A three-dimensional investigation of the effects of excitation frequency and sheath gas mixing in an atmospheric-pressure inductively coupled plasma system

V Colombo (1) , E Ghedini (1) , P Sanibondi (1)

1 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna

A three dimensional numerical model for the simulation of the behavior of a commercial inductively coupled plasma (ICP) torch with non-axisymmetric reaction chamber has been developed, taking in account turbulence and gas mixing through RNG k-? theory and the combined diffusion approach of Murphy, respectively. The effects of changing coil current frequency, the hydrogen mixing in an argon primary gas and the flow patterns and temperature distributions which take place in a reaction chamber with a lateral gas outlet system and two observation windows have been investigated, with the final aim of setting up a computational tool able to predict the main features of plasma assisted treating and processing of injected raw materials. Three-dimensional shapes of the temperature, velocity and mass fraction fields have been obtained and analyzed for an Ar-H 2 mixture at atmospheric pressure. Computations have been performed with two different coil current frequencies, i.e. 3 MHz and 13.56 MHz, showing that for the lower value the 3-D effects in the discharge are enhanced. Accurate mixing and demixing mechanisms have been investigated in both cases, including considerations on the relative importance of different thermal diffusion contributions due to mole fraction and temperature gradients. Temperature distributions in the reaction chamber for different cases have been correlated to different flow patterns and recirculation flows which take place as a consequence of the non-axisymmetry of the reaction chamber.

Mots clés: Physical Sciences

V Colombo, E Ghedini, P Sanibondi. A three-dimensional investigation of the effects of excitation frequency and sheath gas mixing in an atmospheric-pressure inductively coupled plasma system. Journal of Physics D: Applied Physics, 2010, 43 (10), pp.105202. ⟨10.1088/0022-3727/43/10/105202⟩. ⟨hal-00629942⟩