Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
Abstract
A mathematical model is presented for the calculation of the two dimensional temperature fields in an induction-coupled argon plasma torch. The torch has a coaxial cylindrical nozzle for powder feeding. It is assumed that the radial velocity of gas flow is negligible and the axial velocity pattern is two step function of radius. Results were obtained for a plasma torch, 1.4 cm radius and 20 cm long. The oscillator frequency was 4 MH_z. Temperature fields based on the model were calculated for an atmospheric pressure argon plasma at magnetic flux density levels of 53 Gauss with different plasma gas flow rate over the range of 0 to 30 1/min at 0℃. As the nozzle is inserted into the torch, the plasma is cooled in the nozzle region, however, the nozzle does not greatly affect the temperature plofiles in the downstream below the nozzle region. Increasing the radius of the nozzle, firstly, the maximum power input density does not change and power input inside the torch decreases, secondly, maximum power input density is lowered and finally the torch is extinguished
