Rotational Distribution of Oh Molecules in Supersonic Thermal Plasma Jet

Supersonic thermal plasma jet generated by DC plasma torch is studied by means of optical emission spectroscopy. Spectra of OH molecules are used to determine rotational temperature in different axial and radial positions of the jet. Comparison with excitation and ionization temperatures calculated from argon spectral lines is included. In the hot part of the jet rotational temperature reflects kinetic temperature, while in the outer parts of the jet non-thermal effects play significant role in populating excited states of OH molecule.