Development of a non-LTE spectral post-processor for dense plasma simulations with application to spectroscopic diagnostics in spherical implosions at Nova

摘要

A new non-LTE spectroscopy post-processing package is described. The package processes dump files from 1 or 2-dimensional radiation-hydrodynamics code simulations. Given the grid motion, temperatures, and ion densities contained in the dump files, as well as data from an arbitrarily detailed atomic model, the post-processor calculates internally consistent detailed frequency dependent opacities and radiation fields. The radiation transport equation is solved in the S(sub n) approximation using lambda iteration. Sub-cycling is used to achieve a more accurate solution to both the kinetics and radiation field calculations. Line broadening is included using Voigt widths based on the atomic rate coefficients, and Stark widths are included for K-shell spectra. The Sobolev escape factor approximation is available as an option. This post-processing package has been used to analyze spectra obtained recently at Nova with Ar doped deuterium filled capsules. The dopant was designed to be primarily a density diagnostic but can also be used for temperature diagnosis as well. We have run this post-processor with a wide array of atomic models for Argon, ranging from one containing only singly excited levels for the Hydrogenic, He-like, and Li-like sequences, to one containing a large number of doubly- and triply-excited levels in these sequences. We show a strong dependence of the degree of agreement between simulation and experiment on the model complexity with only the most complex model in close agreement.