Abstract: A Superconducting Quantum Interference Device (SQUID) is disclosed comprising a pair of resistively shunted Josephson junctions connected in parallel within a superconducting loop and biased by an external direct current (dc) source. The SQUID comprises a semiconductor substrate and at least one superconducting layer. The metal layer(s) are separated by or covered with a semiconductor material layer having the properties of a conductor at room temperature and the properties of an insulator at operating temperatures (generally less than 100 Kelvins). The properties of the semiconductor material layer greatly reduces the risk of electrostatic discharge that can damage the device during normal handling of the device at room temperature, while still providing the insulating properties desired to allow normal functioning of the device at its operating temperature. A method of manufacturing the SQUID device is also disclosed.

Abstract: This invention provides a superconducting magnet apparatus capable of preventing or restraining the heat invading into the apparatus and reducing the refrigeration load of an external refrigerator, at the time of changeover of a switch in transiting to a persistent current mode, and capable of quick changeover operation. In the superconducting magnet apparatus of the present invention (1), in transiting to a persistent current mode, a thermal superconducting switch (41) placed in a low-temperature domain and a mechanical switch (42) placed in a mid-temperature domain are turned on. Since the mechanical switch (42) is placed in the mid-temperature domain, even if a heat load is generated through the drive mechanism (60), it is not necessary to cool the mechanical switch to an extremely low temperature.

Abstract: A superconducting magnet system with a quench protection circuit includes a superconducting magnet having a plurality of series-connected superconducting coils, a persistent current switch connected in parallel with the superconducting coils, and first and second quench protection circuits connected in parallel with the superconducting coils and the persistent current switch. The first quench protection circuit includes anti-parallel diodes and parallelly connected resistive heaters and shunt resistors, and the resistive heaters and the shunt resistors are each connected in series with the diodes. The second quench protection circuit has a diode and a metal of copper connected with the diode, and a turn-on voltage of the diode in the second quench protection circuit is lower than a turn-on voltage of the diodes in the first quench protection circuit.

Abstract: A method and apparatus for reducing conductive thermal losses in high-current cryogenic power electronics systems needing large cables to interface between warm and cold environments. Thermal losses increase with increasing cross-sectional area. The total current at the warm/cold interface is split into many smaller currents by splitting the power buss into a plurality of parallel leads. Respective physical switches in each smaller lead at the interface interrupt current flow, and at the same time open the path for thermal conduction along the lead. When little or no current is flowing through the system, selected smaller leads of the power buss are physically opened by the associated switches to stop the thermal and electrical flow along these leads. Current diverts to another parallel lead in the buss but the cross section for heat flow is reduced at the interface.

Abstract: A superconducting current limiting device (30) comprising: an interconnected high magnetic permeability structure including a central core (50) interconnected to at least a first and second arm (31, 32) branching off therefrom; a superconductive coil (33, 34) surrounding the central core for biasing the central core; a first alternating current coil (36, 37) surrounding the first arm and interconnected to an alternating current source; a second alternating current coil (38, 39) surrounding a second arm and interconnected to an alternating current load; the first and second alternating current coils being magnetically coupled to the central core wherein the device operates so as to limit the current passing through the device upon the occurrence of a fault condition in the load.

Abstract: A superconducting magnet system includes resistive heaters and bidirectional diodes connected in series with each other installed in a superconducting coil protection circuit, and a diode is installed in a persistent current switch protection circuit.

Abstract: A method of protecting an MR imaging system including a plurality of coil groups includes connecting at least one first diode between terminals of a first coil group, connecting at least one second diode between terminals of a second coil group, wherein the second group is connected to the first coil group via a separation line, and connecting at least one quench heater between the separation line and the first and second diodes.

Abstract: A cryogenic current limiting fuse is disclosed together with a method of manufacturing a cryogenic current limiting fuse, the cryogenic current limiting fuse comprising a first cryogenic composite and a second cryogenic composite wherein at least one of the first and the second cryogenic composites has a non-linear and increasing resistivity with respect to at least one of temperature and current.

