To ensure the more efficient utilization of the plume thermal energy does not represent a simple task because the most thermal plasma jets are neither laminar nor fully turbulent, they are usually transitional.
During the plume laminar-turbulent transition there appear some violent thermal energy transport metamorphoses. A detailed analysis suggests that they are controlled by distinct resonance processes determined by simultaneous wave events produced by the plume mixing layer and plume core instabilities. The consecutive energy transport changes are the products of different energy exchange between them. The limits (maximum and minimum plume heat input, maximum average exit enthalpy), are the results of complete changes in the character of the wave energy distribution. Protruding into the arc chamber cavity, the resonant wave processes control the heat transfer there, too. Thus, in principle, the shear layer instability plays the crucial role not only in plume thermal energy transport but also in thermal energy generation itself.