CALCULATION OF NET EMISSION COEFFICIENT IN N2, SF6 AND SF6-N2 ARC PLASMAS

The net emission coefficient of SF6-N2 mixtures was calculated for temperatures between 8000 and 24 000 K and pressures between 1 and 8 bar. The calculation of the radiative transfer of the lines required a study of line broadening and was performed assuming that line overlapping had a negligible influence. The results show that the resonance lines, although they are strongly absorbed, make up a large part of the net radiation-about as much as the continuum. Also, the nitrogen lines are more strongly absorbed than the lines of sulphur or fluorine. At low temperatures the radiation of SF6 is stronger than that of nitrogen. When T > 12 000 K the net radiation of the mixture is not proportional to the net radiations of the gases owing to variations in emissivity and line broadening with temperature and composition of the mixture.