Abstract: A superconducting shielded core reactor (SSCR) operates as a passive device for limiting excessive AC current in a circuit operating at a high power level under a fault condition such as shorting. The SSCR includes a ferromagnetic core which may be either closed or open (with an air gap) and extends into and through a superconducting tube or superconducting rings arranged in a stacked array. First and second series connected copper coils each disposed about a portion of the iron core are connected to the circuit to be protected and are respectively wound inside and outside of the superconducting tube or rings. A large impedance is inserted into the circuit by the core when the shielding capability of the superconducting arrangement is exceeded by the applied magnetic field generated by the two coils under a fault condition to limit the AC current in the circuit. The proposed SSCR also affords reduced AC loss compared to conventional SSCRs under continuous normal operation.

Abstract: A secondary coil circuit for use with a multi-section protected superconductive magnet coil circuit is disclosed herein. The secondary coil circuit includes two circuit nodes, a ramping switch electrically connected between the two circuit nodes, and a number of secondary coils electrically connected between the two circuit nodes. The secondary coils are made of wire having substantially superconductive capability when cooled below a characteristic critical temperature level and conducting electric current below a characteristic critical current level. The secondary coils are sized and positioned relative to the superconductive magnet coils situated in the individual sections of the multi-section protected superconductive magnet coil circuit so as to functionally cooperate with the multi-section protected superconductive magnet coil circuit in producing and maintaining a magnetic field that is substantially homogeneous.

Abstract: A modular and scalable Matrix-type Fault Current Limiter (MFCL) that functions as a “variable impedance” device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. An inductor is connected in series with the trigger superconductor in the trigger matrix and physically surrounds the superconductor. The current surge during a fault will generate a trigger magnetic field in the series inductor to cause fast and uniform quenching of the trigger superconductor to significantly reduce burnout risk due to superconductor material non-uniformity.

Abstract: A device includes a flux pump and an electromagnet to be fed thereby for the production of highly constant magnetic fields of high field strength. In a flux pump of the rectifier type, switches used are MOSFETs. These MOSFETs include HTc superconductor material at operating temperatures. Preferably, the flux pump and a coil of the electromagnet are arranged in one and the same cryostat housing.

Abstract: An isolation transformer is introduced into a matrix fault current limiter (MFCL) and is used to couple elements in trigger matrices and current limiting matrices. The isolation transformer can either be a voltage step-up or step-down configuration. In step-up configurations, the increased voltage supplied to the current limiting elements improves the quenching of the superconductor. In step-down configurations, current limiting elements are subject to lower voltage potentials thereby reducing the electrical insulation requirement between the trigger matrix and the current limiting matrix. In addition, the voltage amplification coefficient of each isolation transformer can vary for different columns of the current limiting matrix to maximize the current limiting performance.

Abstract: A power system controller design for controlling fault current or load flow current by applying a variable inductive impedance. The device comprising multiple stages of transformers connected such that their primary coils are in series and carry the primary power. Their secondary circuits containing a device for interruption of secondary current. The secondary circuit of each stage having a small part of the primary energy flowing through them. Under normal conditions the interrupter allows secondary current to flow, producing no impedance on primary side. Upon operation of interrupter, inductive impedance appears across primary. Operation of single stages producing low inductive impedance on primary circuit. Operation of multiple stages producing higher inductive impedance on primary circuit. In a preferred embodiment, the transformers have saturating cores such that operation of single stages saturates their cores, producing low inductive impedance on primary circuit.

Abstract: A system and method for protecting a superconductor. The system may comprise a current sensor operable to detect a current flowing through the superconductor. The system may comprise a coolant temperature sensor operable to detect the temperature of a cryogenic coolant used to cool the superconductor to a superconductive state. The control circuit is operable to estimate the superconductor temperature based on the current flow and the coolant temperature. The system may also be operable to compare the estimated superconductor temperature to at least one threshold temperature and to initiate a corrective action when the superconductor temperature exceeds the at least one threshold temperature.

Abstract: A modular and scalable Matrix-type Fault Current Limiter (MFCL) that functions as a “variable impedance” device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. An inductor is connected in series with the trigger superconductor in the trigger matrix and physically surrounds the superconductor. The current surge during a fault will generate a trigger magnetic field in the series inductor to cause fast and uniform quenching of the trigger superconductor to significantly reduce burnout risk due to superconductor material non-uniformity.

