| 摘要 |
PURPOSE:To attain to prolong the life of a power source circuit by lowering the impedance mismatching of a power source and load, by providing a heat resistant conductor in the coupling coil of a plasma torch in a freely accessible manner. CONSTITUTION:A heat resistant conductor 5 comprising a carbon ring is held to the lower end of a stainless rod 6 and made up and down slidable and rotatable. The drawing shows the preparatory state of a plasma ignition wherein the conductor 5 is present at the induction coupling position with a coupling coil L and, in this state, when a predetermined amount of argon gas is supplied to the triple pipe T1-T3 of a plasma torch 2 and a high frequency power source 1 is operated, an induced current is flowed to the conductor 5 which, in turn, becomes while-hot to form arc discharge and, when the conductor 5 is drawn up, a desired plasma flame is grown to complete ignition operation. Prior to ignition, the conductor 5 is coupled to the coil L as the load of the coil L and, after ignition, the impedance mismatching degree of the power source 1 and load is made low before and after ignition because plasma comes to load and the excessive load of the circuit element of the power source 1 is avoided while the life of the power source circuit can be prolonged. |
