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A numerical simulation of a technical radio frequency inductively coupled plasma was made with three coils and coupled power in the range of 2-10 kW. The generator frequency varied from 1.76 to 13.56 MHz. The mechanisms of forming a vortex on the upstream side of the discharge and the influences of coupled power, generator frequency and flow rate of central gas on the vortex dimensions were studied. Special attention was paid to investigate two different kinds of vortex flow pattern-Benard and toroidal-as well as the vortex intensity under those two kinds of flow pattern. A critical flow rate of central gas, above which the flow pattern would transform from a Benard to a toroidal vortex, was found on the basis of force balance between the dynamic head of central cool gas and magneto-hydrodynamic and Stokes drag forces of plasma. The influences of coupled power, generator frequency, diameter of the injection probe and the compositions of central gas on the critical flow rate of the central gas were discussed. The dependences of the vortex intensity and maximum vorticity on the coupled power under different generator frequencies and flow rates of central gas were established.

Numerical simulation of turbulent mixing process of polydisperse quartz particle (particle size distribution in the range of 0.1-0.4 mm) flow with Ar and Ar-H 2 plasma generated by radio frequency inductively coupled plasma (RF-ICP) torch has been made. An approximate two-stage approach has been proposed to calculate the spatial-temporal distributions of temperature and resulting thermal stress in quartz particles during dynamic heating in polydisperse plasma flow. The influence of working gas compositions, particle size distributions, injection angle and flow rate of carrier gas on the thermal destruction conditions of quartz particles has been determined under different particle feed rates. It is found that all the solid quartz particles (0.1-0.4 mm) could be thermal destructed without overheating in RF-ICP torch system, when the hydrogen volume fraction in working gases is more than 1.5%-2% and particle feed rate is in a certain range. The values of the maximum and minimum feed rates have been determined under different hydrogen volume fractions. An optimal particle injection angle and flow rate of carrier gas is found around 50°-60°and 160-220 slpm, under which the value of maximum equivalent thermal stress in quartz particles is highest.

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