Abstract: An isolation transformer is introduced into a matrix fault current limiter (MFCL) and is used to couple elements in trigger matrices and current limiting matrices. The isolation transformer can either be a voltage step-up or step-down configuration. In step-up configurations, the increased voltage supplied to the current limiting elements improves the quenching of the superconductor. In step-down configurations, current limiting elements are subject to lower voltage potentials thereby reducing the electrical insulation requirement between the trigger matrix and the current limiting matrix. In addition, the voltage amplification coefficient of each isolation transformer can vary for different columns of the current limiting matrix to maximize the current limiting performance.

Abstract: The invention is concerned with a resistive fault current limiter (FCL) based on thin superconducting films. The FCL comprises constrictions (2) with a reduced critical current, separated by connecting paths (3). Upon occurrence of a fault current, the former turn resistive simultaneously and build up a resistance which allows the applied voltage to drop entirely only over the constrictions. Only at a later stage, the connecting paths become resistive and dissipate energy. The thickness and width of an electrical bypass determine said normal resistivities of the constrictions and the connecting paths.

Abstract: A method and apparatus for magnetically triggering a superconductor in a superconducting fault current limiter to transition from a superconducting state to a resistive state. The triggering is achieved by employing current-carrying trigger coil or foil on either or both the inner diameter and outer diameter of a superconductor. The current-carrying coil or foil generates a magnetic field with sufficient strength and the superconductor is disposed within essentially uniform magnetic field region. For superconductor in a tubular-configured form, an additional magnetic field can be generated by placing current-carrying wire or foil inside the tube and along the center axial line.

Abstract: The present invention provides an oxide superconductor thick film which is formed on a substrate or a board and has a high Jc and Ic and a method for manufacturing the same. Predetermined amounts of materials containing elements of Bi, Pb, Sr, Ca and Cu are weighed, mixed and subjected to steps of calcining, milling, and drying, and thereafter an organic binder and an organic vehicle are added thereto to prepare a (Bi, Pb)2+aSr2Ca2Cu3Oz, superconductive paste, which is applied to the surface of a substrate or a board in a thickness of 260 &mgr;m or more and dried. Thereafter, the paste is first subjected to burning at temperatures of 835° C. to 840° C. for 100 hours, then pressurization, and further burning at temperatures of 835° C. to 840° C. for 100 hours, thereby preparing an oxide superconductor thick film having a film thickness of 130 &mgr;m or more having a high Jc and Ic.

Abstract: A static excitation system that can eliminate shaft vibrations of a generator and overvoltage when it is underexited is provided. The static excitation system includes an initial excitation equipment; a step-down transformer; a 3-phase diode bridge; a boost chopper provided with a transistor and a resister, and maintaining DC voltage to be constant; a DC chopper provided with a plurality of transistors and diodes, and supplying DC power to a rotor of a generator; a boost controller for controlling the boost chopper; and a DC chopper controller for controlling the DC chopper, wherein, overvoltage applied on the excitation system when underexcited is eliminated owing to the boost chopper preventing any changes at an output terminal of the generator from being transferred to the excitation system, and maintaining the excitation DC voltage to be constant; and also owing to the DC chopper which is capable of 4 quadrant operation, hereby pole slipping of the generator can be prevented.

Abstract: A superconducting device comprises an inductive current limiter with an annular element produced from high-Tc superconducting material. The device is further provided with a soft-magnetic yoke leg enclosed by the material and with a transformer with primary and secondary windings and a soft-magnetic flux element with a plurality of yoke legs. The magnetic flux element is designed to contain between the primary winding and the secondary winding of the transformer the yoke leg of the current limiter, the conductor of one winding producing a switch current for the current limiter.

Abstract: A Winding for high voltage transformer having a predetermined number of spaced winding groups joined to form a single winding transformer, each spaced winding group being solenoid wound from a predetermined number of turns. A method of forming the winding and a transformer including the winding are also disclosed.

Abstract: A superconducting shielded core reactor (SSCR) operates as a passive device for limiting excessive AC current in a circuit operating at a high power level under a fault condition such as shorting. The SSCR includes a ferromagnetic core which may be either closed or open (with an air gap) and extends into and through a superconducting tube or superconducting rings arranged in a stacked array. First and second series connected copper coils each disposed about a portion of the iron core are connected to the circuit to be protected and are respectively wound inside and outside of the superconducting tube or rings. A large impedance is inserted into the circuit by the core when the shielding capability of the superconducting arrangement is exceeded by the applied magnetic field generated by the two coils under a fault condition to limit the AC current in the circuit. The proposed SSCR also affords reduced AC loss compared to conventional SSCRs under continuous normal operation.

