Effects of screening on the energies and transition parameters of Fe XX of fusion interest

Abstract

We present results of accurate fully-relativistic calculations of transition energies and oscillator strengths among the levels of the 2s22p3, 2s2p4, and 2p5 configurations of N-like iron under dense plasma conditions, i.e., 19 times ionized atom of iron. Such highly-ionized species can exist in very hot plasmas, such as in cores of magnetic-fusion reactors, in X-ray free electron laser experiments and in imploaded targets of inertially-confined fusion (ICF) experiments. The ion sphere potential experienced by the electron is parameterized by temperature and electron density. Two independent atomic structure methods, namely the multiconfiguration Dirac-Hartree-Fock method and the flexible atomic code (FAC) representing the plasma shieldings with an average-atom ion-sphere (AAIS) potential and a uniform electron gas model (UEGM) potential, have been developed. The plasma-free values obtained in this work compare well with existing data from literature. Our results show that the levels of all studied configurations shift with the increase in plasma electron density, the shift of the 2s22p3 energies being negative and the shift of 2s2p4 and 2p5 positive. Moreover, the energy shift becomes more sensitive to the plasma electron density when the plasma electron temperature is lower. The oscillator strengths of the lines increase with the increase of electron density for a given temperature. The present results should be useful in fusion related plasmas and fundamental physics.