A mathematical model of electromagnetic processes occurring in the 'arc column-anode regionevaporating anode' system is suggested. Electric charge transfer processes in the multicomponent plasma of the electric arc and in the bulk of the metallic anode are described using the Ohm's law and charge conservation law generalised for a case of discontinuity of the electric field potential at the boundary between the arc plasma and the anode surface. A procedure was developed for finding the numerical solution of the stated problem by the shock capturing method, allowing modelling of the electromagnetic processes in the 'welding arc-evaporating anode' system in the presence of a reverse potential jump in the anode region (negative anode drop). Results of modelling of the said processes for gas metal arc and plasma transferred arc welding of steel in an inert gas (Ar) atmosphere are given.

Transport properties (thermal conductivity, viscosity, and electrical conductivity) for multicomponent Ar-Fe thermal plasmas at atmospheric pressure have been determined by means of two different methods. The transport coefficients set based on Grad's method is compared with the data obtained when using the Chapman-Enskog's method. Results from both applied methods are in good agreement. It is shown that the Grad method is suitable for the determination of transport properties of the thermal plasmas.

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On the basis of the kinetic theory of fluctuations, the processes of the longitudinal Langmuir wave transformation into a transverse electromagnetic wave in the turbulent inhomogeneous plasma have been studied. The plasma turbulence is assumed to arise owing to the parametric decay of the upper hybrid pump wave into a daughter wave and electron-drift oscillations. The transformation coefficient under the parametric instability saturation conditions is determined. The intensity of the electromagnetic radiation emission from the plasma is calculated, and its dependence on the plasma and pump wave parameters is found.