Mesure de la Temperature Basees sur l'Observation du Premier Systéme Negatif de l'Azote

H. Nassar et A. Czernichowski Groupe de Recherches sur l'Energétique des Milieux Ionisés, Université d'Orléans, BP 6759, 45067 Orléans cedex 2, France

Received: August 15, 1992; in final form: May 18, 1993

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TEMPERATURE MEASUREMENTS BASED ON THE FIRST NEGATIVE SPECTRUM OF NITROGEN: Noisy, non-resolved emission spectra of the (0,0) 391.4 nm N2+ molecular band are employed for the rotational (and in some case vibrational) temperature evaluation in different sources in the range of 320-7900 K when the apparatus function of the recording system is unknown. The following sources are examined: an ovoid-shaped transferred arc at atmospheric pressure, a low-pressure transferred arc, a high-voltage high-pressure electric discharge, a low-pressure radio-frequency discharge, and an atmospheric pressure laminar plasma jet. The described method is based on a normalization of the experimental spectrum with respect to the (0,0) band-head amplitude followed by a point-to-point comparison of the real spectrum with respect to a computer simulated spectrum using the best-square fit criterion. This criterion is found as the good one: the relative error on temperature evaluation had the same order of magnitude as the noise-to-signal ratio, even if the last one was relatively high. It was also found that the rotational and vibrational temperatures in the radio-frequency discharge are very different, which indicates an out of thermodynamic equilibrium characteristic of such a discharge. The proposed method of temperature evaluation is shown as quite precise and simple to use for even the non-spectroscopists.

DOI: 10.12693/APhysPolA.84.215 PACS numbers: 33.10.-n, 33.20.-t, 07.20.Ka, 78.40.-q