The DAVROS opacity code: Detailed term accounting calculations for LTE plasmas ☆

Abstract The radiative opacity of a plasma is a key parameter in understanding a diverse range of high energy density systems including inertial confinement fusion and astrophysics. The accurate calculation of opacity is hampered by the potentially enormous number of ionic configurations, the detailed internal structure of each giving rise to the term structure, and the line broadening models which must typically be applicable across densities from 10 −6  g/cc to several times solid. The DAVROS opacity code ( D etailed A ccounting of V arious configurations for R adiative O pacity S pectra) has been developed at AWE over recent years, and by making use of the large scale High Performance Computing (HPC) systems, implements a number of models and algorithms aimed at a more direct calculation of opacities than has traditionally been feasible. The results are both more physically based and spectrally accurate than codes based upon statistical accounting approximations. In particular, the bound–bound line spectrum can be explicitly calculated using the Detailed Term Accounting (DTA) method, which, although computationally expensive, is necessary to understand the true frequency dependent structure of the opacity spectrum. Additionally, M. Baranger (1958) [1] quantum mechanical formulism of pressure (or electron impact) broadening is implemented, thereby representing a significant improvement upon alternative approximations. We present a summary of some of the key issues, models and algorithms in the code, and show some representative results, including comparisons with opacity measurements made at AWE.