Sponsor
This work was performed under the auspices of the U.S. Department of Energy under DOE Field Office. Idaho, Contract No. DE-AC07-76ID01570. supported by the U.S. Department of Energy, Office of Energy Research, Office of Basic Energy Sciences. Division of Engineering and Geosciences.
Published In
Physics of Plasmas
Document Type
Article
Publication Date
1-1-1994
Subjects
Argon plasmas, Plasma (Ionized gases) -- Mathematical models, Thermodynamics
Abstract
Departures from thermal (translational), ionization, and excitation equilibrium in an axisymmetric argon plasma jet have been studied by two?dimensional numerical simulations. Electrons, ions, and excited and ground states of neutral atoms are represented as separate chemical species in the mixture. Transitions between excited states, as well as ionization/recombination reactions due to both collisional and radiative processes, are treated as separate chemical reactions. Resonance radiation transport is represented using Holstein escape factors to simulate both the optically thin and optically thick limits. The optically thin calculation showed significant underpopulation of excited species in the upstream part of the jet core, whereas in the optically thick calculation this region remains close to local thermodynamic equilibrium, consistent with previous experimental observations. Resonance radiation absorption is therefore an important effect. The optically thick calculation results also show overpopulations (relative to equilibrium) of excited species and electron densities in the fringes and downstream part of the jet core. In these regions, however, the electrons and ions are essentially in partial local thermodynamic equilibrium with the excited state at the electron temperature, even though the ionized and excited states are no longer in equilibrium with the ground state. Departures from partial local thermodynamic equilibrium are observed in the outer fringes and far downstream part of the jet. These results are interpreted in terms of the local relative time scales for the various physical and chemical processes occurring in the plasma.
DOI
10.1063/1.870905
Persistent Identifier
http://archives.pdx.edu/ds/psu/7723
Citation Details
C.H. Change and J.D. Ramshaw, "Numerical simulation of nonequilibrium effects in an argon plasma jet," Phys. Plasmas 1, 3698 (1994)
Description
This work was authored as part of the Contributor's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
© 1994 AIP Publishing LLC. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Physics of Plasmas and may be found at: http://dx.doi.org/10.1063/1.870905
* At the time of publication John D. Ramshaw was affiliated with the Idaho National Engineering Laboratory