WorldWideScience

Sample records for single pole superconducting

  1. Development of a superconducting claw-pole motor

    International Nuclear Information System (INIS)

    Watanabe, E.; Kikukawa, K.; Satoh, Y.; Torii, S.

    2008-01-01

    We have developed and produced a superconducting claw-pole motor for a trial purpose as a method to make the best use of the characteristic of superconductivity without collector rings or rotating superconducting coils that need to be cryocooled, and made some examinations. The unique feature in this motor is to have the mechanism that supports the reaction magnetic force generated in the axial direction

  2. Compact high-field superconducting quadrupole magnet with holmium poles

    Energy Technology Data Exchange (ETDEWEB)

    Barlow, D.B.; Kraus, R.H. Jr.; Lobb, C.T.; Menzel, M.T. (Los Alamos National Lab., NM (United States)); Walstrom, P.L. (Grumman Space Systems, Los Alamos, NM (United States))

    1992-03-15

    A compact high-field superconducting quadrupole magnet was designed and built with poles made of the rare-earth metal holmium. The magnet is intended for use in superconducting coupled-cavity linear accelerators where compact high-field quadrupoles are needed, but where the use of permanent magnets is ruled out because of trapped-flux losses. The magnet has a clear bore diameter of 1.8 cm, outside diameter of 11 cm, length of 11 cm, and pole tip length of 6 cm. The effect of using holmium, a material with a higher saturation field than iron, was investigated by replacing poles made of iron with identical poles made of holmium. The magnet was operated at a temperature of 4.2 K and reached a peak quadrupole field gradient of 355 T/m, a 10% increase over the same magnet with iron poles. This increase in performance is consistent with calculations based on B-H curves that were measured for holmium at 4.2 K. (orig.).

  3. Superconducting 63-Pole 2 Tesla Wiggler for Canadian Light Source

    International Nuclear Information System (INIS)

    Khruschev, S.V.; Kuper, E.A.; Lev, V.H.; Mezentsev, N.A.; Miginsky, E.G.; Repkov, V.V.; Shkaruba, B.A.; Syrovatin, V.M.; Tsukanov, V.M.

    2006-01-01

    A superconducting 63-pole wiggler with the average period 34 mm designed and fabricated at the Institute of Nuclear Physics in Novosibirsk for Synchrotron Radiation Center (CLS) in Canada is described. The maximum field 2.2 Tesla in the median plane has been achieved. The liquid helium consumption less than 0.03 liters per hour in operating mode has been reached. In January 2005, the wiggler was installed in the storage ring in CLS and now experiments are already underway. The main parameters of the magnet and the cryogenic systems as well as test results are presented

  4. Superconducting 63-pole 2 T wiggler for Canadian Light Source

    International Nuclear Information System (INIS)

    Khruschev, S.V.; Kuper, E.A.; Lev, V.H.; Mezentsev, N.A.; Miginsky, E.G.; Repkov, V.V.; Shkaruba, V.A.; Syrovatin, V.M.; Tsukanov, V.M.

    2007-01-01

    A superconducting 63-pole wiggler with the average period 34 mm designed and fabricated in the Institute of Nuclear Physics in Novosibirsk for Synchrotron Radiation Center Canadian Light Source (CLS) in Canada is described. The maximum field 2.2 T in the median plane has been achieved. The liquid helium consumption less than 0.03 L h in operating mode has been reached. It allows refilling liquid helium once a year. In January 2005, the wiggler was installed in the storage ring in CLS and now experiments are carried out. The main parameters of the magnet and the cryogenic systems as well as test results are presented

  5. Tree-loop duality relation beyond single poles

    Energy Technology Data Exchange (ETDEWEB)

    Bierenbaum, Isabella [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Buchta, Sebastian; Draggiotis, Petros; Malamos, Ioannis; Rodrigo, German [Valencia Univ. Paterna (Spain). Inst. de Fisica Corpuscular

    2012-11-15

    We develop the Tree-Loop Duality Relation for two- and three-loop integrals with multiple identical propagators (multiple poles). This is the extension of the Duality Relation for single poles and multi-loop integrals derived in previous publications. We prove a generalization of the formula for single poles to multiple poles and we develop a strategy for dealing with higher-order pole integrals by reducing them to single pole integrals using Integration By Parts.

  6. Superconducting Single Photon Detectors

    NARCIS (Netherlands)

    Dorenbos, S.N.

    2011-01-01

    This thesis is about the development of a detector for single photons, particles of light. New techniques are being developed that require high performance single photon detection, such as quantum cryptography, single molecule detection, optical radar, ballistic imaging, circuit testing and

  7. A Pole Pair Segment of a 2-MW High-Temperature Superconducting Wind Turbine Generator

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Mijatovic, Nenad; Kellers, Jürgen

    2017-01-01

    A 2-MW high-temperature superconducting (HTS) generator with 24 pole pairs has been designed for the wind turbine application. In order to identify potential challenges and obtain practical knowledge prior to production, a full-size stationary experimental setup, which is one pole pair segment...... and the setup in terms of the flux density, the operating condition of the HTS winding, and the force-generation capability. Finite element (FE) software MagNet is used to carry out numerical simulations. The findings show that the HTS winding in the setup is a good surrogate for these that would be used...

  8. A Pole Pair Segment of a 2 MW High Temperature Superconducting Wind Turbine Generator

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Mijatovic, Nenad; Kellers, Jürgen

    2016-01-01

    A 2 MW high temperature superconducting (HTS) generator with 24 pole pairs has been designed for the wind turbine application. In order to identify potential challenges and obtain practical knowledge prior to production, a fullsize stationary experimental set-up, which is one pole pair segment...... generator and the set-up in terms of the flux density, the operating condition of the HTS winding, and the force-generation capability. Finite element (FE) software MagNet is used to carry out numerical simulations. The findings show that the HTS winding in the set-up is a good surrogate...

  9. Control System of the Superconducting 63-Pole 2-Tesla Wiggler for Canadian Light Source

    International Nuclear Information System (INIS)

    Kuper, E.A.; Mezentsev, N.A.; Miginsky, E.G.; Repkov, V.V.; Tsukanov, V.M.

    2006-01-01

    A control system of the superconducting 63-pole wiggler fabricated at the Institute of Nuclear Physics in Novosibirsk (BINP) for Synchrotron Radiation Center in Canada (CLS) is described. Specific electronics and software which provide continuos monitoring of all the superconducting wiggler parameters as well as full control and monitoring of power suppliers and cryogenics machines, have been designed. The control system is VME-based. A client/server architecture of the software allowed us to integrate easily this system into the CLS distributed control system

  10. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhen, E-mail: zhen.huang@sjtu.edu.cn [Academy of Information Technology and Electrical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Ruiz, H.S., E-mail: dr.harold.ruiz@le.ac.uk [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Coombs, T.A., E-mail: tac1000@cam.ac.uk [Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2017-03-15

    Highlights: • Different compositions of the magnetic poles have been obtained depending on the relative orientation of the magnetizing coil and the surfaces of the columns of bulks that conform a magnetic pole. • Two bidimensional models accounting for the electromagnetic response of the top and lateral cross sections of three columns of HTS bulks subjected to multiple pulsed magnetic fields have been created. • An extended PFM strategy has been proposed by considering the magnetization of at least three successive columns of HTS bulks per pole. In the extended PFM strategy the area of each one of the poles can be seen increased by a factor of 200%-400% - Abstract: High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied

  11. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    International Nuclear Information System (INIS)

    Huang, Zhen; Ruiz, H.S.; Coombs, T.A.

    2017-01-01

    Highlights: • Different compositions of the magnetic poles have been obtained depending on the relative orientation of the magnetizing coil and the surfaces of the columns of bulks that conform a magnetic pole. • Two bidimensional models accounting for the electromagnetic response of the top and lateral cross sections of three columns of HTS bulks subjected to multiple pulsed magnetic fields have been created. • An extended PFM strategy has been proposed by considering the magnetization of at least three successive columns of HTS bulks per pole. In the extended PFM strategy the area of each one of the poles can be seen increased by a factor of 200%-400% - Abstract: High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied

  12. An electrical gearbox by means of pole variation for induction and superconducting disc motor

    International Nuclear Information System (INIS)

    Inacio, S; Inacio, D; Pina, J M; Valtchev, S; Neves, M V; Rodrigues, A L

    2008-01-01

    In this paper, a poly-phase disc motor innovative feeding and control strategy, based on a variable poles approach, and its application to a HTS disc motor, are presented. The stator windings may be electronically commutated to implement a 2, 4, 6 or 8 poles winding, thus changing the motor's torque/speed characteristics. The motor may be a conventional induction motor with a conductive disc rotor, or a new HTS disc motor, with conventional copper windings at its two iron semi-stators, and a HTS disc as a rotor. The conventional induction motor's operation principle is related with the induced electromotive forces in the conductive rotor. Its behaviour, characteristics (namely their torque/speed characteristics for different number of pole pairs) and modelling through Steinmetz and others theories are well known. The operation principle of the motor with HTS rotor, however, is rather different and is related with vortices' dynamics and pinning characteristics; this is a much more complex process than induction, and its modelling is quite complicated. In this paper, the operation was simulated through finite-elements commercial software, whereas superconductivity was simulated by the E-J power law. The Electromechanical performances of both motors where computed and are presented and compared. Considerations about the systems overall efficiency, including cryogenics, are also discussed

  13. Superconductivity in single wall carbon nanotubes

    Directory of Open Access Journals (Sweden)

    H Yavari

    2009-08-01

    Full Text Available   By using Greens function method we first show that the effective interaction between two electrons mediated by plasmon exchange can become attractive which in turn can lead to superconductivity at a high critical temperature in a singl wall carbon nanotubes (SWCNT. The superconducting transition temperature Tc for the SWCNT (3,3 obtained by this mechanism agrees with the recent experimental result. We also show as the radius of SWCNT increases, plasmon frequency becomes lower and leads to lower Tc.

  14. Operation of a five-pole superconducting wiggler in the DCI positron ring and design of the beamline

    International Nuclear Information System (INIS)

    Bazin, C.; Dubuisson, J.M.; Labeque, A.; Level, M.P.; Raoux, D.; Sommer, M.; Zyngier, H.; Chomillier, J.; Frouin, J.; Garreau, Y.; Loupias, G.; Tarbes, J.

    1989-01-01

    A five-pole superconducting wiggler has been installed in the DCI positron ring and operated without disturbing the machine characteristics at full energy (1.85 GeV) and maximum current (300 mA). Three beamlines have been built which feed six beam ports. The first two-crystal monochromator to be used for Compton scattering has been commissioned although the sagittal focusing has not yet been tested

  15. A two-pole Halbach permanent magnet guideway for high temperature superconducting Maglev vehicle

    International Nuclear Information System (INIS)

    Jing, H.; Wang, J.; Wang, S.; Wang, L.; Liu, L.; Zheng, J.; Deng, Z.; Ma, G.; Zhang, Y.; Li, J.

    2007-01-01

    In order to improve the levitation performance of the high temperature superconducting (HTS) magnetic levitation (Maglev) vehicle, a two-pole Halbach array's permanent magnet guideway (PMG) is proposed, which is called as Halbach PMG. The finite element method (FEM) calculations indicate that Halbach PMG has a wider high-field region than the present PMG of equal PM's transverse section. The levitation force of bulk HTSCs with the present PMG and Halbach PMG are measured. The results show that at different levitation gaps, the force ratios based on the Halbach PMG are about 2.3 times larger than that on the present PMG, which greatly increases the load capability of the system. Therefore, both the numerical analysis and experimental results have confirmed that the Halbach PMG will further enhance the performance of the vehicle and it is possible to decrease the total numbers of onboard HTSCs, reducing overall costs. So based on the Halbach PMG, we further study the width ratios between HTSCs and PMG for making the better use of the onboard HTSCs. Some preliminary results are given. These results are important for further HTS Maglev vehicle system designs using Halbach PMG

  16. Mechanical design and analysis of an eight-pole superconducting vector magnet for soft x-ray magnetic dichroism measurements

    Energy Technology Data Exchange (ETDEWEB)

    Arbelaez, D.; Black, A.; Prestemon, S.O.; Wang, S.; Chen, J.; Arenholz, E.

    2010-01-13

    An eight-pole superconducting magnet is being developed for soft x-ray magnetic dichroism (XMD) experiments at the Advanced Light Source, Lawrence Berkley National Laboratory (LBNL). Eight conical Nb{sub 3}Sn coils with Holmium poles are arranged in octahedral symmetry to form four dipole pairs that provide magnetic fields of up to 5 T in any direction relative to the incoming x-ray beam. The dimensions of the magnet yoke as well as pole taper, diameter, and length were optimized for maximum peak field in the magnet center using the software package TOSCA. The structural analysis of the magnet is performed using ANSYS with the coil properties derived using a numerical homogenization scheme. It is found that the use of orthotropic material properties for the coil has an important influence in the design of the magnet.

  17. 1D-transport properties of single superconducting lead nanowires

    DEFF Research Database (Denmark)

    Michotte, S.; Mátéfi-Tempfli, Stefan; Piraux, L.

    2003-01-01

    of the nanowire is small enough to ensure a 1D superconducting regime in a wide temperature range below T. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied DC current......We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ̃40 nm and a very large aspect ratio (̃500). The diameter...

  18. Modeling and Development of Superconducting Nanowire Single Photon Detectors

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal outlines a research project as the central component of a Ph.D. program focused on the device physics of superconducting nanowire single photon...

  19. A high efficiency superconducting nanowire single electron detector

    NARCIS (Netherlands)

    Rosticher, M.; Ladan, F.R.; Maneval, J.P.; Dorenbos, S.N.; Zijlstra, T.; Klapwijk, T.M.; Zwiller, V.; Lupa?cu, A.; Nogues, G.

    2010-01-01

    We report the detection of single electrons using a Nb0.7Ti0.3N superconducting wire deposited on an oxidized silicon substrate. While it is known that this device is sensitive to single photons, we show that it also detects single electrons with kilo-electron-volt energy emitted from the cathode of

  20. Suite of three protein crystallography beamlines with single superconducting bend magnet as the source

    International Nuclear Information System (INIS)

    MacDowell, Alastair A.; Celestre, Richard S.; Howells, Malcolm; McKinney, Wayne; Krupnick, James; Cambie, Daniella; Domning, Edward E; Duarte, Robert M.; Kelez, Nicholas; Plate, David W.; Cork, Carl W.; Earnest, Thomas N.; Dickert, Jeffery; Meigs, George; Ralston, Corie; Holton, James M.; Alber, Thomas; Berger, James M.; Agard, David A.; Padmore, Howard A.

    2004-01-01

    At the Advanced Light Source (ALS), three protein crystallography (PX) beamlines have been built that use as a source one of the three 6 Tesla single pole superconducting bending magnets (superbends) that were recently installed in the ring. The use of such single pole superconducting bend magnets enables the development of a hard x-ray program on a relatively low energy 1.9 GeV ring without taking up insertion device straight sections. The source is of relatively low power, but due to the small electron beam emittance, it has high brightness. X-ray optics are required to preserve the brightness and to match the illumination requirements for protein crystallography. This was achieved by means of a collimating premirror bent to a plane parabola, a double crystal monochromator followed by a toroidal mirror that focuses in the horizontal direction with a 2:1 demagnification. This optical arrangement partially balances aberrations from the collimating and toroidal mirrors such that a tight focused spot size is achieved. The optical properties of the beamline are an excellent match to those required by the small protein crystals that are typically measured. The design and performance of these new beamlines are described

  1. Suite of three protein crystallography beamlines with single superconducting bend magnet as the source.

    Science.gov (United States)

    MacDowell, Alastair A; Celestre, Rich S; Howells, Malcolm; McKinney, Wayne; Krupnick, James; Cambie, Daniella; Domning, Edward E; Duarte, Robert M; Kelez, Nicholas; Plate, David W; Cork, Carl W; Earnest, Thomas N; Dickert, Jeffery; Meigs, George; Ralston, Corie; Holton, James M; Alber, Tom; Berger, James M; Agard, David A; Padmore, Howard A

    2004-11-01

    At the Advanced Light Source, three protein crystallography beamlines have been built that use as a source one of the three 6 T single-pole superconducting bending magnets (superbends) that were recently installed in the ring. The use of such single-pole superconducting bend magnets enables the development of a hard X-ray program on a relatively low-energy 1.9 GeV ring without taking up insertion-device straight sections. The source is of relatively low power but, owing to the small electron beam emittance, it has high brightness. X-ray optics are required to preserve the brightness and to match the illumination requirements for protein crystallography. This was achieved by means of a collimating premirror bent to a plane parabola, a double-crystal monochromator followed by a toroidal mirror that focuses in the horizontal direction with a 2:1 demagnification. This optical arrangement partially balances aberrations from the collimating and toroidal mirrors such that a tight focused spot size is achieved. The optical properties of the beamline are an excellent match to those required by the small protein crystals that are typically measured. The design and performance of these new beamlines are described.

  2. Suite of three protein crystallography beamlines with single superconducting bend magnet as the source

    Energy Technology Data Exchange (ETDEWEB)

    MacDowell, Alastair A.; Celestre, Richard S.; Howells, Malcolm; McKinney, Wayne; Krupnick, James; Cambie, Daniella; Domning, Edward E; Duarte, Robert M.; Kelez, Nicholas; Plate, David W.; Cork, Carl W.; Earnest, Thomas N.; Dickert, Jeffery; Meigs, George; Ralston, Corie; Holton, James M.; Alber, Thomas; Berger, James M.; Agard, David A.; Padmore, Howard A.

    2004-08-01

    At the Advanced Light Source (ALS), three protein crystallography (PX) beamlines have been built that use as a source one of the three 6 Tesla single pole superconducting bending magnets (superbends) that were recently installed in the ring. The use of such single pole superconducting bend magnets enables the development of a hard x-ray program on a relatively low energy 1.9 GeV ring without taking up insertion device straight sections. The source is of relatively low power, but due to the small electron beam emittance, it has high brightness. X-ray optics are required to preserve the brightness and to match the illumination requirements for protein crystallography. This was achieved by means of a collimating premirror bent to a plane parabola, a double crystal monochromator followed by a toroidal mirror that focuses in the horizontal direction with a 2:1 demagnification. This optical arrangement partially balances aberrations from the collimating and toroidal mirrors such that a tight focused spot size is achieved. The optical properties of the beamline are an excellent match to those required by the small protein crystals that are typically measured. The design and performance of these new beamlines are described.

  3. Athermal avalanche in bilayer superconducting nanowire single-photon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Verma, V. B., E-mail: verma@nist.gov; Lita, A. E.; Stevens, M. J.; Mirin, R. P.; Nam, S. W. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States)

    2016-03-28

    We demonstrate that two superconducting nanowires separated by a thin insulating barrier can undergo an avalanche process. In this process, Joule heating caused by a photodetection event in one nanowire and the associated production of athermal phonons which are transmitted through the barrier cause the transition of the adjacent nanowire from the superconducting to the normal state. We show that this process can be utilized in the fabrication of superconducting nanowire single photon detectors to improve the signal-to-noise ratio, reduce system jitter, maximize device area, and increase the external efficiency over a very broad range of wavelengths. Furthermore, the avalanche mechanism may provide a path towards a superconducting logic element based on athermal gating.

  4. Flux Concentration and Pole Shaping in a Single Phase Hybrid Switched Reluctance Motor Drive

    DEFF Research Database (Denmark)

    Jakobsen, Uffe; Lu, Kaiyuan

    2010-01-01

    The single phase hybrid switched reluctance motor (HSRM) may be a good candidate for low-cost drives used for pump applications. This paper presents a new design of the HSRM with improved starting torque achieved by stator pole shaping, and a better arrangement of the embedded stator permanent...

  5. Waveguide superconducting single-photon autocorrelators for quantum photonic applications

    NARCIS (Netherlands)

    Sahin, D.; Gaggero, A.; Frucci, G.; Jahanmirinejad, S.; Sprengers, J.P.; Mattioli, F.; Leoni, R.; Beetz, J.; Lermer, M.; Kamp, M.; Höfling, S.; Fiore, A.; Hasan, Z.U.; Hemmer, P.R.; Lee, H.; Santori, C.M.

    2013-01-01

    We report a novel component for integrated quantum photonic applications, a waveguide single-photon autocorrelator. It is based on two superconducting nanowire detectors patterned onto the same GaAs ridge waveguide. Combining the electrical output of the two detectors in a correlation card enables

  6. Waveguide-Coupled Superconducting Nanowire Single-Photon Detectors

    Science.gov (United States)

    Beyer, Andrew D.; Briggs, Ryan M.; Marsili, Francesco; Cohen, Justin D.; Meenehan, Sean M.; Painter, Oskar J.; Shaw, Matthew D.

    2015-01-01

    We have demonstrated WSi-based superconducting nanowire single-photon detectors coupled to SiNx waveguides with integrated ring resonators. This photonics platform enables the implementation of robust and efficient photon-counting detectors with fine spectral resolution near 1550 nm.

  7. The physics of nanowire superconducting single-photon detectors

    NARCIS (Netherlands)

    Renema, Jelmer Jan

    2015-01-01

    We investigate the detection mechanism in superconducting single photon detectors via quantum detector tomography. We find that the detection event is caused by diffusion of quasiparticles from the absorption spot, combined with entrance of a vortex. Moreover, we investigate the behaviour of

  8. Multiplexing Superconducting Qubit Circuit for Single Microwave Photon Generation

    Science.gov (United States)

    George, R. E.; Senior, J.; Saira, O.-P.; Pekola, J. P.; de Graaf, S. E.; Lindström, T.; Pashkin, Yu A.

    2017-10-01

    We report on a device that integrates eight superconducting transmon qubits in λ /4 superconducting coplanar waveguide resonators fed from a common feedline. Using this multiplexing architecture, each resonator and qubit can be addressed individually, thus reducing the required hardware resources and allowing their individual characterisation by spectroscopic methods. The measured device parameters agree with the designed values, and the resonators and qubits exhibit excellent coherence properties and strong coupling, with the qubit relaxation rate dominated by the Purcell effect when brought in resonance with the resonator. Our analysis shows that the circuit is suitable for generation of single microwave photons on demand with an efficiency exceeding 80%.

  9. Finite Element Analysis of Doorframe Structure of Single Oblique Pole Type in Container Crane

    Science.gov (United States)

    Cheng, X. F.; Wu, F. Q.; Tang, G.; Hu, X.

    2017-07-01

    Compared with the composite type, the single oblique pole type has more advantages, such as simple structure, thrift steel and high safe overhead clearance. The finite element model of the single oblique pole type is established in nodes by ANSYS, and more details are considered when the model is simplified, such as the section of Girder and Boom, torque in Girder and Boom occurred by Machinery house and Trolley, density according to the way of simplification etc. The stress and deformation of ten observation points are compared and analyzed, when the trolley is in nine dangerous positions. Based on the result of analysis, six dangerous points are selected to provide reference for the detection and evaluation of container crane.

  10. New Generation of Superconducting Nanowire Single-Photon Detectors

    Directory of Open Access Journals (Sweden)

    Goltsman G.N.

    2015-01-01

    Full Text Available We present an overview of recent results for new generation of infrared and optical superconducting nanowire single-photon detectors (SNSPDs that has already demonstrated a performance that makes them devices-of-choice for many applications. SNSPDs provide high efficiency for detecting individual photons while keeping dark counts and timing jitter minimal. Besides superior detection performance over a broad optical bandwidth, SNSPDs are also compatible with an integrated optical platform as a crucial requirement for applications in emerging quantum photonic technologies. By embedding SNSPDs in nanophotonic circuits we realize waveguide integrated single photon detectors which unite all desirable detector properties in a single device.

  11. All-periodically poled, high-power, continuous-wave, single-frequency tunable UV source.

    Science.gov (United States)

    Aadhi, A; Chaitanya N, Apurv; Jabir, M V; Singh, R P; Samanta, G K

    2015-01-01

    We report on experimental demonstration of an all-periodically poled, continuous-wave (CW), high-power, single-frequency, ultra-violet (UV) source. Based on internal second-harmonic-generation (SHG) of a CW singly resonant optical parametric oscillator (OPO) pumped in the green, the UV source provides tunable radiation across 398.94-417.08 nm. The compact source comprising of a 25-mm-long MgO-doped periodically poled stoichiometric lithium tantalate (MgO:sPPLT) crystal of period Λ(SLT)=8.5  μm for OPO and a 5-mm-long, multi-grating (Λ(KTP)=3.3, 3.4, 3.6 and 3.8 μm), periodically poled potassium titanium phosphate (PPKTP) for intra-cavity SHG, provides as much as 336 mW of UV power at 398.94 nm, corresponding to a green-to-UV conversion efficiency of ∼6.7%. In addition, the singly resonant OPO (SRO) provides 840 mW of idler at 1541.61 nm and substantial signal power of 108 mW at 812.33 nm transmitted through the high reflective cavity mirrors. UV source provides single-frequency radiation with instantaneous line-width of ∼18.3  MHz and power >100  mW in Gaussian beam profile (ellipticity >92%) across the entire tuning range. Access to lower UV wavelengths requires smaller grating periods to compensate high phase-mismatch resulting from high material dispersion in the UV wavelength range. Additionally, we have measured the normalized temperature and spectral acceptance bandwidth of PPKTP crystal in the UV wavelength range to be ∼2.25°C·cm and ∼0.15  nm·cm, respectively.

  12. Single pole rapid reclosing: effective damping of ehv switching surges through discharge resistors

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, T

    1965-04-30

    The stability of interconnecting circuits is very important and loss of synchronism of a complete network due to a temporary single-phase fault is operationally and economically undesirable. The use of grounding resistors together with load-break isolators which can be electrically or mechanically coupled to the circuit-breakers yield interesting possibilities in extra-high-voltage networks. The three problems, i.e., discharging of charged lines, damping of switching surges, and single-pole rapid-reclosing, can be solved through the use of a number of similar resistors and load-break isolators connected in series according to the voltage. The thermal and electrical stresses of the resistors can be kept within permissible limits. The time required for arc extinction and the limits in respect of length of lines will have to be determined by actual tests. For single-pole rapid-reclosing during a single-phase earth fault the switching operations on both sides of the line must be simultaneous. Because of the very small divergence of the opening and making times of modern circuit-breakers it will be sufficient only to synchronise the operating impulse.

  13. Superconductivity in SrNi2P2 single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ronning, Filip [Los Alamos National Laboratory; Bauer, Eric D [Los Alamos National Laboratory; Park, Tuscon [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory

    2009-01-01

    Heat capacity, magnetic susceptibility, and resistivity of SrNi{sub 2}P{sub 2} single crystals are presented, illustrating the structural transition at 325 K, and bulk superconductivity at 1.4 K. The magnitude of {Tc}, fits to the heat capacity data, the small upper critical field H{sub c2} = 390 Oe, and {kappa} = 2.1 suggests a conventional fully gapped superconductor. With applied pressure we find that superconductivity persists into the so-called 'collapsed tetragonal' phase, although the transition temperature is monotonically suppressed with increasing pressure. This argues that reduced dimensionality can be a mechanism for increasing the transition temperatures of layered NiP, as well as layered FeAs and NiAs, superconductors.

  14. Superconducting nanowire single-photon detectors: physics and applications

    International Nuclear Information System (INIS)

    Natarajan, Chandra M; Tanner, Michael G; Hadfield, Robert H

    2012-01-01

    Single-photon detectors based on superconducting nanowires (SSPDs or SNSPDs) have rapidly emerged as a highly promising photon-counting technology for infrared wavelengths. These devices offer high efficiency, low dark counts and excellent timing resolution. In this review, we consider the basic SNSPD operating principle and models of device behaviour. We give an overview of the evolution of SNSPD device design and the improvements in performance which have been achieved. We also evaluate device limitations and noise mechanisms. We survey practical refrigeration technologies and optical coupling schemes for SNSPDs. Finally we summarize promising application areas, ranging from quantum cryptography to remote sensing. Our goal is to capture a detailed snapshot of an emerging superconducting detector technology on the threshold of maturity. (topical review)

  15. A Direct Algorithm for Pole Placement by State-derivative Feedback for Single-input Linear Systems

    Directory of Open Access Journals (Sweden)

    Taha H. S. Abdelaziz

    2003-01-01

    Full Text Available This paper deals with the direct solution of the pole placement problem for single-input linear systems using state-derivative feedback. This pole placement problem is always solvable for any controllable systems if all eigenvalues of the original system are nonzero. Then any arbitrary closed-loop poles can be placed in order to achieve the desired system performance. The solving procedure results in a formula similar to the Ackermann formula. Its derivation is based on the transformation of a linear single-input system into Frobenius canonical form by a special coordinate transformation, then solving the pole placement problem by state derivative feedback. Finally the solution is extended also for single-input time-varying control systems. The simulation results are included to show the effectiveness of the proposed approach.

