The screening effect of the plasma ions on the electron-impact excitation process and subsequent polarization of X-ray photoemission

Abstract

In this manuscript, we calculate the spectral properties and the electron-impact excitation cross sections in the semiclassical dense hydrogen plasmas, by solving the modified relativistic Dirac equation based on the Dirac-Coulomb Hamiltonian and using the suggested relativistic distorted wave method, respectively. The obtained cross sections are then used to study the polarization of the de-excitation X-ray photoemission, which allows a deeper probe of the electronic structural properties of the atoms/ions, thus yielding a comprehensive understanding of the underlying atomic processes. We employ the effective model potential proposed by Ramazanov et al. (2015) to replace the electron-nucleus Coulomb potential, where the former (potential) is derived for general two interacting charged particles taking into account the quantum mechanical and screening effects in semiclassical dense plasmas. Relativistic effects, including the Breit interaction and dominant quantum electrodynamics corrections, are included. Our study involves a comprehensive investigation of the screening effect of the plasma ions on the various properties such as the bound state energies, excitation energies, transition rates, electron-impact excitation cross sections and subsequent polarizations of X-ray photoemission across a wide range of plasma parameters. We compare our numerical results with other available experimental and theoretical data, showing good agreement. The outcomes of this work not only help to better understand the fundamental properties of plasmas, but also provide important applications in fusion, astrophysics, and other fields.