| 摘要 |
PURPOSE:To generate the plasma easily, by positioning a shield plate between a high-frequency induction coil and a plasma torch, connecting the shield plate to the earth potential through a switch, generating a high-frequency induction coupling plasma in the condition that the switch is turned off, and turning on the switch after the plasma is generated. CONSTITUTION:When a switch 9 is turned off, argon gas is let flow in a plasma torch 1, and a high-frequency current is fed in a coil 2 to form a high-frequency magnetic field, a plasma 4 is generated easily and instantly. This is because the switch 9 is turned off, and the capacity coupling between the coil 2 and the plasma 4 is made larger. Since the plasma 4 has a specific high-frequency potential, a shield plate main 7a is connected to an earth 8 when the switch 9 is turned on, and the whole body of the shield plate 7 is made to have the earth potential. As a result, the shielding effect by the shield plate 7 is improved, and the capacity coupling of the coil 2 and the plasma 4 is made into the minimum. Therefore, the shielding is made rigid and the plasma is generated easily.
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