Possibilities of applying plasma technologies for processing organic-containing substances: the effect of the shape of the voltage curve on the working mode of the plasma torch

The features of alternating current plasma torches with rod electrodes and the phenomena and regularities observed during their work in a wide power range of $0.1$–$7$ MW have been considered. The mechanism of the reignition of the arc in the single-phase and three-phase working modes of a plasma torch has been studied. The characteristic differences of these processes, the existence of which is explained by the conservation of the concentration of current carriers in the interelectrode gap in the three-phase mode, have been given. It was shown that the reignition voltage varies in accordance with the variation of the temperature of the electrode surface, and the electrode temperature saturated with the increase in the current and the reignition voltage is constant. Particular attention is paid to analysis of the external characteristics of plasma torches in different working modes when using nitrogen, hydrogen, or argon as the working gas. The effect of the physical parameters of plasma on the shape of the voltage curves and volt–ampere characteristics of arcs has been considered, and the dependence of the energy parameters of plasma torches on them has been described.