度，所得结果与其他理论和实验结果都符合得很好. 在此基础上进一步研究了高离化态U离子的KLL双电子复合过程，并与已有的实验和理论结果作了比较.     

Polarization characteristics of the radiation of ions formed during dielectronic recombination

The polarization characteristics of the radiation emitted during dielectronic recombination of free plasma electrons are considered. It is shown that taking into account the correlation between the orders of the angular momenta of a doubly excited state of an ion leads to a significant difference in the dependence of the radiation polarization on the plasma parameters.     

类铷W37+离子双电子复合速率系数的理论研究

 利用全相对论组态相互作用理论方法,研究了类铷W³⁷⁺离子从基组态3s²3p⁶3d¹⁰4s²4p⁶4d经过双激发态(3s²3p⁶3d¹⁰4s²4p⁶4d)^-1nln′l′(n,n′=4,5)的双电子复合过程,得到了该离子在温度为1~5×10⁴ eV范围内的总双电子复合速率系数。分析比较了不同电子激发的双电子复合速率系数,结果表明:4p电子激发的双电子复合速率系数在低温时给出了主要贡献,而3d的贡献在高温时突出。由于强组态相互作用,两电子一光子跃迁对双电子复合速率系数的贡献不可忽略,其中辐射跃迁4p⁵4d5d5f-4p⁶4f5d的贡献是双激发态4p⁵4d5d5f总的双电子复合速率系数的5%。对双电子复合、辐射复合以及三体复合速率系数的比较表明,在所研究的温度范围内双电子复合速率系数最大。     

类钠Ni~(17+)离子双电子复合过程理论研究

使用基于相对论多组态方法的FAC程序,研究了类钠Ni17+(3s)离子通过双激发态Ni16+(3pnl,3dnl)(Δn=0激发)的双电子复合过程,得到了态选择的双电子复合截面和速率系数,并与文献中的实验和理论数据进行了对比.结果发现,计算通过3p3/210l和3p1/211l共振态的双电子复合积分截面在实验误差范围内与实验测量很好地符合,并好于全相对论的多体微扰理论计算结果.结合量子亏损理论,发现包含高里德伯态的共振双激发态的辐射跃迁和自电离速率具有较好的标度关系,利用该关系给出了近激发阈值的所有共振态的双电子复合积分截面和速率系数.比较3pnl和3dnl两个系列,发现在低温(大约小于100eV)等离子体情况下前者速率系数比后者大,更高的温度后者大.     

高离化态Cu18+离子的双电子复合及共振转移激发过程的理论研究

在准相对论理论框架下计算了Cu¹⁸⁺离子的双电子复合截面，分析了组态相互作用对截面的影响.基于这些数据，在冲量近似下，通过对靶原子中电子动量分布的卷积，进一步得到了Cu¹⁸⁺与H₂碰撞过程中的共振转移激发截面，并与已有的实验结果作了比较，符合得很好.A 关键词： 双电子复合 共振转移激发     

Measurement of field effects on dielectronic recombination of Si11+ ions

Cross sections for dielectronic recombination can be influenced by the presence of external electric fields in the electron--ion collision region. In most of the previous experiments with multiply charged ions such fields were present but unknown. Therefore, comparisons of experimental results with theoretical calculations were ambiguous: for obtaining best possible agreement, theory could use the field strength as a free parameter to adjust the calculated cross sections to the experiment. In recent measurements with 10 MeV/u Si¹¹⁺ ions stored in CRYRING, controlled external motional electric fields up to 183 V/cm were introduced in the electron cooler. Significant cross section enhancements were found for Rydberg states n > 20. This revised version was published online in August 2006 with corrections to the Cover Date.     

激光在大气中驱动的强太赫兹辐射的理论和实验研究

两束双色激光脉冲能在大气中产生MV/cm的强太赫兹波.本文主要介绍了我们最近的三项理论和实验工作,澄清了双色激光方案的物理机制这个长期存在的问题,并对该方案进行了推广.为了在气体中有效地产生太赫兹波,在广泛研究的双色激光方案中两束激光的频率比ω_2/ω_1总是被取为1:2.首先从理论上预测采用其他频率比时,此方案仍能有效地工作,并通过实验进行证实.实验上观察到在新的频率比ω_2/ω_1=1:4,2:3下,也能有效地产生太赫兹波;观察到通过旋转较长波长的激光脉冲的偏振方向,能够有效地调节太赫兹波的偏振,但是旋转波长较短的激光脉冲的偏振方向,太赫兹波的偏振几乎没有变化,这违背了多波混频理论中极化率张量对称性的要求;采用不同的频率比时,太赫兹能量定标率并没有显示出明显的区别,这与多波混频理论预测的能量定标率不符.这些实验结果与等离子体电流模型及粒子模拟结果符合得很好.因此,该研究不仅对双色激光方案进行了推广,而且证实了其物理机制应该归结为等离子体电流模型.     

