The electric field and voltage of dc tungsten-inert gas arcs and their role in the bidirectional plasma-electrode interaction

Abstract

Abstract Electrical measurements and numerical modelling of dc tungsten-inert gas arcs are carried out in order to determine the electric field and the voltage, and to study their importance to the plasma-electrode interaction. The configuration under consideration is very typical for tungsten-inert gas welding processes and includes a conically shaped cathode made of doped tungsten and atmospheric pressure argon as a shielding gas. The studies analyze the effects of the inter-electrode distance and the electric current over wide ranges of variation—currents from below 10 A up to 200 A, and distances from 20 mm down to 2 mm in the modelling and to the short-circuit in the experiment. The comparison of the experimentally obtained and the computed current–voltage and arc length-voltage characteristics clearly prove the predictive capability of the advanced non-equilibrium model of the arc and the electrodes. Moreover, the self-consistent model yields the structure of the electric potential and the electric field and is capable of describing the peculiarities of the plasma-electrode interaction.