Plasma broadened line shapes and oscillator strengths of cesium

Abstract

Theoretical line shapes and oscillator strengths for cesium are presented in this paper. These enable independent measurements of density and temperature for cesium plasma. The oscillator strengths have been determined from one electron wave functions that have been obtained by numerical solution of the Schrodinger equation with the spin-orbit term. A potential constructed by a semi-systematic improvement of the Hartree potential for Cs + was used. This single potential gives binding energies accurate to less than 1 per cent for all but the lower levels; the lower levels agree within 3 per cent. The validity of the wave functions is demonstrated by comparing with experiment calculated values of fine structure splitting, ground state hyperfine splitting, and principal series oscillator strengths. These wave functions are used to calculate oscillator strengths for over 100 transitions in or near the visible region. Definite improvements over other theoretical oscillator strengths are observed. Under equilibrium conditions these oscillator strengths in conjunction with measured line intensities enable a determination of plasma temperature. Plasma broadened line shapes of the fundamental series of cesium have also been calculated and compared with experiment (see preceding paper). Plasma conditions included in the calculations range from 10 3 to 10 4K and 10 13 to 10 16 ions/cm 3. The impact limit with the classical path approximation is used to calculate the electron contribution to broadening, while the ions are treated in the usual static limit. Only isolated lines have been considered. Graphs of the calculated width and shift versus ion density are presented. In view of the good agreement between calculated and experimental widths these plots can be used henceforth to determine ion density. Densities obtained in this manner are insensitive to temperature and accuracies of 20 per cent are possible.