Influence of atomic radiative and collisional processes on the plasma modeling of Mg¹⁰⁺ at low electron densities

MITNIK, D. M.; PINDZOLA, M. S.; GRIFFIN, D. C.

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

The American Physical Society

Año: 2000 vol. 62 p. 62711 - 62721

1050-2947

In this paper, we report on theoretical calculations of electron-impact excitation cross sections and radiative transition rates for Mg10+. The excitation cross sections were calculated using semirelativistic close-coupling and fully relativistic distorted-wave theory and the radiative rates were determined using semirelativistic and fully relativistic atomic-structure theory. After the solution of the corresponding collisional-radiative equations, the Kα2/Kα1 (1s2p 3P1-->1s2 1S0 over 1s2p 1P1-->1s2 1S0) emission line ratio and the Kβ2/Kβ1 (1s3p 3P1-->1s2 1S0 over 1s3p 1P1-->1s2 1S0) emission line ratio were calculated as a function of electron temperature and density. The various scattering calculations involving different numbers of levels enabled us to study the influence of resonance structures and cascades from highly excited levels on the collisional-radiative modeling and we found that they have little effect on the level populations. However, even in this ten-times ionized species, the effects of orbital relaxation are found to be important in the determination of accurate electric-dipole radiative transition rates. Both line ratios were found to be strongly affected by whether the magnetic-dipole radiative transition from the 1s2s 3S1 level to the ground state was included or not. At very low electron densities, the 1s2s 1S0 two-photon transition to the ground state also has an effect on the Kα2/Kα1 line ratio. In addition, we found that the line ratios are enhanced at high temperatures by radiative and dielectronic recombination from the hydrogenic Mg11+ ion. However, the dielectronic satellite lines have no effect on the line ratios for the low-density astrophysical, solar, and magnetic-fusion plasmas considered in this paper.