Bruker Biospin Ag

René Flükiger

Daniel M Eckert

Florin Buta

Carmine Senatore

Vital Abächerli

Davide Uglietti

A device for the high pressure densification of superconducting wire from compacted superconductor material or superconductor precursor powder particles, has four hard metal anvils () with a total length (L2) parallel to the superconducting wire, the hard metal anvils borne in external independent pressure blocks (), which are in turn either fixed or connected to high pressure devices, preferably hydraulic presses. At least one of the hard metal anvils is a free moving anvil () having clearances of at least 0.01 mm up to 0.2 mm towards the neighboring hard metal anvils (), so that no wall friction occurs between the free moving anvil and the neighboring anvils. This allows for high critical current densities Jat reduced pressure applied to the hard metal anvils.

Device and method for the densification of filaments in a long superconductive wire

A method for producing a superconductive wire, whereby an elongated intermediate element is formed out of an initial element in a deformation step and whereby the superconductive filaments are formed by a final reaction heat treatment, is characterized in that prior to the final reaction heat treatment the filaments in the intermediate element are densified in one or more high pressure densification steps following up the deformation step, said densification steps comprising a simultaneous action of at least four hard surfaces perpendicular to the axis of the elongated intermediate element, building up high pressure P&#x2267;100 MPa on a part of the intermediate element having an axial length L. This leads to a substantial increase of the critical current density J, whereby the anisotropy factor &#x393; is be almost not affected thus enabling production of almost isotropic wires or tapes.

Procedure of densifying filaments for a superconductive wire

The invention relates to a composite (), comprising a Cu&#x2014;Sn bronze matrix () and filaments () surrounded by the bronze matrix (), wherein the filaments () contain niobium (&#x2550;Nb) or a Nb alloy, characterized in that the filaments () contain between 0.3% and 20% of volume of copper (&#x2550;Cu) substructures (), which are distributed within the Nb or the Nb alloy. The composite can be used to produce a superconducting element with the bronze route which has an improved critical current density.

Superconductive elements containing copper inclusions, and a composite and a method for their production

A superconductive element containing NbSn, in particular a multifilament wire, comprising at least one superconductive filament () which is obtained by a solid state diffusion reaction from a preliminary filament structure (), said preliminary filament structure () containing an elongated hollow pipe () having an inner surface () and an outer surface (), wherein said hollow pipe () consists of Nb or an Nb alloy, in particular NbTa, wherein the outer surface () is in close contact with a surrounding bronze matrix () containing Cu and Sn, and wherein the inner surface () is in close contact with an inner bronze matrix () also containing Cu and Sn, is characterized in that the inner bronze matrix () of the preliminary filament structure () encloses in its central region an elongated core () consisting of a metallic material, said metallic material having at room temperature (=RT) a thermal expansion coefficient &#x3b1;&#x3c;17*10K, preferably &#x3b1;&#x2266;8*10K, said metallic material having at RT a yield strength R&#x3e;300 MPa, said metallic material having at RT an elongation at rupture A&#x3e;20%, and wherein the metallic material of the core () is chemically inert with respect to the material of the inner bronze matrix () up to a reaction temperature T of the solid state diffusion reaction. This element has improved superconductive properties in a large volume fraction of its superconductive filaments, in particular a high critical temperature Tand a high critical magnetic filed strength B, and is mechanically stable enough for commercial applications such as magnet coils.

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Plan-Les-Onates, Switzerland

René Flükiger