An Official Journal of the American Society of Thermal and Fluids Engineers

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EXPRESS ANALYSIS OF PARAMETERS OF HIGH ENTHALPY PLASMA JETS

ABSTRACT

This paper reports on current approach to optically determining basic parameters of energetic atomic and molecular plasma jets generated by powerful electric arc plasmatrons. The emission spectra are taken in the 200−1000 nm range with a spectral resolution of ∼ 0.01−0.02 nm. The exposure times are 6·10⁻⁶−2·10⁻² s and the spatial resolution is 0.02−0.03 mm. The spectra obtained show hundreds of atomic and ion lines and tens of molecular bands. To interpret and process these spectra a purpose-developed automated processing system is applied. The use of a CCD camera at the spectrograph output allows a simultaneous recording of the spectral and chord intensity distributions of spectral lines, which can yet belong to the overlapped spectra of the first and second orders of interference. The employed modern optical diagnostic means and methods permit determination of spatial distributions of electron number densities and temperatures and evaluation of rotational temperatures. The radial profiles of the irradiating plasma components can also be obtained. Special attention is given to the method of deriving rotational temperatures using the vibronic bands with an incompletely identified rotational structure.