Abstract: A laser decontamination method includes the steps of incorporation of a condenser lens in a gas supply nozzle, supplying a gas toward a contaminated member while moving the gas supply nozzle relatively to and along a surface of the contaminated member with a laser beam which is condensed by the condenser lens applied thereto, and thereby continuously melting or evaporating a contaminated surface layer so as to remove the same to clean the contaminated member. The gas is supplied asymmetrically with respect to the axis of the laser beam.

Abstract: An indirect cooling system suitable for a plasma jet cutting method is established to prevent the leakage of cooling water and to enable a stable plasma jet to be obtained. A tip having a nozzle for emitting a plasma jet is fitted to a nozzle sleeve through which cooling water circulates, and electric discharge is induced between the tip and an electrode extending through the nozzle sleeve to the neighborhood of the tip, thereby ionizing a neutral gas and emitting a plasma jet through the nozzle. In the indirectly-cooled plasma jet torch, the tip is brought into surface contact with the nozzle sleeve to fit them to each other, and contact portions of the tip and the nozzle sleeve are tapered.