Oxford Superconducting Technology

Bruker Ost LLC

The University of Chicago

Bruker Eas Gmbh

Michael Field

Jeff Parrell

Youzhu Zhang

Seung Hong

Seungok Hong

Hanping Miao

Carlos Sanabria

Jeffrey Parrell

Klaus Schlenga

William G Marancik

Manfred Thoener

Bernd Sailer

Dean J Miller

Vital Abaecherli

Matheus Wanior

Carl Buehler

Huang Yibing

Maarten Meinesz

Kenneth Marken

Boleslaw Czabai

Hanping Maio

Carl BÜHLER

Manfred THÖNER

Vital ABÄCHERLI

For producing an Nb3Sn superconductor wire, restack rod process (RRP) subelements () are grouped to form a bundle having an approximately circular cross section and are arranged together with filling elements (-) in an internally and externally round outer tube (). To the inside the filling elements form a serrated profile () for abutment against the hexagonal subelements, and to the outside they form a round profile () for direct or indirect abutment in the outer tube. In fabricating the RRP subelements, and before a reshaping with a reduction in cross section, an externally hexagonal and internally round casing structure () is provided, into which the remaining parts of the subelements are inserted, in particular, an annular arrangement of hexagonal Nb-containing rod elements (), which are surrounded externally by an outer matrix () and internally by an inner matrix ().

Finished conductor arrangement for an NB3SN superconductor wire and method for producing a subelement for an NB3SN superconductor wire

A new heat treatment for Internal-Tin NbSn strands is described. The heat treatment uses Nausite membranes to decrease the volume fraction of the &#x3b7; phase and therefore minimize its liquefaction&#x2014;ultimately resulting in better connected NbSn. The heat treatment requires only one stage aside from the final NbSn reaction stage. This heat treatment enables an increase in critical current density (at 16 T) of 28%.

Strand critical current density in NbSn superconducting strands via a novel heat treatment

Methods for producing a multifilament NbSn superconducting wire having a Jc value of at least 2000 A/mmat 4.2 K and 12 T by a) packing a plurality of Cu encased Nb rods within a first matrix which is surrounded by an intervening Nb diffusion barrier and a second matrix on the other side of the barrier remote from the rods thereby forming a packed subelement for the superconducting wire; b) providing a source of Sn within the subelement; c) assembling the metals within the subelement, the relative sizes and ratios of Nb, Cu and Sn being selected such that (i) the Nb fraction of the subelement cross section including and within the diffusion barrier is from 50 to 65% by area; (ii) the atomic ratio of the Nb to Sn including and within the diffusion barrier of the subelement is from 2.7 to 3.7; (iii) the ratio of the Sn to Cu within the diffusion barrier of the subelement is such that the Sn wt %/(Sn wt %+Cu wt %) is 45%-65%; (iv) the Cu to Nb local area ratio (LAR) of the Cu-encased Nb rods is from 0.10 to 0.30; (v) the Nb diffusion barrier being fully or partially converted to NbSn by subsequent heat treatment; and (vi) the thickness of the Nb diffusion barrier is greater than the radius of the Nb portions of the Cu encased Nb rods; and d) assembling the subelements in a further matrix and reducing the assemblage to wire form such that (i) the multifilamentary NbSn superconducting wire is formed of a plurality of the subelements, each having a Nb diffusion barrier to thereby form a wire having a distributed barrier design; (ii) the Nb portions of the copper encased Nb rods in the final wire are of diameter from 0.5 to 7 &#x3bc;m before reaction, and (iii) the Nb diffusion barrier that is fully or partially converted to NbSn by heat treatment is from 0.8 to 11 &#x3bc;m thickness before reaction; and e) heat treating the final size wire from step d) to form the NbSn superconducting phases, and multifilament NbSn superconducting wires made thereby are described herein.

Method for producing a multifilament NbSn superconducting wire

A device for use as an adjunct in assuring that a manufactured wire is substantially free of internal flaws. A plurality of successively adjacent wire bending stations are provided, where each station includes means for bending the wire into bending planes which are different for each of the stations. The wire is passed through the successive stations, whereby the different bending planes at each station subject the wire at each station to tensile bending strain at portions of the wire cross-section which are different for each station. As a result the probability is increased that a given internal flaw in the wire will be exposed to the tensile bending strain condition as the wire passes through the successive stations, increasing likelihood of breakage of the wire at the flaw or of flaw magnification to improve detection of the flaw during subsequent wire inspections.

