Calculation of radiative opacity of plasma mixtures using a relativistic screened hydrogenic model

- A new opacity code, ATMED, based on the average atom approximation is presented.
- Atomic data are computed by means of a relativistic screened hydrogenic model.
- An effective bound level degeneracy is included for accounting pressure ionization.
- A new dielectronic line broadening is included to improve the mean opacities.
- ATMED has the possibility to handle with single element and multicomponent plasmas.

We present the code ATMED based on an average atom model and conceived for fast computing the population distribution and radiative properties of hot and dense single and multicomponent plasmas under LTE conditions. A relativistic screened hydrogenic model (RSHM), built on a new set of universal constants considering j-splitting, is used to calculate the required atomic data. The opacity model includes radiative bound-bound, bound-free, free-free, and scattering processes. Bound-bound line-shape function has contributions from natural, Doppler and electron-impact broadenings. An additional dielectronic broadening to account for fluctuations in the average level populations has been included, which improves substantially the Rosseland mean opacity results. To illustrate the main features of the code and its capabilities, calculations of several fundamental quantities of one-component plasmas and mixtures are presented, and a comparison with previously published data is performed. Results are satisfactorily compared with those predicted by more elaborate codes.