Abstract: A current limiting device having an electrical superconductor for attachment in an electrical circuit, the superconductor being made of material having a critical current density which varies with applied magnetic field. A magnetic field generator generates a magnetic field to which the superconductor is exposed. Under normal working conditions a magnetic field applied causes the critical current density to be less than a maximum critical current density. A controller adjusts the critical current density such that after a current carried by the superconductor exceeds the critical current density so that the superconductor transforms to a resistive state, the controller can be activated to increase the critical current density causing the superconductor to return the superconducting condition without terminating the flow of current through the superconductor.

Abstract: A current limiting device including at least one superconductor and at least one nonsuperconducting shunt resistor in parallel with each superconductor. Each superconductor has a first main superconductor face in contact with a main shunt resistor face of a shunt resistor so as to form a compound conductor generally in the form of a meandering band having a band width greater than approximately 3.5 times the superconductor thickness. At least one insulator has opposing faces each in contact with a compound conductor. Multiple compound conductors are arranged such that current flows in opposite directions through adjacent compound conductors.

Abstract: High T.sub.c superconducting magnetic shields are provided, together with a method of fabricating such shields, wherein the shields exhibit very high critical applied magnetic field values of at least about 50 Gauss at 77 K. In fabrication procedures, a particulate superconducting ceramic oxide (24) (e.g., thallium 2223) is placed within an uniaxial die assembly (10) and subjected to compression while the die is heated via an external heating jacket (26). After formation of a self-sustaining body (24a), the die (10) is additionally heated via the jacket (26). External heating of the die (10) with the superconducting material therein reduces internal stresses within the shield body.

Abstract: A superconductive switch has a first layer of a superconductive coil wire wound around a shaft clockwise from the first end to the middle and counterclockwise from the middle to the second end. A second layer of the wire is wound around the first layer in identical fashion. A third layer of the wire is wound around the second layer counterclockwise from the first end to the middle and clockwise from the middle to the second end. An electrical heater is located between the first and second layers, and a stratum of electrical insulation, discrete from that of the coil wire, is located between the second and third layers.

Abstract: The present invention relates to a superconductive coil assembly which may be used particularly for a current limiter, the coil assembly comprising a plurality of coaxial cylindrical coils electrically connected in series, each coil comprising two windings of superconductive material electrically connected in parallel, arranged coaxially and wound in opposite directions, wherein in each coil, the windings are separated by a material which has a surface resistance in the radial direction lying in the range 10.sup.-5 .OMEGA..m.sup.2 to 10.sup.-2 .OMEGA..m.sup.2 at the temperature of the cryostat, and in which the strands which constitute the superconductive wires may themselves be covered with a layer of the same material.

Abstract: A superconducting switch is composed of anisotropic magnetic material. The switch has a first superconducting section, a variable resistive section and a second superconducting section. An external magnetic field is applied so that the first and second superconducting sections remain superconducting and the resistive section changes resistance when the magnetic field applied exceeds the critical field of the variable resistance section. The different critical field regions are achieved by exploiting the natural critical field anisotropy of the ceramic superconductors (a previously unobserved phenomena in metal superconductors). By making the different sections with different orientations they will exhibit different critical field valves for a given direction of applied fields. The state of the switch is changed by either increasing or decreasing the external magnetic field about the critical field value of the resistive section of the switch.

Abstract: A semiconductor film is provided characterized by having high carrier mobility and carrier density. The semiconductor film is doped with the rare-earth element erbium so as to improve its temperature stability. The semiconductor film is thereby particularly suited for use as a magnetic field sensing device, such as a Hall effect sensor or magnetoresistor. The semiconductor film is formed from a narrow-gap Group III-V compound, preferably indium antimonide, which is n-doped with the erbium to provide an electron density sufficient to increase temperature stability. In particular, the semiconductor film is characterized by a nini-structure which is generated using a slab-doping technique. The slab-doping process encompasses the growing of alternating layers of doped and undoped layers of the Group III-V compound, with the doped layers being substantially thinner than the undoped layers, and preferably as thin as one atomic plane.

Abstract: A method for sensing an applied magnetic field uses a superconductor element with superconductive material as a sensor. The element is cooled to its superconducting state and current is supplied to the element. An applied magnetic field is applied to the superconducting material and an output from the superconductor element is fed to a feed back power source. In the feedback power source a comparison is made between an input voltage from the superconductive element and a reference voltage. Current is applied to a coil for applying a bias magnetic field to the superconductor element based on the comparison. With this method, the input voltage and the reference voltage are made as equal as possible. A superconductive device includes a coil for applying an AC power source and a coil for applying a DC power source.

