A STUDY ON THE TRANSPORT OF VAPOR STREAM AND ARC TEMPERATURE IN THE EXCITATION SOURCE OF THE CUP SOLUTION METHOD

Abstract

The cup electrode solution arc method is a new technique for spectrographic analysis. With this we analysed a variety of slags as well as some steel samples. Fractional distillation is found to be absent. In order to improve the sensitivity and precision of this method the authors studied the transport of the vapor stream and distribution of arc temperature in the light source.To begin with, we found that the arc column consists of two parts: (1) a very bright central column, (2) a moving arc flame around the central part, between the [upper electrodes and the surface of the cup electrode. Experimental results show that the area of contact between the surface of the sample solution and flame determines the intensities of spectral lines. According to the OH rotational band spectra the temperature of the central part of the arc is higher than that of the flame by about 1000°K. In the spectrogram of the flame we could not find any line of the metallic elements besides that of the alkali and alkali earths (Na, K, Ca, Mg). In contrary all the metal spectral lines appeared in the spectrogram of the central column. In the discharge column the intensity of spectral lines is not uniform which is closely related to the variation of arc temperature.It is also found, that the stabilization of the position of arc flame by anexternal magnetic field results more stable volatilization of the sample solutionthus increase of precision could be attained. By focusing the image of the part with maximum intensity on the slit of the spectrograph increases sensitivity in practice.