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.

The partial Characteristics of the radiation which correspond to partial sources and partial sinks of radiation along a given direction, were calculated for a SF, arc plasma between 3 000 and 30000 K. These partial characteristics allow rapid calculation of the 3 D radiative transfer in this type of plasma. The method was applied to several simple cases and showed the validity limits of the use of a net emission coefficient in the modelling of the arcs. It was shown that, to calculate the radiative transfer and the temperature in the hot regions, the use of a net emission coefficient is valid when the plasma is approximately isothermal. In the case of strong temperature gradients in the hot regions, the net emission coefficient depends strongly on the chosen plasma thickness whose value is difficult to estimate.

The radiative transfer in SF6 and SF6-Cu arcs was calculated using the method of partial characteristics. The partial sources and sinks of radiation were tabulated for a temperature range 300-30 000 K and a pressure range 0.1-1 MPa. The method was applied to one- and three-dimensional calculations of radiative transfer and in arc plasma models. In circuit breakers, radiation absorption increases the upstream pressure either by direct heating or by accentuating the clogging effect in the nozzle throat.