The volt-ampere charateristics (VAC) of an elecric arc are correlated with longitudinal vortex air and nitrogen flows in plasmatrons with a rod-like cathode and two tubular electrodes. Two types of exponent approximations are used: a simple empirical formula and a relationship between generalized variables. It is shown by methods of regression analysis that the use of generalized variables provides similarity of the VAC upon variations in the gas-flow rate. © 1996 Plenum Publishing Corporation.686758762