In-situ probing of gas phase nucleation dynamics in yttria-argon plasma system

Theoretical investigation of chemical kinetics in Argon plasma and experimental investigation of chemical kinetics in Ar, Yttria-Argon plasma are presented. Chemical kinetics of plasma species are presented in argon plasma under thermal non-equilibrium parameter (8=Te/Th) ranging from 1 to 20, electron temperature ranging from 0 to 50000K and pressure ranging from 0.1 to 5 Atm. The data will be useful in understanding plasma synthesis processes over wide parametric range. Chemical kinetics behind synthesis of yttria nano-particles in gas phase nucleation process is explored through in-situ emission spectroscopy and high speed camera. It was observed that as soon as precursor is fed to the plasma argon atomic lines disappears and YI, YII, O lines appear. YO band at the nozzle exit was not observed. It starts appearing after 3 cm from the nozzle exit. With increase in distance, the band becomes stronger and stronger up to certain distance and then starts falling. The band is clearly visible up to 6 cm from the nozzle exit. Spectra clearly show one of synthesis mechanism of Y₂O₃ nano powder in a low pressure dc plasma torch system. Image and voltage analysis of the plasma jet show the effect of powder feeding on the plasma jet dynamics. (author)