Abstract: A superconducting wired electrical circuit has two portions (1a, 1b) each having a superconducting cable core (2a, 2b), an electrical insulation layer (3a, 3b), a screen (4a, 4b) and a cryogenic jacket (5a, 5b) surrounding the screen (4a, 4b) to allow the circulation of a cryogenic fluid. At least a first arrangement (A) has a cryostatic junction unit (7) electrically connecting, in series, the two portions (1a, 1b), an inlet/outlet duct (14) for cryogenic fluid. A distinct tap-off module (12) has at least one inlet/outlet tapping (15) for the flow of a cryogenic fluid in the second portion (1b). A device (13) for blocking the passage of cryogenic fluid is interposed between the duct (14) and the tapping (15) and positioned around and in contact with the screen (4b) of the second portion (1b).

Abstract: An electricity transmission cable with mass-impregnated paper insulation has around at least one conductor (1), an impregnated paper layer (2) and a metal layer (3) adjacent to the impregnated paper layer, this metal layer (3) consisting of copper or aluminum. The cable has, directly around said metal layer (3), an insulating material layer (4) and, directly around the insulating material layer (4), a transverse reinforcement layer (5) made of steel or made of glass fiber tape.

Abstract: The present invention relates to a device comprising at least one electrical cable (10a, 10b, and 10c) for transporting DC current, said electrical cable comprising an elongate electrical conductor (11a, 11b, and 11c) surrounded by at least one first semiconducting layer (12c), an electrically insulating layer (13a, 13b and 13c) surrounding the first semiconducting layer and a second semiconducting layer (14a, 14b and 14c) surrounding the electrically insulating layer, characterized in that the electrical cable (10a, 10b, and 10c) furthermore comprises a space charge trapping layer (15a, 15b, and 15c) obtained on the basis of a polymeric composition comprising at least one organic polymer and at least one linear filler, the space charge trapping layer (15a, 15b, and 15c) replacing at least in part the second semiconducting layer (14a, 14b, and 14c) of the electrical cable, so that the space charge trapping layer is in physical contact with the electrically insulating layer (13a, 13b, and 13c) of the electrica

Abstract: The invention relates to an electricity transmission cable with mass-impregnated paper insulation comprising around at least one conductor (1), an impregnated paper layer (2) and a metal layer (3) adjacent to said impregnated paper layer, this metal layer (3) consisting of copper or aluminium. According to the invention, the cable comprises, directly around said metal layer (3), an insulating material layer (4) and, directly around said insulating material layer (4), a transverse reinforcement layer (5) made of steel or made of glass fibre tape.

Abstract: The present invention relates to a device comprising at least one electrical cable (10a, 10b, and 10c) for transporting DC current, said electrical cable comprising an elongate electrical conductor (11a, 11b, and 11c) surrounded by at least one first semiconducting layer (12c), an electrically insulating layer (13a, 13b and 13c) surrounding the first semiconducting layer and a second semiconducting layer (14a, 14b and 14c) surrounding the electrically insulating layer, characterized in that the electrical cable (10a, 10b, and 10c) furthermore comprises a space charge trapping layer (15a, 15b, and 15c) obtained on the basis of a polymeric composition comprising at least one organic polymer and at least one linear filler, the space charge trapping layer (15a, 15b, and 15c) replacing at least in part the second semiconducting layer (14a, 14b, and 14c) of the electrical cable, so that the space charge trapping layer is in physical contact with the electrically insulating layer (13a, 13b, and 13c) of the electrica

Abstract: The invention relates to a method of doping silica with fluorine. The method described comprises mixing a powder of silica granules with a solid fluorine compound, thermally decomposing the solid fluorine compound under an inert atmosphere, and densifying the granules to obtain dense grains of doped silica. It is preferable to use ammonium bifluoride. The invention is applicable to preparing high index silica glass, in particular for fabricating optical fiber preforms.

Abstract: A method of manufacturing an optical fiber preform (3) comprising: forming at least one silica-based outer deposition layer (23) by depositing silica on a primary preform (24) constituted by a bar mainly comprising silica and including a silica-based outer peripheral portion (22), the method being characterized in that the viscosity of the outer deposition layer (23) is adjusted to be substantially identical to the viscosity of the outer peripheral portion (22) of the primary preform (24) by adding to the silica, over a substantial portion of the outer deposition layer (23), at least one compound selected from the group formed by the following compounds: CaF2, MgF2, AlF3, B2O3, and Al2O3.

Abstract: The invention relates to a method of doping silica with fluorine. The method described comprises mixing a powder of silica granules with a solid fluorine compound, thermally decomposing the solid fluorine compound under an inert atmosphere, and densifying the granules to obtain dense grains of doped silica. It is preferable to use ammonium bifluoride. The invention is applicable to preparing high index silica glass, in particular for fabricating optical fiber preforms.

Abstract: A process is described for making silica powder by a sol-gel process whereby an aqueous suspension is made of a silica-based raw material which includes particles containing chlorine, the pH of the suspension is adjusted to a value from 3 to 4.5 if necessary, the suspension is gelled, the gel obtained is dried and the dried gel is fractionated into silica granules. The silica-based raw material preferably includes particles containing chlorine having a specific surface area less than 80 m2/g and less than 5 wt. % relative to the total quantity of particles containing chlorine of silica particles having a specific surface area from 150 m2/g to 300 m2/g. The use of such powder to manufacture an optical fiber preform is also described.

Abstract: Silica granules made up of mutually agglomerated silica soot particles are treated by placing the granules in a crucible inside a furnace which contains an inert gas mixed with a chlorine-containing compound and in which the temperature lies in the range 1000° C. to 1500° C. According to the invention, a crucible is used that is made of porous graphite firstly to increase the surface area of the crucible through which the chlorine-containing compound diffuses. This gives rise to faster exchange between the granules and the gas for given partial pressure of the chlorine-containing compound, thereby improving purification. Secondly, the difference between the chemical natures of the silicas and the crucible make the two materials inert relative to each other so that the granules do not adhere to the walls of the crucible, thereby making it possible to recover the granules without having to apply any mechanical operation that might contaminate them.