| 摘要 |
An electrode for supporting an arc in a plasma arc torch. The electrode includes a metallic holder having a front end, and a cavity in the front end, the cavity having an enlarged outer end portion. An insert assembly is mounted in the cavity and includes an emissive insert composed of a metallic material having a relatively low work function, a sleeve which substantially surrounds the emissive insert so as to separate the emissive insert from contact with the holder at least at the front end. The sleeve is composed of a metal which is selected from the group consisting of silver, gold, platinum, rhodium, iridium, palladium, nickel, and alloys thereof. The insert assembly further includes an aluminum face plate disposed in the enlarged outer end portion of the cavity and which is exposed at the front end of the metallic holder so as to surround a front portion of the sleeve.
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