Collisional cooling in an inductively coupled plasma torch

Author(s): A.Khalili, S.M.Sadat Kiai, H.Mahdian

The paper presents a simulated model of inductively coupled plasma torches using a numerical code developed in FlexPDE environment. The EMfields, temperature and fluid flow are calculated numerically in a two-dimensional geometry for typical ICP torch. The model is within the assumptions of laminar flow, optically thin plasma and local thermodynamic equilibrium (LTE), negligible viscous dissipation and 2D axisymmetric geometry. This yields a mathematical and virtual tool for predicting the torch performance before running. The main factor in plasma behavior, working gas, is studied in this paper. Various amounts of Helium, Krypton and Xenon are included in the primary Argon gas. The obtained results show a cooling effect in plasma, as a result of collisions, via buffer gas effectively by Krypton and Xenon compared to the Argon case which is taken to be reference case here. There were no signs of heating inside the plasma. Axial velocity of particles is increased byHeliumwith amounts ofmore than%0.02 and generally is decreased by Krypton and Xenon different values. The most striking effect observed in this study was elimination of circulating flows (negative axial velocity) inside the torch which would be energy dissipating. The results for gas additive in pure Argon are reported firstly. The importance of the present work would be enabling us to tune and adjust the plasma instability for operation improvements.

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