Abstract: A superconducting fault current controller/current controller employs a superconducting-shielded core reactor (SSCR) with a variable impedance in a secondary circuit to control current in a primary circuit such as an electrical distribution system. In a second embodiment, a variable current source is employed in a secondary circuit of an SSCR to control current in the primary circuit. In a third embodiment, both a variable impedance in one secondary circuit and a variable current source in a second circuit of an SSCR are employed for separate and independent control of current in the primary circuit.

Abstract: A semiconductor device that includes an integrated circuit and an HBM structure formed on different semiconductor substrates is provided. The HBM structure may include input or output or input/output circuitry coupled to the integrated circuit and protection structures coupled to the input or output or input/output circuitry. In an embodiment, the integrated circuit may include input or output or input/output structures spaced across an area of the integrated circuit. The input or output or input/output circuitry of the HBM structure may be coupled to the input or output or input/output structures of the integrated circuit. A method for developing a design for an HBM structure is also provided. The method may include coupling an HBM structure formed on a first semiconductor substrate to an integrated circuit formed on a second semiconductor substrate. The method may also include testing the HBM structure and altering the HBM design based on the testing.

Abstract: An over-voltage protected integrated circuit is provided, which includes a discharge node, an input-output pad, a signal trace, which is coupled to the input-output pad, and a pair of back-to-back diodes, which is coupled between the first signal trace and the discharge node.

Abstract: A superconducting magnet electrical circuit is provided for quench protection. A superconducting coil assemblage is provided including a plurality of spatially separated main and secondary magnet coil portions. The main magnet coil portions are connected in series to form at least one main coil series circuit. The secondary magnet coil portions are also connected in a series to form at least one secondary coil series circuit. At least one temperature limiting circuit is also provided. The temperature limiting circuit may be a quench heater circuit or a quench resistor circuit. The temperature limiting circuit has a plurality of quench heaters or a plurality of quench resistors connected with the superconducting coil assemblage. A superconductive switch is coupled with the superconducting coil assemblage.

Abstract: The invention is concerned with a resistive fault current limiter (FCL) based on thin superconducting films. The FCL comprises constrictions (2) with a reduced critical current, separated by connecting paths (3). Upon occurrence of a fault current, the former turn resistive simultaneously and build up a resistance which allows the applied voltage to drop entirely only over the constrictions. Only at a later stage, the connecting paths become resistive and dissipate energy. The thickness and width of an electrical bypass determine said normal resistivities of the constrictions and the connecting paths.

Abstract: A superconducting magnet electrical circuit is provided for quench protection. A superconducting coil assemblage is provided including a plurality of spatially separated main and secondary magnet coil portions. The main magnet coil portions are connected in series to form at least one main coil series circuit. The secondary magnet coil portions are also connected in a series to form at least one secondary coil series circuit. At least one temperature limiting circuit is also provided. The temperature limiting circuit may be a quench heater circuit or a quench resistor circuit. The temperature limiting circuit has a plurality of quench heaters or a plurality of quench resistors connected with the superconducting coil assemblage. A superconductive switch is coupled with the superconducting coil assemblage.

Abstract: Protection systems are described for electrical systems such as electrical arc furnaces. The protection systems may be designed and used to detect and clear faults that may occur within the electric arc furnace. For example, a pair of Rogowski coils may be used to detect current at their respective locations along a conductors, and output corresponding signals to a multi-function, differential relay having multiple voltage and current inputs. By comparing the signals from the Rogowski coils, the differential relay may determine whether a fault exists at some point along the conductors and between the pair of Rogowski coils. Further, the relay may then, in response to the fault, trip a circuit breaker or other network protection device, so that the fault may be corrected.

Abstract: A modular and scalable Matrix-type Fault Current Limiter (MFCL) that functions as a “variable impedance” device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. The detection of a fault and subsequent activation of the current-limiting impedance of the MFCL are done passively by built-in matrix design, without assistance of active control mechanisms.