Abstract: The invention relates to a resistive current limiter having at least one conductor of a superconductive high-temperature material, carrying the rated current. The electrically active length of said conductor is at least three times greater than its linear extent.

Abstract: A resistive current limiter takes the form of a hollow cylinder and is composed of high-temperature superconducting material. In this connection, the high-temperature superconducting material may be a polynary oxide.To produce said resistive current limiter, a homogeneous melt is prepared from an oxide mixture, suitable for forming high-temperature superconductors, in a specified stoichiometry and said melt is allowed to run, at temperatures above 900.degree. C., into a casting zone which rotates about its horizontal axis. The molding, solidified as a cylinder, is removed from the casting zone. The cylinder is sawn so as to produce a gap extending parallel to its axis. Furthermore, a multiplicity of slits are sawn into the cylinder parallel to the gap. Finally, the cylinder is heat-treated for up to 150 hours at 700.degree. to 900.degree. C. in an oxygen-containing atmosphere.

Abstract: A superconductinve magneto-resistive device for use in a sensor system for sensing an external magnetic field which is formed so as to have a predetermined pattern for a current path through which a supplied current flows. The pattern includes portions formed close and parallel to each other so that magnetic fields induced by respective currents flowing through the portions can be cancelled with each other.

Abstract: A superconductive switch is provided with a pair of superconductive routes which are wound around a cylindrical core in a bifilar fashion. One superconductive wire is constituted of a pair of superconductive routes. The superconductive routes are twisted around each other at a uniform pitch. By virtue of the twisting, electromagnetic force which may exerted in the superconductive wires cancel each other, so that the wire-movement of the superconductive wire is restrained. Accordingly, the electrical current flowing through the superconductive switch can be increased.

Abstract: A magnetic field distribution measuring apparatus for measuring an external magnetic field distribution includes a substrate made of a nonmagnetic material and having opposite surfaces, a plurality of magnetoresistive elements deposited on one surface of the substrate and each made of a superconductive material having a weak coupling at the grain boundaries. Coils are provided on the other surface of the substrate at positions corresponding to the magnetoresistive elements. The coils are sequentially applied with AC current to produce AC magnetic field having a peak value greater than a magnetic field threshold level at which the magnetoresistive element changes the state from a superconductive state to a magnetoresistive state. Detecting the degree of magnetoresistive from each magnetoresistive element, the magnetic field distribution can be detected.

Abstract: A superconductive apparatus has a superconductive device such as a superconductive magneto-resistive device. The superconductive device is mounted within an airtight package which is sealed to create an airtight state. Before sealing, the airtight package is evacuated to replace the internal air thereof with an inert gas.

Abstract: Novel methods of electronically modulating magnetic fields are described. The basic principle of the instant invention is based on the well known Meissner Effect. A superconducting element is placed within a magnetic field whose strength is much less than the critical field of the superconductor. The field flux is excluded out of the superconducting medium. When the superconductor is now forced into its mixed or normal phase by external means, the magnetic field around it is modified and thus modulation of that field near the superconductor surface is possible. Three distinct methods of modulating magnetic fields on the surfaces of superconductors are detailed and some applications disclosed.

Abstract: A magnetic image detection device which measures a magnetic image in the first or second dimension by using a superconducting body. In the magnetic image detection device, multiple band-shaped superconducting bodies are provided in parallel on a nonmagnetic dielectric substrate, and electrodes are provided on both ends of the superconducting bodies so as to form pairs. A detection circuit detects resistance between the electrodes on both ends of the multiple superconducting bodies according to intensity of external magnetic field.

Abstract: A superconducting temperature controller that can sense the temperature of an area and also heat the enclosed area. A superconducting thin film resistor mounted on a substrate is disposed in an enclosed housing that forms a vacuum. Also disposed within the housing is a heat sink that keeps the temperature inside the housing below the transition temperature of the superconducting material that forms the thin film resistor. By applying a constant voltage to the thin film resistor, the temperature of the substrate and thin film resistor can be maintained at a predetermined level that is within the transition temperature region of the superconducting material being used.

Abstract: A current controlled superconducting switch has a current controlling constriction such that the level of the input determines the condition of the switch. A plurality of the superconducting switches are connected to produce a logic scheme.

Abstract: A current limiter according to the invention has two resistors, the first one consisting of a thin layer of a material which may become superconducting and the second one is a resistance layer applied on first resistor, the latter resistor layer being dimensioned such that its resistance becomes considerably lower than the resistance of the superconducting layer when it is not superconducting, however with a resistance of such a magnitude that, in the current circuit in question, it limits the current to a permissible value. For mechanical support of the resistors, an insulator is included in the current limiter, and the superconducting material is applied on insulator. The resistors and the insulator are arranged immersed into a cryotank.

