Study On The Radiative Opacity Of Aluminum Plasmas Using A Model Based On The Detailed-term-accounting Approximation

The main physical problems related to the calculations of the radiative opacity of plasmas using the detailed-term-accounting (DTA) approximation have been discussed and investigated in details. These physical problems include two main aspects: the first one is the population distributions of the ions in certain plasma condition; the second one is dealing with the method of acquiring the atomic data of two main atomic processes, i.e., the bound-bound and bound-free absorptions. The detailed method has been developed to calculate the radiative opacity of plasmas under local thermodynamic equilibrium using the detailed-term-accounting (DTA) approximation. The radiative opacities and transmission have been studied for aluminum plasmas under different temperatures and densities using the model based on the DTA approximation. The following is the main contents of the present paper:1. Two numerical methods of solving the Saha equation have been discussed in details. The computer code has been developed to solve the Saha equation. The results obtained by the two methods are accurately coincident. Our results are also in good agreement with other theoretical results.2. Detailed investigations are carried out to study two main atomic processes, i.e., the bound-bound and bound-free absorptions. A large amount of accurate atomic data has been obtained, including energy levels, oscillator strengths and photoionization cross sections, etc. A few physical effects related to these atomic quantities, including configuration interaction and autoionization resonance and so on, have been investigated and discussed in details.(1) Researches are carried out for the energy levels, oscillator strengths between the dipole allowed terms of atoms and ions, including the valence and inner-shell excited states and transitions. For examples, the energy levels of the inner-shell excited states of C IV have been calculated using the R-matrix method for the first time. Good agreement is obtained between the theoretical results and the experimental values. The oscillator strengths of the ls-2p transitions have been calculated using configuration interaction (CI) method for different LS dipole allowed transition series. The trends of the oscillator strengths of these series are analyzed and explained. The energy levels and oscillator strengths of the valence-excited states of C IV are obtained using configuration interaction (CI) method. The results show that the CI effect is rather strong. To obtain a good agreement with the experiment, this kind of effect must be adequately accounted. Comparison investigations are given to the excitation energies and oscillator strengths of the ls-2p transitions of O IV using the CI scheme and the R-matrix method. The results show thatthe interaction between the K-shell excited states and the continuum states as well as thecoupling between the different ionization channels have definite effects on the excitation energies and oscillator strengths of the K-shell transitions of O IV. A large amount of accurate atomic data has been derived for aluminum and its ions for practical applications.(2) The basic theory of electron impact broadening has been discussed, with the emphasis on the method of calculating the width using the quantum mechanical method. The electron impact broadening and shift of the CIV resonance line 2s 2S-2p 2P have been determined by the R-matrix method. Comparison studies are carried out on the electron impact broadening and shift of the Al X resonance line 2s21 S-2s2p 'P using the quantum mechanical and simplified semi-empirical methods. Good agreement is obtained between the two results at temperatures of more than 50000 K.(3) Extensive researches are conducted on the photoionization of atoms and ions. As examples, six- and ten-state close-coupling calculations using the R-matrix method are provided for the photoionization cross section of the ground state of C II ion. Good agreement is found with other theoretical results in the vicinity of the first ionization...