Oxford Superconducting Technology

Jeff Parrell

Michael Field

Youzhu Zhang

Seung Hong

Seungok Hong

William G Marancik

Robert William Hentges

Boleslaw Czabai

Maarten Meinesz

Kenneth Marken

Field Michael

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

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

A method for increasing the copper to superconductor ratio of a superconductor core wire by forming a copper-based strip about the core wire which at least partially encloses the core wire in contact therewith by deforming the strip longitudinally into a U shape nested about the wire; and soldering the wire and strip in the assembly of step (a) to form a strong mechanical, electrical and thermal bond therebetween.

Increasing the copper to superconductor ratio of a superconductor wire by cladding with copper-based strip

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.

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Roselle Park, NJ, United States of America

Jeff Parrell