  16. Superconductivity

    International Nuclear Information System (INIS)

    Taylor, A.W.B.; Noakes, G.R.

    1981-01-01

    This book is an elementray introduction into superconductivity. The topics are the superconducting state, the magnetic properties of superconductors, type I superconductors, type II superconductors and a chapter on the superconductivity theory. (WL)

  17. Optimised quantum hacking of superconducting nanowire single-photon detectors.

    Science.gov (United States)

    Tanner, Michael G; Makarov, Vadim; Hadfield, Robert H

    2014-03-24

    We explore bright-light control of superconducting nanowire single-photon detectors (SNSPDs) in the shunted configuration (a practical measure to avoid latching). In an experiment, we simulate an illumination pattern the SNSPD would receive in a typical quantum key distribution system under hacking attack. We show that it effectively blinds and controls the SNSPD. The transient blinding illumination lasts for a fraction of a microsecond and produces several deterministic fake clicks during this time. This attack does not lead to elevated timing jitter in the spoofed output pulse, and hence does not introduce significant errors. Five different SNSPD chip designs were tested. We consider possible countermeasures to this attack.

  18. Optimised quantum hacking of superconducting nanowire single-photon detectors

    Science.gov (United States)

    Tanner, Michael G.; Makarov, Vadim; Hadfield, Robert H.

    2014-03-01

    We explore bright-light control of superconducting nanowire single-photon detectors (SNSPDs) in the shunted configuration (a practical measure to avoid latching). In an experiment, we simulate an illumination pattern the SNSPD would receive in a typical quantum key distribution system under hacking attack. We show that it effectively blinds and controls the SNSPD. The transient blinding illumination lasts for a fraction of a microsecond and produces several deterministic fake clicks during this time. This attack does not lead to elevated timing jitter in the spoofed output pulse, and hence does not introduce significant errors. Five different SNSPD chip designs were tested. We consider possible countermeasures to this attack.

  19. Single-flux-quantum circuit technology for superconducting radiation detectors

    International Nuclear Information System (INIS)

    Fujimaki, Akira; Onogi, Masashi; Matsumoto, Tomohiro; Tanaka, Masamitsu; Sekiya, Akito; Hayakawa, Hisao; Yorozu, Shinichi; Terai, Hirotaka; Yoshikawa, Nobuyuki

    2003-01-01

    We discuss the application of the single-flux-quantum (SFQ) logic circuits to multi superconducting radiation detectors system. The SFQ-based analog-to-digital converters (ADCs) have the advantage in current sensitivity, which can reach less than 10 nA in a well-tuned ADC. We have also developed the design technology of the SFQ circuits. We demonstrate high-speed operation of large-scale integrated circuits such as a 2x2 cross/bar switch, arithmetic logic unit, indicating that our present SFQ technology is applicable to the multi radiation detectors system. (author)

  20. Single-particle properties of the Hubbard model in a novel three-pole approximation

    Science.gov (United States)

    Di Ciolo, Andrea; Avella, Adolfo

    2018-05-01

    We study the 2D Hubbard model using the Composite Operator Method within a novel three-pole approximation. Motivated by the long-standing experimental puzzle of the single-particle properties of the underdoped cuprates, we include in the operatorial basis, together with the usual Hubbard operators, a field describing the electronic transitions dressed by the nearest-neighbor spin fluctuations, which play a crucial role in the unconventional behavior of the Fermi surface and of the electronic dispersion. Then, we adopt this approximation to study the single-particle properties in the strong coupling regime and find an unexpected behavior of the van Hove singularity that can be seen as a precursor of a pseudogap regime.

  1. Superconductivity

    CERN Document Server

    Poole, Charles P; Farach, Horacio A

    1995-01-01

    Superconductivity covers the nature of the phenomenon of superconductivity. The book discusses the fundamental principles of superconductivity; the essential features of the superconducting state-the phenomena of zero resistance and perfect diamagnetism; and the properties of the various classes of superconductors, including the organics, the buckministerfullerenes, and the precursors to the cuprates. The text also describes superconductivity from the viewpoint of thermodynamics and provides expressions for the free energy; the Ginzburg-Landau and BCS theories; and the structures of the high

  2. Bulk Superconductivity and Disorder in Single Crystals of LaFePO

    Energy Technology Data Exchange (ETDEWEB)

    Analytis, James G.; Chu, Jiun-Haw; Erickson, Ann S.; Kucharczyk, Chris; /Stanford U., Appl. Phys. Dept.; Serafin, Alessandro; Carrington, Antony; /Bristol U.; Cox, Catherine; Kauzlarich, Susan M.; Hope, Hakon; /UC, Davis. Dept. Chem.

    2010-02-15

    We have studied the intrinsic normal and superconducting properties of the oxypnictide LaFePO. These samples exhibit bulk superconductivity and the evidence suggests that stoichiometric LaFePO is indeed superconducting, in contrast to other reports. We find that superconductivity is independent of the interplane residual resistivity {rho}{sub 0} and discuss the implications of this on the nature of the superconducting order parameter. Finally we find that, unlike T{sub c}, other properties in single-crystal LaFePO including the resistivity and magnetoresistance, can be very sensitive to disorder.

  3. Superconductivity

    International Nuclear Information System (INIS)

    Langone, J.

    1989-01-01

    This book explains the theoretical background of superconductivity. Includes discussion of electricity, material fabrication, maglev trains, the superconducting supercollider, and Japanese-US competition. The authors reports the latest discoveries

  4. Superconductivity

    International Nuclear Information System (INIS)

    Onnes, H.K.

    1988-01-01

    The author traces the development of superconductivity from 1911 to 1986. Some of the areas he explores are the Meissner Effect, theoretical developments, experimental developments, engineering achievements, research in superconducting magnets, and research in superconducting electronics. The article also mentions applications shown to be technically feasible, but not yet commercialized. High-temperature superconductivity may provide enough leverage to bring these applications to the marketplace

  5. Superconductivity

    International Nuclear Information System (INIS)

    Andersen, N.H.; Mortensen, K.

    1988-12-01

    This report contains lecture notes of the basic lectures presented at the 1st Topsoee Summer School on Superconductivity held at Risoe National Laboratory, June 20-24, 1988. The following lecture notes are included: L.M. Falicov: 'Superconductivity: Phenomenology', A. Bohr and O. Ulfbeck: 'Quantal structure of superconductivity. Gauge angle', G. Aeppli: 'Muons, neutrons and superconductivity', N.F. Pedersen: 'The Josephson junction', C. Michel: 'Physicochemistry of high-T c superconductors', C. Laverick and J.K. Hulm: 'Manufacturing and application of superconducting wires', J. Clarke: 'SQUID concepts and systems'. (orig.) With 10 tabs., 128 figs., 219 refs

  6. Superconductivity

    International Nuclear Information System (INIS)

    Palmieri, V.

    1990-01-01

    This paper reports on superconductivity the absence of electrical resistance has always fascinated the mind of researchers with a promise of applications unachievable by conventional technologies. Since its discovery superconductivity has been posing many questions and challenges to solid state physics, quantum mechanics, chemistry and material science. Simulations arrived to superconductivity from particle physics, astrophysic, electronics, electrical engineering and so on. In seventy-five years the original promises of superconductivity were going to become reality: a microscopical theory gave to superconductivity the cloth of the science and the level of technological advances was getting higher and higher. High field superconducting magnets became commercially available, superconducting electronic devices were invented, high field accelerating gradients were obtained in superconductive cavities and superconducting particle detectors were under study. Other improvements came in a quiet progression when a tornado brought a revolution in the field: new materials had been discovered and superconductivity, from being a phenomenon relegated to the liquid Helium temperatures, became achievable over the liquid Nitrogen temperature. All the physics and the technological implications under superconductivity have to be considered ab initio

  7. Superconductivity

    CERN Document Server

    Thomas, D B

    1974-01-01

    A short general review is presented of the progress made in applied superconductivity as a result of work performed in connection with the high-energy physics program in Europe. The phenomenon of superconductivity and properties of superconductors of Types I and II are outlined. The main body of the paper deals with the development of niobium-titanium superconducting magnets and of radio-frequency superconducting cavities and accelerating structures. Examples of applications in and for high-energy physics experiments are given, including the large superconducting magnet for the Big European Bubble Chamber, prototype synchrotron magnets for the Super Proton Synchrotron, superconducting d.c. beam line magnets, and superconducting RF cavities for use in various laboratories. (0 refs).

  8. Reluctance motor employing superconducting magnetic flux switches

    International Nuclear Information System (INIS)

    Spyker, R.L.; Ruckstadter, E.J.

    1992-01-01

    This paper reports that superconducting flux switches controlling the magnetic flux in the poles of a motor will enable the implementation of a reluctance motor using one central single phase winding. A superconducting flux switch consists of a ring of superconducting material surrounding a ferromagnetic pole of the motor. When in the superconducting state the switch will block all magnetic flux attempting to flow in the ferromagnetic core. When switched to the normal state the superconducting switch will allow the magnetic flux to flow freely in that pole. By using one high turns-count coil as a flux generator, and selectively channeling flux among the various poles using the superconducting flux switch, 3-phase operation can be emulated with a single-hase central AC source. The motor will also operate when the flux generating coil is driven by a DC current, provided the magnetic flux switches see a continuously varying magnetic flux. Rotor rotation provides this varying flux due to the change in stator pole inductance it produces

  9. Superconductivity

    International Nuclear Information System (INIS)

    Kakani, S.L.; Kakani, Shubhra

    2007-01-01

    The monograph provides readable introduction to the basics of superconductivity for beginners and experimentalists. For theorists, the monograph provides nice and brief description of the broad spectrum of experimental properties, theoretical concepts with all details, which theorists should learn, and provides a sound basis for students interested in studying superconducting theory at the microscopic level. Special chapter on the theory of high-temperature superconductivity in cuprates is devoted

  10. Fiber-coupled NbN superconducting single-photon detectors for quantum correlation measurements

    NARCIS (Netherlands)

    Slysz, W.; Wegrzecki, M.; Bar, J.; Grabiec, P.; Gorska, M.; Reiger, E.; Dorenbos, S.; Zwiller, V.; Milostnaya, I.; Minaeva, O.

    2007-01-01

    We have fabricated fiber-coupled superconducting single-photon detectors (SSPDs), designed for quantum-correlationtype experiments. The SSPDs are nanostructured (~100-nm wide and 4-nm thick) NbN superconducting meandering stripes, operated in the 2 to 4.2 K temperature range, and known for ultrafast

  11. Growth rate of YBCO-Ag superconducting single grains

    Science.gov (United States)

    Congreve, J. V. J.; Shi, Y. H.; Dennis, A. R.; Durrell, J. H.; Cardwell, D. A.

    2017-12-01

    The large scale use of (RE)Ba2Cu3O7 bulk superconductors, where RE=Y, Gd, Sm, is, in part, limited by the relatively poor mechanical properties of these inherently brittle ceramic materials. It is reported that alloying of (RE)Ba2Cu3O7 with silver enables a significant improvement in the mechanical strength of bulk, single grain samples without any detrimental effect on their superconducting properties. However, due to the complexity and number of inter-related variables involved in the top seeded melt growth (TSMG) process, the growth of large single grains is difficult and the addition of silver makes it even more difficult to achieve successful growth reliably. The key processing variables in the TSMG process include the times and temperatures of the stages within the heating profile, which can be derived from the growth rate during the growth process. To date, the growth rate of the YBa2Cu3O7-Ag system has not been reported in detail and it is this lacuna that we have sought to address. In this work we measure the growth rate of the YBCO-Ag system using a method based on continuous cooling and isothermal holding (CCIH). We have determined the growth rate by measuring the side length of the crystallised region for a number of samples for specified isothermal hold temperatures and periods. This has enabled the growth rate to be modelled and from this an optimized heating profile for the successful growth of YBCO-Ag single grains to be derived.

  12. Superconductivity

    International Nuclear Information System (INIS)

    Caruana, C.M.

    1988-01-01

    Despite reports of new, high-temperature superconductive materials almost every day, participants at the First Congress on Superconductivity do not anticipate commercial applications with these materials soon. What many do envision is the discovery of superconducting materials that can function at much warmer, perhaps even room temperatures. Others hope superconductivity will usher in a new age of technology as semiconductors and transistors did. This article reviews what the speakers had to say at the four-day congress held in Houston last February. Several speakers voiced concern that the Reagan administration's apparent lack of interest in funding superconductivity research while other countries, notably Japan, continue to pour money into research and development could hamper America's international competitiveness

  13. Ultrafast time measurements by time-correlated single photon counting coupled with superconducting single photon detector

    Energy Technology Data Exchange (ETDEWEB)

    Shcheslavskiy, V., E-mail: vis@becker-hickl.de; Becker, W. [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Morozov, P.; Divochiy, A. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Vakhtomin, Yu. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991 (Russian Federation); Smirnov, K. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991 (Russian Federation); National Research University Higher School of Economics, 20 Myasnitskaya St., Moscow 101000 (Russian Federation)

    2016-05-15

    Time resolution is one of the main characteristics of the single photon detectors besides quantum efficiency and dark count rate. We demonstrate here an ultrafast time-correlated single photon counting (TCSPC) setup consisting of a newly developed single photon counting board SPC-150NX and a superconducting NbN single photon detector with a sensitive area of 7 × 7 μm. The combination delivers a record instrument response function with a full width at half maximum of 17.8 ps and system quantum efficiency ∼15% at wavelength of 1560 nm. A calculation of the root mean square value of the timing jitter for channels with counts more than 1% of the peak value yielded about 7.6 ps. The setup has also good timing stability of the detector–TCSPC board.

  14. Superconductivity

    CERN Document Server

    Ketterson, John B

    2008-01-01

    Conceived as the definitive reference in a classic and important field of modern physics, this extensive and comprehensive handbook systematically reviews the basic physics, theory and recent advances in the field of superconductivity. Leading researchers, including Nobel laureates, describe the state-of-the-art in conventional and unconventional superconductors at a particularly opportune time, as new experimental techniques and field-theoretical methods have emerged. In addition to full-coverage of novel materials and underlying mechanisms, the handbook reflects continued intense research into electron-phone based superconductivity. Considerable attention is devoted to high-Tc superconductivity, novel superconductivity, including triplet pairing in the ruthenates, novel superconductors, such as heavy-Fermion metals and organic materials, and also granular superconductors. What’s more, several contributions address superconductors with impurities and nanostructured superconductors. Important new results on...

  15. High-power, continuous-wave, single-frequency, all-periodically-poled, near-infrared source.

    Science.gov (United States)

    Devi, Kavita; Chaitanya Kumar, S; Ebrahim-Zadeh, M

    2012-12-15

    We report a high-power, single-frequency, continuous-wave (cw) source tunable across 775-807 nm in the near-infrared, based on internal second harmonic generation (SHG) of a cw singly-resonant optical parametric oscillator (OPO) pumped by a Yb-fiber laser. The compact, all-periodically-poled source employs a 48-mm-long, multigrating MgO doped periodically poled lithium niobate (MgO:PPLN) crystal for the OPO and a 30-mm-long, fan-out grating MgO-doped stoichiometric periodically poled lithium tantalate (MgO:sPPLT) crystal for intracavity SHG, providing as much as 3.7 W of near-infrared power at 793 nm, together with 4 W of idler power at 3232 nm, at an overall extraction efficiency of 28%. Further, the cw OPO is tunable across 3125-3396 nm in the idler, providing as much as 4.3 W at 3133 nm with >3.8  W over 77% of the tuning range together with >3  W of near-infrared power across 56% of SHG tuning range, in high-spatial beam-quality with M2<1.4. The SHG output has an instantaneous linewidth of 8.5 MHz and exhibits a passive power stability better than 3.5% rms over more than 1 min.

  16. Superconducting and charge density wave transition in single crystalline LaPt2Si2

    Science.gov (United States)

    Gupta, Ritu; Dhar, S. K.; Thamizhavel, A.; Rajeev, K. P.; Hossain, Z.

    2017-06-01

    We present results of our comprehensive studies on single crystalline LaPt2Si2. Pronounced anomaly in electrical resistivity and heat capacity confirms the bulk nature of superconductivity (SC) and charge density wave (CDW) transition in the single crystals. While the charge density wave transition temperature is lower, the superconducting transition temperature is higher in single crystal compared to the polycrystalline sample. This result confirms the competing nature of CDW and SC. Another important finding is the anomalous temperature dependence of upper critical field H C2(T). We also report the anisotropy in the transport and magnetic measurements of the single crystal.

  17. CT-QMC-simulations on the single impurity Anderson model with a superconducting bath

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Florian; Pruschke, Thomas [Institut fuer theoretische Physik, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)

    2016-07-01

    Coupling a heavy fermion impurity to a superconducting lead induces a competition between the Kondo effect and superconductivity in the low temperature regime. This situation has been modeled with a single impurity Anderson model, where the normal state bath is replaced by a BCS-type superconducting bath in mean field approximation. We study this model using a continuous-time quantum Monte Carlo hybridization expansion algorithm. Results include the impurity Green's functions as well as the corresponding spectral functions obtained from analytic continuation. Two side bands are observed which we discuss in the light of Yu-Shiba-Rusinov states.

  18. Superconductivity

    CERN Document Server

    Poole, Charles P; Creswick, Richard J; Prozorov, Ruslan

    2014-01-01

    Superconductivity, Third Edition is an encyclopedic treatment of all aspects of the subject, from classic materials to fullerenes. Emphasis is on balanced coverage, with a comprehensive reference list and significant graphics from all areas of the published literature. Widely used theoretical approaches are explained in detail. Topics of special interest include high temperature superconductors, spectroscopy, critical states, transport properties, and tunneling. This book covers the whole field of superconductivity from both the theoretical and the experimental point of view. This third edition features extensive revisions throughout, and new chapters on second critical field and iron based superconductors.

  19. Single-flavor color superconductivity with color-sextet pairing

    Czech Academy of Sciences Publication Activity Database

    Brauner, Tomáš

    2005-01-01

    Roč. 55, č. 1 (2005), s. 9-16 ISSN 0011-4626 R&D Projects: GA ČR(CZ) GA202/02/0847 Keywords : color superconductivity * spontaneous symmetry breaking Subject RIV: BE - Theoretical Physics Impact factor: 0.360, year: 2005

  20. Single-particle spectra and magnetic field effects within precursor superconductivity

    International Nuclear Information System (INIS)

    Pieri, P.; Pisani, L.; Strinati, G.C.; Perali, A.

    2004-01-01

    We study the single-particle spectra below the superconducting critical temperature from weak to strong coupling within a precursor superconductivity scenario. The spectral-weight function is obtained from a self-energy that includes pairing-fluctuations within a continuum model representing the hot spots of the Brillouin zone. The effects of strong magnetic fields on the pseudogap temperature are also discussed within the same scenario

  1. Pairing fluctuation effects on the single-particle spectra for the superconducting state

    International Nuclear Information System (INIS)

    Pieri, P.; Pisani, L.; Strinati, G.C.

    2004-01-01

    Single-particle spectra are calculated in the superconducting state for a fermionic system with an attractive interaction, as functions of temperature and coupling strength from weak to strong. The fermionic system is described by a single-particle self-energy that includes pairing-fluctuation effects in the superconducting state. The theory reduces to the ordinary BCS approximation in weak coupling and to the Bogoliubov approximation for the composite bosons in strong coupling. Several features of the single-particle spectral function are shown to compare favorably with experimental data for cuprate superconductors

  2. Annealing effect on superconductivity of La2CuO4 single crystals

    International Nuclear Information System (INIS)

    Tanaka, I.; Takahashi, H.; Kojima, H.

    1992-01-01

    This paper reports that La 2 CuO 4 single crystals grown at an oxygen pressure of 0.2 MPa by TSFZ method are superconducting below 32 K, and show a semiconducting behavior in nonsuperconducting state. The single crystals of La 2 CuO 4 are changed from superconductors to semiconductors by annealing in argon, and are returned to superconductors by annealing at ambient pressure of oxygen. Therefore, superconductivity of the La 2 CuO 4 single crystals is due to excess oxygen

  3. Annealing effect on superconductivity of La2CuO4 single crystals

    International Nuclear Information System (INIS)

    Tanaka, L.; Takahashi, H.; Kojima, H.

    1992-01-01

    La 2 CuO 4 single crystals grown at an oxygen pressure of 0.2 MPa by TSFZ method are superconducting below 32 K, and show a semiconducting behavior in nonsuperconducting state. The single crystals of La 2 CuO 4 are changed from superconductors to semiconductors by annealing in argon, and are returned to superconductors by annealing at ambient pressure of oxygen. Therefore, superconductivity of the La 2 CuO 4 single crystals is due to excess oxygen. (orig.)

  4. A single bout of exercise with a flexible pole induces significant cardiac autonomic responses in healthy men

    Directory of Open Access Journals (Sweden)

    Cristiane M. Ogata

    2014-09-01

    Full Text Available OBJECTIVES: Flexible poles can provide rapid eccentric and concentric muscle contractions. Muscle vibration is associated with a "tonic vibration reflex” that is stimulated by a sequence of rapid muscle stretching, activation of the muscle spindles and stimulation of a response that is similar to the myotatic reflex. Literature studies analyzing the acute cardiovascular responses to different exercises performed with this instrument are lacking. We investigated the acute effects of exercise with flexible poles on the heart period in healthy men. METHOD: The study was performed on ten young adult males between 18 and 25 years old. We evaluated the heart rate variability in the time and frequency domains. The subjects remained at rest for 10 min. After the rest period, the volunteers performed the exercises with the flexible poles. Immediately after the exercise protocol, the volunteers remained seated at rest for 30 min and their heart rate variability was analyzed. RESULTS: The pNN50 was reduced at 5-10 and 15-20 min after exercise compared to 25-30 min after exercise (p = 0.0019, the SDNN was increased at 25-30 min after exercise compared to at rest and 0-10 min after exercise (p = 0.0073 and the RMSSD was increased at 25-30 min after exercise compared to 5-15 min after exercise (p = 0.0043. The LF in absolute units was increased at 25-30 min after exercise compared to 5-20 min after exercise (p = 0.0184. CONCLUSION: A single bout of exercise with a flexible pole reduced the heart rate variability and parasympathetic recovery was observed approximately 30 min after exercise.

  5. Superconductivity

    International Nuclear Information System (INIS)

    Narlikar, A.V.

    1993-01-01

    Amongst the numerous scientific discoveries that the 20th century has to its credit, superconductivity stands out as an exceptional example of having retained its original dynamism and excitement even for more than 80 years after its discovery. It has proved itself to be a rich field by continually offering frontal challenges in both research and applications. Indeed, one finds that a majority of internationally renowned condensed matter theorists, at some point of their career, have found excitement in working in this important area. Superconductivity presents a unique example of having fetched Nobel awards as many as four times to date, and yet, interestingly enough, the field still remains open for new insights and discoveries which could undeniably be of immense technological value. 1 fig

  6. Superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    This book profiles the research activity of 42 companies in the superconductivity field, worldwide. It forms a unique and comprehensive directory to this emerging technology. For each research site, it details the various projects in progress, analyzes the level of activity, pinpoints applications and R and D areas, reviews strategies and provides complete contact information. It lists key individuals, offers international comparisons of government funding, reviews market forecasts and development timetables and features a bibliography of selected articles on the subject

  7. Superconductivity

    International Nuclear Information System (INIS)

    Buller, L.; Carrillo, F.; Dietert, R.; Kotziapashis, A.

    1989-01-01

    Superconductors are materials which combine the property of zero electric resistance with the capability to exclude any adjacent magnetic field. This leads to many large scale applications such as the much publicized levitating train, generation of magnetic fields in MHD electric generators, and special medical diagnostic equipment. On a smaller-scale, superconductive materials could replace existing resistive connectors and decrease signal delays by reducing the RLC time constants. Thus, a computer could operate at much higher speeds, and consequently at lower power levels which would reduce the need for heat removal and allow closer spacing of circuitry. Although technical advances and proposed applications are constantly being published, it should be recognized that superconductivity is a slowly developing technology. It has taken scientists almost eighty years to learn what they now know about this material and its function. The present paper provides an overview of the historical development of superconductivity and describes some of the potential applications for this new technology as it pertains to the electronics industry

  8. Quantum routing of single optical photons with a superconducting flux qubit

    Science.gov (United States)

    Xia, Keyu; Jelezko, Fedor; Twamley, Jason

    2018-05-01

    Interconnecting optical photons with superconducting circuits is a challenging problem but essential for building long-range superconducting quantum networks. We propose a hybrid quantum interface between the microwave and optical domains where the propagation of a single-photon pulse along a nanowaveguide is controlled in a coherent way by tuning the electromagnetically induced transparency window with the quantum state of a flux qubit mediated by the spin in a nanodiamond. The qubit can route a single-photon pulse using the nanodiamond into a quantum superposition of paths without the aid of an optical cavity—simplifying the setup. By preparing the flux qubit in a superposition state our cavityless scheme creates a hybrid state-path entanglement between a flying single optical photon and a static superconducting qubit.

  9. Superconductivity

    International Nuclear Information System (INIS)

    2007-01-01

    During 2007, a large amount of the work was centred on the ITER project and related tasks. The activities based on low-temperature superconducting (LTS) materials included the manufacture and qualification of ITER full-size conductors under relevant operating conditions, the design of conductors and magnets for the JT-60SA tokamak and the manufacture of the conductors for the European dipole facility. A preliminary study was also performed to develop a new test facility at ENEA in order to test long-length ITER or DEMO full-size conductors. Several studies on different superconducting materials were also started to create a more complete database of superconductor properties, and also for use in magnet design. In this context, an extensive measurement campaign on transport and magnetic properties was carried out on commercially available NbTi strands. Work was started on characterising MgB 2 wire and bulk samples to optimise their performance. In addition, an intense experimental study was started to clarify the effect of mechanical loads on the transport properties of multi-filamentary Nb 3 Sn strands with twisted or untwisted superconducting filaments. The experimental activity on high-temperature superconducting (HTS) materials was mainly focussed on the development and characterisation of YBa 2 Cu 3 O 7-X (YBCO) based coated conductors. Several characteristics regarding YBCO deposition, current transport performance and tape manufacture were investigated. In the framework of chemical approaches for YBCO film growth, a new method, developed in collaboration with the Technical University of Cluj-Napoca (TUCN), Romania, was studied to obtain YBCO film via chemical solution deposition, which modifies the well-assessed metallic organic deposition trifluoroacetate (MOD-TFA) approach. The results are promising in terms of critical current and film thickness values. YBCO properties in films with artificially added pinning sites were characterised in collaboration with

  10. Multiple superconducting gaps in MgB2 single crystals from magnetic torque

    International Nuclear Information System (INIS)

    Atsumi, Toshiyuki; Xu, Mingxiang; Kitazawa, Hideaki; Ishida, Takekazu

    2004-01-01

    We have measured the magnetic torque of an MgB 2 single crystal in the various different fields below 10 kG by using a torque magnetometer and a 4 K closed cycle refrigerator. The MgB 2 single crystal was synthesized by the vapor transport method. The torque can be measured as an off-balance signal of the Wheatstone bridge of the four piezoresistors on a Si cantilever. The torque curves are analyzed by the Kogan model. The superconducting anisotropy γ is rather independent of temperature in 5 and 10 kG, but is dependent on field up to 60 kG. We consider that the field dependence of γ comes from the nature of the multiple superconducting gaps. The experimental results show that the π-band superconducting gaps have been deteriorated gradually up to a crossover field H * (π) ∼ 20 kG at 10 K when the magnetic field increases

  11. Superconducting nanowire single-photon detectors (SNSPDs) on SOI for near-infrared range

    Energy Technology Data Exchange (ETDEWEB)

    Trojan, Philipp; Il' in, Konstantin; Henrich, Dagmar; Hofherr, Matthias; Doerner, Steffen; Siegel, Michael [Institut fuer Mikro- und Nanoelektronische Systeme (IMS), Karlsruher Institut fuer Technologie (KIT) (Germany); Semenov, Alexey [Institut fuer Planetenforschung, DLR, Berlin-Adlershof (Germany); Huebers, Heinz-Wilhelm [Institut fuer Planetenforschung, DLR, Berlin-Adlershof (Germany); Institut fuer Optik und Atomare Physik, Technische Universitaet Berlin (Germany)

    2013-07-01

    Superconducting nanowire single-photon detectors are promising devices for photon detectors with high count rates, low dark count rates and low dead times. At wavelengths beyond the visible range, the detection efficiency of today's SNSPDs drops significantly. Moreover, the low absorption in ultra-thin detector films is a limiting factor over the entire spectral range. Solving this problem requires approaches for an enhancement of the absorption range in feeding the light to the detector element. A possibility to obtain a better absorption is the use of multilayer substrate materials for photonic waveguide structures. We present results on development of superconducting nanowire single-photon detectors made from niobium nitride on silicon-on-insulator (SOI) multilayer substrates. Optical and superconducting properties of SNSPDs on SOI will be discussed and compared with the characteristics of detectors on common substrates.

