A subelement (1) for an Nb.sub.3Sn-containing superconductor wire includes an Sn-containing core (2), an inner matrix (5) which includes Cu and surrounds the Sn-containing core (2), a region (7) of mutually abutting Nb-containing rod elements (8, 30), which surrounds the inner matrix (5), where the Nb-containing rod elements (8, 30) are each configured with an Nb-containing core filament (9; 31) and a Cu-containing filament casing (10), an outer matrix (6) which includes Cu and surrounds the region (7) of Nb-containing rod elements (8, 30). The Sn-containing core (2) has a core tube (3) into which an Sn-containing powder (4) has been introduced, the Sn-containing powder (4) being in a compacted state. This provides a subelement for an Nb.sub.3Sn-containing superconductor wire which cost-effectively yields an improved superconducting current carrying capacity.

For producing an Nb3Sn superconductor wire, restack rod process (RRP) subelements (1a; 60a) are grouped to form a bundle having an approximately circular cross section and are arranged together with filling elements (18a-18c) in an internally and externally round outer tube (19; 52). To the inside the filling elements form a serrated profile (25) for abutment against the hexagonal subelements, and to the outside they form a round profile (24) 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 (9) is provided, into which the remaining parts of the subelements are inserted, in particular, an annular arrangement of hexagonal Nb-containing rod elements (4), which are surrounded externally by an outer matrix (7, 61) and internally by an inner matrix (3).

In various embodiments, superconducting wires incorporate diffusion barriers composed of Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.

A system and method for treating a cavity comprises arranging a niobium structure in a coating chamber, the coating chamber being arranged inside a furnace, coating the niobium structure with tin thereby forming an Nb.sub.3Sn layer on the niobium structure, and doping the Nb.sub.3Sn layer with nitrogen, thereby forming a nitrogen doped Nb.sub.3Sn layer on the niobium structure.

A method of fabricating a superconductor device includes providing a first metal layer on top of the substrate. An oxidation of a top surface of the first metal layer is rejected. A second metal layer is deposited on top of the second metal layer. A superconducting alloy of the first metal layer and the second metal layer is created between the first metal layer and the second metal layer. There is no oxide layer between the superconducting alloy and the first metal layer.

In various embodiments, superconducting wires feature assemblies of clad composite filaments and/or stabilized composite filaments embedded within a wire matrix. The wires may include one or more stabilizing elements for improved mechanical properties.

A semifinished wire (1) for a superconducting wire containing Nb3Sn has a Cu stabilization cladding tube (2), a ring-shaped closed diffusion barrier (3) in the inside of the Cu stabilization cladding tube (2) and a plurality of PIT elements (6) in the inside of the diffusion barrier (3), each having a cladding (8) containing Cu, a small tube (9), and a powder core (10) containing Sn. The small tube (9) consists of Nb or an alloy containing Nb and the diffusion barrier (3) has a percentage of area ADF in cross-section of the semifinished wire (1) of 3% ADF 9% and a wall thickness WDF with 8 μm≦WDF≦25 μm. A plurality of filler elements (5) are arranged inside the diffusion barrier (3), with the inner sides of the filler elements (5) abutting the PIT elements (6).

In various embodiments, superconducting wires incorporate diffusion barriers composed of Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.

A system and method for treating a cavity comprises arranging a niobium structure in a coating chamber, the coating chamber being arranged inside a furnace, coating the niobium structure with tin thereby forming an Nb.sub.3Sn layer on the niobium structure, and doping the Nb.sub.3Sn layer with nitrogen, thereby forming a nitrogen doped Nb.sub.3Sn layer on the niobium structure.

For producing an Nb3Sn superconductor wire, restack rod process (RRP) subelements (1a; 60a) are grouped to form a bundle having an approximately circular cross section and are arranged together with filling elements (18a-18c) in an internally and externally round outer tube (19; 52). To the inside the filling elements form a serrated profile (25) for abutment against the hexagonal subelements, and to the outside they form a round profile (24) 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 (9) is provided, into which the remaining parts of the subelements are inserted, in particular, an annular arrangement of hexagonal Nb-containing rod elements (4), which are surrounded externally by an outer matrix (7, 61) and internally by an inner matrix (3).