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Collisional-radiative model and Saha decrements for a nonequilibrium oxygen plasma. Memorandum report

Technical Report ·
OSTI ID:5319607

When air is heated and becomes highly ionized, the primary constituents consist of nitrogen, oxygen, and their ions. Emissions from this plasma provide diagnostic information as well as contribute to cooling the plasma. To describe such a plasma under nonequilibrium conditions one must known the population densities of various excited states. Using a time-dependent approach, a collisional-radiative model is developed for an oxygen plasma. Effective recombination and ionization coefficients are calculated for two specific cases, optically thin and optically thick in bound-bound uv radiation. The steady-state population densities for neutral and ionic states are presented in terms of their deviations from Saha equilibrium predictions. These results show the approach of the plasma to a state of local thermodynamic equilibrium (LTE) as a function of electron temperatures between 1.0 and 3.0 eV and electron densities between 10/sup 16/ and 10/sup 19//cc.

Research Organization:
Naval Research Lab., Washington, DC (USA)
OSTI ID:
5319607
Report Number(s):
AD-A-168082/6/XAB; NRL-MR-5792
Country of Publication:
United States
Language:
English