  12. Pressure-sensing properties of single-walled carbon nanotubes covered with a corona-poled piezoelectric polymer

    Energy Technology Data Exchange (ETDEWEB)

    Ikawa, Takeshi; Tabata, Hiroshi, E-mail: tabata@eei.eng.osaka-u.ac.jp; Yoshizawa, Takeshi; Utaka, Ken; Kubo, Osamu; Katayama, Mitsuhiro [Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2016-07-18

    Single-walled carbon nanotubes (SWNTs) have been studied extensively as sensing elements for chemical and biochemical sensors because of their excellent electrical properties, their ultrahigh ratio of surface area to volume, and the consequent extremely high sensitivity of their surface to the surrounding environment. The extremely high sensitivity indicates that SWNTs can operate as excellent transducers when combined with piezoelectric materials. In this paper, we present a touch sensor based on SWNT thin-film transistors (SWNT-TFTs) covered with a thin film of the piezoelectric polymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)). Devices were fabricated by spin-coating a P(VDF-TrFE) layer on an SWNT-TFT, which was followed by in situ corona poling to polarize the P(VDF-TrFE) layer. We studied the effect of the corona polarity on the device characteristics and revealed that poling with a negative corona discharge induced a large amount of hole doping in the SWNTs and improved the touch-sensing performance of the devices, while a positive discharge had a negligible effect. The poled devices exhibited regular, stable, and positive drain current modulation in response to intermittent pressing, and the response was proportional to the magnitude of the applied pressure, suggesting that it was caused by the piezoelectric effect of the polarized P(VDF-TrFE) layer. Furthermore, we also fabricated a device using horizontally aligned SWNTs with a lower SWNT density as an alternative transducer to an SWNT thin film, which demonstrated sensitivity as high as 70%/MPa.

  13. Suppression of superconductivity in a single Pb layer on Ag/Si(111)

    Energy Technology Data Exchange (ETDEWEB)

    Leon-Vanegas, Augusto; Kirschner, Juergen [Max Plank Instituet fuer Mikrostukturphysik (Germany); Martin Luther Univeristaet, Halle-Wittenberg (Germany); Caminale, Michael; Stepniak, Agnieszka; Oka, Hirofumi; Sanna, Antonio; Linscheid, Andreas; Sander, Dirk [Max Plank Instituet fuer Mikrostukturphysik (Germany)

    2015-07-01

    Recently, superconductivity was reported in a single layer of Pb on Si(111) with a critical temperature of 1.83 K. It has been proposed that the interaction of Pb with the Si substrate provides the electron phonon coupling to support superconductivity in this system. We have used a {sup 3}He-cooled STM with a vector magnetic field to study the effect of insertion of a Ag interlayer on the superconducting properties of a single Pb layer on Si(111). In contrast to the experiments on Pb/Si(111), the differential conductance of Pb/Ag/Si(111) does not show a gap indicative of superconductivity even at the lowest experimental temperature of 0.38 K. We ascribe this to the suppression of superconductivity. This result is explained by means of ab-initio calculations, showing that the effect of a chemical hybridization between Pb and Ag/Si occurring at the Fermi level dramatically reduces the strength of the electron phonon coupling. This contrasts with the case of Pb/Si(111), where no overlap between Pb and Si electronic states at the Fermi level is found in the calculations.

  14. Periodically poled self-frequency-doubling green laser fabricated from Nd:Mg:LiNbO₃ single crystal.

    Science.gov (United States)

    Wang, Dong Zhou; Sun, De Hui; Kang, Xue Liang; Sang, Yuan Hua; Yan, Bo Xia; Liu, Hong; Bi, Yong

    2015-07-13

    Although a breakthrough in the fabrication of green laser diodes has occurred, the high costs associated with the difficulty of manufacture still present a great obstacle for its practical application. Another approach for producing a green laser, by combining a laser device and a nonlinear crystal, entails the fabrication of complex structures and exhibits unstable performance due to interface contact defects, thus limiting its application. In this work, we report the fabrication by domain engineering of high quality periodically poled LiNbO₃, co-doped with Nd³⁺ and Mg²⁺, which combines a laser medium and a high efficiency second harmonic conversion crystal into a single system that is designed to overcome the above problems. An 80 mW self-frequency doubling green laser was constructed for the first time from a periodically poled Nd:Mg:LiNbO₃ crystal of 16 mm in length. This crystal can be used for developing compact, stable, highly efficient mini-solid-state-lasers, which promise to have many applications in portable laser-based spectroscopy, photo-communications, terahertz wave generation, and laser displays.

  15. Quantitative analysis of Josephson-quasiparticle current in superconducting single-electron transistors

    International Nuclear Information System (INIS)

    Nakamura, Y.; Chen, C.D.; Tsai, J.S.

    1996-01-01

    We have investigated Josephson-quasiparticle (JQP) current in superconducting single-electron transistors in which charging energy E C was larger than superconducting gap energy Δ and junction resistances were much larger than R Q ≡h/4e 2 . We found that not only the shapes of the JQP peaks but also their absolute height were reproduced quantitatively with a theory by Averin and Aleshkin using a Josephson energy of Ambegaokar-Baratoff close-quote s value. copyright 1996 The American Physical Society

  16. Remarkable effects of disorder on superconductivity of single atomic layers of lead on silicon

    Science.gov (United States)

    Brun, Christophe

    2015-03-01

    It is well known that conventional superconductivity is very robust against non-magnetic disorder. Nevertheless for thin and ultrathin films the structural properties play a major role in determining the superconducting properties, through a subtle interplay between disorder and Coulomb interactions. Unexpectedly, in 2010 superconductivity was discovered in single atomic layers of lead and indium grown on silicon substrate using scanning tunneling spectroscopy and confirmed later on by macroscopic transport measurements. Such well-controlled and tunable crystalline monolayers are ideal systems for studying the influence of various kinds of structural defects on the superconducting properties at the atomic and mesoscopic scale. In particular, Pb monolayers offer the opportunity of probing new effects of disorder because not only superconductivity is 2D but also the electronic wave functions are 2D. Our study of two Pb monolayers of different crystal structures by very-low temperature STM (300 mK) under magnetic field reveals unexpected results involving new spatial spectroscopic variations. Our results show that although the sheet resistance of the Pb monolayers is much below the resistance quantum, strong non-BCS corrections appear leading to peak heights fluctuations in the dI/dV tunneling spectra at a spatial scale much smaller than the superconducting coherence length. Furthermore, strong local evidence of the signature of Rashba effect on the superconductivity of the Pb/Si(111) monolayer is revealed through filling of in gap states and local spatial variations of this filling. Finally the nature of vortices in a monolayer is found to be very sensitive to the properties of step edges areas. This work was supported by University Pierre et Marie Curie UPMC `Emergence' project, French ANR Project `ElectroVortex,' ANR-QuDec and Templeton Foundation (40381), ARO (W911NF-13-1-0431) and CNRS PICS funds. Partial funding by US-DOE Grant DE-AC02-07CH1.

  17. Influence of material and geometry on the performance of superconducting nanowire single-photon detectors

    CERN Document Server

    Henrich, Dagmar

    2013-01-01

    Superconducting Nanowire Single-Photon Detectors offer the capability to detect electromagnetic waves on a single photon level in a wavelength range that far exceeds that of alternative detector types. However, above a certain threshold wavelength, the efficiency of those detectors decreases stronlgy, leading to a poor performance in the far-infrared range. Influences on this threshold are studied and approaches for improvement are verified experimentally by measurement of the device performance.

  18. Tunnelling determined superconducting energy gap of bulk single crystal aluminum

    International Nuclear Information System (INIS)

    Civiak, R.L.

    1974-01-01

    A procedure has been developed for fabricating Giaver tunnel junctions on bulk aluminum. Al-I-Ag junctions were prepared, where I is the naturally formed oxide on the polished, chemically treated aluminum surface. The aluminum energy gap was determined from tunneling conductance curves obtained from samples oriented in three different crystal directions, and as a function of magnetic field in each of these orientations. In contrast to the results of microwave absorption measurements on superconducting aluminum, no magnetic field dependence could be measured for either the average gap or the spread in gap values of the tunneling electrons. This is consistent with commonly accepted tunneling selection rules, and Garfunkel's interpretation of the microwave behavior which depended upon adjusting the energy spectrum of only the electrons traveling parallel to the surface in the presence of a magnetic field. The energy gaps measured for samples oriented in the 100, 110 and 111 directions are 3.52, 3.50 and 3.39 kT/sub c/, respectively. The trend in the anisotropy is the same as in the calculation of Leavens and Carbotte, however, the magnitude of the anisotropy is smaller than in their calculation and that which previous measurements have indicated

  19. High Isolation Single-Pole Four-Throw RF MEMS Switch Based on Series-Shunt Configuration

    Directory of Open Access Journals (Sweden)

    Tejinder Singh

    2014-01-01

    Full Text Available This paper presents a novel design of single-pole four-throw (SP4T RF-MEMS switch employing both capacitive and ohmic switches. It is designed on high-resistivity silicon substrate and has a compact area of 1.06 mm2. The series or ohmic switches have been designed to provide low insertion loss with good ohmic contact. The pull-in voltage for ohmic switches is calculated to be 7.19 V. Shunt or capacitive switches have been used in each port to improve the isolation for higher frequencies. The proposed SP4T switch provides excellent RF performances with isolation better than 70.64 dB and insertion loss less than 0.72 dB for X-band between the input port and each output port.

  20. Compact source of narrow-band counterpropagating polarization-entangled photon pairs using a single dual-periodically-poled crystal

    International Nuclear Information System (INIS)

    Gong, Yan-Xiao; Xie, Zhen-Da; Xu, Ping; Zhu, Shi-Ning; Yu, Xiao-Qiang; Xue, Peng

    2011-01-01

    We propose a scheme for the generation of counterpropagating polarization-entangled photon pairs from a dual-periodically-poled crystal. Compared with the usual forward-wave-type source, this source, in the backward-wave way, has a much narrower bandwidth. With a 2-cm-long bulk crystal, the bandwidths of the example sources are estimated to be 3.6 GHz, and the spectral brightnesses are more than 100 pairs/(s GHz mW). Two concurrent quasi-phase-matched spontaneous parametric down-conversion processes in a single crystal enable our source to be compact and stable. This scheme does not rely on any state projection and applies to both degenerate and nondegenerate cases, facilitating applications of the entangled photons.

  1. Ultrathin NbN film superconducting single-photon detector array

    International Nuclear Information System (INIS)

    Smirnov, K; Korneev, A; Minaeva, O; Divochiy, A; Tarkhov, M; Ryabchun, S; Seleznev, V; Kaurova, N; Voronov, B; Gol'tsman, G; Polonsky, S

    2007-01-01

    We report on the fabrication process of the 2 x 2 superconducting single-photon detector (SSPD) array. The SSPD array is made from ultrathin NbN film and is operated at liquid helium temperatures. Each detector is a nanowire-based structure patterned by electron beam lithography process. The advances in fabrication technology allowed us to produce highly uniform strips and preserve superconducting properties of the unpatterned film. SSPD exhibit up to 30% quantum efficiency in near infrared and up to 1% at 5-μm wavelength. Due to 120 MHz counting rate and 18 ps jitter, the time-domain multiplexing read-out is proposed for large scale SSPD arrays. Single-pixel SSPD has already found a practical application in non-invasive testing of semiconductor very-large scale integrated circuits. The SSPD significantly outperformed traditional single-photon counting avalanche diodes

  2. Parallel superconducting strip-line detectors: reset behaviour in the single-strip switch regime

    International Nuclear Information System (INIS)

    Casaburi, A; Heath, R M; Tanner, M G; Hadfield, R H; Cristiano, R; Ejrnaes, M; Nappi, C

    2014-01-01

    Superconducting strip-line detectors (SSLDs) are an important emerging technology for the detection of single molecules in time-of-flight mass spectrometry (TOF-MS). We present an experimental investigation of a SSLD laid out in a parallel configuration, designed to address selected single strip-lines operating in the single-strip switch regime. Fast laser pulses were tightly focused onto the device, allowing controllable nucleation of a resistive region at a specific location and study of the subsequent device response dynamics. We observed that in this regime, although the strip-line returns to the superconducting state after triggering, no effective recovery of the bias current occurs, in qualitative agreement with a phenomenological circuit simulation that we performed. Moreover, from theoretical considerations and by looking at the experimental pulse amplitude distribution histogram, we have the first confirmation of the fact that the phenomenological London model governs the current redistribution in these large area devices also after detection events. (paper)

  3. Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Batistoni, Paola; De Marco, Francesco; Pieroni, Leonardo [ed.

    2005-07-01

    Research on superconductivity at ENEA is mainly devoted to projects related to the ITER magnet system. In this framework, ENEA has been strongly involved in the design, manufacturing and test campaigns of the ITER toroidal field model coil (TFMC), which reached a world record in operating current (up to 80 kA). Further to this result, the activities in 2004 were devoted to optimising the ITER conductor performance. ENEA participated in the tasks launched by EFDA to define and produce industrial-scale advanced Nb3Sn strand to be used in manufacturing the ITER high-field central solenoid (CS) and toroidal field (TF) magnets. As well as contributing to the design of the new strand and the final conductor layout, ENEA will also perform characterisation tests, addressing in particular the influence of mechanical stress on the Nb3Sn performance. As a member of the international ITER-magnet testing group, ENEA plays a central role in the measurement campaigns and data analyses for each ITER-related conductor and coil. The next phase in the R and D of the ITER magnets will be their mechanical characterisation in order to define the fabrication route of the coils and structures. During 2004 the cryogenic measurement campaign on the Large Hadron Collider (LHC) by-pass diode stacks was completed. As the diode-test activity was the only LHC contract to be finished on schedule, the 'Centre Europeenne pour la Recherche Nucleaire' (CERN) asked ENEA to participate in an international tender for the cold check of the current leads for the LHC magnets. The contract was obtained, and during 2004, the experimental setup was designed and realised and the data acquisition system was developed. The measurement campaign was successfully started at the end of 2004 and will be completed in 2006.

  4. Waveguide-integrated single- and multi-photon detection at telecom wavelengths using superconducting nanowires

    International Nuclear Information System (INIS)

    Ferrari, Simone; Kahl, Oliver; Kovalyuk, Vadim; Goltsman, Gregory N.; Korneev, Alexander; Pernice, Wolfram H. P.

    2015-01-01

    We investigate single- and multi-photon detection regimes of superconducting nanowire detectors embedded in silicon nitride nanophotonic circuits. At near-infrared wavelengths, simultaneous detection of up to three photons is observed for 120 nm wide nanowires biased far from the critical current, while narrow nanowires below 100 nm provide efficient single photon detection. A theoretical model is proposed to determine the different detection regimes and to calculate the corresponding internal quantum efficiency. The predicted saturation of the internal quantum efficiency in the single photon regime agrees well with plateau behavior observed at high bias currents

  5. Waveguide-integrated single- and multi-photon detection at telecom wavelengths using superconducting nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, Simone; Kahl, Oliver [Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76132 (Germany); Kovalyuk, Vadim [Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76132 (Germany); Department of Physics, Moscow State Pedagogical University, Moscow 119992 (Russian Federation); Goltsman, Gregory N. [Department of Physics, Moscow State Pedagogical University, Moscow 119992 (Russian Federation); National Research University Higher School of Economics, 20 Myasnitskaya Ulitsa, Moscow 101000 (Russian Federation); Korneev, Alexander [Department of Physics, Moscow State Pedagogical University, Moscow 119992 (Russian Federation); Moscow Institute of Physics and Technology (State University), Moscow 141700 (Russian Federation); Pernice, Wolfram H. P., E-mail: wolfram.pernice@kit.edu [Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76132 (Germany); Department of Physics, University of Münster, 48149 Münster (Germany)

    2015-04-13

    We investigate single- and multi-photon detection regimes of superconducting nanowire detectors embedded in silicon nitride nanophotonic circuits. At near-infrared wavelengths, simultaneous detection of up to three photons is observed for 120 nm wide nanowires biased far from the critical current, while narrow nanowires below 100 nm provide efficient single photon detection. A theoretical model is proposed to determine the different detection regimes and to calculate the corresponding internal quantum efficiency. The predicted saturation of the internal quantum efficiency in the single photon regime agrees well with plateau behavior observed at high bias currents.

  6. Nano-optical observation of cascade switching in a parallel superconducting nanowire single photon detector

    International Nuclear Information System (INIS)

    Heath, Robert M.; Tanner, Michael G.; Casaburi, Alessandro; Hadfield, Robert H.; Webster, Mark G.; San Emeterio Alvarez, Lara; Jiang, Weitao; Barber, Zoe H.; Warburton, Richard J.

    2014-01-01

    The device physics of parallel-wire superconducting nanowire single photon detectors is based on a cascade process. Using nano-optical techniques and a parallel wire device with spatially separate pixels, we explicitly demonstrate the single- and multi-photon triggering regimes. We develop a model for describing efficiency of a detector operating in the arm-trigger regime. We investigate the timing response of the detector when illuminating a single pixel and two pixels. We see a change in the active area of the detector between the two regimes and find the two-pixel trigger regime to have a faster timing response than the one-pixel regime

  7. Single flux pulses affecting the ensemble of superconducting qubits

    Science.gov (United States)

    Denisenko, M. V.; Klenov, N. V.; Satanin, A. M.

    2018-02-01

    The present study is devoted to development of a technique for numerical simulation of the wave function dynamics the single Josephson qubits and arrays of noninteracting qubits controlled by ultra-short pulses. We wish to demonstrate the feasibility of a new principle of basic logical operations on the picosecond timescale. The influence of the unipolar pulse ("fluxon") form on the evolution of the state during the execution of the quantum one-qubit operations - "NOT", "READ" and " √{N O T } " - is investigated in the presence of decoherence. In the array of non interacting qubits, the question of the influence of the spread of their energy parameters (tunnel constants) is studied. It is shown that a single unipolar pulse can control a huge array of artificial atoms with 10% spread of geometric parameters in the array.

  8. Rise time of voltage pulses in NbN superconducting single photon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, K. V. [Moscow State Pedagogical University, 1 Malaya Pirogovskaya St., 119435 Moscow (Russian Federation); CJSC “Superconducting Nanotechnology” (Scontel), 5/22-1 Rossolimo St., 119021 Moscow (Russian Federation); National Research University Higher School of Economics, Moscow Institute of Electronics and Mathematics, 34 Tallinskaya St., 109028 Moscow (Russian Federation); Divochiy, A. V.; Karpova, U. V.; Morozov, P. V. [CJSC “Superconducting Nanotechnology” (Scontel), 5/22-1 Rossolimo St., 119021 Moscow (Russian Federation); Vakhtomin, Yu. B.; Seleznev, V. A. [Moscow State Pedagogical University, 1 Malaya Pirogovskaya St., 119435 Moscow (Russian Federation); CJSC “Superconducting Nanotechnology” (Scontel), 5/22-1 Rossolimo St., 119021 Moscow (Russian Federation); Sidorova, M. V. [Moscow State Pedagogical University, 1 Malaya Pirogovskaya St., 119435 Moscow (Russian Federation); Zotova, A. N.; Vodolazov, D. Yu. [Institute for Physics of Microstructure, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603950 Nizhny Novgorod (Russian Federation)

    2016-08-01

    We have found experimentally that the rise time of voltage pulse in NbN superconducting single photon detectors increases nonlinearly with increasing the length of the detector L. The effect is connected with dependence of resistance of the detector R{sub n}, which appears after photon absorption, on its kinetic inductance L{sub k} and, hence, on the length of the detector. This conclusion is confirmed by our calculations in the framework of two temperature model.

  9. Superconducting, magnetic and magnetotransport properties of FeTe1-xSex single crystals

    Science.gov (United States)

    Kumar, Rohit; Sudesh, Varma, G. D.

    2018-05-01

    The single crystalline samples with compositions FeTe1-xSex (0.25 ≤ x ≤ 0.50) have been prepared via self-flux method and the superconducting, magnetic and magnetotransport properties of the grown crystals were investigated. The superconducting onset temperatures have been determined from the measurements of zero field cooled magnetization and resistance with temperatures. In the present case, highest superconducting transition temperature TC (onset) ˜ 15 K has been obtained for x=0.5. The HC2 (T=0 K) values have been estimated by fitting the experimental HC2 - T plots with WHH model. The highest HC2(0) has been obtained for x=0.5. The activation energy of the thermally activated flux flow has been found from the broadening of superconducting transition in an applied magnetic field using the Arrhenius law. Our results show that the activation energy (U0) decreases with the increasing magnetic field. Furthermore, the magnetization measurements for x=0.4 and 0.5 samples have been performed at T=5 K in the magnetic field range ±7 T to estimate critical current density at different applied magnetic fields using Bean formula. We see that the sample x=0.5 has higher values of JC as compared to that of x=0.4 at all magnetic fields. This is in conformity with the behavior of U0-H plots.

  10. The rewritable effects of bonded magnet for large starting torque and high efficiency in the small power single-phase written pole motor

    Science.gov (United States)

    Choi, Jae-Hak; Lee, Sung-Ho

    2009-04-01

    This paper presents a single-phase written pole motor using a bonded ring magnet for the small power home application. The motor has an exciter pole structure inside the stator and hybrid characteristics of an induction motor and permanent magnet motor. The design parameters and operating characteristics of the hybrid concept motor are investigated to increase starting torque and efficiency, which is most important for the small power home application. Larger starting torque and higher efficiency than those of the conventional induction motor could be obtained by using the rewritable characteristics of bonded magnet on the starting and running conditions.

  11. Testing of the large bore single aperture 1-meter superconducting dipoles made with phenolic inserts

    CERN Document Server

    Boschmann, H; Dubbeldam, R L; Kirby, G A; Lucas, J; Ostojic, R; Russenschuck, Stephan; Siemko, A; Taylor, T M; Vanenkov, I; Weterings, W

    1998-01-01

    Two identical single aperture 1-metre superconducting dipoles have been built in collaboration with HMA Power Systems and tested at CERN. The 87.8 mm aperture magnets feature a single layer coil wound using LHC main dipole outer layer cable, phenolic spacer type collars, and a keyed two part structural iron yoke. The magnets are designed as models of the D1 separation dipole in the LHC experimental insertions, whose nominal field is 4.5 T at 4.5 K. In this report we present the test results of the two magnets at 4.3 K and 1.9 K.

  12. Superconducting Qubit with Integrated Single Flux Quantum Controller Part II: Experimental Characterization

    Science.gov (United States)

    Leonard, Edward, Jr.; Beck, Matthew; Thorbeck, Ted; Zhu, Shaojiang; Howington, Caleb; Nelson, Jj; Plourde, Britton; McDermott, Robert

    We describe the characterization of a single flux quantum (SFQ) pulse generator cofabricated with a superconducting quantum circuit on a single chip. Resonant trains of SFQ pulses are used to induce coherent qubit rotations on the Bloch sphere. We describe the SFQ drive characteristics of the qubit at the fundamental transition frequency and at subharmonics (ω01 / n , n = 2 , 3 , 4 , ⋯). We address the issue of quasiparticle poisoning due to the proximal SFQ pulse generator, and we characterize the fidelity of SFQ-based rotations using randomized benchmarking. Present address: IBM T.J. Watson Research Center.

  13. Superconducting Qubit with Integrated Single Flux Quantum Controller Part I: Theory and Fabrication

    Science.gov (United States)

    Beck, Matthew; Leonard, Edward, Jr.; Thorbeck, Ted; Zhu, Shaojiang; Howington, Caleb; Nelson, Jj; Plourde, Britton; McDermott, Robert

    As the size of quantum processors grow, so do the classical control requirements. The single flux quantum (SFQ) Josephson digital logic family offers an attractive route to proximal classical control of multi-qubit processors. Here we describe coherent control of qubits via trains of SFQ pulses. We discuss the fabrication of an SFQ-based pulse generator and a superconducting transmon qubit on a single chip. Sources of excess microwave loss stemming from the complex multilayer fabrication of the SFQ circuit are discussed. We show how to mitigate this loss through judicious choice of process workflow and appropriate use of sacrificial protection layers. Present address: IBM T.J. Watson Research Center.

  14. Probing the Nanodomain Origin and Phase Transition Mechanisms in (Un)Poled PMN-PT Single Crystals and Textured Ceramics

    Science.gov (United States)

    Slodczyk, Aneta; Colomban, Philippe

    2010-01-01

    Outstanding electrical properties of solids are often due to the composition heterogeneity and/or the competition between two or more sublattices. This is true for superionic and superprotonic conductors and supraconductors, as well as for many ferroelectric materials. As in PLZT ferroelectric materials, the exceptional ferro- and piezoelectric properties of the PMN-PT ((1−x)PbMg1/3Nb2/3O3−xPbTiO3) solid solutions arise from the coexistence of different symmetries with long and short scales in the morphotropic phase boundary (MPB) region. This complex physical behavior requires the use of experimental techniques able to probe the local structure at the nanoregion scale. Since both Raman signature and thermal expansion behavior depend on the chemical bond anharmonicity, these techniques are very efficient to detect and then to analyze the subtitle structural modifications with an efficiency comparable to neutron scattering. Using the example of poled (field cooling or room temperature) and unpoled PMN-PT single crystal and textured ceramic, we show how the competition between the different sublattices with competing degrees of freedom, namely the Pb-Pb dominated by the Coulombian interactions and those built of covalent bonded entities (NbO6 and TiO6), determine the short range arrangement and the outstanding ferro- and piezoelectric properties. PMID:28883367

  15. A superconducting microcalorimeter for low-flux detection of near-infrared single photons

    International Nuclear Information System (INIS)

    Dreyling-Eschweiler, Jan

    2014-07-01

    This thesis covers the development and the characterization of a single photon detector based on a superconducting microcalorimeter. The detector development is motivated by the Any Light Particle Search II (ALPS II) experiment at DESY in Hamburg, which searches for weakly interacting sub-eV particles (WISPs). Therefore, a detection of low-fluxes of 1064 nm light is required. The work is divided in three analyses: the characterization of a milli-kelvin (mK) cryostat, the characterization of superconducting sensors for single photon detection, and the determination of dark count rates concerning 1064 nm signals. Firstly, an adiabatic demagnetization refrigerator (ADR) is characterized, which allows to reach mK-temperatures. During commissioning, the ADR cryostat is optimized and prepared to stably cool superconducting sensors at 80 mK±25 μK. It is found that sensors can be continuously operated for ∝20 h before recharging the system in -4 s -1 . By operating a fiber-coupled TES, it is found that the dark count rate for 1064 nm signals is dominated by pile-up events of near-infrared thermal photons coming through the fiber from the warm environment. Considering a detection efficiency of ∝18 %, a dark count rate of 8.6 . 10 -3 s -1 is determined for 1064 nm ALPS photons.Concerning ALPS II, this results in a sensitivity gain compared to the ALPS I detector. Furthermore, this thesis is the starting point of TES detector development in Hamburg, Germany.

  16. Ultrathin NbN Films for Superconducting Single-Photon Detectors

    International Nuclear Information System (INIS)

    Slysz, W.; Guziewicz, M.; Borysiewicz, M.

    2011-01-01

    We present our research on fabrication and structural and transport characterization of ultrathin superconducting NbN layers deposited on both single-crystal Al 2 O 3 and Si wafers, and SiO 2 and Si 3 N 4 buffer layers grown directly on Si wafers. The thicknesses of our films varied from 6 nm to 50 nm and they were grown using reactive RF magnetron sputtering on substrates maintained at the temperature 850 o C. We have performed extensive morphology characterization of our films using the X-ray diffraction method and atomic force microscopy, and related the results to the type of the substrate used for the film deposition. Our transport measurements showed that even the thinnest, 6 nm thick NbN films had the superconducting critical temperature of 10-12 K, which was increased to 14 K for thicker films. (author)

  17. Superconductivity in Sm-doped CaFe2As2 single crystals

    Science.gov (United States)

    Dong-Yun, Chen; Bin-Bin, Ruan; Jia, Yu; Qi, Guo; Xiao-Chuan, Wang; Qing-Ge, Mu; Bo-Jin, Pan; Tong, Liu; Gen-Fu, Chen; Zhi-An, Ren

    2016-06-01

    In this article, the Sm-doping single crystals Ca1 - x Sm x Fe2As2 (x = 0 ˜ 0.2) were prepared by the CaAs flux method, and followed by a rapid quenching treatment after the high temperature growth. The samples were characterized by structural, resistive, and magnetic measurements. The successful Sm-substitution was revealed by the reduction of the lattice parameter c, due to the smaller ionic radius of Sm3+ than Ca2+. Superconductivity was observed in all samples with onset T c varying from 27 K to 44 K upon Sm-doping. The coexistence of a collapsed phase transition and the superconducting transition was found for the lower Sm-doping samples. Zero resistivity and substantial superconducting volume fraction only happen in higher Sm-doping crystals with the nominal x > 0.10. The doping dependences of the c-axis length and onset T c were summarized. The high-T c observed in these quenched crystals may be attributed to simultaneous tuning of electron carriers doping and strain effect caused by lattice reduction of Sm-substitution. Project supported by the National Natural Science Foundation of China (Grant No. 11474339), the National Basic Research Program of China (Grant Nos. 2010CB923000 and 2011CBA00100), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB07020100).

