The Emission Coefficient of the Continuum in an Argon and Nitrogen Plasma at High Temperatures

Abstract

The continuum emission of an argon-and nitrogen plasma developed in an electrical discharge has been investigated in the wavelength range from 3000 Å to 6700 Å. To this purpose the time-and radial dependent plasma parameters such as temperature and the total pressure have been determined in the high conducting stage of the spark by measuring several line intensities. The continuum coefficient was calculated from these data according to the Kramers-Unsöld theory. The comparison of the theoretical and the measured values shows deviations which are discussed. In the case of the argon continuum the ξ-factors for T = 14 000 K agree with the calculated values of Schlüter and the experimental ones of Schulz-Gulde. In the case of the nitrogen plasma the ξ-fac­tors have been determined in the temperature interval from 18 000 K to 45 000 K. Since at these temperatures the particles NII-NIV contribute to the total continuum coefficient, the measured ξ-factors can only be correlated to ξII, ξIII, ... in a narrow temperature range. The measured cor­rection factor ξ for λ = 5050 Å has been applied to determine the temperatures and the pressure of a laser produced spark. The plasma parameters agree with those determined by measuring the line-intensity of the NII-line at 5000 A.