Device for internal flaw magnification during wire drawing

A method for successfully heat treating magnet coils of braided BiSrCaCuO(Bi-2212) strand. The Bi-2212 coil is fabricated using standard round wire powder-in-tube techniques, and braided with a ceramic-glass braid with integrated carbonaceous binder. The coil is heated in an atmosphere controlled furnace below the high current density phase reaction sequence to burn off the carbonaceous binder and evacuated to remove unwanted gases from the inner windings. The oxygen environment is then reintroduced and the coil is heat treated to the high Jreaction temperature and then processed as normal. As the local atmosphere around the surface of the wire, particularly the concentration of oxygen, is critical to a successful reaction sequence, high current Bi-2212 coils can thereby be obtained.

Manufacture of high temperature superconductor coils

Critical current densities of internal tin wire having values of at least 2000 A/mmat temperature of 4.2 K and in magnetic field of 12 T are achieved by controlling the following parameters in a distributed barrier subelement design: wt % Sn in bronze; atomic Nb:Sn; local area ratio; reactable barrier; and barrier thickness relative to the filament thickness; and the design for restacking and wire reduction to control the maximum filament diameter at the subsequent heat reaction stage.

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A method for fabrication of nanometer scale metal fibers, followed by optional further processing into cables, yarns and textiles composed of the primary nanofibers. A multicomponent composite is first formed by drilling a billet of matrix metal, and inserting rods of the metal desired as nanofibers. Hexed or round rods can also be inserted into a matrix metal can. The diameter of this composite is then reduced by mechanical deformation methods. This composite is then cut to shorter lengths and reinserted into another billet of matrix metal, and again the diameter is reduced by mechanical deformation. This process of large scale metal stacking followed by mechanical deformation is repeated until the desired fiber size scale is reached, the fibers being contained in the matrix metal. After size reduction, the composite metal wires may be further processed into built up configurations, depending on intended application, by stranding, cabling, braiding, weaving, knitting, felting, etc., to form yarns or textiles. After the built up configuration is formed, the matrix metal is removed by chemical etching, leaving a cable, yarn or textile composed of the primary nanofibers.

Method for producing metal nanofibers, yarns and textiles

Critical current densities of internal tin wire to the range of 3000 A/mmat temperature of 4.2 K and in magnetic field 12 T are achieved by controlling the following parameters in a distributed barrier subelement design: wt % Sn in bronze; atomic Nb:Sn; local area ratio; reactable barrier; barrier thickness relative to the filament thickness; additions of a dopant such as Ti or Ta to the NbSn; and the design for restacking and wire reduction to control the maximum filament diameter at the subsequent heat reaction stage.

A method for decreasing the effective magnetic filament sizes for high current internal tin NbSn superconductors. During processing composite rods preferably comprised of copper clad Ta rods of approximately the same dimensions as the hexes in the designed filament billet stack are used as dividers in the subelement. Along with the Ta rods, Ta strips are strategically situated against the Nb or Nb alloy barrier tube which surrounds the subelement. The use of Ta as a spacer instead of copper prevents any reasonable likelihood of bridging of the superconducting phases formed after final reaction.

Method for using divider rods for separating superconducting regions in fine filament internal tin wire

An improvement is disclosed in the method for producing a multifilament (Nb, Ti)Sn superconducting wire by the steps of preparing a plurality of Nb or Nb alloy rods where Nb or Nb alloy monofilaments are encased in copper or copper alloy sheaths; packing the Nb or Nb alloy rods within a copper containing matrix to form a packed subelement for the superconducting wire; providing sources of Sn, and sources of Ti within said subelement; assembling the subelements within a further copper containing matrix; and diffusing the Sn and Ti into the Nb or Nb alloy rods to form (Nb, Ti)Sn. The method is improved by diffusing the Ti into the Nb from a minor number of Ti dopant source rods which are distributed among the Nb or Nb alloy rods.

A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15&deg;; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm . The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15&deg;. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

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Jersey City, NJ, United States of America

Michael Field