Abstract: A higher harmonic suppressor element 10 includes a higher harmonic coil 12 for suppressing a higher harmonic and a thermal fuse 14 which is connected in series with the higher harmonic coil 12 and also which is melted down by heat generated by the higher harmonic coil 12. The higher harmonic coil 12 and the thermal fuse 14 are both contained in the same envelope body 16. Also, the higher harmonic coil 12 is equipped with a magnetic core 121 and a winding 122 wound around the magnetic core 121. In this configuration, the thermal fuse 14 is in tight contact with the magnetic core by means of an adhesive agent etc. If an over-current flows through the higher harmonic coil 12, it runs hot to thereby melt down the thermal fuse 14. With the melting down of the thermal fuse 14, which is connected in series with the higher harmonic coil 12, the over-current flow to the higher harmonic coil 12 is blocked.

Abstract: A superconducting magnet circuit includes, besides a closed circuit formed of a plurality of unit superconducting coils 2a and 2b connected in series and a first persistent-current switch 4, a second persistent-current switch 5 which forms a closed circuit by connecting the ends of an arbitrary unit superconducting coil 2a, and is therefore made up of the two closed circuits, whereby their mutual induction suppresses the decay of the magnet apparatus' central magnetic field to provide extreme stability.

Abstract: A method for reducing ac loss in a superconducting coil of cable-in-conduit type superconductor made from chrome-coated compound superconducting strands, characterized in that when a superconducting coil is produced by the wind-and-react technique, bending or twist strain is applied in an amount of 0.15˜0.3% to the conductor cable portion after it has been heat-treated to form the superconducting compound, thereby separating the individual superconducting strands the chrome coat on which sintered as the result of heat treatment and further characterized in that the applied bending or twist strain is thereafter reverted to 0.1% or less, thereby reducing the ac loss of the superconducting coil.

Abstract: A superconducting magnet assembly comprises a superconducting magnet (1) which, under working conditions, generates a magnetic field in a working volume, the superconducting magnet being connected in parallel with a superconducting switch (3), the switch and magnet being adapted to be connected in parallel to a power source (4) whereby under working conditions with the switch (3) open, the magnet (1) can be energised by the power source to generate a desired magnetic field in the working volume following which the switch (3) is closed, characterised in that the assembly further comprises a resistor (5) connected in series with the switch (3), the resistor (5) and switch (3) being connected in parallel to each of the magnet (1) and the power source (4).

Abstract: The present invention relates to an electrical transformer which includes a primary winding coupled to first and second magnetic circuits. A magnetic flux is driven through the magnetic circuits by the primary winding. First and second secondary windings are also provided, each associated with a respective one of the magnetic circuits and being electrically connected together in series opposition. A closed superconducting fault current winding is also provided to link with the magnetic flux in the second magnetic circuit.

Abstract: An apparatus in the field of power transmission, the apparatus includes a superconducting component or another component to be cooled, in a cryostat. A vacuum switch is provided in order to prevent heat being introduced into the cryostat by means of thermal conduction through the electricity cable of the component in the event of an electricity failure. This vacuum switch is integrated in a bushing in the electricity cable, so that its vacuum completes the thermal insulation of the cryostat.

Abstract: A polymer material comprising channels whose temperature-independent conductivity exceeds 106 S/cm is used to form conductive films and various devices containing such films. Conduction takes place through threads and channels passing through the film which is otherwise a dielectric. The film is produced by first depositing a macromolecular polymer substance on a substrate. During preparation, the substance is preferably in a viscous liquid state. Stable free electrons (polarons) are then created by ionizing the substance. This is assisted by exposure to UV radiation and the presence of strong polar groups in the polymer. Various enrichment techniques, such as applying a strong electric field, are then used to join the superpolarons together into conducting threads within the medium. To stabilize the positions of the threads, the medium is then solidified, preferably by cooling it below its glass transition point or inducing cross-linking between the macromolecules. The film may be a membrane.

Abstract: A flux pump of the rectifier type having high-temperature superconductors with switches, which can be controlled by way of a heater, in particular with trigger pulses D′ and self-stabilization in time with the rectifier is disclosed. An arrangement of the flux pump and a superconductor electromagnet, which may be supplied using the flux pump, may be integrated in a common cryostat housing.

