Abstract: A discharge circuit for pulsed laser comprising a power source, main discharge electrodes for generating a laser beam, a main discharge capacitor charged with electrical charges for generating the main discharge between the main discharge electrodes, and a switching circuit for performing switching operations to charge the main discharge capacitor with electrical charges supplied from the power source in a prescribed repetition cycle, is provided, in parallel to the main discharge capacitors, with a circuit element for consuming or grounding the reverse current from the power source caused by overshoot generated directly after the main discharge, thereby attaining stable laser output without ill effects from overshoot voltage generated directly following discharge.

Abstract: A discharge circuit for pulsed laser comprising a power source, main discharge electrodes for generating a laser beam, a main discharge capacitor charged with electrical charges for generating the main discharge between the main discharge electrodes, and a switching circuit for performing switching operations to charge the main discharge capacitor with electrical charges supplied from the power source in a prescribed repetition cycle, is provided, in parallel to the main discharge capacitors, with a circuit element for consuming or grounding the reverse current from the power source caused by overshoot generated directly after the main discharge, thereby attaining stable laser output without ill effects from overshoot voltage generated directly following discharge.

Abstract: A plasma torch is provided with a sharply converging nozzle which can prevent the lower end of the torch from making contact with a workpiece which has concavities and convexities during the cutting of the workpiece with the plasma torch. An upper portion (1a) of the nozzle (1) is provided with an outwardly directed flange (1h) so as to make close contact with a seat surface (2d) formed in the inner periphery of the lower portion of the cap (2), so as to ensure electrical conduction between the nozzle (1) and the cap (2) and to secure to a torch body (8) the nozzle (1) and components (3, 4, 5) contained in the nozzle (1). O-rings (6, 6a, 9) provide seals for the cooling water passage (7). The lower end of cylindrical portion (1a) of the nozzle (1) below the flange (1f), as well as the conical portion (1b), constitutes part of the exterior surface of the plasma torch, while the apex angle (.theta..sub.1) of the nozzle structure is made smaller so that the nozzle structure is more sharply tapered.

Abstract: In a plasma torch, the contact surface (61) between the nozzle (6) and the swirler (5), the contact surface (4b) between the swirler (5) and the insulating cylindrical body (4), the contact surface between the insulating cylindrical body (4) and the electrode (3), and the contact surface (3a) between the electrode (3) and the electrode table (2) are arranged in line from the nozzle (6) to the torch body (1). The inner diameter (d1) of the portion of insulating cylindrical body (4) positioned in contact with the flange (31) of the electrode (3) is smaller than the inner diameter (d2) of the flat surface (4b) of insulating cylindrical body (4) which is in contact with the end of swirler (5). An upper stepped chamber (65) or an upper tapered chamber (66) can be formed in the cylindrical portion (62) of the nozzle (6) above the swirler (5) which upper chamber has a diameter larger than that of the swirler (5) to permit easy removal of the swirler (5) from the cylindrical portion (62).