Arc welding, plasma cutting and plasma spraying

Thermal plasmas are of immense and increasing industrial importance. Their many applications can be divided into those that require relatively low power such as arc welding, plasma cutting, plasma spraying and arc lighting, and those that typically operate at much high powers, including mineral processing, waste treatment and nanoparticle production. The subject of this special issue is the three small-scale thermal plasma applications that are most important in manufacturing: arc welding, plasma cutting and plasma spraying. All are well-established industrial technologies, with long histories and widespread implementation. In all three applications, an arc plasma is struck between two electrodes, typically at or close to atmospheric pressure. In arc welding and plasma cutting, the arc is transferred to a metal workpiece. In welding, the workpiece consists of two pieces of metal, which are partially melted and joined by the arc. In cutting, the power transferred by the arc, augmented in some cases by chemical energy released by oxidation reactions, is sufficient to cut the metal.