A superconducting coil device includes a vacuum vessel, a superconducting coil located inside the vacuum vessel, a heat shield surrounding the superconducting coil within the vacuum vessel, and an electric current introduction line for introducing an electric current into the superconducting coil. The electric current introduction line includes an outer current lead part located outside of the heat shield, within the vacuum vessel, and thermally coupled to the heat shield, and an inner current lead part located inside of the heat shield and connecting the outer current lead part to the superconducting coil. The outer current lead part includes a main body serving as an electric current path to the superconducting coil, an insulation layer that covers the main body, and a heat shield layer that covers the insulation layer and has a lower emissivity than the insulation layer.

One example includes a superconducting current control system. The system includes an inductive coupler comprising a load inductor and a control inductor. The inductive coupler can be configured to inductively provide a control current from the control inductor to a superconducting circuit device based on a load current being provided through the load inductor. The system also includes a current control element comprising a superconducting quantum interference device (SQUID) array comprising a plurality of SQUIDs. The current control element can be coupled to the inductive coupler to control an amplitude of the load current through the load inductor, and thus to control an amplitude of the control current to the superconducting circuit device.

The invention relates to a superconducting electrical switch. The switch comprises two parallel branches of superconducting material in a loop, and a magnetic field generator which generates a time-varying magnetic field through the loop in a direction generally parallel to the axis of the loop. The magnetic field generator is selectively activated and de-activated to switch the electrical switch between a low-resistance state and a higher-resistance state. In the low-resistance state, there is no magnetic field through the loop and transport current flows through the loop. In the higher-resistance state, a magnetic field through the loop induces a screening current such that the sum of the transport current and the screening current is substantially equal to the critical current or is greater than the critical current of the superconducting material. The switch may be used in, for example, a rectifier or fault current limiter.

Charging method for a superconductor magnet system with reduced stray field, weight and space includes: arranging the system within a charger magnet bore; with T.sub.main>T.sub.main.sup.crit and T.sub.shield>T.sub.shield.sup.crit, applying a current I.sub.charger to the charger magnet and increasing I.sub.charger to a first current I.sub.1>0; lowering a main superconductor bulk magnet temperature T.sub.main to an operation temperature T.sub.main.sup.op, with T.sub.main.sup.op<T.sub.main.sup.crit, while keeping T.sub.shield>T.sub.shield.sup.crit; lowering I.sub.charger to a second current I.sub.2<0, thereby inducing a persistent current IP.sub.main in the main magnet; lowering a shield magnet temperature T.sub.shield to an operation temperature T.sub.shield.sup.op, with T.sub.shield.sup.op<T.sub.shield.sup.crit; increasing I.sub.charger to zero, thereby inducing a persistent current IP.sub.shield in the shield magnet; removing the magnet system from the charger bore, and keeping T.sub.main≤T.sub.main.sup.op with T.sub.main.sup.op<T.sub.main.sup.crit and T.sub.shield≤T.sub.shield.sup.op with T.sub.shield.sup.op<T.sub.shield.sup.crit; where: T.sub.main.sup.crit: main magnet critical temperature and T.sub.shield.sup.crit: shield magnet critical temperature.

In examples, provided are leadless power couplers that include (1) a thermal insulating system having an outer wall and an inner wall, (2) a first electrically conductive winding located outside the thermal insulating system, where the first electrically conductive winding is configured to create a varying magnetic field, (3) a plurality of second electrically conductive windings located inside the thermal insulating system and configured to couple to the varying magnetic field, the plurality of second electrically conductive windings being superconductors, (4) a plurality of cryogenic rectifiers, each cryogenic rectifier being coupled to a respective second electrically conductive winding in the plurality of second electrically conductive windings, and (5) a plurality of cryogenic cables coupled between respective outputs of the plurality of cryogenic rectifiers and respective loads.

A magnetic resonance imaging (MRI) system includes a superconducting magnet assembly with a superconducting field coil for generating a stationary uniform main magnetic field. A gradient system includes a gradient coil for generating gradient magnetic fields and a gradient amplifier which is connectable to the gradient coil for driving the gradient coil. A switch assembly is adapted for galvanically coupling the superconducting field coil to the gradient amplifier. In this way, it is possible for energizing and discharging a superconducting magnet of an MRI system in an easy and cost-efficient way.

A system comprises a superconducting magnet comprising a coil of superconducting material. The coil includes electrical terminals. The windings of the coil are separated by a metallic conductor. A control circuit is coupled to the terminals to drive a current through the coil to charge the superconducting magnet and configured to provide a current through the coil that is sufficiently small to avoid a quenching effect of the superconducting magnet but also large enough to charge the magnet within a predetermined time period. A cooling structure is thermally coupled to the coil to remove heat caused by charging the superconducting magnet with the current to allow for the current to be sufficiently large to charge the magnet within the predetermined time period without causing the quenching effect.

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.

This superconducting magnet includes: a superconducting coil that is formed by winding a first superconducting wire rod; a second superconducting wire rod, which is disposed by being thermally in contact with and electrically insulated from the superconducting coil, and which has a superconducting transition temperature that is lower than that of the first superconducting wire rod; voltage terminals that are disposed at a plurality of areas of the second superconducting wire rod; a voltmeter connected to the voltage terminals; and a switch circuit connected to the voltmeter. The switch circuit interrupts a current when receiving an output from the voltmeter, the current being one that is to be supplied to the superconducting coil.

A system for activating trapped field magnets in a superconducting material is disclosed. The system includes a superconducting material element and an electromagnet source disposed proximate the superconducting material element. The electromagnet source is configured to produce a magnetic field pulse sufficient to activate the superconducting material element. Furthermore, substantially all of a magnetic field generated by the magnetic field pulse is contained within an area that has smaller physical lateral dimensions than the superconducting material element.