Theoretical Study On Excitation Process Of Electron And Ion Collisions

In Atomic and Molecular Physics, the theoretical study, together with relevant atomic data, for electron-ion collision is an important topic. It is closely related to the research of astrophysical plasma, X-ray laser and ICF (Inertially Controlled Fusion). Moreover, it has a lot to do with the EBIT (Electron beam ion trap) project in the institute of modern physics of Fudan University. Using both the second-order many-body perturbation theory (MBPT) approach and relativistic configuration interaction method, we carry on with the detailed and systematic research on the ionic structure. Meanwhile, we carry on with the detailed and systematic research on electron-ion collision, using the Dirac R-matrix theory and relativistic distorted-wave method in conjunction with isolated resonance approx-imation. The details are as follows:1. We report calculations of energy levels and radiative rates for transitions among the lowest116fine-structure levels arising from the n≤5configurations in Be-like ions with Z=10-30. The wavelengths, oscillator strengths, line strengths, and radiative rates for all possible electric diople, magnetic dipole, elec-tric quadrupole, and magnetic quadrupole transitions among the116levels have been calculated using the combined configuration-interaction and many-body per-turbation method. The accuracy of the results is determined through extensive comparisons with existing laboratory measurements and theoretical results. A complete set of results should be of great help in line identification and interpreta-tion of spectra, and is likely to be useful for the modeling of a variety of plasmas. Meanwhile, these results cover a substantially larger number of transitions than previously available in the literature. We hope that these results will be useful in analyzing older experiments and planning new ones.This work has been contributed to The Astrophysical Journal Supplement Series (see Appendix).2. We report the calculations on energy levels, radiative rates, electron im-pact collision strengths, and effective collision strengths for transitions among the241fine-structure levels arising from2l8and2l7n’V (n’≤6and l’≤n’-1) configurations of Ne-like Se XXV. Flexible atomic code (FAC) is adopted for the calculations. Energy levels and radiative rates are calculated within rela- tivistic configuration-interaction method. Direct excitation collision strengths are calculated using relativistic distorted-wave approximation. High-energy collision strengths are obtained by relativistic plane-wave approximation. Resonance con-tributions through the relevant Na-like doubly-excited configurations2l7n’l’n"l"(3≤n’≤7, l’≤n’-1, n’≤n"≤50, and l"≤8) are explicitly tak-en into account via the independent process and isolated resonance approxima-tion using distorted-waves. In addition, the resonance contributions from Na-like2l63l’3l"nf"l’"(n’"=3-6) are included and found to be predominant for many transitions among the singly-excited states in Ne-like Se XXV. Resonant stabilizing transitions and possibly important radiative decays from the resonances towards low-lying autoionizing levels are considered. We present the radiative rates, os-cillator strengths, and line strengths for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), magnetic quadrupole (M2), electric octopole (E3), and magnetic octopole (M3) transitions among the241levels. Collision strengths and effective collision strengths are reported for all28920transitions among the241levels over a wide energy (temperature) range up to7.2keV (10keV). We have performed yet a limited27-states close-coupling calculation, employing the Dirac R-matrix theory. The comparison with the independent process calculation for the identical target states shows that the close-coupling effects are small for Ne-like Se XXV.This work has been published in Atomic Data and Nuclear Data Tables (see Appendix).3. We report the calculations on effective collision strengths for electron im-pact excitations among the41levels of3s23p3,3s3p4, and3s23p23d configurations in Ni XIV. The Dirac R-matrix theory and relativistic distorted-wave method in conjunction with isolated resonance approximation are adopted for the calcula-tions. Detailed comparisons between the results obtained from the above two methods show that the independent process and isolated resonance approxima-tion using distorted-waves can describe the near threshold resonances reasonably well for most transitions in Ni XIV, though channel-coupling effects are found to be important for weak transitions. Resonances enlarge significantly the effective collision strengths for many transitions, even by over two orders of magnitude.This work has been published in Journal of Physics B:Atomic, Molecular and Optical Physics(see Appendix). 4. We have calculated the atomic data including electron impact excitations and radiative decays among the lowest143fine-structure levels arising from3s23p3,3s3p4,3s23p23d,3p5,3s3p33dt and3s23p3d2configurations in P-like NiⅩⅣ. Direct excitation collision strengths are calculated employing relativistic distorted-wave method. Resonances are included via the isolated resonance approximation using distorted-waves. Resonance contributions from S-like [3s23p3,3s3p4,3s23p23d,3p5,3s3p33d,3s23p3d2,3p43d,3s3p23d2,3s23d3]n’l’ complexes series are taken into ac-count. Effective collision strengths are reported over electron temperature range of1.0×105-1.0×108K.This work has been published in Atomic Data and Nuclear Data Tables (see Appendix).