Mass and energy transfer between a confined plasma jet and a gaseous coolant

Abstract

Mass and energy transfer between confined plasma and coolant gas streams was studied experimentally. Argon was used as the plasma gas and nitrogen was used as the coolant gas. The temperature profiles present in the mixing region were determined by optical-spectrographic methods. Both the electronic excitation temperature of the argon atoms and the rotational temperatures of the nitrogen molecules were determined. The compositions and axial velocities present in the plasma coolant mixing region were determined by sampling probe methods. The measured nitrogen temperatures were found to be much lower than the argon temperatures present at the same point in the flow. The difference could be explained on the basis of incomplete mixing and thermal equilibration on the microscopic scale. The composition profiles indicated that direct induction of coolant into the high-velocity plasma jet and the formation of a recirculation eddy increased the mixing of plasma and coolant. From the standpoint of carrying out a chemical reaction in the plasma jet, the results indicate that the mixing of a reactant injected into a plasma jet reaction chamber with the plasma would be very rapid but that the internal energy modes of the reactant molecule might not be fully excited during the short residence time in the high-velocity flow.