Abstract: A superconducting switch is bifilarly wound with two cupro-nickel matrix superconductors. Three layers of the wire is wound, with each layer of windings wrapped with four wires in hand and input and output portions of the wires adjacent to one another. This configuration and relationship between adjacent wires is maintained throughout all the layers of the entire winding. The windings are started 180.degree. apart and input and output leads are extracted 180.degree. degrees apart. The switch also includes a core around which the wires and a heater are wound, a casing to enclose the core, heater and wire windings, and a solid epoxy body which fills substantially all of the voids in the switch. Switch leads are stabilized using a copper channel in which they are soldered to avoid quenching when they are subjected to a high current in a magnetic field, and the copper channel is surrounded and soldered to a copper braid.

Abstract: A superconducting switch is bifilarly wound with two superconductors. The superconductors are wound around a core inside a housing and are electrically insulated from one another. One of the superconductors is radially further out than the other and a common heater element is between the superconductors to switch both superconductors substantially simultaneously between the persistent and non-persistent states.

Abstract: Electrical switches used in conjunction with high energy superconductive windings must be able to quickly absorb large amounts of electrical energy since switching of the superconducting current is accomplished by means of transition to the resistive state in the switch portion of the superconducting current loop. Furthermore, to minimize the heat generated during the transition to the resistive state, the switch itself should exhibit a relatively high resistance while at the same time exhibiting a low external magnetic field. The switch should also exhibit minimal stray magnetic fields, especially in those applications requiring field uniformity. These objectives are achieved in a persistent current switch which includes a length of superconductive material disposed in a compact, thermally insulated volume which also includes a mechanism for heating at least a portion of the superconductive conductor in the switch in order to return it to its resistive state.

Abstract: A thermometer capable of providing temperature measurement over a wide temperature range comprises at least one temperature detection unit consisting of a first superconductor as a core, and a normal conductor and a second supercondutor sequentially superposed coaxially on the first superconductor; a first power source disposed to pass electric current between the first and second superconductors, a second power source disposed between the opposite terminals of the first superconductor, and a voltmeter connected to the first and second superconductors. This thermometer effects measurement of temperature by fixing the value of the electric current from the first power source and changing the value of the electric current from the second power source thereby causing cyclic change of the voltage and measuring the increment of electric current from the second power which is required to cause one cycle of change of the voltage.

Abstract: A magnetically controllable variable resistor comprises two separate elements between which a layer applied to at least one of the elements and a material with a magnetically variable specific resistance is sandwiched under mechanical pressure at least one of the elements having at least three tapering structures on its surface adjacent to the layer so that pressure contacts are formed in the region of these structures.

Abstract: A persistence switch comprises a diode and superconductive wire in thermal contact with the diode. The heat evolved by current through the forward biased diode raises the temperature of the superconductor above the transition temperature. The diode characteristic of the switch permits a plurality of such switches to be arranged in a network for selection by a relatively few signal conductors.

Abstract: Contacts and resistors are provided for circuitry which are very resistant to interdiffusion and which have good stability. In particular, contacts to superconductive circuitry and resistors for superconductive circuitry are provided. In general, a contact or resistor material is in thermodynamic equilibrium with the materials which are to be contacted. Additionally, the contact or resistor is comprised of an intermediate phase or solid solution which is present in stable form in the materials to be contacted. These intermediate phases or solid solutions are multicomponent systems, such as intermetallic compounds. The contacts or resistors can be formed by layering of suitable materials and the invention can be used to provide good chip-module connections for many types of circuitry.

Abstract: A superconducting microbridge is provided for use in superconducting quantum interference devices wherein a pair of spaced layers of superconductive material are connected by a weak link bridge to establish an electrical junction. The superconductive layers and bridge are coated with a semiconductor material shunting the bridge at room temperatures to prevent the destruction of the device by minute electrical currents while the coating acts as a dielectric permitting normal electrical behavior of the microbridge at cryogenic temperatures.

Abstract: A superconducting switch or bistable device comprising a superconductor in a cryogen maintaining a temperature just below the transition temperature, having a window of the proper optical frequency band for passing a laser beam which may impinge on the superconductor when desired. The frequency of the laser is equal to or greater than the optical absorption frequency of the superconducting material and is consistent with the ratio of the gap energy of the switch material to Planck's constant, to cause depairing of electrons, and thereby normalize the superconductor. Some embodiments comprise first and second superconducting metals. Other embodiments feature the two superconducting metals separated by a thin film insulator through which the superconducting electrons tunnel during superconductivity.