The thermodynamic properties and the transport coefficients of thermal plasmas formed in SF6-copper vapour mixtures were calculated as a function of temperature and pressure for molar concentrations of copper between 0 and 10%. The material property that is most affected by the presence of copper is the electrical conductivity for temperatures up to 10000 K. The results given in this paper enabled a data bank to be built up for modelling arcs in SF6 seeded with copper vapour.
An experimental study of the oxygen plasma jet of an OCP 150 cutting torch marketed by Air Liquide is presented. A fast CCD camera is used to visualize the shock wave geometry at the nozzle exit. Optical emission spectroscopy techniques are used to determine the temperature, the electron number density, the pressure and the fraction of nitrogen in the plasma jet between the nozzle exit and the anode. Measurements are performed in a real cutting configuration and compared with the results of a rotating anode device. The influence of several cutting parameters (voltage, torch velocity and plasma producing gas injection pressure) on the macroscopic properties of the arc is dealt with.
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.
Spectroscopic measurements have been made on a transferred arc burning in pure argon at atmospheric pressure seeded with iron vapours arising from the anode erosion. The transferred arc was operated with a current intensity of 90 A, an arc length of 18 mm, and a gas flow rate of 8 l min −1 . Temperature and relative iron concentration profiles determined experimentally were compared to theoretical values obtained from a two-dimensional model based on mass, momentum, and energy conservation equations and taking into account anode erosion. This comparison partially validated the model and showed that the presence of iron vapours, with a relative concentration of about 0.1%, led to a temperature decrease of about 1000 K. Differences between experimental and calculated temperature fields may be due to departures from equilibrium and to uncertainties about the iron vapour concentration and the radiative losses.
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