Patent ID: 6066827
Filing Date: 2000-05-23
Classification: B23K,H05H

Abstract:
An emissive element for supporting an electric arc in a plasma arc torch using an oxygen gas to create the plasma, said element comprising:a body having a front face for supporting the electric arc, said front face being defined by at least two distinct components formed from different materials, said materials comprising:an emissive material having a low work function for readily emitting electrons in support of the arc and being reactive with the oxygen plasma gas to form an oxide during an operation of the torch, said oxide forming an electrically resistive layer on the front face of the body upon cooling subsequent to the operation of the torch; anda conductive metal material having an electrical conductivity greater than the oxide layer for supporting the arc during the initiation of a subsequent torch operation at least until the oxide reaches an operating temperature, the conductive material being disposed on the front face of the body in a predetermined pattern defining a path from a periphery of the front face toward a central region thereof.