Electrothermal ef???ciency, temperature and thermal conductivity of plasma jet in a DC plasma spray torch

摘要

A study was made to evaluate the electrothermal ef???ciency of a DC arc plasma torch and temperature and thermal conductivity of plasma jet in the torch. The torch was operated at power levels from 4 to 20 kW in non-transferred arc mode. The effect of nitrogen in combination with argon as plasma gas on the above properties was investigated. Calculations were made from experimental data. The electrothermal ef???ciency increased signi???cantly with increase in nitrogen content. The plasma jet temperature and thermal conductivity exhibited a decrease with increase in nitrogen content. The experiment was done at different total gas ???ow rates. The results are explained on the basis of dissociation energy of nitrogen molecules and plasma jet energy loss to the cathode, anode and the walls of the torch.