Modeling and spectroscopic investigations on the evaporation of zirconia in a thermal rf plasma

The evaporation process of zirconia powders injected in a thermal rf plasma is investigated. Both model calculations and optical emission spectroscopy are used to study the evaporation behavior. Gas temperatures and velocity distributions are determined numerically from conservation laws and Maxwell equations. The influence of plasma and particle parameters on the thermal history of entrained particles is discussed. Asymmetric Abel inversion is a pplied to detect asymmetric emission profiles in the plasma source. Spectro scopic measurements reveal that evaporated zirconium is concentrated near t he axis of the plasma. Numerical calculations show that line-integrated emi ssion profiles can be used to distinguish the cases of complete and incompl ete evaporation. Axial emission profiles confirm that the evaporation zone is shifted upstream of the plasma when smaller precursor particles are used .