Plasma-screening effects on the electron-impact excitation of hydrogenic ions in dense plasmas

Abstract

Plasma-screening effects are investigated on electron-impact excitation of hydrogenic ions in dense plasmas. Scaled cross sections Z4⋅σ for 1s→2s and 1s→2p are obtained for a Debye–Hückel model of the screened Coulomb interaction. Ground and excited bound wave functions are modified in the screened Coulomb potential (Debye–Hückel model) using the Ritz variation method. The resulting atomic wave functions and their eigenenergies agree well with the numerical and high-order perturbation theory calculations for the interesting domain of the Debye length Λ/aZ≥10. The Born approximation is used to describe the continuum states of the projectile electron. Plasma screening effects on the atomic electrons cannot be neglected in the high-density cases. Including these effects, the cross sections are appreciably increased for 1s→2s transitions and decreased for 1s→2p transitions.