Influence of Laser radiation on the collisional-radiative recombination and ionization coefficients

It is shown that irradiation of a plasma by a Laser beam lowers the collisional-radiative coefficient for recombination (α) and increases the one for ionization (S) compared to unirradiated plasmas. Numerical values ofα andS are given for a hydrogen plasma irradiated by CO₂, Ruby, and Ar-Ion Lasers. The calculations are based on a collisional-radiative model in which photoionization and stimulated recombination intervene. Stimulated recombination has an important effect and can lead to saturation of free-bound transitions at high power density of the Laser beam as long as multiphoton ionization effects and plasma heating by inverse bremsstrahlung remain negligibly small.     

基于双激发态对稠密等离子体中双电子复合速率系数的研究

讨论了稠密等离子体中双电子复合速率系数的计算方法,推导出了在双激发态间跃迁过程和关于双激发态的碰撞电离和自电离过程的影响下双电子复合速率系数作为关于电子密度函数的计算公式,并以类氖镍离子为例进行了计算.计算结果展示了双电子复合速率系数随电子密度增大的具体变化趋势.此外,还给出了在不同原子过程影响下双电子复合速率系数的数据,并进行了分析.     

类锂离子双电子复合过程中辐射光子角分布和极化特性的理论研究

基于多组态Dirac-Fock 方法和密度矩阵理论,本文详细计算了高电荷态类锂离子（26 ≤ Z ≤ 92）KLL 双电子复合过程中,自由电子被共振俘获到中间双激发态1s2s²2p_3/2J = 1 的磁子能级截面以及该双激发态的取向参数,进而得到了此激发态向基态电偶极辐射跃迁1s2s²2p_3/2J = 1→1s²2s²J = 0 所发出光子的角分布和极化度,重点讨论了Breit 相互作用对相关物理量的影响. 研究表明,Breit 相互作用极大地改变了中间双激发态1s2s²2p_3/2J = 1 不同磁子能级的截面,从而导致了随后退激发放出光子的角分布和极化特性的显著变化. 关键词： 角分布和极化特性 多组态Dirac-Fock方法 密度矩阵理论     

Measurement of the FeXXV dielectronic recombination rate coefficient in the PLT tokamak plasma

The FeXXV dielectronic recombination rate coefficient associated with the 1s-2p core excitation has been measured as a function of the electron temperature in the range from 0.9–3 keV from the observations of the satellite lines emitted from the PLT (Princeton large torus) tokamak plasma. These measurements are compared with recent theoretical predictions of Bely-Dubau et al. as well as with the approximation formulae of Burgess and Merts et al., and the results of Jacobs et al. Excellent agreement is obtained with the more recent calculations.     

Theoretical study of the KLL dielectronic recombination for highly charged iodine ions

With a developed program for calculation of dielectronic recombination (DR) process, which is based on multi-configuration Dirac-Fock (MCDF) method, the KLL DR processes of the highly charged helium-like to carbon-like iodine ions have been studied systematically. The contributions to doubly excited states from quantum electrodynamic (QED) and Breit effects have been discussed. The KLL DR resonant energies and corresponding resonant strengths have been calculated. The behavior of KLL resonant strengths with increasing Z are analyzed for He-like ions in particular. The theoretical DR spectra for each highly charged ion species are obtained in the KLL region. Comparison has been made between the present calculations and the latest experiments in Tokyo-EBIT.     

Polarization of the dielectronic recombination satellites including the generalized Breit interaction effects

The polarizations of dielectronic recombination satellite lines for hydrogenlike F to U ions are calculated including the generalized Breit interaction(GBI). The calculated values of the asymmetry parameter are compared with other theoretical results and good agreements are obtained for all lines except for those from the level 2s2p3P1. The GBI effects on the polarization become much stronger as the atomic number increases. However, for different lines, the GBI effects on the polarization are different.     

类铷W37+离子双电子复合速率系数的理论研究

利用全相对论组态相互作用理论方法,研究了类铷W37+离子从基组态3s23p63d104s24p64d经过双激发态(3s23p63d104s24p64d)-1nln′l′(n,n′=4,5)的双电子复合过程,得到了该离子在温度为1~5×104 eV范围内的总双电子复合速率系数。分析比较了不同电子激发的双电子复合速率系数,结果表明:4p电子激发的双电子复合速率系数在低温时给出了主要贡献,而3d的贡献在高温时突出。由于强组态相互作用,两电子一光子跃迁对双电子复合速率系数的贡献不可忽略,其中辐射跃迁4p54d5d5f-4p64f5d的贡献是双激发态4p54d5d5f总的双电子复合速率系数的5%。对双电子复合、辐射复合以及三体复合速率系数的比较表明,在所研究的温度范围内双电子复合速率系数最大。     

Effect of dielectronic recombination excitation on solar line intensities

The intensities of lines emitted from the solar atmosphere and observed on earth are calculated by considering electron-impact excitation followed by radiative emission. In order to determine the contribution of dielectronic-recombination -excitation (DRE), the calculations have been repeated with the inclusion of DRE as a process for excitation, along with electron-impact excitation; the excited electron is assumed to deexcite through radiative emission. The DRE is found to contribute significantly and the contribution generally increases with a decrease in wavelength and an increase of ionic charge.