Analysis of the cross section and characteristic of fluorescence emission of the He atom confined in the plasma conditions

Abstract

The structural properties, angle-integrated total and magnetic sublevel excitation cross sections, alignments of the residual ion, and polarization properties of the line emission are investigated for the plasma-embedded atomic system. This is done using the developed distorted wave approach which solves the Dirac equation by employing a modified Debye potential to represent the screened interaction in plasmas. The effective Hamiltonian is employed to obtain the level energies as functions of the screening parameters. The Coulomb interaction is replaced by shielded Coulomb interaction during the collision dynamics. As an illustrating example, detailed calculations are carried out for the 1s2→1s2p3,1P1 excitations of the plasma-embedded He atom by electron impact. Our results suggest that the energy levels are pushed towards continuum as the effect of (plasma) confinement increases. The cross sections decreases monotonically if the screening effect is enhanced continuously, while the alignments of the residual He+ ion and polarizations of the fluorescence emission change slightly for the corresponding screening parameters. A comparison of our results in the absence of the screening potential with other available experimental and theoretical data shows satisfactory agreement. The present study not only provides a helpful approach to study the influence of plasma effect, but also has important applications in laser produced plasmas, stellar atmospheres, fusion research plasmas and so on.