The present study is devoted to the modelling of the arc formation in a direct current plasma gun newly commercialized by Saint-Gobain Coating Solutions (Avignon, France). The CFD computations were performed using the FLUENT code and the electromagnetic coupling was taken into account on the basis of a three dimensional model. The main advances compared to previous works performed on the same subject are numerous. First of all, whereas most of earlier models include the arc region only, the CFD domain was here extended to the gas injection region (i.e. upstream part of the gun, including the gas injection sleeve), thus allowing a better description of the effect of the gas injection on the plasma flow. Second, whereas earlier works include the fluid domain only, the present model includes a fluid/solid coupling in the anode. In particular, the thermal and electromagnetic equations are solved not only in the fluid parts but also in the tungsten and copper parts of the anode. This change was found to be important because the internal surface of the anode is no more a boundary of the domain. Thus, its temperature (and electric potential) becomes variable and is thus not necessarily imposed. Finally, the implemented model provides interesting results describing the arc behaviour inside the plasma gun.

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