Abstract: There is disclosed a laser beam delivery apparatus comprising a laser (10) having an axis (14), a first mirror (13) at one end of the laser (10) and adapted to reflect the beam normal to the laser axis (14), a second mirror (15) aligned with the first mirror (13), the second mirror (15) adapted to reflect the beam along a further axis (16), a telescopic means (30) joining the first and second mirrors (13, 15), a third mirror (19) aligned with the second mirror (15) and a focusing means (33) associated with the third mirror (19) for focusing the beam on a workpiece. Also disclosed is a sensing means (63) for sensing the distance of a focusing head (33) of a laser delivery system above a workpiece to be subjected to the action of the laser beam.

Abstract: The invention concerns plasma torches comprising an upstream electrode (12), a downstream electrode (11), a chamber (15) for the injection of plasma producing gas, a priming electrode (13) and optionally a magnetic field coil (14), in which the upstream root of the arc is displaced on the upstream electrode. According to the invention, in order to control a continuous or reciprocating and/or an oscillatory translation, the field coil is supplied with a variable direct current, if need be a pulsatory undulatory current, and/or a diffuser is placed at the inner end of the upstream electrode which is supplied with a modulated flow of gas which it causes to whirl. Application in high power plasma torches for regularizing and rendering uniform the wear of the electrodes so as to prolong the life thereof.

Abstract: The invention relates to a process and device for injecting at least one stream of a finely divided material into a hot gaseous flow, such as a plasma jet. According to the invention,--there is interposed on the path of said hot gaseous flow a screen pierced with a plurality of orifices spatially distributed about said hot gaseous flow so as to fractionate the latter into a plurality of elementary flows at least approximately in the same general direction; and--said stream of finely divided material, is led to at least one nozzle at least partially surrounded by said orifices, in order to create at least one stream of finely divided material whose direction is at least approximately similar to that of said elementary hot gaseous flows and surrounded by at least certain of them. The invention is particularly applicable to plasma chemistry.

Abstract: The present invention relates to an ionized gas generator with supersonic homogeneous flow. This generator comprises unitary modules comprising:two coaxial electrodes of cylindrical form, the downstream electrode being open and having the flow passing therethrough;means for injecting as vortical gas along planes perpendicular to the axis common to said electrodes, the gas thus injected passing through an electric arc which consequently takes an elongated form;means for striking the arc between the two coaxial electrodes;means for cooling the electrodes, the gas injection devices and the coupling chamber;coils creating around the first upstream electrode a magnetic field ensuring the displacement of the base of the arc around the inner surface of said upstream electrode.The invention is applicable to testing of heat-protection materials.