The Opacity Project: R-Matrix Calculations for Opacities of High-Energy-Density Astrophysical and Laboratory Plasmas

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Main Authors: Pradhan, Anil K., Nahar, Sultana N.
Format: Preprint
Published: 2025
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author Pradhan, Anil K.
Nahar, Sultana N.
author_facet Pradhan, Anil K.
Nahar, Sultana N.
contents Accurate determination of opacity is critical for understanding radiation transport in both astrophysical and laboratory plasmas. We employ atomic data from R-Matrix calculations to investigate radiative properties in high-energy-density (HED) plasma sources. Specifically, we analyze environments such as the base of the convective zone (BCZ) of the Sun 2 x 10^6$ K, N_e = 10^{23}/cc and the inertial confinement fusion (ICF) device at the Sandia Z facility 2.11 x 10^6 K, N_e = 3.16 x 10^{22}/cc. We calculate Rosseland Mean Opacities (RMO) within a range of temperatures and densities and analyze how they vary under different plasma conditions. In this study, we specifically focus on electron collisional and Stark ion microfield broadening effects on autoionizing resonances in photoabsorption cross sections. Our results are relevant to astrophysical models, particularly in the context of the solar opacity problem, and provide insights into discrepancies between theoretical calculations and experimental measurements. In addition, we investigate the equation-of-state (EOS) and its impact on opacities. In addition, we examine the equation-of-state (EOS) and its impact on opacities of the "chemical picture" Mihalas-Hummer-Dappen EOS with respect to level populations of excited levels included in the R-matrix calculations. This study should contribute to improving opacity models of HED sources such as stellar interiors adn laboratory fusion plasma experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2510_20775
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Opacity Project: R-Matrix Calculations for Opacities of High-Energy-Density Astrophysical and Laboratory Plasmas
Pradhan, Anil K.
Nahar, Sultana N.
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
Atomic Physics
Plasma Physics
Accurate determination of opacity is critical for understanding radiation transport in both astrophysical and laboratory plasmas. We employ atomic data from R-Matrix calculations to investigate radiative properties in high-energy-density (HED) plasma sources. Specifically, we analyze environments such as the base of the convective zone (BCZ) of the Sun 2 x 10^6$ K, N_e = 10^{23}/cc and the inertial confinement fusion (ICF) device at the Sandia Z facility 2.11 x 10^6 K, N_e = 3.16 x 10^{22}/cc. We calculate Rosseland Mean Opacities (RMO) within a range of temperatures and densities and analyze how they vary under different plasma conditions. In this study, we specifically focus on electron collisional and Stark ion microfield broadening effects on autoionizing resonances in photoabsorption cross sections. Our results are relevant to astrophysical models, particularly in the context of the solar opacity problem, and provide insights into discrepancies between theoretical calculations and experimental measurements. In addition, we investigate the equation-of-state (EOS) and its impact on opacities. In addition, we examine the equation-of-state (EOS) and its impact on opacities of the "chemical picture" Mihalas-Hummer-Dappen EOS with respect to level populations of excited levels included in the R-matrix calculations. This study should contribute to improving opacity models of HED sources such as stellar interiors adn laboratory fusion plasma experiments.
title The Opacity Project: R-Matrix Calculations for Opacities of High-Energy-Density Astrophysical and Laboratory Plasmas
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
Atomic Physics
Plasma Physics
url https://arxiv.org/abs/2510.20775