A Reducedorder NLTE Kinetic Model for Radiating Plasmas of Outer Envelopes of Stellar Atmospheres
Abstract
The present work proposes a selfconsistent reducedorder NLTE kinetic model for radiating plasmas found in the outer layers of stellar atmospheres. A detailed collisionalradiative kinetic mechanism is constructed by leveraging the most uptodate set of ab initio and experimental data available in the literature. This constitutes the starting point for the derivation of a reducedorder model, obtained by lumping the bound energy states into groups. In order to determine the needed thermophysical group properties, uniform and Maxwell–Boltzmann energy distributions are used to reconstruct the energy population of each group. Finally, the reduced set of governing equations for the material gas and the radiation field is obtained based on the moment method. Applications consider the steady flow across a shock wave in partially ionized hydrogen. The results clearly demonstrate that adopting a Maxwell–Boltzmann grouping allows, on the one hand, for a substantial reduction of the number of unknowns and, on the other, to maintain accuracy for both gas and radiation quantities. Also, it is observed that, when neglecting line radiation, the use of two groups already leads to a very accurate resolution of the photoionization precursor, internal relaxation, and radiative cooling regions. The inclusion of line radiation requires adopting just onemore »
 Authors:
 Aerospace Engineering Department, University of Illinois at UrbanaChampaign, 206A Talbot Lab., 104 S. Wright Street, Urbana, IL 61801 (United States)
 NASA Ames Research Center, Moffett Field, 94035 CA (United States)
 Aerospace Engineering Department, University of Illinois at UrbanaChampaign, 306 Talbot Lab., 104 S. Wright Street, Urbana, IL 61801 (United States)
 Publication Date:
 OSTI Identifier:
 22661195
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Astrophysical Journal; Journal Volume: 838; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; ENERGY SPECTRA; EQUATIONS; HYDROGEN; IONIZATION; LAYERS; LOSSES; PLASMA; RADIANT HEAT TRANSFER; RADIATIVE COOLING; REDUCTION; RELAXATION; RESOLUTION; SHOCK WAVES; STARS; STEADY FLOW; STELLAR ATMOSPHERES
Citation Formats
Munafò, Alessandro, Mansour, Nagi N., and Panesi, Marco, Email: munafo@illinois.edu, Email: nagi.n.mansour@nasa.gov, Email: m.panesi@illinois.edu. A Reducedorder NLTE Kinetic Model for Radiating Plasmas of Outer Envelopes of Stellar Atmospheres. United States: N. p., 2017.
Web. doi:10.3847/15384357/AA602E.
Munafò, Alessandro, Mansour, Nagi N., & Panesi, Marco, Email: munafo@illinois.edu, Email: nagi.n.mansour@nasa.gov, Email: m.panesi@illinois.edu. A Reducedorder NLTE Kinetic Model for Radiating Plasmas of Outer Envelopes of Stellar Atmospheres. United States. doi:10.3847/15384357/AA602E.
Munafò, Alessandro, Mansour, Nagi N., and Panesi, Marco, Email: munafo@illinois.edu, Email: nagi.n.mansour@nasa.gov, Email: m.panesi@illinois.edu. Sat .
"A Reducedorder NLTE Kinetic Model for Radiating Plasmas of Outer Envelopes of Stellar Atmospheres". United States.
doi:10.3847/15384357/AA602E.
@article{osti_22661195,
title = {A Reducedorder NLTE Kinetic Model for Radiating Plasmas of Outer Envelopes of Stellar Atmospheres},
author = {Munafò, Alessandro and Mansour, Nagi N. and Panesi, Marco, Email: munafo@illinois.edu, Email: nagi.n.mansour@nasa.gov, Email: m.panesi@illinois.edu},
abstractNote = {The present work proposes a selfconsistent reducedorder NLTE kinetic model for radiating plasmas found in the outer layers of stellar atmospheres. A detailed collisionalradiative kinetic mechanism is constructed by leveraging the most uptodate set of ab initio and experimental data available in the literature. This constitutes the starting point for the derivation of a reducedorder model, obtained by lumping the bound energy states into groups. In order to determine the needed thermophysical group properties, uniform and Maxwell–Boltzmann energy distributions are used to reconstruct the energy population of each group. Finally, the reduced set of governing equations for the material gas and the radiation field is obtained based on the moment method. Applications consider the steady flow across a shock wave in partially ionized hydrogen. The results clearly demonstrate that adopting a Maxwell–Boltzmann grouping allows, on the one hand, for a substantial reduction of the number of unknowns and, on the other, to maintain accuracy for both gas and radiation quantities. Also, it is observed that, when neglecting line radiation, the use of two groups already leads to a very accurate resolution of the photoionization precursor, internal relaxation, and radiative cooling regions. The inclusion of line radiation requires adopting just one additional group to account for optically thin losses in the α , β , and γ lines of the Balmer and Paschen series. This trend has been observed for a wide range of shock wave velocities.},
doi = {10.3847/15384357/AA602E},
journal = {Astrophysical Journal},
number = 2,
volume = 838,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}

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