Steve Libby, Group Leader

 

OPAL

OPACITY TABLES

The OPAL code was developed at the Lawrence Livermore National Laboratory to compute opacities of low- to mid-Z elements. Briefly, the calculations are based on a physical picture approach that carries out a many-body expansion of the grand canonical partition function. The method includes electron degeneracy and the leading quantum diffraction term as well as systematic corrections necessary for strongly-coupled plasma regimes. The atomic data are obtained from a parametric potential method that is fast enough for in-line calculations while achieving an accuracy comparable to single configuration Dirac-Fock results. The calculations use detailed term accounting; for example, the bound-bound transitions are treated in full intermediate or pure LS coupling depending on the element. Degeneracy and plasma collective effects are included in inverse bremsstrahlung and Thomson scattering. Most line broadening is treated with a Voigt profile that accounts for Doppler, natural width, electron impacts, and for neutral and singly ionized metals broadening by H and He atoms. The exceptions are one-, two-, and three-electron systems where linear Stark broadening by the ions is included.

 

UCRL-WEB-145059