Lowering of the Populations of Excited Hydrogen and Helium Atoms in Plasmas Irradiated by a Laser Beam

Autor:	B. Dubreuil, H. W. Drawin, F. Emard, J. Chapelle
Rok vydání:	1974
Předmět:	Glow discharge Materials science chemistry.chemical_element Laser pumping Photoionization Plasma Condensed Matter Physics Laser law.invention chemistry Physics::Plasma Physics law Excited state Physics::Atomic Physics Irradiation Atomic physics Helium
Zdroj:	Beiträge aus der Plasmaphysik. 14:103-120
ISSN:	1521-3986 0005-8025
DOI:	10.1002/ctpp.19740140402
Popis:	The populations of excited hydrogen and helium atoms in non-L.T.E. plasmas have been calculated for two different physical situations, namely (i) no external radiation field present, and (ii) strong superposed radiation originating from a CO2, Ruby or Argon Ion Laser. The radiation field intervenes in the collisional-radiative model via two new terms: Photoionization and stimulated recombination induced by the Laser radiation field. The solutions of the rate equations yield a lowering of the populations when a plasma is irradiated by a Laser beam. The lowering is different for cold recombining and hot diffusion-dominated plasmas. At high radiation densities a saturation effect occurs, since the photoionization rate becomes equal to the rate of stimulated recombination. Measurements of the populations of excited H and He atoms in a glow discharge irradiated by a CO2 Laser beam of power density 105 W/cm2 are in broad agreement with the theoretical predictions.
Databáze:	OpenAIRE
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