Steady-state ionization-balance calculations for a selenium plasma

• Published in: Physical review. A, Atomic, molecular, and optical physics Vol. 45; no. 6; pp. 3980 - 3986
• Main Authors: ABDALLAH, J. JR, CLARK, R. E. H, PEEK, J. M
• Format: Journal Article
• Language: English
• Published: College Park, MD American Physical Society 15-03-1992
• Subjects: 426002 > Engineering > Lasers & Masers > (1990-); 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CHARGED PARTICLES; ENERGY-LEVEL TRANSITIONS; ENGINEERING; Exact sciences and technology; EXCITATION; IONIZATION; IONS; LASERS 700330 > Plasma Kinetics, Transport, & Impurities > (1992-); MULTICHARGED IONS; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; PLASMA; Plasma properties; RECOMBINATION; SELENIUM IONS; STEADY-STATE CONDITIONS; TEMPERATURE EFFECTS; X-RAY LASERS; Theoretical study; Plasma; Selenium; Ionization; Steady state
• ISSN: 1050-2947; 1094-1622
• DOI: 10.1103/PhysRevA.45.3980

A steady-state model is used to calculate the ionization balance for a selenium plasma at electron temperatures where the Ne-like stage is dominant. In this model, the ion distribution and free-electron density are calculated for a specified particle density and temperature. In addition, each state of a given ion is connected to appropriate states of the same ion by excitation and deexcitation and connected to the appropriate states of adjacent ions by ionization and recombination. Excited states including autoionizing states are treated explicitly. Rate coefficients for all processes are based consistently on atomic-structure calculations. The calculations indicate that hundreds of electron configurations are necessary to obtain suitable results and that electron configurations must be included consistently across ion stages. Autoionizing states are shown to be the major influence in determining the ionization balance. The use of plane-wave Born collision strengths instead of better distorted-wave collision strengths appears to have a negligible effect on the overall ion stage distribution at moderate densities. The results may explain why F-like lasing transitions were not observed in the experiments by Matthews {ital et} {ital al}. (Phys. Rev. Lett. 54, 110 (1985)).