NUMERICAL STUDY OF HIGH-INTENSITY FREE-BURNING ARC

The behavior of a free-burning argon are including the cathode region is investigated from a theoretical perspective. Two-dimensional differ ential equations describing the conservation of mass, momentum, energy , and electrical current density are solved together with Ohm's law an d Maxwell's equation for the magnetic field in a cylindrical coordinat e system using an iterative finite volume method. Recent data of the r adiative losses from an argon plasma in the form of net emission coeff icients are used. Simulations are made at various electrical currents for different electrode gaps. Predicted isotherms of the are are in fa ir agreement with existing experimental results. Particularly, reasona ble profiles of current density at a plane beneath the cathode tip are predicted, even though nonequilibrium behavior in the cathode sheath is neglected. Comparisons of the present current density profile with reported results are made. In addition, the effect of the length scale required in the use of net emission coefficients to model the radiati ve characteristics of the are is studied.