Theoretical and experimental study of an argon free burning arc dicharge at very high-pressure and low-intensity

This paper deals to study a low current intensity, very high-pressure (PGt105 Pa) free-burning argon arc discharge in a tip-tip configuration. A 2D axisymmetric two-temperature fluids model has been developed. The model contains three chemical species (e, Ar, Ar⁺), the appropriated thermodynamics and transport properties expressed as a function of electron and heavy temperatures and pressure, and the electrodes sheath submodel. Theoretical results were compared with experimental data obtained under pressure comprised between 0,1 to 10 MPa and 0.1 to 500 mA. Highest voltages are obtained at very high pressures and low current intensities. Theoretical model indicates that pressure increment causes an arc diameter reduction. This is due to the augmentation of radial heat losses by natural convection at arc fringes and by conduction due to a better energy transfer by neutral- electrons collisions. Surprisingly, the very high-pressure conditions seems having a stabilizing effect on the arc discharge.