Capturing the Influence of Jet Fluctuations on Particles in Plasma Spraying

Instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affect the properties of plasma sprayed coatings. Presented in this paper is a novel method for capturing the effects, particles are exposed to in the plasma spraying process. High-speed camera images of a plasma jet generated by a cascaded three cathode plasma generator (TriplexPro-210) are recorded for varying operating conditions. The images are processed using the Abel transform. This transformation accounts for the fact that the images represent a 2-D projection and generates correct intensity values of the plasma jet images. These images are then combined with particle tracks resulting from CFD simulations of the plasma free jet to match the particles path with the recorded plasma jet. This new method allows a precise description of the plasma intensity experienced by individual particles with a high temporal resolution. The results show a high sensitivity of the method, which can even detect the influence of the plasma jet originating from the cascaded three cathode plasma generator, which is considered as rather stable, on the particles.