| 摘要 |
PURPOSE:To obtain the plasma jet of weak power without deteriorating a cooling action, by providing a first gas hole and a second gas hole on the center and the side face, respectively, of a nozzle electrode which confronts the tip of a bar electrode, and making the total cross-sectional area of the second gas hole larger than the cross- sectional area of the first gas hole. CONSTITUTION:A cathode 12 being excellent in an electron radiation is embedded in the tip part of a bar electrode 11 and an electron radiation surface is formed. On the tip center part of a nozzle electrode 13, the first gas hole 14 is provided, and on the side face, plural second holes 15 are provided. Also, the total cross-section area of the second gas holes 15 is made larger than that of the first gas hole 14. Accordingly, working gas 21 supplied to a cathode conduit 16 cools the cathode conduit 16 and other parts, thereafter, passes through an orifice 17 and goes into the inside of the nozzle electrode 13, and discharged to the outside through the first gas hole 14 and the second gas hole 15. An arc generated between the bar electrode 11 and the nozzle electrode 13 passes through the first gas hole 14 and jets out as a plasma jet. In this case, gas passing through the first gas hole 14 becomes the plasma gas flow of a small flow rate, and the plasma jet of a weak power is obtained. On the other hand, gas passing through the second gas hole 15 becomes a side gas flow.
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