Using a transferred arc burning in argon at atmospheric pressure, emission spectroscopy measurements have been performed to determine the temperature field in the plasma column. The transferred arc was operated with a current intensity of 90 A, two arc lengths of 11 mm and 18 mm and a gas flow rate of 8 slpm. In the area near the anode, it was found that copper vapour arising from the anode may have a significant influence on the plasma temperature distribution. The presence of copper vapour with a relative concentration lower than 1% led to a temperature decrease of the order of 2000 K.

The interaction between a metallic plasma produced by laser ablation and an ambient gas (argon, air and nitrogen) at atmospheric pressure is studied. The experimental results are compared with theoretical ones given by numerical simulation. Aluminium and copper targets are used. The uniform repartition of iron impurities included in the target (1.6% for Al and 2% for Cu) is warranted by the manufacturer. The Nd : YAG laser delivers pulses of 8 ns FWHM duration with an energy ranging from 70 to 100 mJ at a rate of 10 Hz. The temperature measurements have been performed by the Boltzmann diagram method using iron lines. The influence of ambient gas and target material is studied. After an Abel transform, we observe a maximum of the line intensities off the plasma axis. This shows the formation of gas plasma around the metallic one before complete diffusion of the ambient gas in the metallic plasma. The hydrodynamic model built in one dimension uses the continuity equations. This code is based on the control volume method of Patankar. A temperature and mass fraction profiles are needed as initial conditions. This model is able to describe the temporal evolution of the temperature and of the diffusion in the plasma. It allows us to study the mixture of the metallic plasma and the ambient gas as soon as the plasma is thermalized and local thermodynamic equilibrium is established. There is good agreement between the results of the simulation and the experimental results.

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Using the method ofChapman and Enskog, the transport coefficients of a copper-nitrogen mixture at atmospheric pressure were calculated. With the most appropriate methods the authors determined the cross-sections of collisions between copper and the othe r particles. The results obtained show that at low temperatures (5000K