Spatial distribution of radiation intensity in high-frequency electrodeless discharge lamps

Abstract

The spatial distribution of the intensity of radiation from high-frequency electrodeless discharge lamps of LV-2 and VSB-2 types, used as radiation sources in atomic absorption spectrometry, was investigated. Radiation intensity distributions over the cross section of the lamps were measured on the atomic and ionic lines of a buffer gas and a filler element. It is shown that in a lamp filled with buffer gas only the distribution of the intensity of atomic and ionic lines is dome-shaped, and that it is determined by the electron density distribution in the plasma as well as by the mechanism of excitation and ionization of the buffer gas. The distribution of the intensity of radiation from the filler element is strongly nonuniform, with a maximum that is concentric with the bulb walls and a minimum on the lamp axis. The observed spatial intensity distributions are explained by the redistribution of filler-element atoms over the volume of the lamp under the conditions of high electron concentrations. The time dynamics of the spatial intensity distributions during warm-up of the lamps was investigated. It is shown that the process of establishment of stationary distributions goes on nonmonotonically, which is due to the redistribution of energy among different components of the discharge plasma.