A plasma gun system comprising: a plasma gun comprising an outlet, wherein the plasma gun is configured to generate a plasma stream and provide the plasma stream to the outlet; and a plasma gun extension assembly configured to be coupled to the plasma gun, wherein the plasma gun extension assembly comprises an extension chamber and a port, the extension chamber having an interior diameter defined by a chamber wall and being configured to receive the plasma stream from the outlet of the plasma gun and to enable the plasma stream to expand upon entering the extension chamber, and the port being configured to introduce a powder to the expanded plasma stream at a location outside of the plasma gun.