搜索

x
中国物理学会期刊

U^q+(q=3–92)与H原子低能碰撞电荷转移过程研究

Charge transfer in low-energy U^q+ (q=3-92) + H collisions

PDF
导出引用
  • 铀离子与氢原子碰撞的电荷转移截面及速率系数是千新星辐射输运建模、聚变等离子体诊断及重离子加速器束流设计的重要输入参数,但迄今缺乏覆盖完整电离序列的系统理论研究。本文在多通道Landau-Zener理论框架下,对U^q+(q=3-92)+H(1s)单电子俘获过程的总截面与速率系数展开系统研究,碰撞能量覆盖0.001-1000 eV/u,首次将铀的几乎完整电离序列纳入统一的理论框架。对于低电荷态(q\le12),截面在各自特征转折能量E_t以下近似遵循E^-1标度;由于入射通道有效势垒的影响,截面随能量升高呈现非单调变化,且E_t随q增大而整体升高。对于q\ge13的高电荷态,非单调转折在本文计算能区内基本消失,截面在全能区近似保持E^-1标度行为。截面随电荷态的演化揭示了清晰的壳层调制规律:每当铀离子电子组态从未满壳层过渡至满壳层或满半壳层时,交换能稳定化使电离能异常偏高,俘获截面相应出现极小值,该对应关系在5d、4f、4d、3d等亚壳层的逐级剥离中均得到体现。经Maxwell-Boltzmann热平均获得1-10^5 K温度下的速率系数,其温度依赖行为与截面的能量依赖规律相一致。本文结果可为上述领域的等离子体建模与束流设计提供系统理论参考数据。本文数据集可在https://doi.org/10.57760/sciencedb.j00213.00235中访问获取。

     

    Charge transfer cross sections and rate coefficients for ion-hydrogen collisions are fundamental input data for kilonova radiative transfer modeling, fusion edge plasma diagnostics, and heavy-ion accelerator beam lifetime evaluation. Despite this broad demand, systematic theoretical data for the U^q+ + H system at low energies have been almost entirely absent prior to this work. In this study, total charge transfer cross sections and rate coefficients for single-electron capture in U^q+ (q = 3-92) + H(1s) collisions are investigated within the multichannel Landau-Zener (MCLZ) framework over collision energies from 0.001 to 1000 eV/u, representing the first unified treatment of nearly the complete uranium ionization sequence. The entrance-channel potential incorporates polarization attraction and short-range repulsion, while exit-channel potentials are constructed from Coulomb repulsion with asymptotic energy shifts derived from NIST spectroscopic data. Nonadiabatic coupling matrix elements are evaluated using the Butler-Dalgarno model for q \leq 4 and the Taulbjerg model for q > 4. Multichannel transition probabilities are computed via the recursive formula, and rate coefficients are obtained through Maxwell-Boltzmann thermal averaging over 1-10^5 K. For low charge states (q = 3-12), the cross sections approximately follow an E^-1 scaling below their characteristic turnover energies E_t and exhibit non-monotonic energy dependences at higher energies. The turnover energy generally shifts upward with increasing q. For q \gtrsim 13, no resolvable turnover is observed within the present energy range, and the cross sections approximately retain the E^-1 scaling behavior over the whole calculated range. The charge state dependence of the cross sections reveals pronounced shell structure modulation. Systematic minima occur at closed-shell (d^10 and f^14) and half filled shell (f^7) configurations, as exemplified by q = 15, 33, 40, and 65. This behavior is attributed to exchange energy stabilization at these configurations, which produces anomalously high ionization energies, increases the energy defect, shifts the avoided crossing inward, and suppresses the electron capture probability. The thermally averaged rate coefficients preserve these shell-structure oscillations, and those for high charge states show an approximate T^-1/2 monotonic decrease. The present dataset covers temperature ranges relevant to kilonova ejecta (10^3-10^4 K), fusion edge plasmas (10^4-10^5 K), and accelerator beam pipes from room temperature to 10^3 K. It therefore provides systematic theoretical reference data for plasma modeling and beam transport design. The dataset presented in this paper is openly available at https://doi.org/10.57760/sciencedb.j00213.00235

     

    目录

    /

    返回文章
    返回