Collisions of highly charged ions with relativistic effects by electron impact in plasmas

离子在等离子体中的发射和电子碰撞离子的激发截面可用于等离子体诊断的电子温度和电子密度。本项目的目的是研究电子碰撞离子激发截面的相对论效应。我们使用了三种R-矩阵方法，即。非相对论R-矩阵(RMAT)、半相对论R-矩阵(BPRMAT)和全相对论R-矩阵(DRMAT)具有Breit-Pauri近似和Dirac近似。现有的理论结果可用作等离子体诊断中碰撞辐射模型的输入数据。研究结果总结如下：1.研究成果。用DRMAT、紧耦合和库仑-玻恩近似计算了类氢离子n=2精细结构能级之间的电子碰撞跃迁。研究发现，电子交换效应对光学禁忌跃迁的截面有相当大的贡献。用DRMAT、BPRMAT和RMAT计算了类氦离子(Z=16-26)的电子碰撞激发截面和速率系数。计算中考虑了最低的45个靶能级，得到了n=2、3和4的基态到激发态的速率系数。验证了n=5能级的耦合和共振对跃迁到n=4能级的速率系数起着重要的作用。用RMAT和BPRMAT测量了类锂离子、类镁离子和钙离子的激发截面和斯托克斯参数。结果表明，本文的结果与实验结果吻合很好，为等离子体诊断提供了可靠的依据。

Emissions from ion in plasmas and excitation cross sections of the ion by electron impact can be used to obtain electron temperature and density for plasma diagnostics. The aim of this project is to study relativistic effects for excitation cross sections of ions by electron impact. We used three kinds of R-matrix methods viz. non-relativistic R-matrix (RMAT), semi-relativistic R-matrix (BPRMAT) with the Breit-Pauri approximation and full relativistic R-matrix (DRMAT) with the Dirac approximation.Present theoretical results are available to use as input data on a collisional radiative model for plasma diagnostics. The results are summarized as follows.1. The electron-impact transitions between the n=2 fine-structure levels of hydrogenic ions were calculated using the DRMAT, the close-coupling and the Coulomb-Born approximations. It was found that the electron-exchange effect was a considerable contribution to the cross-section of optically forbidden transitions.2. Cross sections and rate coefficients for electron-impact excitation of He-like ions (Z=16-26) were calculated by use of the DRMAT, the BPRMAT and the RMAT. The lowest 45 target levels were included in the calculation to obtain the rate coefficients for the ground state to the excited states with n=2, 3 and 4. It was verified that the effects of coupling and resonances from n=5 levels play an important role in rate coefficients for the transitions to the n=4 levels.3. Excitation cross sections and Stokes parameters of Li-like and Mg-like ions, and Ca were obtained by using the RMAT and BPRMAT. It was shown that present results were in excellent agreement with the experiments and reliable for plasma diagnostics.