A high-speed rotary atomizer for applying powder coating includes a housing to the front end of which a bell disc is rotatably mounted. Bell disc is driven by a motor arranged inside housing. At least one powder supply channel passes through housing, and emerges at the front of housing. This channel contains an acceleration jet in which the coating powder particles are accelerated to a higher velocity which is maintained over at least a certain distance. The increased velocity, preferably supported by acceleration air forming a surface layer, prevents coating powder particles from being deposited on the walls of powder supply channel. In this way an insulating section is formed by which a backflash of the high voltage used to ionise the coating powder particles, from the internal electrode of the high-speed rotary atomizer towards the powder supply, is prevented.