Plasma cutting method

Method for cutting a workpiece 40 comprising; i) providing a device 1 comprising an electrode 11 (which may comprise an emissive element formed from hafnium, a hafnium alloy, zirconium or a zirconium alloy) for generating a plasma arc 2, and, a gas supply system 3 for providing a gas flow 30 around the electrode; ii) providing a pre-gas flow 31 around the electrode comprising an oxidizing gas at a concentration of 50 ppm to 10000 ppm; iii) providing a main gas flow 32 around the electrode comprising an oxidizing gas at a concentration above 10000 ppm; iv) generating a plasma arc between the electrode and the workpiece, and, v) cutting the workpiece by means of the plasma arc. Preferably the oxidizing gas is oxygen, nitrogen monoxide, nitrogen dioxide or ozone. There may be a post-gas flow 33 in addition to the pre- and main gas flows, which comprises an oxidizing gas at a concentration of 50 ppm to 10000 ppm. The current provided to the electrode may be tailored in line with the concentration of the pre-, main- and post-gas flows. A second aspect is directed towards an apparatus for carrying out the method according to the first aspect.