Abstract: A tubular case closed at its two ends respectively by a first side wall carrying two electric supply terminals and a second side wall carrying a hot gas outlet nozzle for discharging a jet of heated oxygen. A heating tube extends axially through the case constituting a heating resistance, the wall or this heating tube being provided in one of its end portions with at least one opening for the passage of the gas to the interior of the heating tube and the outlet nozzle. The case also includes a heat exchanger of thermoconductive material and gas pre-heating means.

Abstract: A heat treating method in which a microwave plasma torch is used, comprising an outlet nozzle and a sleeve surrounding and spaced from the nozzle. The nozzle has a central passage surrounded by a generally annular passage formed preferably by a series of conduits arranged in a ring around the central passage. A plasmagenic gas is supplied to the central passage and a combustible gas to the annular passage, while microwave energy is supplied between the sleeve and the nozzle, thereby to form a central plasma jet sheathed by a flame of the burning combustible gas having a generally annular shape. The resulting plasma jet sheathed by a flame is much more stable and much longer, with a much more distinct contour, than in the absence of the flame. The plasma is stable both in the free atmosphere and when it is directed onto an object such as a metal plate.

Abstract: The hyperfrequency energy is conveyed through a waveguide (1) having a rectangular section. A central plasmagenic gas and an annular sheathing gas are supplied through a T-shaped transverse pipe (2). The upper branches of the T extend in a sealed manner through the small sides of the waveguide. The stem of the T extends with clearance through an opening (7) formed in a large side of the waveguide and is provided with a nozzle (22) which is surrounded by a sleeve (3) terminating in a rolled-over flange (25). Application in the treatment of surfaces and the production of chemical reactions.