The plasma spray gun is a part of thermal spray coating system called plasma spray process. The flexibility of the plasma spray process comes from its ability to develop sufficient energy to melt almost any coating feedstock material in powder form and the plasma spray gun plays a vital part in that. The plasma spray gun utilizes a chamber with one or more cathodes (electrodes) and an anode (nozzle). With process gases flowing through the chamber, direct current power is applied to the cathode, which arcs to the anode. The powerful arc strips the gas molecules of their electrons to form a plasma plume. As the unstable plasma ions recombine back to the gaseous state, a tremendous level of thermal energy is released. The feedstock material is injected into the hot gas plume, where it is melted and propelled towards the target substrate to form the coating.
The distance of the plasma spray gun from the target components, the relative motion of the spray gun and target component to each other, as well as part cooling — usually as air jets focused on the target substrate —keep the substrate at a controlled temperature in the range of 38 °C to 260 °C (100 °F to 500 °F).