  18. Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

    International Nuclear Information System (INIS)

    Kirillov, D.; Bozovic, I.; Geballe, T.H.; Kapitulnik, A.; Mitzi, D.B.

    1988-01-01

    Raman spectra of Bi 2 Sr 2 CaCu 2 O 8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 was found

  19. Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

    Science.gov (United States)

    Kirillov, D.; Bozovic, I.; Geballe, T. H.; Kapitulnik, A.; Mitzi, D. B.

    1988-12-01

    Raman spectra of Bi2Sr2CaCu2O8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi2Sr2CaCu2O8 and YBa2Cu3O7 was found.

  20. Superconducting transition and low-field magnetoresistance of a niobium single crystal at 4.2 deg. K

    International Nuclear Information System (INIS)

    Perriot, G.

    1967-01-01

    We report the study of the electrical resistance of a niobium single crystal, at 4.2 deg. K, from the beginning of the superconductive transition to 80 kilo oersteds. Critical fieldsH c2 and H c3 have been determined. Influences on superconductive transition of current density, field-current angle, crystal orientation and magnetoresistance have been studied. Variation laws of low-field transverse and longitudinal magneto-resistances have been determined. (author) [fr

  1. Photoacoustic wave propagating from normal into superconductive phases in Pb single crystals

    OpenAIRE

    Iwanaga, Masanobu

    2005-01-01

    Photoacoustic (PA) wave has been examined in a superconductor of the first kind, Pb single crystal. The PA wave is induced by optical excitation of electronic state and propagates from normal into superconductive phases below T$_{\\rm C}$. It is clearly shown by wavelet analysis that the measured PA wave includes two different components. The high-frequency component is MHz-ultrasonic and the relative low-frequency one is induced by thermal wave. The latter is observed in a similar manner irre...

  2. Magnetophoretic velocimetry of manganese(II) in a single microdroplet in a flow system under a high gradient magnetic field generated with a superconducting magnet.

    Science.gov (United States)

    Suwa, Masayori; Watarai, Hitoshi

    2002-10-01

    An experimental system for magnetophoretic velocimetry, which could determine the volume magnetic susceptibility of a single particle dispersed in a liquid phase from a magnetophoretic velocity, has been developed. A micrometer-sized high-gradient magnetic field could be generated in a capillary by a pair of iron pole pieces in a superconducting magnet (10 T). The magnetophoretic behavior of a single particle in a capillary flow system was investigated under the inhomogeneous magnetic field. From the magnetophoretic velocity of a polystyrene latex particle dispersed in a MnCl2 aqueous solution, the product of the magnetic flux density and the gradient, B(dB/dx), was determined as a function of the position along the capillary. The maximum value of B(dB/dx) was 4.7 x 10(4) T2 m(-1), which was approximately 100 times higher than that obtained by two Nd-Fe-B permanent magnets (0.4 T). Organic droplets extracting manganese(II) with 2-thenoyltrifluoroacetone and tri-n-octylphosphine oxide from MnCl2 solution were used as test samples. The difference of the volume magnetic susceptibility between the droplet and the medium could be determined from the magnetophoretic velocity. This method allowed us to continuously measure a volume magnetic susceptibility of 10-6 level for a picoliter droplet and to determine manganese(II) in the single droplet at the attomole level.

  3. Coulomb Blockade and Multiple Andreev Reflection in a Superconducting Single-Electron Transistor

    Science.gov (United States)

    Lorenz, Thomas; Sprenger, Susanne; Scheer, Elke

    2018-06-01

    In superconducting quantum point contacts, multiple Andreev reflection (MAR), which describes the coherent transport of m quasiparticles each carrying an electron charge with m≥3, sets in at voltage thresholds eV = 2Δ /m. In single-electron transistors, Coulomb blockade, however, suppresses the current at low voltage. The required voltage for charge transport increases with the square of the effective charge eV∝ ( me) ^2. Thus, studying the charge transport in all-superconducting single-electron transistors (SSETs) sets these two phenomena into competition. In this article, we present the fabrication as well as a measurement scheme and transport data for a SSET with one junction in which the transmission and thereby the MAR contributions can be continuously tuned. All regimes from weak to strong coupling are addressed. We extend the Orthodox theory by incorporating MAR processes to describe the observed data qualitatively. We detect a new transport process the nature of which is unclear at present. Furthermore, we observe a renormalization of the charging energy when approaching the strong coupling regime.

  4. Real-time imaging systems for superconducting nanowire single-photon detector arrays

    Energy Technology Data Exchange (ETDEWEB)

    Hofherr, Matthias

    2014-07-01

    Superconducting nanowire singe-photon detectors (SNSPD) are promising detectors in the field of applications, where single-photon resolution is required like in quantum optics, spectroscopy or astronomy. These cryogenic detectors gain from a broad spectrum in the optical and infrared range and deliver low dark counts and low jitter. This work provides a piece of deeper physical understanding of detector functionality in combination with highly engineered readout development. A detailed analysis focuses on the intrinsic detection mechanism of SNSPDs related to the detection in the infrared regime and the evolution of dark counts. With this fundamental knowledge, the next step is the development of a multi-pixel readout at cryogenic conditions. It is demonstrated, how two auspicious multi-pixel readout concepts can be realized, which enables statistical framing like in imaging applications using RSFQ electronics with fast framing rates and the readout of a detector array with continuous real-time single-photon resolution.

  5. Comparison of Deformation in High-Purity Single/Large Grain and Polycrystalline Niobium Superconducting Cavities

    International Nuclear Information System (INIS)

    Ganapati Rao Myneni; Peter Kneisel

    2005-01-01

    The current approach for the fabrication of superconducting radio frequency (SRF) cavities is to roll and deep draw sheets of polycrystalline high-purity niobium. Recently, a new technique was developed at Jefferson Laboratory that enables the fabrication of single-crystal high-purity Nb SRF cavities. To better understand the differences between SRF cavities fabricated out of fine-grained polycrystalline sheet in the standard manner and single crystal cavities fabricated by the new technique, two half-cells were produced according to the two different procedures and compared using a variety of analytical techniques including optical microscopy, scanning laser confocal microscopy, profilometry, and X-ray diffraction. Crystallographic orientations, texture, and residual stresses were determined in the samples before and after forming and this poster presents the results of this ongoing study

  6. A superconducting microcalorimeter for low-flux detection of near-infrared single photons

    Energy Technology Data Exchange (ETDEWEB)

    Dreyling-Eschweiler, Jan

    2014-07-15

    This thesis covers the development and the characterization of a single photon detector based on a superconducting microcalorimeter. The detector development is motivated by the Any Light Particle Search II (ALPS II) experiment at DESY in Hamburg, which searches for weakly interacting sub-eV particles (WISPs). Therefore, a detection of low-fluxes of 1064 nm light is required. The work is divided in three analyses: the characterization of a milli-kelvin (mK) cryostat, the characterization of superconducting sensors for single photon detection, and the determination of dark count rates concerning 1064 nm signals. Firstly, an adiabatic demagnetization refrigerator (ADR) is characterized, which allows to reach mK-temperatures. During commissioning, the ADR cryostat is optimized and prepared to stably cool superconducting sensors at 80 mK±25 μK. It is found that sensors can be continuously operated for ∝20 h before recharging the system in <2 h. Furthermore, the adiabatic system reaches a chance of success of ∝80 % for a recharge without technical problems. Secondly, superconducting sensors are analyzed. The focus is on microcalorimetric transition-edge sensors (TESs) based on 20 nm Tungsten (W) films fabricated by the U.S. National Institute of Standards and Technology (NIST). NIST TESs have a near unity detection efficiency for 1064 nm light (literature value). The energy resolution for 1064 nm signals is measured to be <8 %. The exponential falling time of a photon pulse is 1.5 μs. Furthermore, by determining TES parameters, it is found that the linear TES theory describes measured photon pulses well. The TES response is read out by a superconducting quantum interference device (SQUID) fabricated by Physikalisch-Technische Bundesanstalt (PTB). The system bandwidth is measured to be 0.9 MHz. Finally, the operation in the ADR cryostat as well as the ALPS II laboratory is optimized. This setup forms the ALPS TES detector. Thirdly, the background is measured to

  7. The influence of Si on the superconducting properties of LiFeAs single crystals

    International Nuclear Information System (INIS)

    Shlyk, L; Bischoff, M; Niewa, R

    2012-01-01

    The results of Si doping on the superconducting transition temperature, critical current density, irreversibility field, upper critical field, coherence length and magnetic relaxation of LiFeAs single crystals are reported for H ∥ c. The superconducting transition temperature of the Si doped sample decreases by about of 6.4 K/at.%, which is likely due to the pair breaking effect. The presence of a secondary high-field fishtail maximum, which shifts progressively with temperature, is associated with the extrinsic pinning centers created by Si. The increase of the critical current densities in intermediate magnetic fields of about three times as compared to our undoped material indicates that very small amounts of Si act as effective pinning sites for the flux pinning enhancement in the material. Pinning force curves measured at different temperatures obey a normalized form of Kramer’s law, which indicates that the critical current density is limited by one predominant flux pinning mechanism. Analysis of the temperature and field dependences of the magnetic relaxation is consistent with the collective pinning model. The magnetic relaxation measurements combined with the peak position of the critical current density in the B–T phase diagram suggest an elastic–plastic transition of the vortex lattice at higher temperatures and fields. (paper)

  8. Microfiber-coupled superconducting nanowire single-photon detector for near-infrared wavelengths.

    Science.gov (United States)

    You, Lixing; Wu, Junjie; Xu, Yingxin; Hou, Xintong; Fang, Wei; Li, Hao; Zhang, Weijun; Zhang, Lu; Liu, Xiaoyu; Tong, Limin; Wang, Zhen; Xie, Xiaoming

    2017-12-11

    High-performance superconducting nanowire single-photon detectors (SNSPDs) have facilitated numerous experiments and applications, particularly in the fields of modern quantum optics and quantum communication. Two kinds of optical coupling methods have thus far been developed for SNSPDs: one produces standard fiber-coupled SNSPDs in which the fibers vertically illuminate the meandered nanowires; the other produces waveguide-coupled SNSPDs in which nanowires are fabricated on the surface of a waveguide that guides photons, and the fibers are coupled to the waveguide. In this paper, we report on first experimental demonstration of a new type of SNSPD that is coupled with a microfiber (MF). Photons are guided by the MF and are evanescently absorbed by the nanowires of the SNSPD when the MF is placed on top of superconducting NbN nanowires. Room-temperature optical experiments indicated that this device has a coupling efficiency of up to 90% when a 1.3 μm-diameter MF is used for light with wavelength of 1550 nm. We were also able to demonstrate that our MF-coupled detector achieved system detection efficiencies of 50% and 20% at incident wavelengths of 1064 and 1550 nm, respectively, for a 2 μm-diameter MF at 2.2K. We expect that MF-coupled SNSPDs may show both high efficiency and broadband characteristics upon optimization and will be used for various novel applications, such as micro/nano-fiber optics.

  9. Superconducting properties of single-crystal Nb sphere formed by large-undercooling solidification process

    Energy Technology Data Exchange (ETDEWEB)

    Takeya, H.; Sung, Y.S.; Hirata, K.; Togano, K

    2003-10-15

    An electrostatic levitation (ESL) system has been used for investigating undercooling effects on superconducting materials. In this report, preliminary experiments on Nb (melting temperature: T{sub m}=2477 deg. C) have been performed by melting Nb in levitation using 150 and 250 W Nd-YAG lasers. Since molten Nb is solidified without any contact in a high vacuum condition, a significantly undercooled state up to 400 deg. C is maintained before recalescence followed by solidification. Spherical single crystals of Nb are formed by the ESL process due to the suppression of heterogeneous nucleation. The field dependence of magnetization of Nb shows a reversible behavior as an ideal type II superconductor, implying that it contains almost no flux-pinning centers.

  10. Comparison of higher order modes damping techniques for 800 MHz single cell superconducting cavities

    Science.gov (United States)

    Shashkov, Ya. V.; Sobenin, N. P.; Petrushina, I. I.; Zobov, M. M.

    2014-12-01

    At present, applications of 800 MHz harmonic cavities in both bunch lengthening and shortening regimes are under consideration and discussion in the framework of the High Luminosity LHC project. In this paper we study electromagnetic characteristics of high order modes (HOMs) for a single cell 800 MHz superconducting cavity and arrays of such cavities connected by drifts tubes. Different techniques for the HOMs damping such as beam pipe grooves, coaxial-notch loads, fluted beam pipes etc. are investigated and compared. The influence of the sizes and geometry of the drift tubes on the HOMs damping is analyzed. The problems of a multipacting discharge in the considered structures are discussed and the operating frequency detuning due to the Lorentz force is evaluated.

  11. Comparison of higher order modes damping techniques for 800 MHz single cell superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Shashkov, Ya.V., E-mail: shashkovyv@mail.ru [National Research Nuclear University MEPhI, Moscow (Russian Federation); Sobenin, N.P.; Petrushina, I.I. [National Research Nuclear University MEPhI, Moscow (Russian Federation); Zobov, M.M. [Laboratori Nazionali di Frascati INFN, Rome (Italy)

    2014-12-11

    At present, applications of 800 MHz harmonic cavities in both bunch lengthening and shortening regimes are under consideration and discussion in the framework of the High Luminosity LHC project. In this paper we study electromagnetic characteristics of high order modes (HOMs) for a single cell 800 MHz superconducting cavity and arrays of such cavities connected by drifts tubes. Different techniques for the HOMs damping such as beam pipe grooves, coaxial-notch loads, fluted beam pipes etc. are investigated and compared. The influence of the sizes and geometry of the drift tubes on the HOMs damping is analyzed. The problems of a multipacting discharge in the considered structures are discussed and the operating frequency detuning due to the Lorentz force is evaluated.

  12. Phase transitions in trajectories of a superconducting single-electron transistor coupled to a resonator.

    Science.gov (United States)

    Genway, Sam; Garrahan, Juan P; Lesanovsky, Igor; Armour, Andrew D

    2012-05-01

    Recent progress in the study of dynamical phase transitions has been made with a large-deviation approach to study trajectories of stochastic jumps using a thermodynamic formalism. We study this method applied to an open quantum system consisting of a superconducting single-electron transistor, near the Josephson quasiparticle resonance, coupled to a resonator. We find that the dynamical behavior shown in rare trajectories can be rich even when the mean dynamical activity is small, and thus the formalism gives insights into the form of fluctuations. The structure of the dynamical phase diagram found from the quantum-jump trajectories of the resonator is studied, and we see that sharp transitions in the dynamical activity may be related to the appearance and disappearance of bistabilities in the state of the resonator as system parameters are changed. We also demonstrate that for a fast resonator, the trajectories of quasiparticles are similar to the resonator trajectories.

  13. Magnetic field modeling and optimal operational control of a single-side axial-flux permanent magnet motor with center poles

    International Nuclear Information System (INIS)

    Liu, C.-T.; Lee, S.-C.

    2006-01-01

    A detailed approach for analyzing magnetic field distributions of a single-sided axial-flux permanent magnet motor with center poles will be provided. Based on the devised flux model, the related position-dependent torque and axial force of the motor can be systematically developed. By incorporating adequate control designs, the optimal operational performance of the motor system can be conveniently achieved. Results showed that not only the motor structure is suitable for related military and transportation applications, but also the magnetic field model can provide appropriate mathematical basis for relative operational realizations

  14. Continuous-wave sodium D2 resonance radiation generated in single-pass sum-frequency generation with periodically poled lithium niobate.

    Science.gov (United States)

    Yue, J; She, C-Y; Williams, B P; Vance, J D; Acott, P E; Kawahara, T D

    2009-04-01

    With two cw single-mode Nd:YAG lasers at 1064 and 1319 nm and a periodically poled lithium niobate crystal, 11 mW of 2 kHz/100 ms bandwidth single-mode tunable 589 nm cw radiation has been detected using single-pass sum-frequency generation. The demonstrated conversion efficiency is approximately 3.2%[W(-1) cm(-1)]. This compact solid-state light source has been used in a solid-state-dye laser hybrid sodium fluorescence lidar transmitter to measure temperatures and winds in the upper atmosphere (80-105 km); it is being implemented into the transmitter of a mobile all-solid-state sodium temperature and wind lidar under construction.

  15. Superconductivity and transport properties in LaRu4Sb12 single crystals probed by radiation-induced disordering

    International Nuclear Information System (INIS)

    Goshchitskii, B.; Naumov, S.; Kostromitina, N.; Karkin, A.

    2007-01-01

    Resistivity ρ(T) and Hall coefficient R H (T) in magnetic fields H up to 14 T were studied in superconducting (T c = 3.3 K) LaRu 4 Sb 12 single crystals disordered by fast neutron irradiation. Atomic disordering leads to increase in residual resistivity ρ 0 , decrease of Hall number and suppression of superconductivity. The upper critical field slope -dH c2 /dT increases approximately linear with ρ 0 . The irradiation effects are almost recovered after annealing at 500 deg. C. The observed radiation-induced effects in LaRu 4 Sb 12 are compared with those in PrOs 4 Sb 12 in terms of unconventional mechanisms of superconductivity

  16. Study of coexistence of ferromagnetism and superconductivity in single-crystal ErRh4B4

    International Nuclear Information System (INIS)

    Sinha, S.K.; Crabtree, G.W.; Hinks, D.G.; Mook, H.

    1981-01-01

    Neutron diffraction and resistivity measurements on single crystals of ErRh 4 B 4 have revealed that both superconductivity and ferromagnetic order coexist in this material between 0.71 and 1.2 0 K. In this intermediate phase, a linear polarized modulated structure with a wavelength of approximately 100 A is observed. The modulated moment increases faster than the ferromagnetic moment down to 0.71 K and then disappears suddenly, with loss of superconductivity and a transition to a normal ferromagnetic state. This transition is accompanied by temperature hysteresis of about 60 mK. The same hysteresis, in the inverse sense, is exhibited by the ferromagnetic component. We interpret the intermediate phase as being one of coexisting normal ferromagnetic domains and superconducting sinusoidally ordered domains. Evidence of a small percentage of small ferromagnetic regions of size approx. 100 A is also seen in both the intermediate and ferromagnetic phases. 3 figures

  17. Designing Kerr interactions using multiple superconducting qubit types in a single circuit

    Science.gov (United States)

    Elliott, Matthew; Joo, Jaewoo; Ginossar, Eran

    2018-02-01

    The engineering of Kerr interactions is of great interest for processing quantum information in multipartite quantum systems and for investigating many-body physics in a complex cavity-qubit network. We study how coupling multiple different types of superconducting qubits to the same cavity modes can be used to modify the self- and cross-Kerr effects acting on the cavities and demonstrate that this type of architecture could be of significant benefit for quantum technologies. Using both analytical perturbation theory results and numerical simulations, we first show that coupling two superconducting qubits with opposite anharmonicities to a single cavity enables the effective self-Kerr interaction to be diminished, while retaining the number splitting effect that enables control and measurement of the cavity field. We demonstrate that this reduction of the self-Kerr effect can maintain the fidelity of coherent states and generalised Schrödinger cat states for much longer than typical coherence times in realistic devices. Next, we find that the cross-Kerr interaction between two cavities can be modified by coupling them both to the same pair of qubit devices. When one of the qubits is tunable in frequency, the strength of entangling interactions between the cavities can be varied on demand, forming the basis for logic operations on the two modes. Finally, we discuss the feasibility of producing an array of cavities and qubits where intermediary and on-site qubits can tune the strength of self- and cross-Kerr interactions across the whole system. This architecture could provide a way to engineer interesting many-body Hamiltonians and be a useful platform for quantum simulation in circuit quantum electrodynamics.

  18. Superconducting single electron transistor for charge sensing in Si/SiGe-based quantum dots

    Science.gov (United States)

    Yang, Zhen

    Si-based quantum devices, including Si/SiGe quantum dots (QD), are promising candidates for spin-based quantum bits (quits), which are a potential platform for quantum information processing. Meanwhile, qubit readout remains a challenging task related to semiconductor-based quantum computation. This thesis describes two readout devices for Si/SiGe QDs and the techniques for developing them from a traditional single electron transistor (SET). By embedding an SET in a tank circuit and operating it in the radio-frequency (RF) regime, a superconducting RF-SET has quick response as well as ultra high charge sensitivity and can be an excellent charge sensor for the QDs. We demonstrate such RF-SETs for QDs in a Si/SiGe heterostructure. Characterization of the SET in magnetic fields is studied for future exploration of advanced techniques such as spin detection and spin state manipulation. By replacing the tank circuit with a high-quality-factor microwave cavity, the embedded SET will be operated in the supercurrent regime as a single Cooper pair transistor (CPT) to further increase the charge sensitivity and reduce any dissipation. The operating principle and implementation of the cavity-embedded CPT (cCPT) will be introduced.

  19. Force-free state in a superconducting single crystal and angle-dependent vortex helical instability

    Science.gov (United States)

    del Valle, J.; Gomez, A.; Gonzalez, E. M.; Manas-Valero, S.; Coronado, E.; Vicent, J. L.

    2017-06-01

    Superconducting 2 H -NbS e2 single crystals show intrinsic low pinning values. Therefore, they are ideal materials with which to explore fundamental properties of vortices. (V , I ) characteristics are the experimental data we have used to investigate the dissipation mechanisms in a rectangular-shaped 2 H -NbS e2 single crystal. Particularly, we have studied dissipation behavior with magnetic fields applied in the plane of the crystal and parallel to the injected currents, i.e., in the force-free state where the vortex helical instability governs the vortex dynamics. In this regime, the data follow the elliptic critical state model and the voltage dissipation shows an exponential dependence, V ∝eα (I -IC ∥ ) , IC ∥ being the critical current in the force-free configuration and α a linear temperature-dependent parameter. Moreover, this exponential dependence can be observed for in-plane applied magnetic fields up to 40° off the current direction, which implies that the vortex helical instability plays a role in dissipation even out of the force-free configuration.

  20. Frequency-multiplexed bias and readout of a 16-pixel superconducting nanowire single-photon detector array

    Science.gov (United States)

    Doerner, S.; Kuzmin, A.; Wuensch, S.; Charaev, I.; Boes, F.; Zwick, T.; Siegel, M.

    2017-07-01

    We demonstrate a 16-pixel array of microwave-current driven superconducting nanowire single-photon detectors with an integrated and scalable frequency-division multiplexing architecture, which reduces the required number of bias and readout lines to a single microwave feed line. The electrical behavior of the photon-sensitive nanowires, embedded in a resonant circuit, as well as the optical performance and timing jitter of the single detectors is discussed. Besides the single pixel measurements, we also demonstrate the operation of a 16-pixel array with a temporal, spatial, and photon-number resolution.

  1. Magnetism and superconductivity in CeFe2-xTxAs2 (T = Co and Ni) single crystals

    International Nuclear Information System (INIS)

    Thamizhavel, A.

    2010-01-01

    Single crystals of pure and transition metal doped CaFe 2- x T x As 2 (T = Co and Ni) have been grown by flux method using molten Sn as solvent. The magnetic and superconducting properties of the grown crystals were studied by measuring the electrical resistivity, magnetic susceptibility and neutron diffraction measurements. A spin density wave (SDW)/structural transition is observed at 170 K for the pure CaFe 2 As 2 single crystal and it gets suppressed with T (Co and Ni) doping. For an optimum dopant concentration of x = 0.06, the sample becomes superconducting. From the detailed studies on CaFe 2- x Ni x As 2 single crystals we have constructed a magnetic phase diagram. (author)

  2. Impacts of Co-doping on the superconductivity and the orbital ordering state in Fe1-xCoxSe single crystal studied by the electrical transport.

    Science.gov (United States)

    Urata, Takahiro; Tanabe, Yoichi; Heguri, Satoshi; Tanigaki, Katsumi

    2015-03-01

    In the FeSe with the simplest crystal structure in the Fe-based superconductor families, although both the superconductivity and the orbital ordering states are investigated, the relation between them is still unclear. Here, we report Co doping effects on the superconductivity and the orbital ordering state in Fe1-xCoxSe single crystals. The electrical transport measurements demonstrated that the superconductivity vanishes at 4 % Co doping while the orbital ordering state may be robust against Co doping. Present results suggest that the orbital ordering state is not related to the emergence of the superconductivity in FeSe.

  3. Comparison of 2D and 3D magnetic field analysis of single-phase shaded pole induction motors

    Directory of Open Access Journals (Sweden)

    Adem Dalcali

    2016-03-01

    Full Text Available There has always been doubt on the accuracy of 2D analysis of small electric machines. To investigate the validity of this doubt, in this present work a small uni-coil shaded-pole induction motor is analyzed in 2D and 3D and the results are compared. In order to maintain the paper size as compact, the analysis is limited to the air-gap flux density distribution, variation of the main winding inductance against current and the force acting on the rotor body; which are the important components of the motor performance. It is found that although 3D analysis consumes several times more computing time and storage space, improvement achieved in performance by use of 3D analysis is not very significant. % rms difference between the two cases is obtained as 0.76% for the main winding inductance and 0.59% for the force acting on the rotor body. Also the air-gap flux density distribution obtained from the two types of analysis is found to be very close to each other. Therefore it is concluded that despite more computing time, more storage requirements and more human effort in the case of 3D analysis, the degree of improvement is not proportionally rewarding, and hence, 2D analysis is sufficient for the analysis of small machines.

  4. Magnetoresistance in single-electron transistors comprising a superconducting island with ferromagnetic leads

    Science.gov (United States)

    Mizugaki, Yoshinao; Takiguchi, Masashi; Tamura, Nobuyuki; Shimada, Hiroshi

    2018-03-01

    We report electric and magnetic field responses of single-electron transistors (SETs) comprising a superconducting island with ferromagnetic (FM) leads. We fabricated two SETs, one of which had relatively high resistance and the other had relatively low resistance. The SETs had two states for the gate charge: SET-ON or SET-OFF. They also had two states for the FM lead magnetization: parallel (P) or anti-parallel (AP) configuration. Current-voltage characteristics of four SET states (“P & SET-ON,” “P & SET-OFF,” “AP & SET-ON,” and “AP & SET-OFF”) were measured at approximately 0.1 K in a compact dilution refrigerator. Magnetoresistance ratio (MRR) values were obtained for the SET-ON and SET-OFF states, respectively. The higher-resistance SET1 exhibited positive MRR values for all measured bias voltages. The MRR enhancement was confirmed for the SET-OFF state, which agreed well with the co-tunneling model. The lower-resistance SET2, on the other hand, exhibited negative and positive MRR values for higher and lower bias voltage conditions, respectively. The bias voltage for the MRR polarity reversal was changed by the gate voltage. It was also confirmed that the co-tunneling model was partially valid for negative MRR values.

  5. Single-nitrogen-vacancy-center quantum memory for a superconducting flux qubit mediated by a ferromagnet

    Science.gov (United States)

    Lai, Yen-Yu; Lin, Guin-Dar; Twamley, Jason; Goan, Hsi-Sheng

    2018-05-01

    We propose a quantum memory scheme to transfer and store the quantum state of a superconducting flux qubit (FQ) into the electron spin of a single nitrogen-vacancy (NV) center in diamond via yttrium iron garnet (YIG), a ferromagnet. Unlike an ensemble of NV centers, the YIG moderator can enhance the effective FQ-NV-center coupling strength without introducing additional appreciable decoherence. We derive the effective interaction between the FQ and the NV center by tracing out the degrees of freedom of the collective mode of the YIG spins. We demonstrate the transfer, storage, and retrieval procedures, taking into account the effects of spontaneous decay and pure dephasing. Using realistic experimental parameters for the FQ, NV center and YIG, we find that a combined transfer, storage, and retrieval fidelity higher than 0.9, with a long storage time of 10 ms, can be achieved. This hybrid system not only acts as a promising quantum memory, but also provides an example of enhanced coupling between various systems through collective degrees of freedom.

