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Thermal plasma diagnosis by optical molecular spectroscopy

Scientific team : Faure G. , André P., Shkol'nik S.M.*, Barinov S.M.*, Kaplan V.*
* A.F IOFFE Phys. Techn. Inst. Rus. Acad. Sci. - Polytechnicheskaya 26, Petersburg 194021 Russia

In the thermal plasmas studied in the laboratory, molecular spectra (diatomic molecules) and atomic spectra are often observed. To determine some parameters such as internal temperatures (rotational, vibrational temperatures for molecules and atomic excitation temperature), it is necessary to calculate the spectrum to obtain these informations by comparison.

We are able to calculate spectrum of CN, N2,N2+ ,C2 ,NO, OH, CO... molecules.

We calculate spectra taking into account some different parameters :

The composition calculation and the diatomic species calculation spectra form an attractive analysis method of plasma.

Spectra of the ultraviolet system of OH and the second positive system of N2 (Dv=0) in relation to the FWHM. (Trot=Tvib=Texc=2500K , [OH]=10E24m³ , [N2]=10E22m³ ).

Spectra of the ultraviolet system of OH and the second positive system of N2 (Dv=0) in relation to the heavy translational temperature ([OH] = 10E24m³ [N2] =10E20m³ ,LMH=0.17nm, θ=3, vib=1).

Application: The discharge with liquid non-metallic electrodes in air at atmospheric pressure

This study is made in collaboration with Sergey Shkol'nik's team. The experiment has been built at St-Petersburg. Many investigations in this discharge are made : electric probe, microwave absorption and optical emission spectroscopy measurements.

Schema of the cross-section of the discharge with liquid non-metallic electrodes: 1 metal connectors, 2 - ceramic walls, 3 - tap-water streams (electrodes), 4 - discharge plasma : a - near-cathode region, b - discharge column, c - near-anode region.

Axial distributions of rotational and vibrational temperatures determined from the second positive system of N2 (sequence -2).

Application: Detection of pollutants

Creation Elforia Design