Abstract: Apparatus for measuring gravitational attraction of the Earth comprising a loop formed from a superconductor material. The loop being divided into a first portion and a second portion having a predetermined length and configuration. The loop being positioned under predetermined angle with respect to a horizontal plane. There are also means for initiation of a flow of superconducting carriers in each of first and second portions, and at least one phase shift inducing means formed in the loop. The first portion being positioned with respect to the second portion in such a way that the superconducting carriers conducted through the first portion spend a period of time at a different gravitational potential of the Earth than superconducting carriers conducted through the second portion, thus creating a gravitationally induced phase shift. The apparatus being completely isolated from influence of any external magnetic field.

Abstract: Method and apparatus of measuring a critical current value of a superconducting wire formed by wire sections S(n), n being 1.ltoreq.n.ltoreq.N and initially set to 1, comprising a first step (a) of determining electric currents I(m), m being 1.ltoreq.m.ltoreq.M; a second step (b) of setting m to 1; a third step (c) of passing the electric current I(m) through the wire section S(n); a fourth step (d) of detecting a voltage generated in the wire section S(n) by the electric current I(m); a fifth step (e) of replacing m with m+1; a sixth step (f) of repeating the steps (c) to (e) until m is equal to M; a seventh step (g) of replacing n with n+1; an eighth step (h) of repeating the steps (b)-(g) until n is equal to N, thereby obtaining N.times.

Abstract: In a radiation detection device using superconducting tunnel junctions, the increase in electric capacitance and the decrease in electric resistance due to the increase in junction area for improvement of the detection efficiency are largely repressed by the invention. The junctions are connected in series. The number of the series-connected junctions is settled in the range of larger than 0.05 (SC.sub.o /C')0.5 and smaller than 20 (SC.sub.o /C')0.5 or 10SCo/C', whichever is larger, where S is the total area of the junctions, cm.sup.2, C.sub.o is the electric capacitance per unit area of the junctions, F/cm.sup.2, and C' is the electric capacitance connected to the device in parallel so as to transfer and amplify the signals from the device, F.

Abstract: A magnetic telescope utilized to detect flaws in underground articles such as underground piping, implements multiple stages in the form of geometric and electronic configurations to enhance noise suppression. The geometric configuration includes a differential configuration of two pair of source coils which generate the magnetic flux, and gradiometers which pick-up the magnetic flux. A superconducting quantum interference device (SQUID) is utilized to detect the magnetic flux. The electronic configuration includes circuitry to adjust the current in the source coil pairs to minimize the signal seen by the SQUID when no underground article is present. The electronic configuration also includes feedback circuitry to feed back magnetic flux to the SQUID based on the signal detected by the SQUID. Combining the geometric and electronic configurations provides enhanced noise suppression so that the SQUID is capable of detecting smaller flaws in the underground piping for the same amount of source magnetic flux.

Abstract: The invention comprises a method for determining the hole or electron concentration, transition temperature, ratio T.sub.c /T.sub.c (max), or state of doping of a material capable of exhibiting superconductivity when cooled below its critical temperature, by measuring the thermopower of a sample of the material above the critical temperature of the material and determining from the thermopower the hole or electron concentration, transition temperature, ratio T.sub.c /T.sub.c (max), or state of doping of the material as to whether it is underdoped, overdoped or optimally doped. The sample may be differentially heated and/or cooled to generate a temperature difference across the sample, the temperature difference across the sample measured, the voltage across the sample measured, and the hole concentration or similar determined from the measured temperature difference and the measured voltage. Means for determining the hole concentration, transition temperature, or doping of the material is also claimed.

Abstract: A magnetic head has a superconducting quantum interference device having a ring made of a superconductive material including a Josephson junction which links to a magnetic flux generated by a magnetic recording medium, and a magnetic pole for guiding the magnetic flux generated by the magnetic recording medium or the ring made of a superconductive material arranged in parallel to a plane of the magnetic recording medium so that the magnetic flux generated by the magnetic recording medium flows into a through-hole of the ring. A magnetic recording and reproducing apparatus includes such a magnetic head, a winding to which a reproduced signal from the magnetic head is applied and the superconductive ring including the Josephson junction arranged such that the magnetic flux generated by the winding flows thereto.