  6. High-fidelity frequency down-conversion of visible entangled photon pairs with superconducting single-photon detectors

    International Nuclear Information System (INIS)

    Ikuta, Rikizo; Kato, Hiroshi; Kusaka, Yoshiaki; Yamamoto, Takashi; Imoto, Nobuyuki; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Wang, Zhen; Fujiwara, Mikio; Sasaki, Masahide; Koashi, Masato

    2014-01-01

    We experimentally demonstrate a high-fidelity visible-to-telecommunicationwavelength conversion of a photon by using a solid-state-based difference frequency generation. In the experiment, one half of a pico-second visible entangled photon pair at 780 nm is converted to a 1522-nm photon. Using superconducting single-photon detectors with low dark count rates and small timing jitters, we observed a fidelity of 0.93±0.04 after the wavelength conversion

  7. Fidelity study of the superconducting phase diagram in the two-dimensional single-band Hubbard model

    Science.gov (United States)

    Jia, C. J.; Moritz, B.; Chen, C.-C.; Shastry, B. Sriram; Devereaux, T. P.

    2011-09-01

    Extensive numerical studies have demonstrated that the two-dimensional single-band Hubbard model contains much of the key physics in cuprate high-temperature superconductors. However, there is no definitive proof that the Hubbard model truly possesses a superconducting ground state or, if it does, of how it depends on model parameters. To answer these longstanding questions, we study an extension of the Hubbard model including an infinite-range d-wave pair field term, which precipitates a superconducting state in the d-wave channel. Using exact diagonalization on 16-site square clusters, we study the evolution of the ground state as a function of the strength of the pairing term. This is achieved by monitoring the fidelity metric of the ground state, as well as determining the ratio between the two largest eigenvalues of the d-wave pair/spin/charge-density matrices. The calculations show a d-wave superconducting ground state in doped clusters bracketed by a strong antiferromagnetic state at half filling controlled by the Coulomb repulsion U and a weak short-range checkerboard charge ordered state at larger hole doping controlled by the next-nearest-neighbor hopping t'. We also demonstrate that negative t' plays an important role in facilitating d-wave superconductivity.

  8. Design, Fabrication and Initial Testing of a Large Bore Single Aperture 1 m Long Superconducting Dipole Made with Phenolic Inserts

    CERN Document Server

    Boschmann, H; Kirby, G A; Lucas, J; Ostojic, R; Russenschuck, Stephan; Siemko, A; Vanenkov, I; Weterings, W

    1997-01-01

    In the framework of the LHC magnet development programme, a large bore single aperture 1-meter long superconducting dipole has been built in collaboration with HOLEC. The magnet features a single layer coil wound using the LHC main dipole outer layer cable, phenolic inserts, and a keyed two part structural iron yoke. This paper presents the magnetic and mechanical design and optimisation of the magnet. We describe the coil winding and curing, and present the construction and assembly procedures. Finally we report on the mechanical behaviour during assembly and cooling, and present the magnet training behaviour.

  9. An absorptive single-pole four-throw switch using multiple-contact MEMS switches and its application to a monolithic millimeter-wave beam-forming network

    International Nuclear Information System (INIS)

    Lee, Sanghyo; Kim, Jong-Man; Kim, Yong-Kweon; Kwon, Youngwoo

    2009-01-01

    In this paper, a new absorptive single-pole four-throw (SP4T) switch based on multiple-contact switching is proposed and integrated with a Butler matrix to demonstrate a monolithic beam-forming network at millimeter waves (mm waves). In order to simplify the switching driving circuit and reduce the number of unit switches in an absorptive SP4T switch, the individual switches were replaced with long-span multiple-contact switches using stress-free single-crystalline-silicon MEMS technology. This approach improves the mechanical stability as well as the manufacturing yield, thereby allowing successful integration into a monolithic beam former. The fabricated absorptive SP4T MEMS switch shows insertion loss less than 1.3 dB, return losses better than 11 dB at 30 GHz and wideband isolation performance higher than 39 dB from 20 to 40 GHz. The absorptive SP4T MEMS switch is integrated with a 4 × 4 Butler matrix on a single chip to implement a monolithic beam-forming network, directing beam into four distinct angles. Array factors from the measured data show that the proposed absorptive SPnT MEMS switch can be effectively used for high-performance mm-wave beam-switching systems. This work corresponds to the first demonstration of a monolithic beam-forming network using switched beams

  10. Performance and Characterization of a Modular Superconducting Nanowire Single Photon Detector System for Space-to-Earth Optical Communications Links

    Science.gov (United States)

    Vyhnalek, Brian E.; Tedder, Sarah A.; Nappier, Jennifer M.

    2018-01-01

    Space-to-ground photon-counting optical communication links supporting high data rates over large distances require enhanced ground receiver sensitivity in order to reduce the mass and power burden on the spacecraft transmitter. Superconducting nanowire single-photon detectors (SNSPDs) have been demonstrated to offer superior performance in detection efficiency, timing resolution, and count rates over semiconductor photodetectors, and are a suitable technology for high photon efficiency links. Recently photon detectors based on superconducting nanowires have become commercially available, and we have assessed the characteristics and performance of one such commercial system as a candidate for potential utilization in ground receiver designs. The SNSPD system features independent channels which can be added modularly, and we analyze the scalability of the system to support different data rates, as well as consider coupling concepts and issues as the number of channels increases.

  11. Growth and superconducting properties of Bi2Sr2Ca2Cu3O10 single crystals

    International Nuclear Information System (INIS)

    Clayton, N; Musolino, N; Giannini, E; Garnier, V; Fluekiger, R

    2004-01-01

    Single crystals of Bi 2 Sr 2 Ca 2 Cu 3 O 10 (Bi-2223) have been grown using the travelling solvent floating zone technique in an image furnace. Annealing the crystals under high pressures of O 2 increased their critical temperature to 109 K, and resulted in sharp superconducting transitions of ΔT c = 1 K. The superconducting anisotropy of Bi-2223 was found to be ∼ 50, from measurements of the lower critical field with the magnetic field applied parallel and perpendicular to the c-axis. The anisotropy of Bi-2223 is significantly reduced compared to that of Bi 2 Sr 2 CaCu 2 O 8 (Bi-2212), and this accounts for the enhanced irreversibility fields in Bi-2223. Furthermore, Bi-2223 has a higher critical current density, and a reduced magnetic relaxation rate compared to Bi-2212, which are both signatures of more effective pinning in Bi-2223 due to its reduced anisotropy

  12. Femtosecond single-beam direct laser poling of stable and efficient second-order nonlinear optical properties in glass

    International Nuclear Information System (INIS)

    Papon, G.; Marquestaut, N.; Royon, A.; Canioni, L.; Petit, Y.; Dussauze, M.; Rodriguez, V.; Cardinal, T.

    2014-01-01

    We depict a new approach for the localized creation in three dimensions (3D) of a highly demanded nonlinear optical function for integrated optics, namely second harmonic generation. We report on the nonlinear optical characteristics induced by single-beam femtosecond direct laser writing in a tailored silver-containing phosphate glass. The original spatial distribution of the nonlinear pattern, composed of four lines after one single laser writing translation, is observed and modeled with success, demonstrating the electric field induced origin of the second harmonic generation. These efficient second-order nonlinear structures (with χ eff (2)  ∼ 0.6 pm V −1 ) with sub-micron scale are impressively stable under thermal constraint up to glass transition temperature, which makes them very promising for new photonic applications, especially when 3D nonlinear architectures are desired

  13. Interface-enhanced high-temperature superconductivity in single-unit-cell FeT e1 -xS ex films on SrTi O3

    Science.gov (United States)

    Li, Fangsen; Ding, Hao; Tang, Chenjia; Peng, Junping; Zhang, Qinghua; Zhang, Wenhao; Zhou, Guanyu; Zhang, Ding; Song, Can-Li; He, Ke; Ji, Shuaihua; Chen, Xi; Gu, Lin; Wang, Lili; Ma, Xu-Cun; Xue, Qi-Kun

    2015-06-01

    Recently discovered high-temperature superconductivity in single-unit-cell (UC) FeSe films on SrTi O3 (STO) substrate has stimulated tremendous research interest, both experimental and theoretical. Whether this scenario could be extended to other superconductors is vital in both identifying the enhanced superconductivity mechanism and further raising the critical transition temperature (Tc). Here we successfully prepared single-UC FeT e1 -xS ex(0.1 ≤x ≤0.6 ) films on STO substrates by molecular beam epitaxy and observed U -shaped superconducting gaps (Δ ) up to ˜16.5 meV , nearly ten times the gap value (Δ ˜1.7 meV ) of the optimally doped bulk FeT e0 .6S e0 .4 single crystal (Tc˜14.5 K ). No superconducting gap has been observed on the second UC and thicker FeT e1 -xS ex films at 5.7 K, indicating the important role of the interface. This interface-enhanced high-temperature superconductivity is further confirmed by ex situ transport measurements, which revealed an onset superconducting transition temperature above 40 K, nearly two times higher than that of the optimally doped bulk FeT e0 .6S e0 .4 single crystal. This work demonstrates that interface engineering is a feasible way to discover alternative superconductors with higher Tc.

  14. The South Pole Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Ruhl, J.E.; Ade, P.A.R.; Carlstrom, J.E.; Cho, H.M.; Crawford,T.; Dobbs, M.; Greer, C.H.; Halverson, N.W.; Holzapfel, W.L.; Lanting,T.M.; Lee, A.T.; Leitch, E.M.; Leong, J.; Lu, W.; Lueker, M.; Mehl, J.; Meyer, S.S.; Mohr, J.J.; Padin, S.; Plagge, T.; Pryke, C.; Runyan, M.C.; Schwan, D.; Sharp, M.K.; Spieler, H.; Staniszewski, Z.; Stark, A.A.

    2004-11-04

    A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10 m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over 4000 degrees for galaxy clusters using the Sunyaev-Zeldovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable significant constraints to be placed on the equation of state of the dark energy.

  15. ISR Superconducting Quadrupoles

    CERN Multimedia

    1977-01-01

    Michel Bouvier is preparing for curing the 6-pole superconducting windings inbedded in the cylindrical wall separating liquid helium from vacuum in the quadrupole aperture. The heat for curing the epoxy glue was provided by a ramp of infrared lamps which can be seen above the slowly rotating cylinder. See also 7703512X, 7702690X.

  16. Effects of post-annealing and cobalt co-doping on superconducting properties of (Ca,Pr)Fe{sub 2}As{sub 2} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Okada, T., E-mail: 8781303601@mail.ecc.u-tokyo.ac.jp; Ogino, H.; Yakita, H.; Yamamoto, A.; Kishio, K.; Shimoyama, J.

    2014-10-15

    Highlights: • Post-annealing at 400 °C killed superconductivity for Co-free sample. • Pr,Co co-doped samples maintained superconductivity even after annealing. • Two-step superconducting transition was observed via magnetization measurement. • Bulk superconductivity of low-T{sub c} component was confirmed. • Superconducting volume fraction of high-T{sub c} component was always small. - Abstract: In order to clarify the origin of anomalous superconductivity in (Ca,RE)Fe{sub 2}As{sub 2} system, Pr doped and Pr,Co co-doped CaFe{sub 2}As{sub 2} single crystals were grown by the FeAs flux method. These samples showed two-step superconducting transition with T{sub c1} = 25–42 K, and T{sub c2} < 16 K, suggesting that (Ca,RE)Fe{sub 2}As{sub 2} system has two superconducting components. Post-annealing performed for these crystals in evacuated quartz ampoules at various temperatures revealed that post-annealing at ∼400 °C increased the c-axis length for all samples. This indicates that as-grown crystals have a certain level of strain, which is released by post-annealing at ∼400 °C. Superconducting properties also changed dramatically by post-annealing. After annealing at 400 °C, some of the co-doped samples showed large superconducting volume fraction corresponding to the perfect diamagnetism below T{sub c2} and high J{sub c} values of 10{sup 4}–10{sup 5} A cm{sup −2} at 2 K in low field, indicating the bulk superconductivity of (Ca,RE)Fe{sub 2}As{sub 2} phase occurred below T{sub c2}. On the contrary, the superconducting volume fraction above T{sub c2} was always very small, suggesting that 40 K-class superconductivity observed in this system is originating in the local superconductivity in the crystal.

  17. Coherent Anti-Stokes and Coherent Stokes in Raman Scattering by Superconducting Nanowire Single-Photon Detector for Temperature Measurement

    Directory of Open Access Journals (Sweden)

    Annepu Venkata Naga Vamsi

    2016-01-01

    Full Text Available We have reported the measurement of temperature by using coherent anti-Stroke and coherent Stroke Raman scattering using superconducting nano wire single-photon detector. The measured temperatures by both methods (Coherent Anti-Raman scattering & Coherent Stroke Raman scattering and TC 340 are in good accuracy of ± 5 K temperature range. The length of the pipe line under test can be increased by increasing the power of the pump laser. This methodology can be widely used to measure temperatures at instantaneous positions in test pipe line or the entire temperature of the pipe line under test.

  18. Superconducting nanowire single photon detectors fabricated from an amorphous Mo0.75Ge0.25 thin film

    International Nuclear Information System (INIS)

    Verma, V. B.; Lita, A. E.; Vissers, M. R.; Marsili, F.; Pappas, D. P.; Mirin, R. P.; Nam, S. W.

    2014-01-01

    We present the characteristics of superconducting nanowire single photon detectors (SNSPDs) fabricated from amorphous Mo 0.75 Ge 0.25 thin-films. Fabricated devices show a saturation of the internal detection efficiency at temperatures below 1 K, with system dark count rates below 500 cps. Operation in a closed-cycle cryocooler at 2.5 K is possible with system detection efficiencies exceeding 20% for SNSPDs which have not been optimized for high detection efficiency. Jitter is observed to vary between 69 ps at 250 mK and 187 ps at 2.5 K using room temperature amplifiers.

  19. Low field anisotropic properties of a single crystals of superconducting YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Hammann, J.; Ocio, M.; Vincent, E.; Bertinotti, A.; Luzet, D.

    1987-09-01

    Low field (0.4G≤H≤3G) magnetization measurements have been performed on small single crystals of superconducting YBa 2 Cu 3 O 7.δ using a SQUID magnetometer. They revealed anisotropic properties in the temperature dependences of the shielding and the Meissner effects. A sharp unique transition at 95 K is observed with the field parallel to c. In the perpendicular direction a second transition line seems to be crossed at T* = 84 K. This temperature T* remains constant in the range of fields investigated

  20. Elastic flux creep in the mixed state of superconducting L2-xCexCuO4 single crystals

    International Nuclear Information System (INIS)

    Crusellas, M.A.; Fabrega, L.; Fontcuberta, J.; Martinez, B.; Obradors, X.; Pinol, S.

    1994-01-01

    We have performed measurements of the I-V characteristics and magnetic relaxation on L 2-x Ce x CuO 4 (L = Pr, Sm) superconducting single crystals (H//c), well below the critical temperature (T c ∼ 20 K). From both sets of data we have determined the current dependence of the effective flux creep energy barriers. An U(J) ∼-1nJ has been clearly identified in a region of the (H,T) plane. The relevance of the elastic properties of the vortex system on the flux creep energies is discussed. (orig.)

  1. Multi-channeled NbN superconducting single photon detectors (SSPDs) system with NbN meander nanowires

    International Nuclear Information System (INIS)

    Fujiwara, Mikio; Sasaki, Masahide; Miki, Shigehito; Wang Zhen

    2009-01-01

    A superconducting single photon detector (SSPD) is promising candidate of the detector in a quantum key distribution (QKD) system, because of its low dark count and high speed repetition rate. We have developed the SSPD system cooled by a GM cryocooler. In this system, and the work surface can be cooled 2.95 K and up to 6 SSPDs can be installed. The active areas of SSPDs are 10x10 μm 2 or 20x20 μm 2 , and the system detection efficiency at dark count rate of 100 Hz reached 2.6% at a wavelength of 1550 nm.

  2. Multigap superconductivity and Shubnikov-de Haas oscillations in single crystals of the layered boride OsB2

    Science.gov (United States)

    Singh, Yogesh; Martin, C.; Bud'Ko, S. L.; Ellern, A.; Prozorov, R.; Johnston, D. C.

    2010-10-01

    Single crystals of superconducting OsB2 [Tc=2.10(5)K] have been grown using a Cu-B eutectic flux. We confirm that OsB2 crystallizes in the reported orthorhombic structure (space group Pmmn ) at room temperature. Both the normal and superconducting state properties of the crystals are studied using various techniques. Heat capacity versus temperature C(T) measurements yield the normal state electronic specific heat coefficient γ=1.95(1)mJ/molK2 and the Debye temperature ΘD=539(2)K . The measured frequencies of Shubnikov-de Haas oscillations are in good agreement with those predicted by band structure calculations. Magnetic susceptibility χ(T,H) , electrical resistivity ρ(T) , and C(T,H) measurements ( H is the magnetic field) demonstrate that OsB2 is a bulk low- κ [κ(Tc)=2(1)] type-II superconductor that is intermediate between the clean and dirty limits [(ξ(T=0)/ℓ=0.97)] with a small upper critical magnetic field Hc2(T=0)=186(4)Oe . The penetration depth is λ(T=0)=0.300μm . An anomalous (not single-gap BCS) T dependence of λ was fitted by a two-gap model with Δ1(T=0)/kBTc=1.9 and Δ2(T=0)/kBTc=1.25 , respectively. The discontinuity in the heat capacity at Tc , ΔC/γTc=1.32 , is smaller than the weak-coupling BCS value of 1.43, consistent with the two-gap nature of the superconductivity in OsB2 . An anomalous increase in ΔC at Tc of unknown origin is found in finite H ; e.g., ΔC/γTc≈2.5 for H≈25Oe .

  3. 600-year reconstruction of the tri-pole Interdecadal Pacific Oscillation (TPI) using tree-ring chronologies and a single coral proxy from Indonesia, Australia and New Zealand.

    Science.gov (United States)

    Palmer, Jonathan; Cook, Edward; Turney, Chris; Cook, Benjamin; Fenwick, Pavla; Allen, Kathy; Baker, Patrick; Henley, Benjamin

    2017-04-01

    The development of the eastern Australia and New Zealand summer drought atlas (i.e. ANZDA; Palmer et al., 2015) highlighted the potential for exploring the reconstruction of the Henley et al. (2015) tripole Interdecadal Pacific Oscillation index (TPI). The approach taken was to use both the 1375 drought atlas scPDSI (self-calibrating Palmer Drought Severity Index) grid-points and the 176 tree-ring and single coral proxies to determine the strength and spatial expression of their relationship to TPI. An important concern was the potential geographic bias of the proxies relative to the TPI. To examine this concern more closely, each of three main TPI regions of sea surface temperatures were extracted and then correlated to the ANZDA scPDSI grid-points. Results showed a robust correlation field to each of the three poles although the closest "Tasman" pole was, as expected, the strongest. Next, the 177 proxies were used in regressions to calibrate/verify to the TPI over the period CE 1871-1975. The positive results provided confidence for the reconstruction "summer" TPI values extending back to CE 1410. The wavelet pattern of the reconstruction shows the ENSO (2-7 year) band frequency has increased during the 20th century while the longer (10-30 year) periodicities are scattered throughout the entire time interval. Finally, the different recognised phases of the IPO are compared to the two reconstructions (grid-points and TPI) and earlier periods discussed. References: Henley BJ, Gergis J, Karoly DJ, Power S, Kennedy J, Folland CK (2015) A Tripole Index for the Inter-decadal Pacific Oscillation. Climate Dynamics 45, 3077-3090. doi:10.1007/s00382-015-2525-1. Palmer J, Cook ER, Turney CSM, Allen K, Fenwick P, Cook BI, O'Donnell A, Lough J, Grierson P, Baker P (2016) Drought variability in the eastern Australia and New Zealand summer drought atlas (ANZDA, CE 1500-2012) modulated by the Interdecadal Pacific Oscillation. Environmental Research Letters 10, 1-12. doi:10.1088/1748-9326/10/12/124002.

  4. Microscopic coexistence of ferromagnetism and superconductivity in single-crystal UCoGe

    International Nuclear Information System (INIS)

    Ohta, Tetsuya; Hattori, Taisuke; Ishida, Kenji; Nakai, Yusuke; Osaki, Eisuke; Deguchi, Kazuhiko; Sato, Noriaki K.; Satoh, Isamu

    2010-01-01

    Unambiguous evidence for the microscopic coexistence of ferromagnetism and superconductivity in UCoGe (T Curie -2.5 K and T SC -0.6 K) is reported from 59 Co nuclear quadrupole resonance (NQR). The 59 Co-NQR signal below 1 K indicates ferromagnetism throughout the sample volume, while the nuclear spin-lattice relaxation rate 1/T 1 in the ferromagnetic (FM) phase decreases below T SC due to the opening of the superconducting (SC) gap. The SC state is found to be inhomogeneous, suggestive of a self-induced vortex state, potentially realizable in a FM superconductor. In addition, the 59 Co-NQR spectrum around T Curie shows that the FM transition in UCoGe possesses a first-order character, which is consistent with the theoretical prediction that the low-temperature FM transition in itinerant magnets is generically of first-order. (author)

  5. Magnet pole tips

    Science.gov (United States)

    Thorn, Craig E.; Chasman, Chellis; Baltz, Anthony J.

    1984-04-24

    An improved magnet which more easily provides a radially increasing magnetic field, as well as reduced fringe field and requires less power for a given field intensity. The subject invention comprises a pair of spaced, opposed magnetic poles which further comprise a pair of pole roots, each having a pole tip attached to its center. The pole tips define the gap between the magnetic poles and at least a portion of each pole tip is separated from its associated pole root. The separation begins at a predetermined distance from the center of the pole root and increases with increasing radial distance while being constant with azimuth within that portion. Magnets in accordance with the subject invention have been found to be particularly advantageous for use in large isochronous cyclotrons.

  6. 25–34 GHz Single-Pole, Double-Throw CMOS Switches for a Ka-Band Phased-Array Transceiver

    Directory of Open Access Journals (Sweden)

    Sangyong Park

    2018-01-01

    Full Text Available This paper presents two single-pole, double-throw (SPDT mm-wave switches for Ka-band phased-array transceivers, fabricated with a 65-nm complementary metal oxide semiconductor (CMOS process. One switch employs cross-biasing (CB control with a single supply, while the other uses dual-supply biasing (DSB control with positive and negative voltages. Negative voltages were generated internally, using a ring oscillator and a charge pump. Identical gate and body floated N-type metal oxide semiconductor field effect transistors (N-MOSFETs in a triple well were used as the switch core transistors. Inductors were used to improve the isolation between the transmitter (TX and receiver (RX, as well as insertion loss, by canceling the parasitic capacitance of the switch core transistors at resonance. The size of the proposed radio frequency (RF switch is 260 μm × 230 μm, excluding all pads. The minimum insertion losses of the CB and DSB switches were 2.1 dB at 28 GHz and 1.93 dB at 24 GHz, respectively. Between 25 GHz and 34 GHz, the insertion losses were less than 2.3 dB and 2.5 dB, the return losses were less than 16.7 dB and 17.3 dB, and the isolation was over 18.4 dB and 15.3 dB, respectively. The third order input intercept points (IIP3 of the CB and DSB switches were 38.4 dBm and 39 dBm at 28 GHz, respectively.

  7. A high gradient test of a single-cell superconducting radio frequency cavity with a feedback waveguide

    Science.gov (United States)

    Kostin, Roman; Avrakhov, Pavel; Kanareykin, Alexei; Solyak, Nikolay; Yakovlev, Vyacheslav; Kazakov, Sergey; Wu, Genfa; Khabiboulline, Timergali; Rowe, Allan; Rathke, John

    2015-09-01

    The most severe problem of the international linear collider (ILC-type) is its high cost, resulting in part from the enormous length of the collider. This length is determined mainly by the achievable accelerating gradient in the RF system of the collider. In current technology, the maximum acceleration gradient in superconducting (SC) structures is determined mainly by the value of the surface RF magnetic field. In order to increase the gradient, a superconducting traveling wave accelerating (STWA) structure is suggested. Utilization of STWA structure with small phase advance per cell for future high energy linear colliders such as ILCs may provide an accelerating gradient 1.2-1.4 times larger [1] than a standing wave structure. However, STWA structure requires a feedback waveguide for power redirecting from the end of the structure back to the front end of accelerating structure. Recent tests of a 1.3 GHz model of a single-cell cavity with waveguide feedback demonstrated an accelerating gradient comparable to the gradient of a single-cell ILC-type cavity from the same manufacturer [2]. In the present paper, high gradient test results are presented.

  8. Coupling a single nitrogen-vacancy center with a superconducting qubit via the electro-optic effect

    Science.gov (United States)

    Li, Chang-Hao; Li, Peng-Bo

    2018-05-01

    We propose an efficient scheme for transferring quantum states and generating entangled states between two qubits of different nature. The hybrid system consists of a single nitrogen-vacancy (NV) center and a superconducting (SC) qubit, which couple to an optical cavity and a microwave resonator, respectively. Meanwhile, the optical cavity and the microwave resonator are coupled via the electro-optic effect. By adjusting the relative parameters, we can achieve high-fidelity quantum state transfer as well as highly entangled states between the NV center and the SC qubit. This protocol is within the reach of currently available techniques, and may provide interesting applications in quantum communication and computation with single NV centers and SC qubits.

  9. Point-contact spectroscopic studies on normal and superconducting AFe2As2-type iron pnictide single crystals

    International Nuclear Information System (INIS)

    Lu Xin; Park, W K; Greene, L H; Yuan, H Q; Chen, G F; Luo, G L; Wang, N L; Sefat, A S; McGuire, M A; Jin, R; Sales, B C; Mandrus, D; Gillett, J; Sebastian, Suchitra E

    2010-01-01

    Point-contact Andreev reflection spectroscopy is applied to investigate the gap structure in iron pnictide single-crystal superconductors of the AFe 2 As 2 (A = Ba, Sr) family ('Fe-122'). The observed point-contact junction conductance curves, G(V), can be divided into two categories: one where Andreev reflection is present for both (Ba 0.6 K 0.4 )Fe 2 As 2 and Ba(Fe 0.9 Co 0.1 ) 2 As 2 , and the other with a V 2/3 background conductance universally observed, extending even up to 100 meV for Sr 0.6 Na 0.4 Fe 2 As 2 and Sr(Fe 0.9 Co 0.1 ) 2 As 2 . The latter is also observed in point-contact junctions on the nonsuperconducting parent compound BaFe 2 As 2 and superconducting (Ba 0.6 K 0.4 )Fe 2 As 2 crystals. Mesoscopic phase-separated coexistence of magnetic and superconducting orders is considered to explain distinct behaviors in the superconducting samples. For Ba 0.6 K 0.4 Fe 2 As 2 , double peaks due to Andreev reflection with a strongly sloping background are frequently observed for point contacts on freshly cleaved c-axis surfaces. If normalized using a background baseline and analyzed using the Blonder-Tinkham-Klapwijk model, the data show a gap size of ∼ 3.0-4.0 meV with 2Δ 0 /k B T c ∼ 2.0-2.6, consistent with the smaller gap size reported for the LnFeAsO family ('Fe-1111'). For the Ba(Fe 0.9 Co 0.1 ) 2 As 2 , the G(V) curves typically display a zero-bias conductance peak.

  10. High-Tc Superconducting Thick-Film Spiral Magnet: Development and Characterization of a Single Spiral Module

    National Research Council Canada - National Science Library

    McGinnis, W

    1997-01-01

    The objective of this project was to make characterized and numerically model prototype modules of a new type of superconducting electromagnet based on stacked spirals of superconducting thick films...

  11. Poling of Planar Silica Waveguides

    DEFF Research Database (Denmark)

    Arentoft, Jesper; Kristensen, Martin; Jensen, Jesper Bo

    1999-01-01

    UV-written planar silica waveguides are poled using two different poling techniques, thermal poling and UV-poling. Thermal poling induces an electro-optic coefficient of 0.067 pm/V. We also demonstrate simultaneous UV-writing and UV-poling. The induced electro-optic effect shows a linear dependence...

  12. NMR studies of spin excitations in superconducting Bi2Sr2CaCu2O8+δ single crystals

    Science.gov (United States)

    Takigawa, M.; Mitzi, D. B.

    1994-08-01

    The oxygen NMR shift and the Cu nuclear spin-lattice relaxation rate (1/T1) were measured in Bi2.1Sr1.9Ca0.9Cu2.1O8+δ single crystals. While both the shift and 1/(T1T) decrease sharply near Tc, 1/(T1T) becomes nearly constant at low temperatures, indicating a gapless superconducting state with finite density of states at the Fermi level. From the oxygen shift data, the residual spin susceptibility at T=0 is estimated to be 10% of the value at room temperature. Our results are most consistent with a d-wave pairing model with strong (resonant) impurity scattering.

