VELOCITY-MEASUREMENTS FOR ARC JETS PRODUCED BY A DC PLASMA SPRAY TORCH

An optical method was used to determine the axial velocity of plasma j ets produced by a DC plasma spray torch. Different experimental condit ions were tested in order to systemically study the influence of the w orking parameters on the plasma velocity. In this way, the are current ranged between 200 and 600 A, the gas flow rate between 30 and 80 slm , and the internal nozzle diameter between 6 and 10 mm, the plasma gas es were either an Ar-H-2 mixture or N-2. Rather well defined tendencie s were observed and at the same time it appeared that the are stabilit y greatly influenced the fluctuations of the velocity.