Abstract: A superconducting gyroscope of the present invention includes a circuit which produces a magnetic field which is synchronous with the rate of rotation experienced by the gyroscope, a sensing circuit for converting the synchronous magnetic field into an electric signal, a first shield made of superconducting material for performing shielding of external stray fields, and a second shield disposed inside the first shield and made of superconducting material for expelling trapped residual magnetic flux. The synchronous magnetic field producing circuit includes a magnetic core shaped in a toroid with an air gap. The magnetic core may alternatively be formed in meandering shape by a plurality of separate magnetic core members with a plurality of air gaps therebetween. The sensing circuit includes at least one SQUID which can be directly coupled to the magnetic core.

Abstract: The present invention provides a method for determining the granular nature of superconductive materials and devices which includes the steps of: conducting a substantially rectangular current pulse through the superconductive material, maintaining the temperature of the superconductive material at a substantially constant temperature which does not exceed the critical temperature of the superconductive material; determining the amplitude of the current pulse; determining the electrical resistance, R, of the superconductive material resulting from conducting current pulse through the superconductive material; increasing the current until the electrical resistance of the superconductive material becomes saturated; determining the electrical resistance difference, .delta., between the electrical resistance, R, of the saturated superconductive material and a total normal state electrical resistance of the superconductive material; generating a first output signal if .vertline..delta..vertline..ltoreq..epsilon.

Abstract: An improved AC susceptometer and methodology for its use which is particularly suitable for the characterization of the properties of superconducting materials. Added to the circuitry of a conventional AC susceptometer is frequency domain analytical equipment for measuring the induced magnetic response. The addition of frequency domain measuring equipment permits the determination of the harmonic components of the induced magnetic response. The measurement of the harmonic components of the response also provides novel methodology for studying the phenomena of flux penetration, flux pinning and movement and permits the measurement of parameters such as lower critical field, critical temperatures, and the irreversibility line.

Abstract: An improved AC susceptometer and methodology for its use which is particularly suitable for the characterization of the properties of superconducting materials. Added to the circuitry of a conventional AC susceptometer is frequency domain analytical equipment for measuring the induced magnetic response. The addition of frequency domain measuring equipment permits the determination of the harmonic components of the induced magnetic response. The measurement of the harmonic components of the response also provides novel methodology for studying the phenomena of flux penetration, flux pinning and movement and permits the measurement of parameters such as lower critical field, critical temperatures, and the irreversibility line.

Abstract: This invention relates to an apparatus and method for measuring the resistance of superconductors. Structures of this type, generally, allow the resistance of the superconductor to be accurately measured in a non-destructive manner by using a bifilar coil which includes an integrated loop/switch formed from the bifilar coil.

Abstract: The present invention provides a method for measuring the intragranular and ntergranular critical current of a granular superconductive material, comprising the steps of: 1) conducting a substantially rectangular electronic pulse through the material so as to conduct a current through the material such that when the intergranular critical current of the material is exceeded, any grains present in the material remain in a superconducting state when the current level is below the intragranular critical current; 2) measuring the current through the material while conducting the pulse; 3) measuring a voltage difference across the material while conducting the pulse; 4) determining the intergranular critical current through the material by discerning a non-zero voltage difference across the material and contemporaneously measuring the current; and 5) determining the intragranular critical current through the material by varying the current to discern a current level at which the electrical resistance of the materi

Abstract: In a method and apparatus for detecting and locating a quench zone in a superconducting coil, a sensor is positioned adjacent to and in heat transfer communication with the entire length of the superconducting coil. When a portion of the superconducting coil becomes normal, the adjacent portion of the sensor becomes resistive. A series of electrical pulses sent along the sensor are reflected back by the discontinuity in impedance which occurs at such a normal zone. The reflected pulses and echo pulses produced by various terminations on the sensor are detected by an associated receiver and processor which calculates the location of the resistive zone along the sensor and the corresponding quench zone along the superconducting coil using information derived from the pulses. A second embodiment provides two sensors which are adjacent to and in heat transfer communication with the coil which are pulsed from opposite ends.

Abstract: An apparatus for the measurement of the critical current of a superconductive sample, e.g., a clad superconductive sample, the apparatus including a conductive coil, a means for maintaining the coil in proximity to a superconductive sample, an electrical connection means for passing a low amplitude alternating current through the coil, a cooling means for maintaining the superconductive sample at a preselected temperature, a means for passing a current through the superconductive sample, and, a means for monitoring reactance of the coil, is disclosed, together with a process of measuring the critical current of a superconductive material, e.g., a clad superconductive material, by placing a superconductive material into the vicinity of the conductive coil of such an apparatus, cooling the superconductive material to a preselected temperature, passing a low amplitude alternating current through the coil, the alternating current capable of generating a magnetic field sufficient to penetrate, e.g.