Abstract: On transition from the superconducting state to the normal conducting state, current limiters having a high-temperature superconductor increase their electrical resistance and thereby limit an electric current which is flowing through them. To provide electrical stabilization, the high-temperature superconductor is combined with a silver foil having a layer thickness of <50 &mgr;m to form an extensive composite conductor with good conductivity. The ratio of the layer thickness of the high-temperature superconductor to that of the silver foil should be >10. To produce this composite conductor, the silver sheet is placed on one side on a 2 mm thick MgO powder layer and, on the other side, is covered with a 600 &mgr;m thick so-called green sheet which contains a high-temperature superconductor powder and an organic binder.

Abstract: A system and method for removing unwanted magnetic flux from a superconductor. A device can generate a controllable electric field potential using an asymmetric electric field potential to efficiently remove the magnetic flux in different directions in the superconductor.

Abstract: A device includes a flux pump and an electromagnet to be fed thereby for the production of highly constant magnetic fields of high field strength. In a flux pump of the rectifier type, switches used are MOSFETs. These MOSFETs include HTc superconductor material at operating temperatures. Preferably, the flux pump and a coil of the electromagnet are arranged in one and the same cryostat housing.

Abstract: Circuitry detects a quench in a superconducting magnet and discharges the superconducting magnet into a load, such as a utility system, at a substantially constant voltage. The circuitry can be an inverter, arranged between the superconducting magnet and the load, which may operate in overload mode during discharge. Discharging occurs until the amount of energy in the superconducting magnet is below a predetermined level.

Abstract: A current limiting device includes a substrate or carrier body at least partially formed of electrically insulating material. At least one printed conductor configuration formed of high Tc superconductive material is disposed on the substrate or carrier body and has end pieces for establishing contact. The printed conductor configuration has a number of partial conductors which are connected in parallel between their end pieces and have at least approximately the same conductor length. A method for producing the device includes forming the printed conductor configuration by structuring a corresponding layer.

Abstract: In a superconducting coil system an m×n array of wound cores are arranged and n pairs of strands, totalling at 2n strands, are passed in pairs through the hollow center of the cores so that the current will flow in mutually opposite directions in each paired strands. The system can reduce AC loss, completely avoiding current imbalance in strands and being designed easily.

Abstract: In a current limiting arrangement based on a superconducting transformer (30), a load (21) can be supplied with power without any interruption by providing an auxiliary winding (14) in parallel with the superconducting primary winding (12) of the transformer (30). This auxiliary winding (14) carries the excess current in the event of a short circuit and allows the superconducting primary winding (12), which has been heated due to the current limiting, to cool down. Once the short circuit has been cleared, the latter winding can once again carry the rated current, without any losses, immediately. The auxiliary winding (14) is composed of a normally conductive material and has an additional stray impedance.

Abstract: An actively shielded, superconducting magnet arrangement for the generation of a magnetic field in the direction of a z axis in a working volume arranged about z=0, having a radially inner and a radially outer coaxial coil system, wherein the two coil systems carry the same current and have dipole moments of the same magnitude, but of opposite directions, wherein parts of the radially outer coil system (C2′) are electrically connected in series with the radially inner coil system (C1) and wherein a first superconducting switch (S1) is provided via which during operation a superconducting short circuit of a first current path of the magnet arrangement can be effected, is characterized in that a section (A′) of the radially outer coil system (C2′), which can be superconductingly short-circuited during operation via a further superconducting switch (S2) is arranged symmetrically to the plane z=0 and that the further superconducting current path formed by the superconductingly shor

Abstract: Circuitry detects a quench in a superconducting magnet and discharges the superconducting magnet into a load, such as a utility system, at a substantially constant voltage. The circuitry can be an inverter, arranged between the superconducting magnet and the load, which may operate in overload mode during discharge. Discharging occurs until the amount of energy in the conducting magnet is below a predetermined level.

Abstract: The bridge of a fault current limiter of the bridge type used in an AC power transmission and/or distribution system, has a superconducting coil as a first path and a conventional conductor coil as a second path connected in parallel to the first path. The second path has a substantially higher resistance to DC than the first path, and the superconducting path has a substantially higher impedance to AC than the second path. A DC component of a fault current flows through the superconducting path and an AC component of the fault current flows through the second path. Thermal losses and cooling requirements are reduced.