This superconducting wire includes: a strand including a superconducting material; and a stabilizer material for superconductor arranged in contact with the strand, wherein the stabilizer material for superconductor includes a copper material which contains one kind or two kinds or more of additive elements selected from Ca, Sr, Ba, and rare earth elements (RE) for a total amount of 3 ppm by mass or more and 400 ppm by mass or less, with the remainder being Cu and unavoidable impurities, the total concentration of the unavoidable impurities other than O, H, C, N, and S, which are gas components, is 5 ppm by mass or more and 100 ppm by mass or less, and compounds including one kind or two kinds or more selected from CaS, CaSO.sub.4, SrS, SrSO.sub.4, BaS, BaSO.sub.4, (RE)S, and (RE).sub.2SO.sub.2 are present in the matrix.

An electrically connecting device (1) includes a linking part defining an internal channel (12) that opens onto the exterior of the linking part. The internal channel (12) is able to receive two end segments of two superconducting wires (2, 3) that lie parallel in the internal channel (12) over a segment of common length; and an aperture (13) in the external jacket of the linking part. The aperture (13) is in communication with the internal channel (12) in order to allow a brazing material in liquid form to be inserted into the internal channel (12) around the two end segments of the two superconducting wires (2, 3).

An electrically connecting device (1) includes a linking part defining an internal channel (12) that opens onto the exterior of the linking part. The internal channel (12) is able to receive two end segments of two superconducting wires (2, 3) that lie parallel in the internal channel (12) over a segment of common length; and an aperture (13) in the external jacket of the linking part. The aperture (13) is in communication with the internal channel (12) in order to allow a brazing material in liquid form to be inserted into the internal channel (12) around the two end segments of the two superconducting wires (2, 3).

In a high-temperature superconducting conductor 10, a laminated body 15 is formed by laminating a high-temperature superconducting layer 14 on one side surface of a flexible and tape-shaped metal substrate 12 via an intermediate layer 13, and a plurality of thin film wires 11 are formed by providing a stabilization layer 17 around the laminated body 15 via a protective layer 16 and are arranged in a thickness direction. The plurality of thin film wires 11 are connected at both ends in a width direction to each other in a conductible state in a longitudinal direction by means of conductive coupling member 20, in such a manner that a thin film wire 11 disposed at an outermost side is positioned with a surface 18 on a side of the metal substrate 12 directed outward and a surface 19 of each of the plurality of thin film wires 11 facing the high-temperature superconducting layer 14 is held in a non-fixed state with respect to an opposing surface.

In a high-temperature superconducting conductor 10, a laminated body 15 is formed by laminating a high-temperature superconducting layer 14 on one side surface of a flexible and tape-shaped metal substrate 12 via an intermediate layer 13, and a plurality of thin film wires 11 are formed by providing a stabilization layer 17 around the laminated body 15 via a protective layer 16 and are arranged in a thickness direction. The plurality of thin film wires 11 are connected at both ends in a width direction to each other in a conductible state in a longitudinal direction by means of conductive coupling member 20, in such a manner that a thin film wire 11 disposed at an outermost side is positioned with a surface 18 on a side of the metal substrate 12 directed outward and a surface 19 of each of the plurality of thin film wires 11 facing the high-temperature superconducting layer 14 is held in a non-fixed state with respect to an opposing surface.

A connection structure for a superconducting layer according to an embodiment includes a first superconducting layer, a second superconducting layer, and a connection layer between the first superconducting layer and the second superconducting layer, the connection layer including crystal particles containing a rare earth element, barium, copper, and oxygen, the crystal particles having a major diameter distribution including a trimodal distribution. The trimodal distribution has first, second, and third distributions in which major diameter become small in this order. The aspect ratios of the crystal particles included in the first distribution and the second distribution include a bimodal distribution. The median value of the major diameters of the crystal particles included in the distribution on a higher aspect ratio side in the bimodal distribution is greater than the median value of the major diameters of the crystal particles included in the distribution on a lower aspect ratio side.

A connection structure for a superconducting layer according to an embodiment includes a first superconducting layer, a second superconducting layer, and a connection layer between the first superconducting layer and the second superconducting layer, the connection layer including crystal particles containing a rare earth element, barium, copper, and oxygen, the crystal particles having a major diameter distribution including a trimodal distribution. The trimodal distribution has first, second, and third distributions in which major diameter become small in this order. The aspect ratios of the crystal particles included in the first distribution and the second distribution include a bimodal distribution. The median value of the major diameters of the crystal particles included in the distribution on a higher aspect ratio side in the bimodal distribution is greater than the median value of the major diameters of the crystal particles included in the distribution on a lower aspect ratio side.

A superconducting cable includes a core part, in which the core part includes a former including a plurality of copper wires, a superconducting conductor layer including a plurality of superconducting wires connected in parallel to each other, an insulating layer, and a superconducting shield layer including a plurality of superconducting wires are sequentially arranged. A conducting layer formed of a metal having a current-carrying property at room temperature is provided on opposite surfaces of each of the superconducting wires of the superconducting conductor layer to reinforce mechanical rigidity of each of superconducting wires of the superconducting conductor layer, and the former has a cross-sectional area which is smaller than that of a former of a superconducting cable in which the conducting layer is not added to superconducting wires and which is designed on an assumption that all fault current flows to the former.

A superconducting cable includes a core part, in which the core part includes a former including a plurality of copper wires, a superconducting conductor layer including a plurality of superconducting wires connected in parallel to each other, an insulating layer, and a superconducting shield layer including a plurality of superconducting wires are sequentially arranged. A conducting layer formed of a metal having a current-carrying property at room temperature is provided on opposite surfaces of each of the superconducting wires of the superconducting conductor layer to reinforce mechanical rigidity of each of superconducting wires of the superconducting conductor layer, and the former has a cross-sectional area which is smaller than that of a former of a superconducting cable in which the conducting layer is not added to superconducting wires and which is designed on an assumption that all fault current flows to the former.

The purpose of the present invention is to provide a niobium-aluminum precursor wire having properties such as expression of flexibility and ensuring a large single-wire length, as well as a twisted wire, a superconducting wire, and a superconducting twisted wire formed of the niobium-aluminum precursor wire. The present invention provides a niobium-aluminum precursor wire and a twisted wire using the same, the niobium-aluminum precursor wire including: a rod-like winding core (5) formed of a stabilized copper, or a stabilized copper and an unstabilized copper; a laminated body (3) that is wound around the winding core (5) and that is formed of an aluminum foil and a niobium foil laminated one on the other; and a covering body (1) that covers the circumference of the laminated body and that is formed of a stabilized copper, or a stabilized copper and an unstabilized copper. The volume ratio of the stabilized copper with respect to the unstabilized copper contained in the precursor wire is 0.5-2.0, and the volume ratios of the stabilized copper contained in the winding core (5) and the covering body (1) are within prescribed ranges. According to the present invention, a superconducting wire and a superconducting twisted wire are provided by thermally treating the precursor wire and the twisted wire.