CALCULATION OF NET EMISSION COEFFICIENT OF THERMAL PLASMAS IN MIXTURES OF GAS WITH METALLIC VAPOR

The net emission coefficient of Ar-Cu, N2-CU, SF6-Cu and Ar-Fe mixtures was calculated for homogeneous and isothermal plasmas at atmospheric pressure in the temperature range between 3000 and 25000 K. The increase in power radiated due to the presence of metal vapours depends on the vapour itself (the net emission is higher with iron than with copper) and on the type of gas. The influence of pressure was calculated for the SF6-Cu mixture. In the last part of the paper the values of the net emission coefficient were used to calculate the temperature profile in stationary arc in Ar-Cu and N2-CU mixtures. The influence of copper on radiation is preponderant on the temperature field at higher currents whereas the effect on electrical conductivity is important at lower currents.