Abstract: An apparatus for observing a superconductive phenomenon is disclosed. In the apparatus, a cooling unit cools a superconductor having a threshold temperature at which the superconductor changes from the normal conductive phase to the superconductive phase, and a magnetic field is applied thereto. A current is supplied to the superconductor, and there are clearly observed a phenomenon on which an electric resistance thereof becomes zero at a threshold temperature thereof, a phenomenon on which the superconductor changes from the normal conductive phase to the superconductive phase at a threshold current to be supplied thereto, and a phenomenon on which the super conductor changes from the normal conductive phase to the superconductive phase at a threshold magnetic field to be applied thereto.

Abstract: The area of a loop made of superconducting material is decreased to incre the magnetic field on the surface of a test piece adjacent the loop for determining the critical field, H.sub.c, of the test piece. A loop with a gap having a temporary plug placed therein in which a persistent current is established has a nozzle forming the gap thereon for receiving a test piece. The test piece then completes the circuit permitting removal of the temporary plug. The area of the loop is then decreased resulting in an increase in magnetic field at the surface of the test piece. When the critical field of the test piece is reached, magnetic flux will leak from the internal area of the loop, thereby determining the critical field of the test piece. A continuous length of superconducting material can be tested for discontinuities or spots of low critical field, H.sub.c.

Abstract: An apparatus for observing a superconductive phenomenon is disclosed. In the apparatus, a cooling unit cools a superconductor having a threshold temperature at which the superconductor changes from the normal conductive phase to the superconductive phase, and a magnetic field is applied thereto. A current is supplied to the superconductor, and there are clearly observed a phenomenon on which an electric resistance thereof becomes zero at a threshold temperature thereof, a phenomenon on which the superconductor changes from the normal conductive phase to the superconductive phase at a threshold current to be supplied thereto, and a phenomenon on which the superconductor changes from the normal conductive phase to the superconductive phase at a threshold magnetic field to be applied thereto.

Abstract: Device for detecting the quenching of part a superconducting element comprising two identical superconducting conductors electrically connected in parallel is provided with means (104, 105, 109, 110) of detecting a difference in intensity or phase between the currents flowing in the conductors. An application to a superconducting current limiter is described.

Abstract: Weak links in superconductors are detected by observing the effect of magnetic field modulation on the microwave resistance of superconductors. The phase detected response to the magnetic modulation can show a peak at T.sub.c. The presence of peak(s) at temperatures below T.sub.c indicates the presence of weak links in the superconductor.

Abstract: A read/write head particularly suitable for mapping the superconductive properties of a sample of superconducting material. The head is arranged so that the reading and writing gaps are coaxial. Although the gaps are coaxial, the reading gap and the writing gap may be optimized in length and width to provide efficient reading and writing performance. The coaxial disposition of the heads eliminates parallax error to permit detailed mapping of the properties of the surface of a sample of superconductive material.

Abstract: A head with a pick-up coil is attached to a supporter so that the head is freely movable along the direction perpendicular to the surface of a superconductor. Fluid spouted from the spout hole of the head maintains the height (gap space) of the head from the surface. The head is firmly fixed to the supporter in the direction along the surface. Since the relative position of the head in the direction along the surface of the superconductor is changable by drive means for moving the superconductor or the head, the distribution of the magnetic flux which is trapped in the superconductor is measured by scanning the surface of the superconductor with pick-up coil.

Abstract: Apparatus and methodology for mapping the superconductive properties of a sample of superconducting material. The material is cooled so that it is a mixed state and an alternating magnetic field is induced in a portion of the sample to be tested. The harmonic component of the induced alternating magnetic response is measured at a location proximate to the point of induction. As the inducing and measuring devices are displaced relative to the sample the measured amplitude of the harmonic component is stored in suitable storage means as a function of location in the sample. Thus, a map of the superconducting properties of the sample may be generated.

Abstract: Apparatus and method for noncontact, radio-frequency shielding current characterization of materials. Self- or mutual inductance changes in one or more inductive elements, respectively, occur when materials capable of supporting shielding currents are placed in proximity thereto, or undergo change in resistivity while in place. Such changes can be observed by incorporating the inductor(s) in a resonant circuit and determining the frequency of oscillation or by measuring the voltage induced on a coupled inductive element. The present invention is useful for determining the critical temperature and superconducting transition width for superconducting samples.

