Plasma arc torch stabilized by gas sheath

摘要

A plasma arc is claimed comprising:- (a) a cooled cathode (20), with a diameter D, of which the end is a conical point with a summit angle alpha; and (b) a cooled anode (22) made up of an inner wall in the shape of truncated cone, of which the section defines the inlet (28) of a cylindrical tuyere (24). The inner wall of the anode (22) is, in its conical part, parallel to the conical end of the cathode (20), at a distance d from it and over a length 1g. The angle alpha, the diameter D, the distance d and the length 1g are such that a plasma gas injected into the torch is accelerated between the two conical walls, in a manner that is sufficient to create a gaseous sheathing of the arc column from where this latter is developed to the point of the cathode (20) and is capable of sheathing it in the tuyere.