Supersonic plasma spray gun

The invention discloses a supersonic plasma spray gun. The supersonic plasma spray gun comprises an insulating gun body, an anode nozzle which is coaxially and fixedly connected with the insulating gun body, and a cathode which is arranged in the insulating gun body and the anode nozzle, wherein the front end of the cathode is a round table; a nozzle air current channel of the anode nozzle consists of a straight channel segment which is in size fitting with a gun body air current channel of the insulating gun body, and a Laval nozzle channel segment; the front end of the cathode is positioned in the straight channel segment of the anode nozzle; and the contraction segment of the Laval nozzle channel segment is matched with the round table shape of the front end of the cathode. Both the anode nozzle and the cathode adopt special structural designs, so that an ultrasonic plasma jet speed (Ma is greater than 2.2) can be obtained at the power of less than 30KW. The nozzle and electrodes of the spray gun have long service lives; the jet flow is stable; and the cost is low.