Plasma torch with a substantially axi-symmetrical general structure

Abstract

The present invention concerns a plasma torch with an approximately axi-symmetrical structure including a tubular bare torch portion having a single upstream electrode or a pair of coaxial upstream and downstream electrodes. The electrodes are tubular and cooled by a suitable cooling circuit. A field coil moves the arc foot. An injection mechanism injects a plasma gas downstream of the upstream electrode or between the upstream electrode and the downstream electrode. A starter mechanism ensures starting of the torch. An external structure integral with the bare torch at its proximal extremity includes fluid and electric linkings with the outside of the torch. The bare torch includes a bearer structure formed of three coaxial casings overlapping, at least partially, and integral with the external structure. The bearer structure includes a metallic external casing, an intermediate metallic casing defining with the external casing a circuit for return of cooling fluid of the electrode(s) and the field coil, and an internal casing defining with the intermediate metallic casing a circuit for admitting the plasma gas into the injection mechanism and channeling via its internal face an entering flow of the cooling fluid in a direction of the upstream electrode, the field coil, and possibly the downstream electrode.