  13. Fluctuations and dark count rates in superconducting NbN single-photon detectors

    International Nuclear Information System (INIS)

    Engel, Andreas; Semenov, Alexei; Huebers, Heinz-Wilhelm; Il'in, Kostya; Siegel, Michael

    2005-01-01

    We measured the temperature- and current-dependence of dark count rates of a superconducting singlephoton detector. The detector's key element is a 84 nm wide meander strip line fabricated from a 5 nm thick NbN film. Due to its reduced dimensions various types of fluctuations can cause temporal and localized transitions into a resistive state leading to dark count events. Adopting a recent refinement of the hotspot model we achieve a satisfying description of the experimental dark count rates taking into account fluctuations of the Cooper-pair density and current-assisted unbinding of vortex-antivortex pairs. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Superconducting magnetic quadrupole

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.W.; Shepard, K.W.; Nolen, J.A.

    1995-08-01

    A design was developed for a 350 T/m, 2.6-cm clear aperture superconducting quadrupole focussing element for use in a very low q/m superconducting linac as discussed below. The quadrupole incorporates holmium pole tips, and a rectangular-section winding using standard commercially-available Nb-Ti wire. The magnet was modeled numerically using both 2D and 3D codes, as a basis for numerical ray tracing using the quadrupole as a linac element. Components for a prototype singlet are being procured during FY 1995.

  15. Macroscopic Magnetic Coupling Effect: The Physical Origination of a High-Temperature Superconducting Flux Pump

    Science.gov (United States)

    Wang, Wei; Coombs, Tim

    2018-04-01

    We have uncovered at the macroscopic scale a magnetic coupling phenomenon in a superconducting YBa2Cu3O7 -δ (YBCO) film, which physically explains the mechanism of the high-temperature superconducting flux pump. The coupling occurs between the applied magnetic poles and clusters of vortices induced in the YBCO film, with each cluster containing millions of vortices. The coupling energy is verified to originate from the inhomogeneous field of the magnetic poles, which reshapes the vortex distribution, aggregates millions of vortices into a single cluster, and accordingly moves with the poles. A contrast study is designed to verify that, to provide the effective coupling energy, the applied wavelength must be short while the field amplitude must be strong, i.e., local-field inhomogeneity is the crucial factor. This finding broadens our understanding of the collective vortex behavior in an applied magnetic field with strong local inhomogeneity. Moreover, this phenomenon largely increases the controlled vortex flow rate by several orders of magnitude compared with existing methods, providing motivation for and physical support to a new branch of wireless superconducting dc power sources, i.e., the high-temperature superconducting flux pump.

  16. Anatomy of the collecting system of lower pole of the kidney in patients with a single renal stone: a comparative study with individuals with normal kidneys.

    Science.gov (United States)

    Zomorrodi, Afshar; Buhluli, Abulfazel; Fathi, Samad

    2010-07-01

    At least 5% of women and 12% of men during their lives will experience renal colic, at least once. Many theories have been suggested for the etiology of renal stones and variations in the anatomy of the collecting system have been suggested to have a role in stone formation. This study was conducted to examine the role of variation of lower pole collecting system in patients with lower pole kidney stone and compared the same in normal persons (kidney donors). Investigation for the anatomy of the lower pole of the kidney (angle between lower infundibulum and pelvis, length and diameter of the infundibulum and number and pattern distribution of calyces) was carried out using intravenous pyelogram (IVP) in 100 cases with urinary stone (study cases) and 400 persons with normal kidneys (control subjects). The study was a retrospective cross-sectional case control study. Results were analyzed by Mann-Whitney and independent sample chi square tests. The mean infundibulum-pelvic angle (IPA) in control subjects and in patients was 112.5 +/- 10.7 and 96.6 +/- 28.8, respectively. There was significant correlation between reduced angle and stone formation (P= kidney (IPIL) in controls and study patients was 22.5 +/- 4.1 and 27.5 +/- 7.7, respectively, which was statistically significant (Pkidney (LPCN) in controls and study patients was 2.6 +/- 0.6 and 3 +/- 0.9, respectively, which was statistically significant (P = or anatomy was more common in patients with lower pole kidney stone and should be considered a risk factor for forming lower pole kidney stone.

  17. Single Crystal Growth and Superconducting Properties of Antimony-Substituted NdO0.7F0.3BiS2

    Directory of Open Access Journals (Sweden)

    Satoshi Demura

    2017-12-01

    Full Text Available Antimony (Sb substitution of less than 8% was examined on a single crystal of a layered superconductor NdO0.7F0.3BiS2. The superconducting transition temperature of the substituted samples decreased as Sb concentration increased. A lattice constant along the c-axis showed a large decrease compared with that along the a-axis. Since in-plane chemical pressure monotonically decreased as Sb concentration increased, the suppression of the superconductivity is attributed to the decrease in the in-plane chemical pressure.

  18. Two gap superconductivity in Ba0.55K0.45Fe2As2 single crystals studied by the directional point-contact Andreev reflection spectroscopy

    International Nuclear Information System (INIS)

    Szabo, P.; Pribulova, Z.; Pristas, G.; Bud'ko, S.L.; Canfield, P.C.; Samuely, P.

    2009-01-01

    First directional point-contact Andreev reflection spectroscopy on the Ba 0.55 K 0.45 Fe 2 As 2 single crystals is presented. The spectra show significant differences when measured in the ab plane in comparison with those measured in the c direction. In the latter case no traces of superconducting energy gap could be found, just a reduced point-contact conductance persisting up to about 100 K and indicating reduced density of states. On the other hand within the ab plane two nodeless superconducting energy gaps Δ S ∼2-5 meV and Δ L ∼9-11 meV are detected.

  19. Distinctive behavior of superconducting fluctuations and pseudogap in nearly optimally doped single crystal of HgBa2CuO4+δ

    International Nuclear Information System (INIS)

    Grbic, M.S.; Barisic, N.; Dulcic, A.; Kupcic, I.; Li, Y.; Zhao, X.; Yu, G.; Dressel, M.; Greven, M.; Pozek, M.

    2010-01-01

    We have applied an unconventional microwave measurement approach to a nearly optimally doped HgBa 2 CuO 4+δ single crystal. The sample geometry assured the total lateral penetration of microwaves due to weak c-axis screening currents. With this configuration, one can achieve excellent sensitivity to small changes in conductivity. The data show that the pseudogap opens at T*=185(15)K, which is almost twice the superconducting critical temperature T c =94.3 K. In contrast, the superconducting fluctuation regime is clearly confined to a narrow temperature range T c ' ∼105(2)K, far below T*. This is confirmed by the magnetic field dependence of the microwave absorption. Hence, our results support the distinction between the physical processes of pseudogap and the superconducting ordering.

  20. Superconducting Panofsky quadrupoles

    International Nuclear Information System (INIS)

    Harwood, L.H.

    1981-01-01

    A design for a rectangular aperture quadrupole magnet without pole-tips was introduced by Hand and Panofsky in 1959. This design was quite radical but simple to construct. Few magnets of this design were ever built because of the large power needed. With the advent of superconducting coils there has been a renewed interest in them. The mathematical basis, field characteristics, and present and future construction of these magnets are described

  1. Micro-pulse polarization lidar at 1.5  μm using a single superconducting nanowire single-photon detector.

    Science.gov (United States)

    Qiu, Jiawei; Xia, Haiyun; Shangguan, Mingjia; Dou, Xiankang; Li, Manyi; Wang, Chong; Shang, Xiang; Lin, Shengfu; Liu, Jianjiang

    2017-11-01

    An all-fiber, eye-safe and micro-pulse polarization lidar is demonstrated with a polarization-maintaining structure, incorporating a single superconducting nanowire single-photon detector (SNSPD) at 1.5 μm. The time-division multiplexing technique is used to achieve a calibration-free optical layout. A single piece of detector is used to detect the backscatter signals at two orthogonal states in an alternative sequence. Thus, regular calibration of the two detectors in traditional polarization lidars is avoided. The signal-to-noise ratio of the lidar is guaranteed by using an SNSPD, providing high detection efficiency and low dark count noise. The linear depolarization ratio (LDR) of the urban aerosol is observed horizontally over 48 h in Hefei [N31°50'37'', E117°15'54''], when a heavy air pollution is spreading from the north to the central east of China. Phenomena of LDR bursts are detected at a location where a building is under construction. The lidar results show good agreement with the data detected from a sun photometer, a 532 nm visibility lidar, and the weather forecast information.

  2. Thermal and structural performance of a single tube support post for the Superconducting Super Collider dipole magnet cryostat

    International Nuclear Information System (INIS)

    Boroski, W.N.; Nicol, T.H.; Ruschman, M.K.; Schoo, C.J.

    1993-07-01

    The reentrant support post currently incorporated in the Superconducting Super Collider (SSC) dipole cryostat has been shown to meet the structural and thermal requirements of the cryostat, both in prototype magnet assemblies and through component testing. However, the reentrant post design has two major drawbacks: tight dimensional control on all components, and cost driven by these tolerance constraints and a complex assembly procedure. A single tube support post has been developed as an alternative to the reentrant post design. Several prototype assemblies have been fabricated and subjected to structural testing. Compressive, tensile, and bending forces were applied to each assembly with deflection measured at several locations. A prototype support post has also been thermally evaluated in a heat leak measurement facility. Heat load to 4.2 K was measured with the intermediate post intercept operating at various temperatures while thermometers positioned along the conductive path of the post mapped thermal gradients. Results from these measurements indicate the single tube support post meets the design criteria for the SSC dipole magnet cryostat support system

  3. Superconducting NbN single-photon detectors on GaAs with an AlN buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Ekkehart; Merker, Michael; Ilin, Konstantin; Siegel, Michael [Institut fuer Mikro- und Nanoelektronische Systeme (IMS), Karlsruher Institut fuer Technologie, Hertzstrasse 16, 76187 Karlsruhe (Germany)

    2015-07-01

    GaAs is the material of choice for photonic integrated circuits. It allows the monolithic integration of single-photon sources like quantum dots, waveguide based optical circuits and detectors like superconducting nanowire single-photon detectors (SNSPDs) onto one chip. The growth of high quality NbN films on GaAs is challenging, due to natural occurring surface oxides and the large lattice mismatch of about 27%. In this work, we try to overcome these problems by the introduction of a 10 nm AlN buffer layer. Due to the buffer layer, the critical temperature of 6 nm thick NbN films was increased by about 1.5 K. Furthermore, the critical current density at 4.2 K of NbN flim deposited onto GaAs with AlN buffer is 50% higher than of NbN film deposited directly onto GaAs substrate. We successfully fabricated NbN SNSPDs on GaAs with a AlN buffer layer. SNSPDs were patterned using electron-beam lithography and reactive-ion etching techniques. Results on the study of detection efficiency and jitter of a NbN SNSPD on GaAs, with and without AlN buffer layer will be presented and discussed.

  4. Continuous-Wave Single-Photon Transistor Based on a Superconducting Circuit

    DEFF Research Database (Denmark)

    Kyriienko, Oleksandr; Sørensen, Anders Søndberg

    2016-01-01

    We propose a microwave frequency single-photon transistor which can operate under continuous wave probing and represents an efficient single microwave photon detector. It can be realized using an impedance matched system of a three level artificial ladder-type atom coupled to two microwave cavities...... and the appearance of a photon flux leaving the second cavity through a separate input-output port. The proposal does not require time variation of the probe signals, thus corresponding to a passive version of a single-photon transistor. The resulting device is robust to qubit dephasing processes, possesses low dark...

  5. Superconducting single-photon detectors designed for operation at 1.55-μm telecommunication wavelength

    International Nuclear Information System (INIS)

    Milostnaya, I; Korneev, A; Rubtsova, I; Seleznev, V; Minaeva, O; Chulkova, G; Okunev, O; Voronov, B; Smirnov, K; Gol'tsman, G; Slysz, W; Wegrzecki, M; Guziewicz, M; Bar, J; Gorska, M; Pearlman, A; Kitaygorsky, J; Cross, A; Sobolewski, Roman

    2006-01-01

    We report on our progress in development of superconducting single-photon detectors (SSPDs), specifically designed for secure high-speed quantum communications. The SSPDs consist of NbN-based meander nanostructures and operate at liquid helium temperatures. In general, our devices are capable of GHz-rate photon counting in a spectral range from visible light to mid-infrared. The device jitter is 18 ps and dark counts can reach negligibly small levels. The quantum efficiency (QE) of our best SSPDs for visible-light photons approaches a saturation level of ∼30-40%, which is limited by the NbN film absorption. For the infrared range (1.55μm), QE is ∼6% at 4.2 K, but it can be significantly improved by reduction of the operation temperature to the 2-K level, when QE reaches ∼20% for 1.55-μm photons. In order to further enhance the SSPD efficiency at the wavelength of 1.55 μm, we have integrated our detectors with optical cavities, aiming to increase the effective interaction of the photon with the superconducting meander and, therefore, increase the QE. A successful effort was made to fabricate an advanced SSPD structure with an optical microcavity optimized for absorption of 1.55 μm photons. The design consisted of a quarter-wave dielectric layer, combined with a metallic mirror. Early tests performed on relatively low-QE devices integrated with microcavities, showed that the QE value at the resonator maximum (1.55-μm wavelength) was of the factor 3-to-4 higher than that for a nonresonant SSPD. Independently, we have successfully coupled our SSPDs to single-mode optical fibers. The completed receivers, inserted into a liquid-helium transport dewar, reached ∼1% system QE for 1.55 μm photons. The SSPD receivers that are fiber-coupled and, simultaneously, integrated with resonators are expected to be the ultimate photon counters for optical quantum communications

  6. Characteristics of a single-channel superconducting flux flow transistor fabricated by an AFM modification technique

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Seokcheol [Jeonnam Regional Innovation Agency, 1000 Namak-Ri, Samhyang-Myun, Muan-Gun, Jeollanam-Do 534-700 (Korea, Republic of)], E-mail: suntrac@jina.re.kr; Kim, Seong-Jong [Mokpo Maritime University, Chukkyo-Dong, Mokpo City, Cheonnam 530-729 (Korea, Republic of)

    2007-11-01

    The demand for high performance, integrity, and miniaturization in the area of electronic and mechanic devices has drawn interest in the fabrication of nanostructures. However, it is difficult to fabricate the channel with nano-scale using a conventional photography techniques. AFM anodization technique is a maskless process and effective method to overcome the difficulty in fabricating a nano-scale channel. In this paper, we first present a new fabrication of a single-channel SFFT using a selective oxidation process induced by an AFM probe. The modified channel was investigated by electron probe microanalyzer (EPMA) to find the compositional variation of the transformed region. In order to confirm the operation of a single-channel SFFT, we measured the voltage-current characteristics at the temperature of liquid nitrogen by an I-V automatic measurement system. Our results indicate that the single-channel SFFT having effect as a weak link is effectively fabricated by an AFM lithography process.

  7. Characteristics of a single-channel superconducting flux flow transistor fabricated by an AFM modification technique

    International Nuclear Information System (INIS)

    Ko, Seokcheol; Kim, Seong-Jong

    2007-01-01

    The demand for high performance, integrity, and miniaturization in the area of electronic and mechanic devices has drawn interest in the fabrication of nanostructures. However, it is difficult to fabricate the channel with nano-scale using a conventional photography techniques. AFM anodization technique is a maskless process and effective method to overcome the difficulty in fabricating a nano-scale channel. In this paper, we first present a new fabrication of a single-channel SFFT using a selective oxidation process induced by an AFM probe. The modified channel was investigated by electron probe microanalyzer (EPMA) to find the compositional variation of the transformed region. In order to confirm the operation of a single-channel SFFT, we measured the voltage-current characteristics at the temperature of liquid nitrogen by an I-V automatic measurement system. Our results indicate that the single-channel SFFT having effect as a weak link is effectively fabricated by an AFM lithography process

  8. Force interaction and 3D pole movement in double poling.

    Science.gov (United States)

    Stöggl, T; Holmberg, H-C

    2011-12-01

    The aim of this study was to analyze double poling using combined kinetic and 3D kinematic analysis at high skiing speeds as regards pole force components, pole angles and pole behavior during the poling and swing phase. The hypothesis was that a horizontal pole force is more predictive for maximal skiing speed (V(max)) than the resultant pole force. Sixteen elite skiers performed a double-poling V(max) test while treadmill roller skiing. Pole forces and 3D kinematics of pole movement at a speed of 30 km/h were analyzed and related to V(max). The duration of the "preparation phase" showed the strongest relationship with V(max) (r=0.87, Pmax) compared with the resultant pole force. Impact force was not related to V(max). At high skiing speeds, skiers should aim to combine high pole forces with appropriate timing of pole forces and appropriate pole and body positions during the swing and poling phase. The emphasis in training should be on the development of specific strength capacities for pole force production and the utilization of these capacities in double-poling training sessions. © 2011 John Wiley & Sons A/S.

  9. Anisotropic electrical properties of superconducting single crystals YBa2 Cu3 O7-x

    International Nuclear Information System (INIS)

    Konczykowski, M.; Rullier-Albenque, F.

    1988-01-01

    The effect of the hydrostatic pressure (up to 18 kbar) on the transport properties of YBa 2 Cu 3 O 7 single crystals was investigated. A decrease of the resistivity and of its anisotropy was observed under pressure whereas an increase of the critical temperature, of the upper critical field and of its slope vs temperature variation was found

  10. Applied superconductivity

    CERN Document Server

    Newhouse, Vernon L

    1975-01-01

    Applied Superconductivity, Volume II, is part of a two-volume series on applied superconductivity. The first volume dealt with electronic applications and radiation detection, and contains a chapter on liquid helium refrigeration. The present volume discusses magnets, electromechanical applications, accelerators, and microwave and rf devices. The book opens with a chapter on high-field superconducting magnets, covering applications and magnet design. Subsequent chapters discuss superconductive machinery such as superconductive bearings and motors; rf superconducting devices; and future prospec

  11. Superconducting single X-ray photon detector based on W0.8Si0.2

    Directory of Open Access Journals (Sweden)

    Xiaofu Zhang

    2016-11-01

    Full Text Available We fabricated a superconducting single X-ray photon detector based on W0.8Si0.2, and we characterized its basic detection performance for keV-photons at different temperatures. The detector has a critical temperature of 4.97 K, and it is able to be operated up to 4.8 K, just below the critical temperature. The detector starts to react to X-ray photons at relatively low bias currents, less than 1% of Ic at T = 1.8 K, and it shows a saturated count rate dependence on bias current at all temperatures, indicating that the optimum internal quantum efficiency can always be reached. Dark counts are negligible up to the highest investigated bias currents (99% of Ic and operating temperature (4.8 K. The latching effect affects the detector performance at all temperatures due to the fast recovery of the bias current; however, further modifications of the device geometry are expected to reduce the tendency for latching.

  12. Numerical method to optimize the polar-azimuthal orientation of infrared superconducting-nanowire single-photon detectors.

    Science.gov (United States)

    Csete, Mária; Sipos, Áron; Najafi, Faraz; Hu, Xiaolong; Berggren, Karl K

    2011-11-01

    A finite-element method for calculating the illumination-dependence of absorption in three-dimensional nanostructures is presented based on the radio frequency module of the Comsol Multiphysics software package (Comsol AB). This method is capable of numerically determining the optical response and near-field distribution of subwavelength periodic structures as a function of illumination orientations specified by polar angle, φ, and azimuthal angle, γ. The method was applied to determine the illumination-angle-dependent absorptance in cavity-based superconducting-nanowire single-photon detector (SNSPD) designs. Niobium-nitride stripes based on dimensions of conventional SNSPDs and integrated with ~ quarter-wavelength hydrogen-silsesquioxane-filled nano-optical cavity and covered by a thin gold film acting as a reflector were illuminated from below by p-polarized light in this study. The numerical results were compared to results from complementary transfer-matrix-method calculations on composite layers made of analogous film-stacks. This comparison helped to uncover the optical phenomena contributing to the appearance of extrema in the optical response. This paper presents an approach to optimizing the absorptance of different sensing and detecting devices via simultaneous numerical optimization of the polar and azimuthal illumination angles. © 2011 Optical Society of America

  13. Effect of short-range ordering on the electrical conductivity and superconducting properties of Nb6C5 single crystals

    International Nuclear Information System (INIS)

    Utkina, T.G.

    1995-01-01

    Niobium carbide, NbC x , belongs to the family of so called interstital phases. Metal atoms form a face-centered cubic lattice, whose octahedral interstices are occupied by carbon atoms. The fraction (1 - x) of interstices remain vacant, and this determines the nonstoichiometry of these phases: most of them are characterized by a wide homogeneity range, 0.70 m ≅ 3308 - 3886 K). In contrast, the metalloid atoms exhibit high mobility at relatively low temperatures. For compositions close to Nb 6 C 5 (0.81 O-D ≅ 1300 K. The presence of vacancies in the carbon sublattice considerably affects the physical properties of carbides, which depend not only on total vacancy concentration but also on their distribution, i.e., on the degree of ordering (both short-range and long-range order) in the metalloid sublattice. The purpose of this work is to study the effects of such ordering on the superconducting properties of Nb 6 C 5 single crystals

  14. Amplitude distributions of dark counts and photon counts in NbN superconducting single-photon detectors integrated with the HEMT readout

    Energy Technology Data Exchange (ETDEWEB)

    Kitaygorsky, J. [Kavli Institute of Nanoscience Delft, Delft University of Technology, 2600 GA Delft (Netherlands); Department of Electrical and Computer Engineering and Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14627-0231 (United States); Słysz, W., E-mail: wslysz@ite.waw.pl [Institute of Electron Technology, PL-02 668 Warsaw (Poland); Shouten, R.; Dorenbos, S.; Reiger, E.; Zwiller, V. [Kavli Institute of Nanoscience Delft, Delft University of Technology, 2600 GA Delft (Netherlands); Sobolewski, Roman [Department of Electrical and Computer Engineering and Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14627-0231 (United States)

    2017-01-15

    Highlights: • A new operation regime of NbN superconducting single-photon detectors (SSPDs). • A better understanding of the origin of dark counts generated by the detector. • A promise of PNR functionality in SSPD measurements. - Abstract: We present a new operation regime of NbN superconducting single-photon detectors (SSPDs) by integrating them with a low-noise cryogenic high-electron-mobility transistor and a high-load resistor. The integrated sensors are designed to get a better understanding of the origin of dark counts triggered by the detector, as our scheme allows us to distinguish the origin of dark pulses from the actual photon pulses in SSPDs. The presented approach is based on a statistical analysis of amplitude distributions of recorded trains of the SSPD photoresponse transients. It also enables to obtain information on energy of the incident photons, as well as demonstrates some photon-number-resolving capability of meander-type SSPDs.

  15. Correlation of the superconducting transition to oxygen stoichiometry in single-crystal Ba1-xKxBiO3-y

    Science.gov (United States)

    Mosley, W. D.; Dykes, J. W.; Klavins, P.; Shelton, R. N.; Sterne, P. A.; Howell, R. H.

    1993-07-01

    Temperature-dependent positron-lifetime experiments have been performed from room temperature to 15 K on single crystals of the oxide superconductor Ba1-xKxBiO3-y. Results indicate that the filling of oxygen vacancies has a marked impact on the superconducting properties of this system. Cation defect concentrations were below the detectable limit of positron-annihilation-analysis techniques in this material, which is in sharp contrast to identical studies on polycrystalline samples. We find that the positron lifetime in these electrochemically deposited single crystals is determined by the oxygen stoichiometry of the lattice, but there is no experimental signature of strong positron localization. By performing a subsequent oxygen anneal on the crystals, the superconducting transition is sharpened and the onset is raised. The observed change in positron lifetime associated with this annealing procedure is in quantitative agreement with theory.

  16. Low Leakage Superconducting Tunnel Junctions with a Single Crystal Al2O3 Barrier

    Science.gov (United States)

    2016-03-30

    10-6 Torr ). In this low-pressure oxygen environment, Auger electron spectroscopy (AES) study shows that while oxidation of the base layer is...three layers were grown in situ in an ultra high vacuum (UHV) system with a nominal base pressure of ~1×10-10 Torr . First, a 120~150 nm thick...high-temperature annealing in order to crystallize the amorphous AlOx into a single-crystal Al2O3. After the sample was cooled to room temperature

  17. Nb/NiCu bilayers in single and stacked superconductive tunnel junctions: preliminary results

    International Nuclear Information System (INIS)

    Pepe, G.P.; Ruotolo, A.; Parlato, L.; Peluso, G.; Ausanio, G.; Carapella, G.; Latempa, R.

    2004-01-01

    We present preliminary experimental results concerning both single and stacked tunnel junctions in which one of the electrodes was formed by a superconductor/ferromagnet (S/F) bi-layer. In particular, in the stacked configuration a Nb/NiCu bi-layer was used as the intermediate electrode, and it was probed by tunneling on both sides. Tunnel junctions have been characterized in terms of current-voltage characteristics (IVC), and differential conductance. Preliminary steady-state injection-detection measurements performed in the stacked devices at T=4.2 K are also presented and discussed

  18. Peak effect and vortex dynamics in superconducting MgB2 single crystals

    International Nuclear Information System (INIS)

    Lee, Hyun-Sook; Jang, Dong-Jin; Kim, Heon-Jung; Kang, Byeongwon; Lee, Sung-Ik

    2007-01-01

    The dynamic nature of the vortex state of MgB 2 single crystals near the peak effect (PE) region, which is very different either from that of conventional low-temperature superconductors or from that of high-temperature cuprate superconductors, is introduced in this article. Relaxation from a disordered, metastable field-cooled (FC) state to an ordered, stable zero-field-cooled (ZFC) state of the MgB 2 single crystals under an applied magnetic field and current is investigated. From an analysis of the noise properties in the ZFC state, a dynamic vortex phase diagram of the MgB 2 is obtained near the PE region. Between the onset and the peak region in the critical current vs. magnetic field diagram, crossovers from a high-noise state to a noise-free state are observed with increasing current. Above the peak, however, an opposite phenomenon, crossovers from a noise-free to a high-noise state, is observed which has not been observed in any other superconductors. The hysteresis in the I-V curves and the two-level random telegraph noise in the time evolution of the voltage response under an constant applied current at the ZFC state are also studied in detail

  19. Magnetic and superconducting nanowires

    DEFF Research Database (Denmark)

    Piraux, L.; Encinas, A.; Vila, L.

    2005-01-01

    magnetic and superconducting nanowires. Using different approaches entailing measurements on both single wires and arrays, numerous interesting physical properties have been identified in relation to the nanoscopic dimensions of these materials. Finally, various novel applications of the nanowires are also...

  20. Magnetic measurements of superconducting LiFeAs single crystals under high pressure

    Science.gov (United States)

    Miyoshi, Kiyotaka; Otsuka, Keisuke; Ogawa, Saki; Takeuchi, Jun

    2018-05-01

    Measurements of DC magnetization for single crystal specimens of LiFeAs have been performed under pressure using liquid argon and NaCl as pressure transmitting media (PTM) to generate hydrostatic and nearly uniaxial pressure along c-axis, respectively. It has been found that Tc linearly decreases under pressure with pressure coefficient dTc / dP ∼ - 1.6 - 1.7 K/GPa, and then shows a pressure independent behavior with Tc ∼ 8 K above 5 GPa. These behaviors are observed independently of whether we select liquid argon or NaCl as PTM. This suggests that c-axis lattice constant is not an important factor to determine Tc in LiFeAs, in contrast to KxFe2-ySe2 and (NH3)yAxFe2Se2 (A=alkali metal).

  1. Flux free growth of large FeSe1/2Te1/2 superconducting single crystals by an easy high temperature melt and slow cooling method

    Directory of Open Access Journals (Sweden)

    P. K. Maheshwari

    2015-09-01

    Full Text Available We report successful growth of flux free large single crystals of superconducting FeSe1/2Te1/2 with typical dimensions of up to few cm. The AC and DC magnetic measurements revealed the superconducting transition temperature (Tc value of around 11.5K and the isothermal MH showed typical type-II superconducting behavior. The lower critical field (Hc1 being estimated by measuring the low field isothermal magnetization in superconducting regime is found to be above 200Oe at 0K. The temperature dependent electrical resistivity ρ(T  showed the Tc (onset to be 14K and the Tc(ρ = 0 at 11.5K. The electrical resistivity under various magnetic fields i.e., ρ(TH for H//ab and H//c demonstrated the difference in the width of Tc with applied field of 14Tesla to be nearly 2K, confirming the anisotropic nature of superconductivity. The upper critical and irreversibility fields at absolute zero temperature i.e., Hc2(0 and Hirr(0 being determined by the conventional one-band Werthamer–Helfand–Hohenberg (WHH equation for the criteria of normal state resistivity (ρn falling to 90% (onset, and 10% (offset is 76.9Tesla, and 37.45Tesla respectively, for H//c and 135.4Tesla, and 71.41Tesla respectively, for H//ab. The coherence length at the zero temperature is estimated to be above 20Å ´ by using the Ginsburg-Landau theory. The activation energy for the FeSe1/2Te1/2 in both directions H//c and H//ab is determined by using Thermally Activation Flux Flow (TAFF model.

