The various embodiments described herein include methods, devices, and systems for fabricating and operating superconducting circuits. In one aspect, an electric circuit includes: (1) a first superconducting component having a first terminal, a second terminal, and a constriction region between the first terminal and the second terminal; (2) a second superconducting component having a third terminal and a fourth terminal; and (3) a first electrically-insulating component that thermally couples the first superconducting component and the second superconducting component such that heat produced at the constriction region is transferred through the first component to the second superconducting component.

The various embodiments described herein include methods, devices, and systems for fabricating and operating superconducting circuits. In one aspect, an electric circuit includes: (1) a first superconducting component having a first terminal, a second terminal, and a constriction region between the first terminal and the second terminal; (2) a second superconducting component having a third terminal and a fourth terminal; and (3) a first electrically-insulating component that thermally couples the first superconducting component and the second superconducting component such that heat produced at the constriction region is transferred through the first component to the second superconducting component.

An end closure for a superconductive electric cable which has at least one superconductive conductor which is surrounded by a tubular cryostat serving for conducting a cooling agent, which at its end is surrounded by a housing. The housing (G) has two walls (7, 8) which are separated from each other by an intermediate space (9) and having insulating material, wherein a thermal insulation containing gas is placed in the intermediate space. The pressure in the intermediate space (9) of the housing (G) is adjusted to a value of between 10.sup.9 mbar and 1000 mbar and, connected to the intermediate space (9) are a pressure measuring device (12) and a vacuum pump (11) which serve for adjusting the pressure prevailing in the intermediate space (9) of the housing (G).

A superconducting cable (1) includes a superconducting cable core (2) and a corrugated pipe (21) storing the superconducting cable core (2). The superconducting cable core (2) has a corrugated pipe (11), a superconductor (12) provided on the outer peripheral side of the corrugated pipe (11), and a heat insulating pipe (23) stored in the corrugated pipe (11) and having a smooth inner peripheral surface. A coolant flows through a flow passage (FP1) formed in the heat insulating pipe (23) and then flows through a flow passage (FP2) formed between an outer peripheral surface of the corrugated pipe (11) and an inner peripheral surface of the corrugated pipe (21).

A superconducting cable (1) includes a superconducting cable core (2) and a corrugated pipe (21) storing the superconducting cable core (2). The superconducting cable core (2) has a corrugated pipe (11), a superconductor (12) provided on the outer peripheral side of the corrugated pipe (11), and a heat insulating pipe (23) stored in the corrugated pipe (11) and having a smooth inner peripheral surface. A coolant flows through a flow passage (FP1) formed in the heat insulating pipe (23) and then flows through a flow passage (FP2) formed between an outer peripheral surface of the corrugated pipe (11) and an inner peripheral surface of the corrugated pipe (21).

A persistent current switch includes a superconducting wire including a substrate and a superconducting layer disposed on the substrate, and a heater. The superconducting wire includes a surface including a first portion and a second portion that are disposed apart from each other along a longitudinal direction of the superconducting wire. The first portion and the second portion face each other. The heater is sandwiched between the first portion and the second portion.

Provided is a low-temperature superconducting wire having a low stabilizing matrix ratio. The present invention provides a superconducting wire including: a low-temperature superconducting filament; a stabilizing Matrix encompassing the filament; and a sheath of a Metal-Insulator Transition (MIT) material, which encompasses the stabilizing matrix on the exterior of the stabilizing matrix. According to the present invention, a low stabilizing matrix ratio is achieved while coping with heat caused by a quench phenomenon, thereby reducing manufacturing cost and achieving a high current density.

An insulation-coated compound superconducting wire includes a compound superconducting wire having a compound superconducting part which includes a first matrix and a plurality of compound superconducting filaments containing compound superconducting phases, a reinforcing part disposed on the outer circumferential side of the compound superconducting part and includes a plurality of reinforced filaments, a second matrix and a second stabilizing material. A stabilizing part is disposed on at least one side among the inner circumferential side and the outer circumferential side of the reinforcing part. An electrical insulation part covers the outer circumferential surface of the compound superconducting wire, in which the insulation-coated compound superconducting wire has a critical current value (Ic) larger than that of the compound superconducting wire before being covered with the electrical insulation part.

An insulation-coated compound superconducting wire includes a compound superconducting wire having a compound superconducting part which includes a first matrix and a plurality of compound superconducting filaments containing compound superconducting phases, a reinforcing part disposed on the outer circumferential side of the compound superconducting part and includes a plurality of reinforced filaments, a second matrix and a second stabilizing material. A stabilizing part is disposed on at least one side among the inner circumferential side and the outer circumferential side of the reinforcing part. An electrical insulation part covers the outer circumferential surface of the compound superconducting wire, in which the insulation-coated compound superconducting wire has a critical current value (Ic) larger than that of the compound superconducting wire before being covered with the electrical insulation part.

Power transmission systems with cooling mechanisms, and methods of operating the same, are described. A power transmission system can include multiple support tower assemblies. Each of the support tower assemblies includes a support tower. One or more of the support tower assemblies includes a termination (i.e., a connection point via which electrical current and/or coolant can enter the transmission line and/or exit the transmission line). The power transmission system also includes multiple conductor assemblies suspended above a surface of the earth. Each conductor assembly includes an electrical conductor and is positioned between, and mechanically supported by, a pair of the support towers. The power transmission system also includes a coolant supply system that delivers a coolant fluid, during operation of the power transmission system, to at least one of the terminations, for cooling of the conductor assemblies.