Abstract

This paper analyzes the influence of the departure from thermodynamic equilibrium on three spectroscopic methods for determining the excitation temperature: the classical Boltzmann plot method, the method of absolute intensity measurements, and the method of the ratio of atomic to ionic lines for one element. Use of these methods is illustrated with experiments conducted in a helium microwave plasma in nonthermodynamic equilibrium produced by an axial injection torch at atmospheric pressure. The excitation temperature was determined at a variable microwave power and different positions along the flame. The results are discussed in terms of the atomic-state distribution function (ASDF) calculated for the plasma.

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