Abstract: Apparatus and methodology for the rapid and inexpensive characterization of superconducting materials. The method and apparatus induces an alternating magnetic field in the sample to be tested. If the material is a superconductor odd harmonics are generated in the alternating magnetic response of the material near the transition temperature. The superconducting transitions are manifested by a peak or peaks in the odd harmonic components of the alternating magnetic response as a function of temperature. The peaks of the harmonic components are detected to indicate the presence and number of superconducting transitions.

Abstract: The present invention provides a straightforward sensor and method for quench detection in a superconducting coil, magnet or inductor. The superconducting sensor of the present invention consists of a probe having a twisted loop of superconducting wire in a protective sheath which is co-wound with the superconducting coil, and a readout device. A very small amount of energy is applied to the superconducting loop of wire in the probe by the readout device and its resistance is monitored by readout device. When joule heating occurs in the superconducting coil as a result of a portion becoming normal, the heat is transferred to a corresponding portion of the probe causing a portion of the superconducting wires therein to become normal. This causes the resistance in the superconducting wires to change and this change is detected or measured by the readout device which is magnetically coupled to the wires of the probe.

Abstract: Apparatus for determining the electrical characteristics of a superconductive material in a range of microwave frequencies and in a range of cryogenic temperatures has the material incorporated within a resonant cavity mounted on a cold finger for maintaining the material at a predetermined temperature. A pair of test waveguides extend oppositely of the cavity and terminate in separable waveguide junctions for passage of microwave energy to measure the microwave characteristics of the cavity as affected by the superconductive material. The cavity and test waveguides are enclosed in a vacuum chamber from which the cold finger extends for connection to controlled temperature cryogenic cooling equipment. The chamber also contains a plurality of calibration waveguides which extend parallel to the test waveguides, each calibration waveguide terminating oppositely in separable junctions.

Abstract: A cantilever beam is employed to place a magnet in proximity to a sample while the sample is maintained at a superconducting temperature. The magnet causes the sample, assuming it is superconductive, to itself generate a magnetic field which interacts with the magnet. Means are provided for measuring the movement of the cantilever beam, such movement being a measure of the interaction of the sample's magnetic field with the magnet. Several types of cantilever beams are disclosed, one of which is adapted to move in a direction orthogonal to the surface of the sample and another of which is adapted to move parallel to the surface of the sample. This enables the obtaining of quantitative measurements of the bulk properties of high temperature superconducting materials.

Abstract: Disclosed is a distance measuring system suitably usable in a semiconductor microcircuit manufacturing lithographic apparatus such as an aligner or a stepper, for measuring the position or the distance of movement of a movable object such as a mask stage or a wafer stage. The system includes a magnetic field producing portion such as a magnet for producing a predetermined magnetic field, a superconducting quantum interference device coupled to the mask stage or the wafer stage. Further, there are provided a magnetic flux detecting portion for outputting signals corresponding to changes in the magnetic flux, in the magnetic field, passing through the superconducting quantum interference device and a signal processing unit for processing the output signals of the magnetic flux detecting portion to detect the position or the distance of movement of the mask stage or the wafer stage.

Abstract: Weak links in electrically continuous superconductors are detected by observing the effect of magnetic field modulation on the dc resistance of superconductors. The phase detected response to the magnetic modulation shows a peak at T.sub.c. The presence of a second peak at temperatures below T.sub.c, and concomitantly the appearance of a tail on the low temperature end of the dc resistance vs temperature curve indicates the presence of weak links in the superconductor.

Abstract: A microvertex particle detector for use in a high energy physic collider including a plurality of parallel superconducting thin film strips separated from a superconducting ground plane by an insulating layer to form a plurality of superconducting waveguides. The microvertex particle detector indicates passage of a charged subatomic particle by measuring a voltage pulse measured across a superconducting waveguide caused by the transition of the superconducting thin film strip from a superconducting to a non-superconducting state in response to the passage of a charged particle. A plurality of superconducting thin film strips in two orthogonal planes plus the slow electromagnetic wave propogating in a superconducting transmission line are used to resolve N.sup.2 ambiguity of charged particle events.

Abstract: The invention relates to a method and apparatus to detect the superconductive state by measuring the change in the resistance of a sample. A dc magnetic field is imposed on the sample while the temperature is swept. The strength of the magnetic field is held below the critical value and is frequency modulated by the application of an ac field in such a way that total magnetic field is always positive. The resistance of the sample is measured incrementally as the temperature is swept and is phase detected at the modulation frequency. According to this embodiment, only magnetic field dependent changes demonstrating a precipitous drop in resistance identify a composition as superconductive.