Abstract: A closed-loop Brayton cycle rotating machine is provided with a sealed circuit in which a working fluid flows. This circuit comprises a compressor for compressing the working fluid, a hollow cylindrical recovery heat exchanger for preheating the compressed working fluid, a H.T. boiler for heating the preheated compressed working fluid to a high temperature, a turbine for generating mechanical energy by expanding the compressed H.T. working fluid through the turbine, and downstream of and axially aligned with the turbine, an exhaust pipe for the expanded H.T. working fluid. The circuit is configured so that the expanded H.T. working fluid constitutes a heat source of the recovery heat exchanger. The boiler is in the general shape of a hollow cylinder and is interposed coaxially between the axial turbine/exhaust pipe assembly and the recovery heat exchanger.

Abstract: The invention concerns a dynamic sensor for sensing the distance and the position of a surface moving past said sensor, including:a send optical channel (3) emitting radiation (4) towards the surface (1) and two receive optical channels (5, 6) each receiving a portion (4A, 4B) of the radiation (4) reflected or diffusely reflected by said surface (1);a radiation emitter (2) coupled to the other end of the send optical channel (3);an opto-electronic converter (7, 8) coupled to the other end of each of the two receive optical channels (5, 6);a processor device (9) connected to the opto-electronic converters (7, 8);in accordance with the invention:the send optical channel (3) and the receive optical channels (5, 6) respectively have a send axis (3A) and receive axes (5A, 6A) that are parallel to each other; the ends of the optical channels (3, 5, 6) facing the surface (1) are in a common plane perpendicular to the axes (3A, 5A, 6A) of the optical channels (3, 5, 6), each of said ends constituting the vertex of a

Abstract: A bichromatic pyrometer for detecting the high temperature of a surface element of an object comprises two photodiodes (18, 19) receiving radiation from the object, each of the photodiodes having a large forbidden band and being sensitive to radiation in a given range of wavelengths, said sensitivity ranges being different and being situated in the visible or near visible regions of the spectrum, said ranges being obtained by selecting the value of the forbidden band of the material constituting each of the photodiodes (18) and (19), said forbidden band being greater than or equal to that of silicon (.gtoreq.1.11 eV). The pyrometer is capable of measuring rapidly changing surface temperatures with great accuracy.

Abstract: The invention relates to a method and device for producing polycrystalline silicon. The method consists in particular in purifying a bath of molten silicon which contains impurities by bubbling a mixture of chlorine and oxygen and in progressively crystallizing the purified silicon in a receptacle (22) which is moved vertically downwards in a vertical gradient of temperatures which increase towards the top. Application to manufacturing solar photocells.

Abstract: Concentric closed tubes define an outer steam vessel with the inner tube constituted by a selective membrane consisting of a metallic oxide having a first doping to effect passage of oxygen ions through the membrane to the interior of the inner tube acting as an oxygen collector and having a second doping to effect return conduction of electrons through said membrane to increase heating of the steam. A vacuum pump is applied to the interior of the inner tube to provide a pressure differential to facilitate oxygen passage through the membrane.