Characterization of the acoustic behavior of an argon plasma torch

We measured the acoustic Frequencies emitted by an argon plasma torch. At constant intensity, acting on the anode - cathode distance, indirectly monitored the are voltage. The results on the evolution of the observed acoustic frequencies suggest that their position is mainly a function of the are temperature. The poorness of the are temperature estimation from enthalpy balance does not allow to ascertain that it is the case. Direct measurements on the are column must be performed to demonstrate this hypothesis.