Energies and transition data for Be-like hafnium and tantalum ions

Althiyabi, Amal; El-Sayed, Fatma

doi:10.1016/j.adt.2022.101528

Cited by 4 publications

(1 citation statement)

References 13 publications

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“…理论计算方面, Ta, W, Au等高Z元素作为聚变设施中的面等离子体材料, 其高度电离态的原子过程数据在等离子体诊断中有重要作用 [16] . 例如, Jiao等 [17] 基于 GRASP92和RATIP程序计算了Cd + 离子的部分电子碰撞激发截面 [18] ; Althiyabi等 [19] 基于多组态 Dirac-Hartree-Fock (MCDHF)方法计算了类 Be离子Hf 68+ 和Ta 69+ 的能级和跃迁数据, 并考虑了Breit相互作用和量子电动力学(QED)效应的影响; Zhong等 [20] 使用FAC计算了类Ni离子Ta 45+ 的能级、跃迁、电子碰撞激发数据; Motoumba等 [21] 基于相对论性组态相互作用多组态Dirac-Hartree-Fock (MCDHF-RCI)方法和半经验相对论修正的 Hatree-Fock (HFR)方法计算了类Er离子Lu 3+ , Hf 4+ , Ta 5+ 的辐射跃迁速率; Aggarwal [22] 使用GRASP 计算了类Ne离子Hf 62+ , Ta 63+ , Re 65+ 的辐射跃迁速率, 并使用FAC进一步研究组态相互作用的影响; Chen等 [16] 使用FAC计算了从Hf 48+ 到Au 55+ 的类Cr离子的能级和辐射跃迁速率; Jönsson等 [23] 使用GRASP2K计算了类F离子Si 5+ -W 65+ 的能级和辐射跃迁速率; Wang等 [24] 提供了一种成像方法, 能够成像块体材料在XFEL照射条件下的动态压缩响应. 实验上, 随着实验装置和技术的发展, 研究者利用EBIT [25][26][27] 等装置也进行了一系列高精度的光子或电子与高Z离子碰撞过程的实验研究 .…”

Section: Fock方法(mcdf)的原子结构计算软件grasp92unclassified

Fast computation approach of electron-impact ionization and excitation cross-sections for atoms and ions with medium- and high-Z elements

Zhou,

Wang,

et al. 2024

Acta Phys. Sin.

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The atomic data of middle and high-Z elements, such as electron-impact ionization and excitation cross-sections, find extensive applications in fields such as fusion science and X-ray interactions with matter. There are atoms and ions in high energy density plasma with different charge states and energy states from ground states to highly excited states, and the cross-sections of each charge state and energy state need to be calculated. The bottleneck limiting computational performance is the unavoidable relativistic effects of middle to high-Z atoms and the incredibly complex electronic configurations. Taking tantalum (Ta) as an example, by using the relativistic Dirac-Fock theory and distorted wave model, we computed the electron-impact ionization and excitation cross-sections of Ta from the ground state atom up to Ta72+ with the incident electron energy range of 0-150keV. The detailed configuration accounting (DCA) reaction channel cross-sections are derived by summing and weighting the original detailed level accounting (DLA) cross-sections. After examining the data, two regularities are found. In terms of DLA, the pre-averaging DCA cross-sections have varying initial DLA energy levels but are typically close to one another, but there isn't a straightforward function that can explain the discrepancies between them. In terms of DCA, inner subshells typically contribute very little to the total cross-section as their ionization and excitation cross-sections are orders of magnitude smaller than those of outer subshells. We provide two techniques to reduce the computational costs based on the regularities. To minimize the overall number of DLA reaction channels used in the computation, the initial DLA energy levels can be randomly sampled. Through a Monte Carlo numerical experiment, we determine the appropriate number of sampling points that can reduce the total number of DLA channels by an order of magnitude while maintaining a 5% error margin. In terms of impact ionization, since small cross-section DCA channels are insignificant, only a tiny portion of the DCA channels are required to preserve a 95% accuracy of the entire cross-section. It is possible to use the analytical Binary Encounter Bethe (BEB) formula to determine which DCA channels should be neglected before the computation to reduce computational costs. In terms of electron-impact excitation, just the cross-sections of the same excited subshells as the preserved ionized subshells, which are determined in the previous electron-impact ionization (EII) calculation, are needed. Lastly, we compared our EII results with theoretical and experimental results. In the low incident electron energy range of below 2 keV, our results agree with the theoretical result of the 6s EII cross-section of the Ta atom and the experimental result of the total EII cross-section of the Ta1+ ion. In the high energy range of below 150 keV, our results are also consistent with the theoretical results of the 1s EII cross-section of the Ta atom and the experimental result of the 1s EII cross-section of the Cu atom. Our results reasonably matched the previous experiment and theoretical results in both low and high energy ranges, inner and outer subshells, indicating the accuracy of our calculation. The proposed optimizing strategy can be applied to various middle to high-Z elements and is compatible to most computation codes.

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