Spatial and time-dependent distribution of plasma parameters in the metal-halide arc lamp

Abstract

It was shown by several authors that closed high pressure arc a.c. discharge in mercury vapors with addition of metal halide cannot be described in frames of the local thermodynamic equilibrium (LTE) model. However some plasma parameters (electron and high lying excited states densities as well as Hg metastable levels densities) are assumed to be in equilibrium with electron temperature and these assumptions are applied in plasma diagnostics. To verify these supposition the method of local plasma spectroscopy based on spatial and temporal distribution of spectral line profiles was developed. The experimental set up is based on diffraction spectrometer with large aperture, spatial scanning device and photodetector, which allows to carry out the measurements in chosen phases of current period. The software for data acquisition and processing is based on LabVIEW system. The original method of joint data processing was applied to data arrays containing spatial, spectral and temporal distribution of a source surface radiance. The method is based on principal component theory, it takes into account the correlation between spectral emissivities inside spectral line profiles and allows ...