PLASMA GENERATOR AND METHOD OF GENERATING PLASMA WHICH IS CONTROLLED ACCURATELY

摘要

A plasma generating system comprises a plasma gun (10) including a hollow cylindrical anode member (24D), a hollow cylindrical intermediate member (26) electrically isolated from and juxtaposed coaxially with the anode member to form a plasma-forming gas passage (28) through the intermediate member and the anode member, and an axially movable cathode member (20). The intermediate member comprises tubular segments (24A-C) separated by resilient insulating spacing rings (30A-C) held in compression. Arc radiation is blocked from the spacer rings by meanders (90) in the inter-segment slots and further by ceramic barrier rings. An electric motor or pneumatic piston responsive to a measurement of arc voltage continually adjusts the axial position of the cathode tip relative to the anode nozzle (14) so as to maintain a predetermined arc voltage.