Radiative Characteristics in Radial Directions of Micro-air Plasma-jets at an Atmospheric Pressure

Spectroscopic measurements of micro-air plasma-jets were performed at an atmospheric pressure in the wavelength region of 280 to 420 nm where N+21-and N22+ bands were predominant. The spectra were measured at many radial and axial points to obtain its radiative characteristics in detail. Abel inversion method was applied to all the experimental data measured laterally to obtain true spectral intensity distribution at all radial points. The comparison of the experimental and Abel-inverted spectra showed that the experimental data could not be used directly to deduce temperatures without the Abel inversion except around the flow axis. Temperatures of the plasma-jets were estimated by applying the spectral matching method to N+21-bands. Rotational temperature for N+21-bands was about 8000 K, and was almost independent of radial positions. Vibrational temperature was about 28000 K in the core region with much higher in the outermost region.