FESTR: Finite-Element Spectral Transfer of Radiation spectroscopic modeling and analysis code

Abstract

We report on the development of a new spectral postprocessor of hydrodynamic simulations of hot, dense plasmas. Based on given time histories of one-, two-, and three-dimensional spatial distributions of materials, and their local temperature and density conditions, spectroscopically-resolved signals are computed. The effects of radiation emission and absorption by the plasma on the emergent spectra are simultaneously taken into account. This program can also be used independently of hydrodynamic calculations to analyze available experimental data with the goal of inferring plasma conditions. Program summaryProgram title: FESTRCatalogue identifier: AFAR_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AFAR_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: BSD 3-Clause licenseNo. of lines in distributed program, including test data, etc.: 1237516No. of bytes in distributed program, including test data, etc.: 17542918Distribution format: tar.gzProgramming language: C++.Computer: HPC, PC.Operating system: Linux, MacOS.RAM: Problem dependent (based on size of input)Classification: 1.3, 2.2, 20.2.Nature of problem:Calculation of spectral signals by postprocessing hydrodynamics simulations. Analysis of experimental spectroscopic data to infer plasma temperature and density conditions, and its chemical composition. Simultaneous treatment of spatial non-uniformity (on 3D unstructured meshes) along with spectroscopic-quality radiation transport.Solution method:Rays are cast across a 3D unstructured mesh that characterizes local temperature, density, and chemical composition of the material. Analytic solution to the 1D (along the ray) steady-state, local radiation transport equation is repeatedly used to gradually build a synthetic spectrum for each ray.Restrictions:Steady-state approximation of the radiation transport equation is used. Scattering as a radiation source is not included. Given plasma conditions are considered fixed; potential feedback of computed radiation back into plasma temperature and equation-of-state is neglected. Doppler shifts are not modeled at this time. The quality of the computed results critically depends on the accuracy of external atomic databases used as input by FESTR. Polygon objects are assumed to be convex at present.Running time:Problem dependent (based on size of input)—the suite of 1190 enclosed unit tests runs in less than a minute on most tested platforms.