Abstract: A superconducting cable comprises a superconductor 60, two or more coolant passages including an outgoing coolant passage 12 and a returning coolant passage 14 that transfer a coolant that cools the superconductor, and a heat insulating pipe 10 inside which the superconductor 60 and the coolant passages are formed. For the coolant passages, by a double structured tube of an inner tube 6 and an outer tube 8, the outgoing coolant passage 12 is formed in the internal space of the inner tube 6 and the returning coolant passage 14 is formed in the space between the inner tube 6 and the outer tube 8, the inner tube 6 is formed between the outgoing coolant passage 12 and the returning coolant passage 14 of a heat insulating material, the superconductor 60 is disposed on the outer circumferential side of the inner tube 6, and the superconductor is cooled by the coolant that flows through the returning coolant passage.

Abstract: A superconducting cable comprises a superconductor 60, two or more coolant passages including an outgoing coolant passage 12 and a returning coolant passage 14 that transfer a coolant that cools the superconductor, and a heat insulating pipe 10 inside which the superconductor 60 and the coolant passages are formed. For the coolant passages, by a double structured tube of an inner tube 6 and an outer tube 8, the outgoing coolant passage 12 is formed in the internal space of the inner tube 6 and the returning coolant passage 14 is formed in the space between the inner tube 6 and the outer tube 8, the inner tube 6 is formed between the outgoing coolant passage 12 and the returning coolant passage 14 of a heat insulating material, the superconductor 60 is disposed on the outer circumferential side of the inner tube 6, and the superconductor is cooled by the coolant that flows through the returning coolant passage.

Abstract: A transportation system with high-efficiency and large-capacity utilizing potential energy. A transportation vehicle travels at a high speed by potential energy by a level difference on a magnetic levitation guide disposed in a vacuum transportation passage to transport transportation cargoes to a destination location. The transportation vehicle is levitated on the magnetic levitation guide non-contactingly and with a low frictional resistance utilizing a superconduction. Superconductive magnetic levitation holds the transportation vehicle at a stable floated position mainly utilizing a binding force by the pinning effect of a superconductor.