The residence time of the particles in reactive thermal plasma governs mechanisms occuring at high temperature, (solid → liquid, liquid → vapor and oxydation Sil + Og→ Si Og ). The goal is to control the process of particles purification with a partial evaporation in order to have a good yield of manufacture of ultra-pure silicon. In this study, it is evaluated from L.D.A. measurements, which provide the particle velocity.
Experimental measurements by optical Emission Spectroscopy (O.E.S.), confirm the gas temperature range surrounding the particle, down stream all along the 30 cm trajectories. The most remarkable result of particle velocity obtained from L.D.A. measurements on one hand, and particle velocity obtained from modeling calculation and ab-initio numerical calculation on the other hand are in a good fitting, which confirm particles residence time τ Part. along 30 cm trajectory.