  2. Comparison of retrograde intrarenal surgery versus a single-session percutaneous nephrolithotomy for lower-pole stones with a diameter of 15 to 30 mm: A propensity score-matching study.

    Science.gov (United States)

    Jung, Gyoo Hwan; Jung, Jae Hyun; Ahn, Tae Sik; Lee, Joong Sub; Cho, Sung Yong; Jeong, Chang Wook; Lee, Seung Bae; Kim, Hyeon Hoe; Oh, Seung-June

    2015-07-01

    To investigate surgical outcomes between retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PNL) groups for a main stone sized 15 to 30 mm and located in the lower-pole calyx. Patients who underwent PNL or RIRS for a main stone sized 15 to 30 mm and located in the lower-pole calyx were retrospectively reviewed. Each patient in the RIRS group was matched to one in the PNL group on the basis of calculated propensity scores by use of age, sex, body mass index, previous treatment history, stone site, maximum stone size, and stone volume. We compared perioperative outcomes between the unmatched and matched groups. Patients underwent PNL (n=87, 66.4%) or RIRS (n=44, 33.6%). After matching, 44 patients in each group were included. Mean patient age was 54.4 ± 13.7 years. Perioperative hemoglobin drop was significantly higher and the hospital stay was longer in the PNL group than in the RIRS group. The operative time was significantly longer in the RIRS group than in the PNL group. Stone-free rates were higher and complications rates were lower in the RIRS group than in the PNL group without statistical significance. The presence of a stone located in the lower-anterior minor calyx was a predictor of stone-free status. RIRS and single-session PNL for patients with a main stone of 15 to 30 mm located in the lower-pole calyx showed comparable surgical results. However, RIRS can be performed more safely than PNL with less bleeding. Stones in the lower-anterior minor calyx should be carefully removed during these procedures.

  3. Enhanced superconductivity and anisotropy of FeTe0.6Se0.4 single crystals with Li -NH3 intercalation

    Science.gov (United States)

    Li, Chenghe; Sun, Shanshan; Wang, Shaohua; Lei, Hechang

    2017-10-01

    We report a systematic study of anisotropy resistivity, magnetoresistance, and Hall effect of Li0.32(NH3)yFe2Te1.2Se0.8 single crystals. When compared to the parent compound FeTe0.6Se0.4 , the Li-NH3 intercalation not only increases the superconducting transition temperature but also enhances the electronic anisotropy in both normal and superconducting states. Moreover, in contrast to the parent compound, the Hall coefficient RH becomes negative at low temperature, indicating electron-type carriers are dominant due to Li doping. On the other hand, the sign reverse of RH at high temperature and the failure of scaling behavior of magnetoresistance imply that hole pockets may be still crossing or just below the Fermi energy level, leading to the multiband behavior in Li0.32(NH3)yFe2Te1.2Se0.8 .

  4. Ideal metastability fields and field penetration in type-I and type-II superconducting InBi single spheres

    International Nuclear Information System (INIS)

    Pettersen, G.; Parr, H.

    1979-01-01

    In a continuation of earlier work on the InBi alloys system, we have studied the superconducting properties of small, single spheres of InBi 0.80, 1.24, 1.70, 2.15, and 2.65 at.% Bi. The transition temperatures are 3.538, 3.659, 3.796, 3.908, and 4.044 +- 0.008 K. Assuming the penetration depth lambda to be proportional to y = 1(1-t 4 )/sup 1/2/, we determine lambda/sub o/ = dlambda/dy to be 810, 950, 1065, undetermined, and 1720 A +- 3%, respectively. The field dependence of lambda was studied up to the ideal superheating field H/sub sh/. We find lambda (H/sub sh/)/lambda (H = 0) = 1.53, 1.52, 1.42, undetermined, and 1.41 +- 0.05, respectively. Thus the relative increase in lambda close to H/sub sh/ is roughly independent of composition. These are the first measurements of lambda (H) in ''strong'' fields for type-II superconductors. The Ginzburg-Landau parameter kappa was determined from H/sub c/3. We find kappa/sub c/3(t = ) = 0.454, 0.636, 0.835, 0.984, and 1.22. The knowledge of H/sub c/ limits the accuracy to 2--5%. Ideal superheating was observed both in the type-I and type-II region. At t = 1, we find H/sub sh//H/sub c/ = 1.80, 1.48, 1.28, 1.17, and 1.13 +- 3--8%. This roughly agrees with numerical calculations of H/sub sh/(kappa). Thus, ideal superheating of the Meissner state to well above H/sub c/ is firmly established even for type-II superconductors. The results for H/sub sh/ are in good agreement with numerical calculations from Ginzburg-Landau theory. Assuming these theoretical results to hold, kappa (t = 1) can be calculated self-consistently from H/sub c/3 and H/sub sh/ for all metals investigated by the single-sphere method, giving values considered to be more accurate than any other available. Finally, we have obtained qualitative and quantitative results on the intermediate and mixed states in our spheres

  5. A superconducting magnetic gear

    International Nuclear Information System (INIS)

    Campbell, A M

    2016-01-01

    A comparison is made between a magnetic gear using permanent magnets and superconductors. The objective is to see if there are any fundamental reasons why superconducting magnets should not provide higher power densities than permanent magnets. The gear is based on the variable permeability design of Attilah and Howe (2001 IEEE Trans. Magn. 37 2844–46) in which a ring of permanent magnets surrounding a ring of permeable pole pieces with a different spacing gives an internal field component at the beat frequency. Superconductors can provide much larger fields and forces but will saturate the pole pieces. However the gear mechanism still operates, but in a different way. The magnetisation of the pole pieces is now constant but rotates with angle at the beat frequency. The result is a cylindrical Halbach array which produces an internal field with the same symmetry as in the linear regime, but has an analytic solution. In this paper a typical gear system is analysed with finite elements using FlexPDE. It is shown that the gear can work well into the saturation regime and that the Halbach array gives a good approximation to the results. Replacing the permanent magnets with superconducting tapes can give large increases in torque density, and for something like a wind turbine a combined gear and generator is possible. However there are major practical problems. Perhaps the most fundamental is the large high frequency field which is inevitably present and which will cause AC losses. Also large magnetic fields are required, with all the practical problems of high field superconducting magnets in rotating machines. Nevertheless there are ways of mitigating these difficulties and it seems worthwhile to explore the possibilities of this technology further. (paper)

  6. Superconducting Metallic Glass Transition-Edge-Sensors

    Science.gov (United States)

    Hays, Charles C. (Inventor)

    2013-01-01

    A superconducting metallic glass transition-edge sensor (MGTES) and a method for fabricating the MGTES are provided. A single-layer superconducting amorphous metal alloy is deposited on a substrate. The single-layer superconducting amorphous metal alloy is an absorber for the MGTES and is electrically connected to a circuit configured for readout and biasing to sense electromagnetic radiation.

  7. Muon spin rotation study of magnetism and superconductivity in Ba(Fe1-xCox)2As2 single crystals

    OpenAIRE

    Bernhard, C.; Wang, C. N.; Nuccio, L.; Schulz, L.; Zaharko, O.; Larsen, Jacob; Aristizabal, C.; Willis, M.; Drew, A. J.; Varma, G. D.; Wolf, T.; Niedermayer, Ch.

    2012-01-01

    Using muon spin rotation (μSR) we investigated the magnetic and superconducting properties of a series of Ba(Fe1−xCox)2As2 single crystals with 0 ≤x ≤0.15. Our study details how the antiferromagnetic order is suppressed upon Co substitution and how it coexists with superconductivity. In the nonsuperconducting samples at 0 superconductivity this suppression becomes faster and it is most rapid ...

  8. Muon spin rotation study of magnetism and superconductivity in Ba(Fe1-xCox)2As2 single crystals

    DEFF Research Database (Denmark)

    Bernhard, C.; Wang, C. N.; Nuccio, L.

    2012-01-01

    Using muon spin rotation (μSR) we investigated the magnetic and superconducting properties of a series of Ba(Fe1−xCox)2As2 single crystals with 0 ≤x ≤0.15. Our study details how the antiferromagnetic order is suppressed upon Co substitution and how it coexists with superconductivity. In the nonsu......Using muon spin rotation (μSR) we investigated the magnetic and superconducting properties of a series of Ba(Fe1−xCox)2As2 single crystals with 0 ≤x ≤0.15. Our study details how the antiferromagnetic order is suppressed upon Co substitution and how it coexists with superconductivity....... In the nonsuperconducting samples at 0 demonstrated by μSR at x = 0.055 [P. Marsik et al., Phys. Rev. Lett. 105...

  9. Quasiparticle pole strength in nuclear matter

    International Nuclear Information System (INIS)

    Poggioli, R.S.; Jackson, A.D.

    1975-01-01

    It is argued that single-particle-like behavior in nuclear matter is much less probable than Brueckner theory suggests. In particular, the quasiparticle pole strength is evaluated for nuclear matter and it is shown that, contrary to the spirit of Brueckner theory, low momentum states play a crucial role in determining the magnitude of z/sub k/sub F/. (auth)

  10. 'Speedy' superconducting circuits

    International Nuclear Information System (INIS)

    Holst, T.

    1994-01-01

    The most promising concept for realizing ultra-fast superconducting digital circuits is the Rapid Single Flux Quantum (RSFQ) logic. The basic physical principle behind RSFQ logic, which include the storage and transfer of individual magnetic flux quanta in Superconducting Quantum Interference Devices (SQUIDs), is explained. A Set-Reset flip-flop is used as an example of the implementation of an RSFQ based circuit. Finally, the outlook for high-temperature superconducting materials in connection with RSFQ circuits is discussed in some details. (au)

  11. ESCAR superconducting magnet system

    International Nuclear Information System (INIS)

    Gilbert, W.S.; Meuser, R.B.; Pope, W.L.; Green, M.A.

    1975-01-01

    Twenty-four superconducting dipoles, each about 1 meter long, provide the guide field for the Experimental Superconducting Accelerator Ring proton accelerator--storage ring. Injection of 50 MeV protons corresponds to a 3 kG central dipole field, and a peak proton energy of 4.2 GeV corresponds to a 46 kG central field. Thirty-two quadrupoles provide focusing. The 56 superconducting magnets are contained in 40 cryostats that are cryogenically connected in a novel series ''weir'' arrangement. A single 1500 W refrigeration plant is required. Design and testing of the magnet and cryostat system are described. (U.S.)

  12. Effects of magnetic order on the superconducting length scales and critical fields in single crystal ErNi2B2C

    DEFF Research Database (Denmark)

    Gammel, P.L.; Barber, B.P.; Ramirez, A.P.

    1999-01-01

    The flux line form factor in small angle neutron scattering and transport data determines the superconducting length scares and critical fields in single crystal ErNi2B2C. For H parallel to c, the coherence length xi increases and the penetration depth lambda decreases when crossing T-N = 6.0 K......, the Neel transition. The critical fields show corresponding anomalies near T-N. For H perpendicular to c, the fourfold modulation of the upper critical field H-c2 is strongly temperature dependent, changing sign near T-N, and can be modeled using the anisotropy of the sublattice magnetization....

  13. Improvement of the superconducting transition and demagnetization factor in YBa2Cu3O7-δ single crystals by laser cutting

    International Nuclear Information System (INIS)

    Bhattacharya, A.; Grupp, D.E.; Goldman, A.M.; Welp, U.

    1996-01-01

    Single crystals of YBa 2 Cu 3 O 7-δ have been cut into disc shapes using an excimer laser. The bulk superconducting transition was found to be sharpened in all cases measured. This is associated with the removal of material at the edges which may be depleted of oxygen or otherwise damaged. The magneto-optical images for one crystal have been correlated with the optical image. The angular dependence of the demagnetizing factor for field applied in the plane was drastically reduced in disc-shaped crystals relative to rectangular ones. The field of first flux entry was also increased. copyright 1996 American Institute of Physics

  14. Superconductivity - applications

    International Nuclear Information System (INIS)

    The paper deals with the following subjects: 1) Electronics and high-frequency technology, 2) Superconductors for energy technology, 3) Superconducting magnets and their applications, 4) Electric machinery, 5) Superconducting cables. (WBU) [de

  15. Superconduction in limiting-power synchronous generators. State, lines of development, problems

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzen, H W; Sergl, J

    1976-01-01

    The limiting power of conventional 2-pole rotary current synchronous generators is estimated. The limiting power may be raised by using superconducting materials for the field winding. After a short description of superconductive materials, the construction of a synchronous generator with a superconducting field winding is described. Finally, some problems in calculating the magnetic field and the transient behavior are discussed.

  16. Multiband superconductivity in heavy fermion compound CePt3Si without inversion symmetry. An NMR study on a high-quality single crystal

    International Nuclear Information System (INIS)

    Mukuda, Hidekazu; Nishide, Sachihiro; Harada, Atsushi

    2009-01-01

    We report on novel superconducting characteristics of the heavy fermion (HF) superconductor CePt 3 Si without inversion symmetry through 195 Pt-NMR study on a single crystal with T c =0.46 K that is lower than T c - 0.75 K for polycrystals. We show that the intrinsic superconducting characteristics inherent to CePt 3 Si can be understood in terms of the unconventional strong-coupling state with a line-node gap below T c =0.46 K. The mystery about the sample dependence of T c is explained by the fact that more or less polycrystals and single crystals inevitably contain some disordered domains, which exhibit a conventional BCS s-wave superconductivity (SC) below 0.8 K. In contrast, the Neel temperature T N - 2.2 K is present regardless of the quality of samples, revealing that the Fermi surface responsible for SC differ from that for the antiferromagnetic order. These unusual characteristics of CePt 3 Si can be also described by a multiband model; in the homogeneous domains, the coherent HF bands are responsible for the unconventional SC, whereas in the disordered domains the conduction bands existing commonly in LaPt 3 Si may be responsible for the conventional s-wave SC. We remark that some impurity scatterings in the disordered domains break up the 4f-electrons-derived coherent bands but not others. In this context, the small peak in 1/T 1 just below T c reported before [Yogi et al. (2004)] is not due to a two-component order parameter composed of spin-singlet and spin-triplet Cooper pairing states, but due to the contamination of the disorder domains which are in the s-wave SC state. (author)

  17. Effects of argon implantation and vacuum annealing of the superconducting properties of single-crystal niobium films

    International Nuclear Information System (INIS)

    Zakirov, R.M.; Kuznetsov, V.P.; Shermergor, T.D.

    1980-01-01

    Characteristics of superconducting transition (Tsub(K), Hsub(perpendicular)) of monocrystalline niobium films on sapphire, irradiated by 35 keV Ar ions within 0.62x10 15 -5.6x10 16 ion/cm 2 dose range, are investigated. Introduction of argon atoms results in Tsub(K) decrease of films and rhosub(n), Hsub(perpendicular 0) and dHsub(perpendicular)/dT increase due to reduction of free path length of electrons. Shown is an essential difference in the behaviour of superconducting parameters of irradiated monocrystalline niobium films and films with niobium, dassol ved in the niobium lattice. Introduction of oxygen has been carried out by annealing of films in vacuum after their heating in the air

  18. Wood pole overhead lines

    CERN Document Server

    Wareing, Brian

    2005-01-01

    This new book concentrates on the mechanical aspects of distribution wood pole lines, including live line working, environmental influences, climate change and international standards. Other topics include statutory requirements, safety, profiling, traditional and probabilistic design, weather loads, bare and covered conductors, different types of overhead systems, conductor choice, construction and maintenance. A section has also been devoted to the topic of lightning, which is one of the major sources of faults on overhead lines. The book focuses on the effects of this problem and the strate

  19. A 350 mK, 9 T scanning tunneling microscope for the study of superconducting thin films on insulating substrates and single crystals.

    Science.gov (United States)

    Kamlapure, Anand; Saraswat, Garima; Ganguli, Somesh Chandra; Bagwe, Vivas; Raychaudhuri, Pratap; Pai, Subash P

    2013-12-01

    We report the construction and performance of a low temperature, high field scanning tunneling microscope (STM) operating down to 350 mK and in magnetic fields up to 9 T, with thin film deposition and in situ single crystal cleaving capabilities. The main focus lies on the simple design of STM head and a sample holder design that allows us to get spectroscopic data on superconducting thin films grown in situ on insulating substrates. Other design details on sample transport, sample preparation chamber, and vibration isolation schemes are also described. We demonstrate the capability of our instrument through the atomic resolution imaging and spectroscopy on NbSe2 single crystal and spectroscopic maps obtained on homogeneously disordered NbN thin film.

  20. Inducing phase decomposition and superconductivity of Bi2Sr2CaCu2Oy single crystals treated in sulphur atmosphere at low temperature

    International Nuclear Information System (INIS)

    Chen, Q.W.; China Univ. of Science and Technology, Hefei, AH; Wu, W.B.; Qian, Y.T.; China Univ. of Science and Technology, Hefei, AH; Wang, L.B.; Li, F.Q.; Zhou, G.E.; Chen, Z.Y.; Zhang, Y.H.

    1995-01-01

    As it has been pointed out, phase decomposition which may be hard to be detected in a polycrystalline system and is likely to correlate with changes in both oxygen content and microstructure, has been observed frequently in annealed single crystals especially at higher temperatures (> 500 C). This is still an open question to some degree because the mechanism of phase decomposition is very complex and is dominated by the composition of the Bi-2212 phase, the condition of heat treatment, and the atmosphere. Hence, inducing oxygen loss at low temperature to avoid the evaporation of Bi atoms and other undetected structure changes which would occur at higher temperature annealing undoubtedly provides important information about the relationship between oxygen loss and phase decomposition, as well as the relationship between oxygen content and superconductivity. In this note, we report on the results of treatments of Bi 2 Sr 2 CaCu 2 O y single crystals in sulphur atmosphere at 160 C. (orig.)

  1. Periodically poled silicon

    Science.gov (United States)

    Hon, Nick K.; Tsia, Kevin K.; Solli, Daniel R.; Khurgin, Jacob B.; Jalali, Bahram

    2010-02-01

    Bulk centrosymmetric silicon lacks second-order optical nonlinearity χ(2) - a foundational component of nonlinear optics. Here, we propose a new class of photonic device which enables χ(2) as well as quasi-phase matching based on periodic stress fields in silicon - periodically-poled silicon (PePSi). This concept adds the periodic poling capability to silicon photonics, and allows the excellent crystal quality and advanced manufacturing capabilities of silicon to be harnessed for devices based on χ(2)) effects. The concept can also be simply achieved by having periodic arrangement of stressed thin films along a silicon waveguide. As an example of the utility, we present simulations showing that mid-wave infrared radiation can be efficiently generated through difference frequency generation from near-infrared with a conversion efficiency of 50% based on χ(2) values measurements for strained silicon reported in the literature [Jacobson et al. Nature 441, 199 (2006)]. The use of PePSi for frequency conversion can also be extended to terahertz generation. With integrated piezoelectric material, dynamically control of χ(2)nonlinearity in PePSi waveguide may also be achieved. The successful realization of PePSi based devices depends on the strength of the stress induced χ(2) in silicon. Presently, there exists a significant discrepancy in the literature between the theoretical and experimentally measured values. We present a simple theoretical model that produces result consistent with prior theoretical works and use this model to identify possible reasons for this discrepancy.

  2. Superconductivity revisited

    CERN Document Server

    Dougherty, Ralph

    2013-01-01

    While the macroscopic phenomenon of superconductivity is well known and in practical use worldwide in many industries, including MRIs in medical diagnostics, the current theoretical paradigm for superconductivity (BCS theory) suffers from a number of limitations, not the least of which is an adequate explanation of high temperature superconductivity. This book reviews the current theory and its limitations and suggests new ideas and approaches in addressing these issues. The central objective of the book is to develop a new, coherent, understandable theory of superconductivity directly based on molecular quantum mechanics.

  3. Superconductivity in an anomalously tetragonal YB2C3O6.62 single crystal: A possible singularity in the structural phase diagram

    DEFF Research Database (Denmark)

    Frello, T.; Andersen, N.H.; Baziljevich, M.

    2003-01-01

    superconducting. This makes the sample highly anomalous in two respects: with a stoichiometry of YBa2Cu3O6.62 the sample should have an orthorhombic symmetry, and a tetragonal undoped sample should not be superconducting at all. Our results corroborate previous findings of Topnikov [JETP Lett. 46, 577 (1987......)] of a tetragonal superconducting YBCO crystal with x=0.62....

  4. South Pole rockets, (1)

    International Nuclear Information System (INIS)

    Kimura, Iwane

    1977-01-01

    Wave-particle interaction was observed, using three rockets, S-210 JA-20, -21 and S-310 JA-2, launched from the South Pole into aurora. Electron density and temperature were measured with these rockets. Simultaneous observations of waves were also made from a satellite (ISIS-II) and at two ground bases (Showa base and Mizuho base). Observed data are presented in this paper. These include electron density and temperature in relation to altitude; variation of electron (60 - 80 keV) count rate with altitude; VLF spectra measured by the PWL of S-210 JA-20 and -21 rockets and the corresponding VLF spectra at the ground bases; low-energy (<10 keV) electron flux measured by S-310 JA-2 rocket; and VLF spectrum measured with S-310 JA-2 rocket. Scheduled measurements for the next project are also briefly described. (Aoki, K.)

  5. Superconducting nanowire single photon detectors fabricated from an amorphous Mo{sub 0.75}Ge{sub 0.25} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Verma, V. B.; Lita, A. E.; Vissers, M. R.; Marsili, F.; Pappas, D. P.; Mirin, R. P.; Nam, S. W. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States)

    2014-07-14

    We present the characteristics of superconducting nanowire single photon detectors (SNSPDs) fabricated from amorphous Mo{sub 0.75}Ge{sub 0.25} thin-films. Fabricated devices show a saturation of the internal detection efficiency at temperatures below 1 K, with system dark count rates below 500 cps. Operation in a closed-cycle cryocooler at 2.5 K is possible with system detection efficiencies exceeding 20% for SNSPDs which have not been optimized for high detection efficiency. Jitter is observed to vary between 69 ps at 250 mK and 187 ps at 2.5 K using room temperature amplifiers.

  6. Local detection efficiency of a NbN superconducting single photon detector explored by a scattering scanning near-field optical microscope.

    Science.gov (United States)

    Wang, Qiang; Renema, Jelmer J; Engel, Andreas; van Exter, Martin P; de Dood, Michiel J A

    2015-09-21

    We propose an experiment to directly probe the local response of a superconducting single photon detector using a sharp metal tip in a scattering scanning near-field optical microscope. The optical absorption is obtained by simulating the tip-detector system, where the tip-detector is illuminated from the side, with the tip functioning as an optical antenna. The local detection efficiency is calculated by considering the recently introduced position-dependent threshold current in the detector. The calculated response for a 150 nm wide detector shows a peak close to the edge that can be spatially resolved with an estimated resolution of ∼ 20 nm, using a tip with parameters that are experimentally accessible.

  7. Calcination and solid state reaction of ceramic-forming components to provide single-phase superconducting materials having fine particle size

    Science.gov (United States)

    Balachandran, Uthamalingam; Poeppel, Roger B.; Emerson, James E.; Johnson, Stanley A.

    1992-01-01

    An improved method for the preparation of single phase, fine grained ceramic materials from precursor powder mixtures where at least one of the components of the mixture is an alkali earth carbonate. The process consists of heating the precursor powders in a partial vacuum under flowing oxygen and under conditions where the partial pressure of CO.sub.2 evolved during the calcination is kept to a very low level relative to the oxygen. The process has been found particularly suitable for the preparation of high temperature copper oxide superconducting materials such as YBa.sub.2 Cu.sub.3 O.sub.x "123" and YBa.sub.2 Cu.sub.4 O.sub.8 "124".

  8. Possible nucleation of a 2D superconducting phase on WO3 single crystals surface doped with Na+

    International Nuclear Information System (INIS)

    Reich, S.; Tsabba, Y.

    1999-01-01

    WO 3 crystals with a surface composition of Na 0.05 WO 3 were grown. These crystals exhibit a sharp diamagnetic step in magnetization at 91 K, and a magnetic hysteresis below this temperature. As the temperature is lowered below 100 K in transport measurements, a sharp metal to insulator transition is observed, this is followed by a sharp decrease in the resistivity when the temperature is lowered to about 90 K. When the surface of the crystals was covered by gold the depth of the diamagnetic step had decreased considerably. These results indicate a possible nucleation of a superconducting phase on the surface of these crystals. This is a non cuprate system exhibiting a critical temperature in the HTS range. (orig.)

  9. Superconducting cermets

    International Nuclear Information System (INIS)

    Goyal, A.; Funkenbusch, P.D.; Chang, G.C.S.; Burns, S.J.

    1988-01-01

    Two distant classes of superconducting cermets can be distinguished, depending on whether or not a fully superconducting skeleton is established. Both types of cermets have been successfully fabricated using non-noble metals, with as high as 60wt% of the metal phase. The electrical, magnetic and mechanical behavior of these composites is discussed

  10. Superconducting technology

    International Nuclear Information System (INIS)

    2010-01-01

    Superconductivity has a long history of about 100 years. Over the past 50 years, progress in superconducting materials has been mainly in metallic superconductors, such as Nb, Nb-Ti and Nb 3 Sn, resulting in the creation of various application fields based on the superconducting technologies. High-T c superconductors, the first of which was discovered in 1986, have been changing the future vision of superconducting technology through the development of new application fields such as power cables. On basis of these trends, future prospects of superconductor technology up to 2040 are discussed. In this article from the viewpoints of material development and the applications of superconducting wires and electronic devices. (author)

  11. The self-consistent dynamic pole tide in global oceans

    Science.gov (United States)

    Dickman, S. R.

    1985-01-01

    The dynamic pole tide is characterized in a self-consistent manner by means of introducing a single nondifferential matrix equation compatible with the Liouville equation, modelling the ocean as global and of uniform depth. The deviations of the theory from the realistic ocean, associated with the nonglobality of the latter, are also given consideration, with an inference that in realistic oceans long-period modes of resonances would be increasingly likely to exist. The analysis of the nature of the pole tide and its effects on the Chandler wobble indicate that departures of the pole tide from the equilibrium may indeed be minimal.

  12. State-PID Feedback for Pole Placement of LTI Systems

    Directory of Open Access Journals (Sweden)

    Sarawut Sujitjorn

    2011-01-01

    Full Text Available Pole placement problems are especially important for disturbance rejection and stabilization of dynamical systems and regarded as algebraic inverse eigenvalue problems. In this paper, we propose gain formulae of state feedback through PID-elements to achieve desired pole placement for a delay-free LTI system with single input. Real and complex stable poles can be assigned with the proposed compact gain formulae. Numerical examples show that our proposed gain formulae can be used effectively resulting in very satisfactory responses.

  13. Interface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gariglio, S., E-mail: stefano.gariglio@unige.ch [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland); Gabay, M. [Laboratoire de Physique des Solides, Bat 510, Université Paris-Sud 11, Centre d’Orsay, 91405 Orsay Cedex (France); Mannhart, J. [Max Planck Institute for Solid State Research, 70569 Stuttgart (Germany); Triscone, J.-M. [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland)

    2015-07-15

    Highlights: • We discuss interfacial superconductivity, a field boosted by the discovery of the superconducting interface between LaAlO. • This system allows the electric field control and the on/off switching of the superconducting state. • We compare superconductivity at the interface and in bulk doped SrTiO. • We discuss the role of the interfacially induced Rashba type spin–orbit. • We briefly discuss superconductivity in cuprates, in electrical double layer transistor field effect experiments. • Recent observations of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3} are presented. - Abstract: Low dimensional superconducting systems have been the subject of numerous studies for many years. In this article, we focus our attention on interfacial superconductivity, a field that has been boosted by the discovery of superconductivity at the interface between the two band insulators LaAlO{sub 3} and SrTiO{sub 3}. We explore the properties of this amazing system that allows the electric field control and on/off switching of superconductivity. We discuss the similarities and differences between bulk doped SrTiO{sub 3} and the interface system and the possible role of the interfacially induced Rashba type spin–orbit. We also, more briefly, discuss interface superconductivity in cuprates, in electrical double layer transistor field effect experiments, and the recent observation of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3}.

  14. Effects of Out-of-Plane Disorder on the Nodal Quasiparticle and Superconducting Gap in Single-Layer Bi_2Sr_1.6Ln_0.4CuO_6 delta (Ln = La, Nd, Gd)

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, M.

