Abstract: A superconducting cable for alternating current, comprising conductor layers formed by a plurality of tape-shaped superconducting wires wound around a center member, an electric insulating layer formed outside the conductor layers, and a plurality of shielding layers formed outside the insulating layer, wherein, the conductor layers are formed, where N is a number of layers in the conductor layers and expressed by an integer, by gradually increasing a winding pitch of conductor layers in the same direction from an inner first layer to an N/2 layer when the number of layers is even, or from an inner first layer to a (N−1)/2 layer when the number of layers is odd, and then by gradually decreasing a winding pitch of conductor layers in an opposite direction to the inner layers from a N/2+1 layer to an N layer when the number of layers is even, or from a (N+1)/2 layer to an N layer when the number of layers is odd.

Abstract: A superconducting cable for alternating current, comprising conductor layers formed by a plurality of tape-shaped superconducting wires wound around a center member, an electric insulating layer formed outside the conductor layers, and a plurality of shielding layers formed outside the insulating layer, wherein

Abstract: A superconducting accelerating tube which is constructed by welding and connecting a plurality of half cells (11) formed of superconductor material in a dish form having a substantially constant wall thickness of the material, and having a small-diameter portion (11a) and a large-diameter portion (11b) and in which the shell diameter periodically varies. The half cells (11) are welded together via ring-shaped connecting members (12) formed of superconducting material and disposed between the small-diameter portions (11a), and the half cell (11) and connecting member (12) are formed of Nb.

Abstract: A superconducting accelerating tube which is constructed in a manner such that a plurality of components, formed of a superconducting material and individually having peripheral end portions adapted to be butted to one another, are butted to one another at the peripheral end portions, and the butting portions butted to one another are welded together. In the superconducting accelerating tube according to the present invention, the butting portions are welded by means of a laser beam, and the laser beam is applied to the butting portions so that the components are laser-welded to one another. Preferably, the accelerating tube is designed so that at least only the respective inner surfaces of the butting portions are laser-welded, and the depth of welding is not greater than half the thickness of the superconducting material and not smaller than 150 .mu.m.