A railway direct-current system according to the present invention is provided with: a feeding line that is connected to a plurality of electric power substations arranged along a railway; and a trolley line that is connected to the feeding line via feeding branch lines at an arbitrarily defined interval, wherein a superconductive feeding cable is connected to somewhere midway in each of railroad lines extending from the substations to the trolley line via the feeding lines, so as to be parallel with the railroad line.

A railway direct-current system according to the present invention is provided with: a feeding line that is connected to a plurality of electric power substations arranged along a railway; and a trolley line that is connected to the feeding line via feeding branch lines at an arbitrarily defined interval, wherein a superconductive feeding cable is connected to somewhere midway in each of railroad lines extending from the substations to the trolley line via the feeding lines, so as to be parallel with the railroad line.

A superconductor (10, 30) has a twisted structure and is adapted to form windings in a superconducting coil. The superconductor (10, 30) comprises at least one superconductor wire. The superconductor further comprises at least one elongated electrical insulation element (18, 37). The elongated electrical insulation element(s) (18, 37) is/are twisted with or around the superconductor wire(s) in order to create a separation distance with an adjacent superconductor wire in a neighbouring winding. The elongated electrical insulation element(s) (18, 37) and the superconductor wire(s) may be twisted in one and the same twisting operation.

A superconducting integrated circuit, comprising a plurality of superconducting circuit elements, each having a variation in operating voltage over time; a common power line; and a plurality of bias circuits, each connected to the common power line, and to a respective superconducting circuit element, wherein each respective bias circuit is superconducting during at least one time portion of the operation of a respective superconducting circuit element, and is configured to supply the variation in operating voltage over time to the respective superconducting circuit element.

An oxide superconductor according to an embodiment includes an oxide superconducting layer includes a single crystal having a continuous perovskite structure containing at least one rare earth element selected from the group consisting of yttrium, lanthanum, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, barium, and copper, containing praseodymium in a part of the site of the rare earth element in the perovskite structure, and having a molar ratio of praseodymium of 0.00000001 or more and 0.2 or less with respect to the sum of the at least one rare earth element and praseodymium; fluorine in an amount of 2.0×10.sup.15 atoms/cc or more and 5.0×10.sup.19 atoms/cc or less; and carbon in an amount of 1.0×10.sup.17 atoms/cc or more and 5.0×10.sup.20 atoms/cc or less.

An oxide superconductor according to an embodiment includes an oxide superconducting layer includes a single crystal having a continuous perovskite structure containing at least one rare earth element selected from the group consisting of yttrium, lanthanum, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, barium, and copper, containing praseodymium in a part of the site of the rare earth element in the perovskite structure, and having a molar ratio of praseodymium of 0.00000001 or more and 0.2 or less with respect to the sum of the at least one rare earth element and praseodymium; fluorine in an amount of 2.0×10.sup.15 atoms/cc or more and 5.0×10.sup.19 atoms/cc or less; and carbon in an amount of 1.0×10.sup.17 atoms/cc or more and 5.0×10.sup.20 atoms/cc or less.

The present invention relates to pressure generation apparatus and method for superconducting power equipment and, more particularly, to pressure generation apparatus and method for superconducting power equipment, wherein a pressure system separately arranged to apply pressure to liquid nitrogen in the superconducting power equipment is disposed inside a pressure vessel.

The present invention relates to pressure generation apparatus and method for superconducting power equipment and, more particularly, to pressure generation apparatus and method for superconducting power equipment, wherein a pressure system separately arranged to apply pressure to liquid nitrogen in the superconducting power equipment is disposed inside a pressure vessel.

A thermal-insulated multi-walled pipe for superconducting power transmission comprises: a superconducting cable; a multi-walled pipe composed of a plurality of straight pipes and houses the superconducting cable; and a plurality of spacers that are located between adjacent two straight pipes of the plurality of straight pipes, wherein a cross-sectional shape of each spacer is a polygon having three or more vertices, each spacer has a through-hole at a center in the plane, an inner straight pipe is located to pass through the through-hole, a frictional coefficient μ.sub.i between each spacer and the inner straight pipe is 0.1 or less, a frictional coefficient μ.sub.o between each spacer and an outer straight pipe is 0.1 or less, and a ratio L.sub.d/d of a diagonal equivalent length L.sub.d of the polygon to an inner diameter d of the outer straight pipe of the adjacent two straight pipes is 0.9 or less.

Superconductor cable or superconductor cable-in-conduit-conductor having a plurality of generally flat, ribbon-shaped superconductor tapes assembled to form a single stack or multiple stacks or a plurality of round or nearly round superconducting wires assembled to form a single bundle or multiple bundles. The superconductor cable or superconductor cable-in-conduit-conductor has at least one or more clocking features that identify its angular position with respect to the background magnetic field. Multiple types and geometries of superconductor cables and superconductor cable-in-conduit-conductor are disclosed. Superconductor power cable disposed within and separated from an electrical insulator with a space passing cryo-coolant between the superconducting cable and insulator is also disclosed.