Plasma spray apparatus for spraying powdery or gaseous material

A plasma spray apparatus for spraying powdery or gaseous material, comprising:

• an plasmatron adapted to create an elongated plasma torch;
• means for axially feeding said powdery or gaseous material into said plasma torch;
• said plasmatron comprising a cathode assembly, an annular anode member located distantly from said cathode assembly and a plasma channel extending from said cathode assembly to said anode member;
• said plasma channel being delimited by said annular anode member as well as by a plurality of annular neutrode members which are electrically insulated from each other;
• said plasma channel having a zone with a reduced diameter located in that region of said plasma torch which is near to said cathode assembly and thereby forming a plasma channel inlet nozzle;
• said cathode assembly comprising a central electrically insulating member arranged in a fixed position with regard to said plasma channel inlet nozzle and further comprising a plurality of cathode elements embedded in said insulating member, said cathode elements being located and evenly distributed along the periphery of a circle around a central axis of the apparatus;
• each of said cathode elements comprising a cathode pin having an active end on which the plasma torch is created and which extends out of said insulating member into said plasma channel inlet nozzle;
• and
• said means for axially feeding said powdery or gaseous material into said plasma torch comprising a supply tube for the supply of powdery or gaseous spray material into said plasma channel inlet nozzle, said supply tube being located coaxially to said central axis of the apparatus and being fixed in said central insulating member.