Short Live Afterglow in Pure Nitrogen and Nitrogen Containing Traces of Methane and Oxygen

abstract

English

The work presents results obtained during spectroscopic observations of DC flowing post-discharges of pure nitrogen plasma and nitrogen plasma containing traces of oxygen and methane. The plasma has been studied by the emission spectroscopy of three nitrogen spectral systems, NO-beta bands (with oxygen impurities) and two CN spectral systems (when methane was added). The maximum of the pink afterglow intensity of nitrogen 1st positive system decreased more or less exponentially with increasing the oxygen concentration. The position of the maximal pink afterglow emission was shifted to shorter decay times but both nitrogen positive systems showed a slow increase of the decay time of pink afterglow maximum after the initial shift to the earlier post-discharge position. Intensities of both nitrogen positive systems didn't show any significant dependence on the oxygen concentration. The NO-beta bands were observed with low intensity and their intensities were directly proportional to the oxygen concentration. The maxima of the pink afterglow intensities for all three nitrogen systems were decreasing proportionally to the increase of the methane concentration. The position of the maximal pink afterglow emission was also more or less linearly shifted to later decay times, it means on the contrary to the oxygen impurity. The strong CN emission is dominant at methane concentrations beyond 7 ppm and its intensity was more or less directly proportional to the methane concentration in the studied range. On the basis of the experimental results, the appropriate kinetic models of the plasma generated in pure nitrogen and in nitrogen with oxygen or methane traces were designed. The specific state-to-state energy transfer reactions between the studied states are presented.

KRČMA, F.; MAZÁNKOVÁ, V.; SOURAL, I.

22. 8. 2006

Beograd University

Beograd

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