scholarly journals A Comparison of Various NLTE Codes in Computing the Charge-State Populations of an Argon Plasma

1984 ◽  
Vol 86 ◽  
pp. 108-109
Author(s):  
Sam R. Stone ◽  
Jon C. Weisheit
Keyword(s):  
Steady State ◽  
Charge State ◽  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Argon Plasma ◽  
Computational Physics ◽  
Photon Flux ◽  
Easy Problem ◽  
Computer Codes ◽  
Bound Electrons

A comparison among nine computer codes shows surprisingly large differences where it had been believed that the computational physics was well understood. The codes simulate a plasma that is in steady state but not in local thermodynamic equilibrium (NLTE codes). In this study each code treats an “easy” problem, which is an argon plasma, optically thin and with no external photon flux; densities are varied from near-coronal to an intermediate 1021 electrons/cc and above. The temperatures are high enough that most ions have two or fewer bound electrons, which for this plasma means temperatures above about 300 eV.The present study asks only if the codes compute similar charge-state populations (a surprising “no”), and, if not, why not. It does not claim accuracy for any code either by comparison to experiment or by appeal to a concensus.

Influence of Radiative Absorption on the Establishment of Local Thermodynamic Equilibrium

1969 ◽  
Vol 24 (10) ◽  
pp. 1492-1496 ◽  
Author(s):  
H. W. Drawin
Keyword(s):  
Steady State ◽  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Coupled System ◽  
Rate Equations ◽  
Population Densities ◽  
Hydrogen Plasmas ◽  
Radiative Rate ◽  
Radiative Absorption ◽  
State Plasma

Abstract By solving the coupled system of collisional-radiative rate equations for a homogeneous and steady-state plasma as a function of the radiative excitation rates one obtains the population densities of the ground and of the excited levels for any given degree of reabsorption. One finds that in hydrogen plasmas which are completely optically opaque towards all Lyman lines and partially optically opaque towards Hα the equilibrium populations will not be established for electron densities below 1X1016 cm-3.

Transient conditions in inductively heated plasmas: thermodynamic equilibrium and temperature measurements

1982 ◽  
Vol 60 (6) ◽  
pp. 886-892 ◽  
Author(s):  
Paul Meubus
Keyword(s):  
Thermodynamic Equilibrium ◽  
Decay Time ◽  
Concentration Distribution ◽  
Local Thermodynamic Equilibrium ◽  
Energy Levels ◽  
Argon Plasma ◽  
Partition Functions ◽  
Transient Conditions ◽  
Gas Interactions ◽  
Catalytic Effects

A study has been made on transient extinction conditions in an inductively heated argon plasma. It was observed that local thermodynamic equilibrium (LTE) conditions do exist between the metastable 3P2 level and upper energy levels, so that during the decay time it is possible to determine a meaningful temperature, using the 3P2 level as a fundamental level and the partition functions being calculated accordingly. Together with the temperature determination, a concentration distribution of argon metastables was obtained.Studies of this type are useful for the investigation of quenching processes in plasmas, affecting favorably chemical reactions or solid–gas interactions, thus leading to enhanced catalytic effects or modifications of solid particle structures which are liable to generate new electrical, thermal, etc. properties of interest.

scholarly journals Determination of corona, LTE, and NLTE regimes of optically thin carbon plasmas

2008 ◽  
Vol 26 (1) ◽  
pp. 21-32 ◽  
Author(s):  
J.M. Gil ◽  
R. RodrÍguez ◽  
R. Florido ◽  
J.G. Rubiano ◽  
P. Martel ◽  
...  
Keyword(s):  
Steady State ◽  
Plasma Density ◽  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Radiative Properties ◽  
Thin Carbon ◽  
Non Local

AbstractIn this work is accomplished the determination of the corona, local and non-local thermodynamic equilibrium regimes for optically thin carbon plasmas in steady state, in terms of the plasma density and temperature using the ABAKO code. The determination is made through the analysis of the plasma average ionization and ion and level populations. The results are compared whit those obtained applying Griem's criterion. Finally, it is made a brief analysis of the effects of the calculation of level populations assuming different plasma regimes in radiative properties, such as emissivities and opacities.

Blackbody Radiation, Boltzmann Statistics, Temperature, and Thermodynamic Equilibrium

2017 ◽  
Author(s):  
Kelly Chance ◽  
Randall V. Martin
Keyword(s):  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Photophysical Properties ◽  
Blackbody Radiation ◽  
Boltzmann Constant ◽  
Noise Sources ◽  
Atmospheric Molecules ◽  
Tightly Coupled ◽  
Boltzmann Statistics ◽  
Planck’S Law

Blackbody radiation, temperature, and thermodynamic equilibrium give a tightly coupled description of systems (atmospheres, volumes, surfaces) that obey Boltzmann statistics. They provide descriptions of systems when Boltzmann statistics apply, either approximately or nearly exactly. These apply most of the time in the Earth’s stratosphere and troposphere, and in other planetary atmospheres as long as the density is sufficient that collisions among atmospheric molecules, rather than photochemical and photophysical properties, determine the energy populations of the ensemble of molecules. Thermodynamic equilibrium and the approximation of local thermodynamic equilibrium are introduced. Boltzmann statistics, blackbody radiation, and Planck’s law are described. The chapter introduces the Rayleigh-Jeans limit, description of noise sources as temperatures, Kirchoff’s law, the Stefan-Boltzmann constant, and Wien’s law.

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