Abstract
A theoretical investigation is made into the recombination of a thermally heated plasma of a monatomic gas which undergoes gas-dynamic cooling in a supersonic nozzle. A method of approximate analytic calculation makes it possible to determine the necessary conditions for the existence of an effective recombination regime of the flow out of the nozzle that makes possible population inversion of the excited electronic levels of the atom. The conditions of occurrence of inversion are studied as functions of the parameters characterizing the state of the plasma in the reservoir in front of the entrance to the nozzle, the shape of size of the nozzle, and the working substance. Use of the method of blocks of levels made it possible to calculate the degree of expansion needed for the formation of inversion between transitions with different wavelengths, and also to estimate the gain and the specific radiation energy in these transitions. Numerical estimates of the values of the parameters for the case of an argon plasma are given.
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Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 91–97, November–December, 1979.
We thank S. A. Losev for discussing the results and for helpful comments.
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Smekhov, G.D., Fotiev, V.A. On the conditions of formation of population inversion of atomic levels in a thermally heated recombining plasma. Fluid Dyn 14, 885–890 (1979). https://doi.org/10.1007/BF01051992
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DOI: https://doi.org/10.1007/BF01051992