Three-dimensional Fluid Dynamic Simulation of Radio-frequency Inductively Coupled Thermal Plasmas

This paper presents modelling work and numerical simulations of radio-frequency inductively coupled thermal plasmas (RF-ICTPs) without/with a stationary central injection of a direct-current (DC) plasma jet, which has recently yielded new insights into the three-dimensional structure and dynamics of the plasma flows. The numerical results show that the flows have complicated 3D structures with a noticeable recirculating zone. That recirculating flow prevents the cold sheath gas from flowing downstream through the plasma. The higher-temperature regions in and around the plasma exhibit larger vortex structures principally by the Lorentz force, whereas the lower-temperature flows form smaller eddies by fluid dynamical instability near the top and side walls of the torch. A plasma jet breaks such a structure in the RF coil region, and consequently the flow becomes more complicated. In the RF coil region, the region near the torch wall has a larger standard deviation in the vorticity than the central region