Plasma screening effects on the atomic structure and radiative opacity of dense carbon plasmas based on the DLA model

Abstract

A study of plasma screening effects using a Debye-Hückel model is presented. The effects on the energy levels, oscillator strengths, ionization potential and photoionization cross sections of different ionization stages of carbon and on the radiative opacity of hot dense carbon plasmas are presented. The treatment of the atomic structure and radiative opacity is based on the detailed fine-structure level accounting formalism. For the basic atomic data, we compare our calculated energy levels and oscillator strengths with other theoretical results available in the literature and good agreement is found. The calculated ionization potential depressions of helium-like carbon, C V, are compared with the experimental and other theoretical results for a variety of plasma condition. Since the Saha–Boltzmann equation, which determines the ion stage populations, is dependent on the energy levels and ionization potentials of all ionization stages of carbon, the plasma screening effects on these quantities were included to obtain the population distribution. The screening effects play an important role on the spectrally resolved opacity by affecting the position and intensity of the absorption peaks and the K-shell ionization thresholds. With the decrease of Debye screening length, the number and intensity of the absorption peaks are reduced. In particular, the continuum opacity near the K-edge will be so sufficiently affected by the screening effects as to be experimentally observed. Finally, the plasma screening effects on the Rosseland and Planck mean opacities are investigated.