Theoretical Studies On The Electron-impact Excitation Process And Radiative Spectrum Of Abundant Elements In Stellar Atmosphere

Studying plasmas in stellar atmosphere is a feasible way to explore the evolution,structure, and other physical Properties for stellar. Electron-atom(ion) collision is an important process in astrophysical plasmas, which is necessary to be studied for diagnosing the astrophysical spectrum, diagnosis of plasmas, and research in related fields. In this paper, the aim is to study systemically the electron-impact excitation process and radiative spectrum of abundant elements in stellar atmosphere with using the multi-configuration Dirac-Fock(MCDF) method and the fully relativistic distorted-wave(RDW) method. The outline of paper is given following:In chapter one, we introduce some basic physical pictures and terminologies we will confront in following chapter including electron-impact excitation and radiation processes.In chapter two, the details of theory on multi-configuration Dirac-Fock(MCDF)method and the fully relativistic distorted-wave(RDW) are introduced, which is the core to obtain the wavefunctions of target ions(atoms) and continuous electron, and to calculate electron-impact excitation cross sections.In chapter three, electron impact excitation(EIE) process from the ground state2p6 1S0 and the metastate 2p53s3P2 to 2p53l(l=s, p, d) excitated states of neutral Ne atom are studied. The focus is mainly paid on the influence of electron correlation on target energy levels, transition rates and electron impact excitation cross sections. It is found that the electron correlation effect is especially significant for EIE cross section of neutral Ne atom in lower energy collision regions, it will largely reduces the cross sections when more consideration in calculation of target stats the electron correlation from higher excited configurations. Comparison is made between the presented results in correlation model B with earlier theoretic and experimental results available,a generally good agreement is found for 2p53 s and 2p53 p excited states. However, for2p53 d excited states, there are absent experimental results to compare, larger deviation between different theoretical results need further experimental and theoretical study to verify.In chapter four, we calculate the cross sections for ground state 3d2 3F to fine-structure levels of 3d4l(l<4) and 3d5l’(l’=s, p) duo to need of diagnosing theastrophysical and experimental plasmas.In chapter five, there are three sections: In the first section, we calculated the magnetic sublevels and total cross sections of electron-impact excitation form ground state 1s22 s 2S1/2 to excited states 1s2p2 2P3/2, 1s2s2p(3P) 2P3/2, 1s2p2 2D5/2, 1s2s2p(1P)2P3/2, 1s2p2 2D3/2, and 1s2s2p(3P)4P3/2 in Li-like ions(Z=14-32). The linear polarization of spectral a, j, k, q, s, and u lines by the cross sections of excited magnetic sublevels formed by electron-impact excitation are calculated. We also explored that the Breit interaction how to influence the electron-impact excitation process, and the conclusions we get are: the contribution of Breit can be neglected for total cross sections; for the cross sections of magnetic sublevels, the influence on1s2p2 2P3/2, 1s2p2 2D5/2, 1s2p2 2D3/2 is negligible, but 1s2s2p(3P)2P3/2, 1s2s2p(1P)2P3/2,and 1s2s2p(3P) 4P3/2. Meanwhile, we analysis the influence of Breit on linear polarization, then we find that the contribution of Breit interaction is small for a, j, k lines but is great for q, s, and u lines. Breit interaction makes a reduction to q, s, and u lines. A good consistency with available results is obtained shows that our works are credible. In the second section, dielectronic recombination is another process in electron-ions collision, therefore, we study the formation of double excited states1s2p2 2P3/2, 1s2s2p(3P) 2P3/2, 1s2p2 2D5/2, 1s2s2p(1P) 2P3/2, 1s2p2 2D3/2, and 1s2s2p(3P)4P3/2 through capture an electron with He-like ions. The capture cross section and linear polarization of spectral a、j、k、q、s, and u lines are obtained. In the third section,we study the influence on the electron-impact excitation from ground state 1s22 s 2S1/2to excited states 1s2s2p(3P) 2P3/2, 1s2s2p(1P) 2P3/2, and 1s2s2p(3P) 4P3/2 and the linear polarization of spectral q, s, and u lines including the E1-M2 interfrere for higher atomic number(Z=59-92) Li-like ions. Including the Breit interaction shows a tendency of de-polarization.