3-D MODELING OF ICP TORCHES

A three-dimensional model for the simulation of inductively coupled plasma torches (ICPTs) working at atmospheric pressure has been developed, using customized CFD commercial code FLUENT©. The helicoidal coil is taken into account in its actual 3-D shape, showing its effects on the plasma discharge for various geometric, electric and operating conditions. The electromagnetic equations are solved in their vector potential form, while the steady flow and energy equations are solved for optically thin plasmas under the assumptions of LTE and laminar flow; some of the results that will be presented have been obtained by means of an improved turbulent version of the 3-D model. Simulations are performed over a network cluster of double processor calculators in order to use the full capabilities of the 3-D modelling to describe the gas injection section of an industrial TEKNA PL-35 plasma torch without geometry simplifications, in order to perform a more realistic simulation of the inlet region of the discharge. In order to evaluate the importance of various 3-D effects on calculated plasma temperature and flow fields, our new results have been tested against the ones obtainable from 2-D models and from improved 2-D model that includes 3-D coil effects. Three-dimensional results concerning different operating conditions are presented, together with simulations of the trajectory and heating history of powders injected in the torch through a carrier gas.