    2011-01-04

    How out-of-plane disorder affects the electronic structure has been investigated for the single-layer cuprates Bi{sub 2}Sr{sub 1.6}Ln{sub 0.4}CuO{sub 6+{delta}} (Ln = La, Nd, Gd) by angle-resolved photoemission spectroscopy. We have observed that, with increasing disorder, while the Fermi surface shape and band dispersions are not affected, the quasi-particle width increases, the anti-nodal gap is enhanced and the superconducting gap in the nodal region is depressed. The results indicate that the superconductivity is significantly depressed by out-of-plane disorder through the enhancement of the anti-nodal gap and the depression of the superconducting gap in the nodal region.

  15. Evaluation of the pole figure

    International Nuclear Information System (INIS)

    Cabrera B, E.; Macias B, L.R.

    1984-01-01

    In the present work it's shown the possibility of obtaining a pole-figure from the data generated in a conventional X-ray equipment, with a commercial goniometer and no electronic device to process the data. The way to plot the pole-figure on-line is by means of measuring the diffractogram and plot manually the stereographic projections. The atainable precision is very low in such a cumbersome process. In this paper we substitute such method by storing the data in a punched tape from a conventional teletype. The data is processed in a computer and the pole-figure is recorded by a plotter attached to the computer. (author)

  16. Organic superconductivity

    International Nuclear Information System (INIS)

    Jerome, D.

    1980-01-01

    We present the experimental evidences for the existence of a superconducting state in the Quasi One Dimensional organic conductor (TMTSF) 2 PF 6 . Superconductivity occuring at 1 K under 12 kbar is characterized by a zero resistance diamagnetic state. The anistropy of the upper critical field of this type II superconductor is consistent with the band structure anistropy. We present evidences for the existence of large superconducting precursor effects giving rise to a dominant paraconductive contribution below 40 K. We also discuss the anomalously large pressure dependence of T sb(s), which drops to 0.19 K under 24 kbar in terms of the current theories. (author)

  17. Status of superconducting power transformer development

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.C.; McConnell, B.W.; Mehta, S.P. [and others

    1996-03-01

    Development of the superconducting transformer is arguably the most difficult of the ac power applications of superconductivity - this is because of the need for very low ac losses, adequate fault and surge performance, and the rigors of the application environment. This paper briefly summarizes the history of superconducting transformer projects, reviews the key issues for superconducting transformers, and examines the status of HTS transformer development. Both 630-kVA, three-phase and 1-MVA single phase demonstration units are expected to operate in late 1996. Both efforts will further progress toward the development of economical and performance competitive superconducting transformers.

  18. Superconducting linac

    International Nuclear Information System (INIS)

    Bollinger, L.M.; Shepard, K.W.; Wangler, T.P.

    1978-01-01

    This project has two goals: to design, build, and test a small superconducting linac to serve as an energy booster for heavy ions from an FN tandem electrostatic accelerator, and to investigate various aspects of superconducting rf technology. The main design features of the booster are described, a status report on various components (resonators, rf control system, linac control system, cryostats, buncher) is given, and plans for the near future are outlined. Investigations of superconducting-linac technology concern studies on materials and fabrication techniques, resonator diagnostic techniques, rf-phase control, beam dynamics computer programs, asymmetry in accelerating field, and surface-treatment techniques. The overall layout of the to-be-proposed ATLAS, the Argonne Tandem-Linac Accelerator System, is shown; the ATLAS would use superconducting technology to produce beams of 5 to 25 MeV/A. 6 figures

  19. Superconducting materials

    International Nuclear Information System (INIS)

    Kormann, R.; Loiseau, R.; Marcilhac, B.

    1989-01-01

    The invention concerns superconducting ceramics containing essentially barium, calcium and copper fluorinated oxides with close offset and onset temperatures around 97 K and 100 K and containing neither Y nor rare earth [fr

  20. Hole superconductivity

    International Nuclear Information System (INIS)

    Hirsch, J.E.; Marsiglio, F.

    1989-01-01

    The authors review recent work on a mechanism proposed to explain high T c superconductivity in oxides as well as superconductivity of conventional materials. It is based on pairing of hole carriers through their direct Coulomb interaction, and gives rise to superconductivity because of the momentum dependence of the repulsive interaction in the solid state environment. In the regime of parameters appropriate for high T c oxides this mechanism leads to characteristic signatures that should be experimentally verifiable. In the regime of conventional superconductors most of these signatures become unobservable, but the characteristic dependence of T c on band filling survives. New features discussed her include the demonstration that superconductivity can result from repulsive interactions even if the gap function does not change sign and the inclusion of a self-energy correction to the hole propagator that reduces the range of band filling where T c is not zero

  1. Regge poles and alpha scattering

    International Nuclear Information System (INIS)

    Ceuleneer, R.

    1974-01-01

    The direct Regge pole model as a means of describing resonances in elastic particle scattering has been used for the analysis of the so-called ''anormalous large angle scattering'' of alpha particles by spinless nuclei. (Z.M.)

  2. Magnet field design considerations for a high energy superconducting cyclotron

    International Nuclear Information System (INIS)

    Botman, J.I.M.; Craddock, M.K.; Kost, C.J.; Richardson, J.R.

    1983-08-01

    This paper reports the pole shape designs for a two stage superconducting isochronous cyclotron combination (CANUCK) to accelerate 100 μA proton beams to 15 GeV. The pole shape of the 15 sectors of the first stage 3.5 GeV proton cyclotron provides isochronism over the full energy range and a constant axial tune over all but the lowest energies. Progress on the pole design of the 42 sector 15 GeV second stage is also reported. The magnetic fields are computed from the current distribution of the superconducting coils and the infinitely thin current sheets simulating the fully saturated poles. A least squares method is used to minimize deviations from isochronism by adjusting the size of various elemental shim coils placed around the main coil. The method to obtain the desired axial tune is described

  3. Effect of the wire geometry and an externally applied magnetic field on the detection efficiency of superconducting nanowire single-photon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lusche, Robert; Semenov, Alexey; Huebers, Heinz-Willhelm [DLR, Institut fuer Planetenforschung, Berlin (Germany); Ilin, Konstantin; Siegel, Michael [Karlsruher Institut fuer Technologie (Germany); Korneeva, Yuliya; Trifonov, Andrey; Korneev, Alexander; Goltsman, Gregory [Moscow State Pedagogical University (Russian Federation)

    2013-07-01

    The interest in single-photon detectors in the near-infrared wavelength regime for applications, e.g. in quantum cryptography has immensely increased in the last years. Superconducting nanowire single-photon detectors (SNSPD) already show quite reasonable detection efficiencies in the NIR which can even be further improved. Novel theoretical approaches including vortex-assisted photon counting state that the detection efficiency in the long wavelength region can be enhanced by the detector geometry and an applied magnetic field. We present spectral measurements in the wavelength range from 350-2500 nm of the detection efficiency of meander-type TaN and NbN SNSPD with varying nanowire line width from 80 to 250 nm. Due to the used experimental setup we can accurately normalize the measured spectra and are able to extract the intrinsic detection efficiency (IDE) of our detectors. The results clearly indicate an improvement of the IDE depending on the wire width according to the theoretic models. Furthermore we experimentally found that the smallest detectable photon-flux can be increased by applying a small magnetic field to the detectors.

  4. Superconducted tour

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1988-09-15

    Superconductivity - the dramatic drop in electrical resistance in certain materials at very low temperatures - has grown rapidly in importance over the past two or three decades to become a key technology for high energy particle accelerators. It was in this setting that a hundred students and 15 lecturers met in Hamburg in June for a week's course on superconductivity in particle accelerators, organized by the CERN Accelerator School and the nearby DESY Laboratory.

  5. Superconductivity: Phenomenology

    International Nuclear Information System (INIS)

    Falicov, L.M.

    1988-08-01

    This document discusses first the following topics: (a) The superconducting transition temperature; (b) Zero resistivity; (c) The Meissner effect; (d) The isotope effect; (e) Microwave and optical properties; and (f) The superconducting energy gap. Part II of this document investigates the Ginzburg-Landau equations by discussing: (a) The coherence length; (b) The penetration depth; (c) Flux quantization; (d) Magnetic-field dependence of the energy gap; (e) Quantum interference phenomena; and (f) The Josephson effect

  6. Low-leakage superconducting tunnel junctions with a single-crystal Al{sub 2}O{sub 3} barrier

    Energy Technology Data Exchange (ETDEWEB)

    Oh, S [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Department of Physics, University of Illinois, Urbana, IL 61801 (United States); Cicak, K; Osborn, K D; Simmonds, R W; Pappas, D P [National Institute of Standards and Technology, Boulder, CO 80305 (United States); McDermott, R; Cooper, K B; Steffen, M; Martinis, J M [University of California, Santa Barbara, CA 93106 (United States)

    2005-10-01

    We have developed a two-step growth scheme for single-crystal Al{sub 2}O{sub 3} tunnel barriers. The barriers are epitaxially grown on single-crystal rhenium (Re) base electrodes that are grown epitaxially on a sapphire substrate, while polycrystalline Al is used as the top electrode. We show that by first growing an amorphous aluminium (Al) oxide layer at room temperature and crystallizing it at a high temperature in oxygen environment, a morphologically intact single-crystal Al{sub 2}O{sub 3} layer is obtained. Tunnel junctions fabricated from these trilayers show very low subgap leakage current. This single-crystal Al{sub 2}O{sub 3} junction may open a new venue for coherent quantum devices.

  7. Anomalous superconductivity in black phosphorus under high pressures

    International Nuclear Information System (INIS)

    Kawamura, H.; Tachikawa, K.

    1984-01-01

    Pressure induced superconductivity in single crystals of black phosphorus has been studied. Maximum onset Tsub(c) was near 13 K. The anomalous superconductivity may be explained in terms of excitonic mechanism. (author)

  8. The superconducting gaps of C-substituted and Al-substituted MgB2 single crystals by point-contact spectroscopy

    International Nuclear Information System (INIS)

    Daghero, D.; Gonnelli, R.S.; Ummarino, G.A.; Calzolari, A.; Dellarocca, Valeria; Stepanov, V.A.; Zhigadlo, N.; Kazakov, S.M.; Karpinski, J.

    2005-01-01

    We studied the effects of carbon and aluminum substitutions on the gaps of the two-band superconductor MgB 2 by means of point-contact measurements in Mg(B 1-x C x ) 2 and Mg 1-y Al y B 2 single crystals with 0≤x≤0.132 and 0≤y≤0.21. The gap amplitudes, Δ ω and Δ π , were determined by fitting the conductance curves of the point contacts with the standard Blonder-Tinkham-Klapwijk (BTK) model generalized to the two-band case. Whenever possible, their values were confirmed by the independent fit (with a single-band BTK model) of the partial contribution of the two bands to the conductance, separated by means of a suitable magnetic field B*. In C-substituted crystals, the two gaps remain clearly distinct up to x∝0.10, but at x=0.132 we observed for the first time their merging into a single gap Δ≅3 meV with a gap ratio 2Δ=k B T c close to the standard BCS value. In Al-substituted crystals, we found no evidence of this gap merging. Instead, Δ π reaches the value 0.4 meV at y=0.21, where Δ π saturates at about 4 meV. These results are compared with other recent experimental findings in polycrystals and with the predictions of the models for multiband superconductivity. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. High power density superconducting motor for control applications

    International Nuclear Information System (INIS)

    Lopez, J; Granados, X; Lloberas, J; Torres, R; Grau, J; Maynou, R; Bosch, R

    2008-01-01

    A high dynamics superconducting low power motor for control applications has been considered for design. The rotor is cylindrical with machined bulks that generate the field by trapping flux in a four poles configuration. The toothless iron armature is wound by copper, acting iron only as magnetic screen. Details of the magnetic assembling, cryogenics and electrical supply conditioning will be reported. Improvements due to the use of a superconducting set are compared with performances of equivalent conventional motors

  10. Universal doping evolution of the superconducting gap anisotropy in single crystals of electron-doped Ba(Fe1‑x Rh x )2As2 from London penetration depth measurements

    Science.gov (United States)

    Kim, Hyunsoo; Tanatar, M. A.; Martin, C.; Blomberg, E. C.; Ni, Ni; Bud’ko, S. L.; Canfield, P. C.; Prozorov, R.

    2018-06-01

    Doping evolution of the superconducting gap anisotropy was studied in single crystals of 4d-electron doped Ba(Fe1‑x Rh x )2As2 using tunnel diode resonator measurements of the temperature variation of the London penetration depth . Single crystals with doping levels representative of an underdoped regime x  =  0.039 ( K), close to optimal doping x  =  0.057 ( K) and overdoped x  =  0.079 ( K) and x  =  0.131( K) were studied. Superconducting energy gap anisotropy was characterized by the exponent, n, by fitting the data to the power-law, . The exponent n varies non-monotonically with x, increasing to a maximum n  =  2.5 for x  =  0.079 and rapidly decreasing towards overdoped compositions to 1.6 for x  =  0.131. This behavior is qualitatively similar to the doping evolution of the superconducting gap anisotropy in other iron pnictides, including hole-doped (Ba,K)Fe2As2 and 3d-electron-doped Ba(Fe,Co)2As2 superconductors, finding a full gap near optimal doping and strong anisotropy toward the ends of the superconducting dome in the T-x phase diagram. The normalized superfluid density in an optimally Rh-doped sample is almost identical to the temperature-dependence in the optimally doped Ba(Fe,Co)2As2 samples. Our study supports the universal superconducting gap variation with doping and pairing at least in iron based superconductors of the BaFe2As2 family.

  11. Optimisation of thallium ''1223'' high-temperature superconducting wire by a single-stage cold deformation process. [TlPbSrCaCuO

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, B A [IRC in Superconductivity, Cambridge (United Kingdom) Materials Science and Metallurgy, Cambridge (United Kingdom); Ashworth, S P [BICC Cables Ltd., Erith (United Kingdom)

    1992-09-15

    Superconducting tapes containing (Tl[sub 0.5]Pb[sub 0.5])Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub 9] were manufactured by a powder-in-tube technique and a single annealing stage. The (Tl[sub 0.5]Pb[sub 0.5])Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub 9] forms a ''1223'' structure with a Tc of over 120 K. A cold pressing stage was found to be necessary to achieve the higher J[sub c] values at 77 K. The transport J[sub c] was found to depend on: the annealing temperature, annealing time and pressing pressure. SEM examination of the Tl-1223 grain structure showed a marked difference between rolled and pressed tapes. This is ascribed to the production of a lead-rich phase during pressing, this is supported by XRD evidence. No significant degree of grain alignment was found in the Tl-1223 tapes, either by XRD analysis or by the measurement of transport critical current in applied magnetic fields. (orig.).

  12. Variable temperature superconducting microscope

    Science.gov (United States)

    Cheng, Bo; Yeh, W. J.

    2000-03-01

    We have developed and tested a promising type of superconducting quantum interference device (SQUID) microscope, which can be used to detect vortex motion and can operate in magnetic fields over a large temperature range. The system utilizes a single-loop coupling transformer, consisting of a patterned high Tc superconducting thin film. At one end of the transformer, a 20 μm diam detecting loop is placed close to the sample. At the other end, a large loop is coupled to a NbTi coil, which is connected to a low Tc SQUID sensor. Transformers in a variety of sizes have been tested and calibrated. The results show that the system is capable of detecting the motion of a single vortex. We have used the microscope to study the behavior of moving vortices at various positions in a YBa2Cu3O7 thin film bridge.

  13. Mechanical design of a synchronous rotating machines with Gd-Ba-Cu-O HTS bulk pole-field magnets operated by a pulsed-field magnetization with armature copper coils

    Energy Technology Data Exchange (ETDEWEB)

    Matsuzaki, H [Department of Electronic and Mechanical Engineering, Tokyo University of Marine Science and Technology, Koto-ku, Tokyo 135-8533 (Japan); Kimura, Y [Department of Electronic and Mechanical Engineering, Tokyo University of Marine Science and Technology, Koto-ku, Tokyo 135-8533 (Japan); Ohtani, I [Department of Electronic and Mechanical Engineering, Tokyo University of Marine Science and Technology, Koto-ku, Tokyo 135-8533 (Japan); Morita, E [Department of Electronic and Mechanical Engineering, Tokyo University of Marine Science and Technology, Koto-ku, Tokyo 135-8533 (Japan); Ogata, H [Department of Electronic and Mechanical Engineering, Tokyo University of Marine Science and Technology, Koto-ku, Tokyo 135-8533 (Japan); Izumi, M [Department of Electronic and Mechanical Engineering, Tokyo University of Marine Science and Technology, Koto-ku, Tokyo 135-8533 (Japan); Ida, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, Hiroshima 725-0231 (Japan); Sugimoto, H [Department of Electrical and Electronic Engineering, Fukui University, Fukui 910-8507 (Japan); Miki, M [Kitano Seiki Co. Ltd., Ohta-ku, Tokyo 143-0024 (Japan); Kitano, M [Kitano Seiki Co. Ltd., Ohta-ku, Tokyo 143-0024 (Japan)

    2006-06-01

    We studied a high-temperature superconducting (HTS) synchronous motor assembled with melt-textured Gd-Ba-Cu-O bulk pole-field magnets. The structure of a HTS motor is an axial gap type with neither brushes/slip rings nor iron core. The specific feature is that the rotor pole-field magnets of bulk are magnetized with pulsed current flow through vortex-type armature copper windings. The rotor pole bulks and armature coils are cooled down with liquid nitrogen. Cooling and magnetization of bulk pole field magnets are performed inside of the rotor. The trapped peak magnetic field of more than 0.5 T of the bulk magnets provided the motor performance of 3.1 kW with 720 rpm. In order to attain high output, single rotor plate with 8 bulks was substituted with a twinned rotor plates with 16 bulks together with triple layer armature units. We report on the test results and performance of the present twinned rotor-type HTS synchronous motor.

  14. Superconducting cyclotrons

    International Nuclear Information System (INIS)

    Blosser, H.G.; Johnson, D.A.; Burleigh, R.J.

    1976-01-01

    Superconducting cyclotrons are particularly appropriate for acceleration of heavy ions. A review is given of design features of a superconducting cyclotron with energy 440 (Q 2 /A) MeV. A strong magnetic field (4.6 tesla average) leads to small physical size (extraction radius 65 cm) and low construction costs. Operating costs are also low. The design is based on established technology (from present cyclotrons and from large bubble chambers). Two laboratories (in Chalk River, Canada and in East Lansing, Michigan) are proceeding with construction of full-scale prototype components for such cyclotrons

  15. Superconductivity in doped Dirac semimetals

    Science.gov (United States)

    Hashimoto, Tatsuki; Kobayashi, Shingo; Tanaka, Yukio; Sato, Masatoshi

    2016-07-01

    We theoretically study intrinsic superconductivity in doped Dirac semimetals. Dirac semimetals host bulk Dirac points, which are formed by doubly degenerate bands, so the Hamiltonian is described by a 4 ×4 matrix and six types of k -independent pair potentials are allowed by the Fermi-Dirac statistics. We show that the unique spin-orbit coupling leads to characteristic superconducting gap structures and d vectors on the Fermi surface and the electron-electron interaction between intra and interorbitals gives a novel phase diagram of superconductivity. It is found that when the interorbital attraction is dominant, an unconventional superconducting state with point nodes appears. To verify the experimental signature of possible superconducting states, we calculate the temperature dependence of bulk physical properties such as electronic specific heat and spin susceptibility and surface state. In the unconventional superconducting phase, either dispersive or flat Andreev bound states appear between point nodes, which leads to double peaks or a single peak in the surface density of states, respectively. As a result, possible superconducting states can be distinguished by combining bulk and surface measurements.

  16. High temperature interface superconductivity

    International Nuclear Information System (INIS)

    Gozar, A.; Bozovic, I.

    2016-01-01

    Highlight: • This review article covers the topic of high temperature interface superconductivity. • New materials and techniques used for achieving interface superconductivity are discussed. • We emphasize the role played by the differences in structure and electronic properties at the interface with respect to the bulk of the constituents. - Abstract: High-T_c superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T_c Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  17. Evidence for collective {delta}T{sub c} pinning in superconducting (K, Ba)BiO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Harneit, W [Centre National de la Recherche Scientifique (CNRS), 38 -Grenoble (France). Lab. d` Etudes des Proprietes Electroniques des Solides; Klein, T [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France). Lab. d` Etudes des Proprietes Electroniques des Solides; Baril, L [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France). Lab. d` Etudes des Proprietes Electroniques des Solides; Escribe-Filippini, C [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France). Lab. d` Etudes des Proprietes Electroniques des Solides

    1996-10-10

    The nature of pinning has been investigated in the three-dimensional high-T{sub c} superconductor (K, Ba)BiO{sub 3}. We show that the magnetic-field dependence of the critical current deduced from pulsed-field magnetization measurements can be well described by the collective-pinning theory on a large temperature range 0.06single-vortex and vortex bundle regimes. Furthermore, the temperature dependence of the collective-pinning length L{sub c} is in excellent agreement with a model of flux pinning induced by spatial fluctuations of the critical temperature ({delta}T{sub c} pinning model). (orig.).

  18. Critical current, pinning and resistive state of superconducting single-crystal niobium with different types of defect structure

    International Nuclear Information System (INIS)

    Sokolenko, V.I.; Starodubov, Ya.D.

    2005-01-01

    Critical current pinning and resistive state of single crystal niobium of texture orientation are studied for different structural states obtained by rolling at 20 K by 42% and polishing the surface layers. It is found that the heterogeneous structures typical of the strained sample even after its thinning down to approx 10% display a lower current-carrying capability due to an increase of the thermomagnetic instability within the fragmented structure sections in the near-surface layers. For a homogeneous defect structure of the sample core with the density of equilibrium distributed dislocations of 1.3 centre dot 10 11 cm -2 , a correlation between the normal current density and the critical current density in the resistive state is found, in agreement with the concepts of flux creep due to the scatter of local values of J c

  19. Superconducting materials

    International Nuclear Information System (INIS)

    Ruvalds, J.

    1990-01-01

    This report discusses the following topics: Fermi liquid nesting in high temperature superconductors; optical properties of high temperature superconductors; Hall effect in superconducting La 2-x Sr x CuO 4 ; source of high transition temperatures; and prospects for new superconductors

  20. Superconducting transformer

    International Nuclear Information System (INIS)

    Murphy, J.H.

    1982-01-01

    A superconducting transformer having a winding arrangement that provides for current limitation when subjected to a current transient as well as more efficient utilization of radial spacing and winding insulation. Structural innovations disclosed include compressed conical shaped winding layers and a resistive matrix to promote rapid switching of current between parallel windings

  1. Superconducting magnets

    International Nuclear Information System (INIS)

    1994-08-01

    This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-T c superconductor at low temperature

  2. Superconducting magnets

    International Nuclear Information System (INIS)

    Willen, E.

    1996-01-01

    Superconducting dipole magnets for high energy colliders are discussed. As an example, the magnets recently built for the Relativistic Heavy Ion Collider at Brookhaven are reviewed. Their technical performance and the cost for the industry-built production dipoles are given. The cost data is generalized in order to extrapolate the cost of magnets for a new machine

  3. Bipolar superconductivity

    International Nuclear Information System (INIS)

    Pankratov, S.G.

    1987-01-01

    A model of bipolaron superconductivity suggested by Soviet scientist Alexandrov A.S. and French scientist Ranninger is presentes in a popular way. It is noted that the bipolaron theory gives a good explanation of certain properties of new superconductors, high critical temperature, in particular

  4. Superconducting transistor

    International Nuclear Information System (INIS)

    Gray, K.E.

    1978-01-01

    A three film superconducting tunneling device, analogous to a semiconductor transistor, is presented, including a theoretical description and experimental results showing a current gain of four. Much larger current gains are shown to be feasible. Such a development is particularly interesting because of its novelty and the striking analogies with the semiconductor junction transistor

  5. Glass Waveguides for Periodic Poling

    DEFF Research Database (Denmark)

    Fage-Pedersen, Jacob; Jacobsen, Rune Shim; Kristensen, Martin

    2005-01-01

    Planar silica-based waveguide devices have been developed for second-harmonic generation by poling with periodic electrodes. We show that detrimental charge transport can occur along interfaces, but with proper choice of fabrication, high-quality devices are obtained....

  6. Poling of UV-written Waveguides

    DEFF Research Database (Denmark)

    Arentoft, Jesper; Kristensen, Martin; Hübner, Jörg

    1999-01-01

    We report poling of UV-written silica waveguides. Thermal poling induces an electro-optic coefficient of 0.05 pm/V. We also demonstrate simultaneous UV-writing and UV-poling. No measurable decay in the induced electro-optic effect was detected after nine months......We report poling of UV-written silica waveguides. Thermal poling induces an electro-optic coefficient of 0.05 pm/V. We also demonstrate simultaneous UV-writing and UV-poling. No measurable decay in the induced electro-optic effect was detected after nine months...

  7. Theory of superconductivity

    International Nuclear Information System (INIS)

    Crisan, M.

    1988-01-01

    This book discusses the most important aspects of the theory. The phenomenological model is followed by the microscopic theory of superconductivity, in which modern formalism of the many-body theory is used to treat most important problems such as superconducting alloys, coexistence of superconductivity with the magnetic order, and superconductivity in quasi-one-dimensional systems. It concludes with a discussion on models for exotic and high temperature superconductivity. Its main aim is to review, as complete as possible, the theory of superconductivity from classical models and methods up to the 1987 results on high temperature superconductivity. Contents: Phenomenological Theory of Superconductivity; Microscopic Theory of Superconductivity; Theory of Superconducting Alloys; Superconductors in a Magnetic Field; Superconductivity and Magnetic Order; Superconductivity in Quasi-One-Dimensional Systems; and Non-Conventional Superconductivity

  8. Prototype Superconducting Quadrupole for the ISR low-beta insertion

    CERN Multimedia

    CERN PhotoLab

    1977-01-01

    The picture shows the cold mass of the Quadrupole with its outer aluminium alloy rings pre-compressing the superconducting coils via the magnetic yoke split in 4 parts.The end of the inner vacuum chamber,supporting the 6-pole correction windings, can also be seen as well as the electrical connections. See also photos 7702690X, 7702307.

  9. Multipole superconducting electric motors for ship propulsion

    International Nuclear Information System (INIS)

    Thullen, P.; Keim, T.A.; Minervini, J.V.

    1975-01-01

    While a great deal of attention has been paid to two-pole superconducting synchronous machines, very little analysis of low speed, multipole superconducting synchronous machines has been done. Such machines may prove desirable as drive motors in ship drive systems. Results are presented of an analysis which assumes a motor of sufficient size that the airgap may be considered to be flat. A power output expression is given which shows the effects of machine geometry and superconductor characteristics on machine size. Based on this expression, a 40,000 hp 120 rpm motor is sized, and the resulting machine is compared with a conventional ship drive motor. The comparison illustrates possible size reductions through the application of superconductivity

  10. Spontaneous fluxoid formation in superconducting loops

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, Jesper; Rivers, R.

    2009-01-01

    We report on the experimental verification of the Zurek-Kibble scenario in an isolated superconducting ring over a wide parameter range. The probability of creating a single flux quantum spontaneously during the fast normal-superconducting phase transition of a wide Nb loop clearly follows...

  11. INTERLAYER OPTICAL CONDUCTIVITY OF A SUPERCONDUCTING BILAYER

    NARCIS (Netherlands)

    GARTSTEIN, YN; RICE, MJ; VANDERMAREL, D

    1994-01-01

    We employ the Bardeen-Cooper-Schrieffer theory to calculate the frequency-dependent interlayer conductivity of a superconducting bilayer, the two layers of which are coupled by weak single-particle tunneling. The effect of the superconducting transition on the normal-state absorption band is to

  12. Two gap superconductivity in Ba{sub 0.55}K{sub 0.45}Fe{sub 2}As{sub 2} single crystals studied by the directional point-contact Andreev reflection spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, P.; Pribulova, Z. [Centre of Low Temperature Physics, IEP Slovak Academy of Sciences and P.J.Safarik University, Watsonova 47, SK-04001 Kosice (Slovakia); Pristas, G.; Bud' ko, S.L.; Canfield, P.C. [Ames Laboratory and Iowa State University, Ames, IA 50011 (United States); Samuely, P., E-mail: samuely@saske.s [Centre of Low Temperature Physics, IEP Slovak Academy of Sciences and P.J.Safarik University, Watsonova 47, SK-04001 Kosice (Slovakia)

    2009-10-15

    First directional point-contact Andreev reflection spectroscopy on the Ba{sub 0.55}K{sub 0.45}Fe{sub 2}As{sub 2} single crystals is presented. The spectra show significant differences when measured in the ab plane in comparison with those measured in the c direction. In the latter case no traces of superconducting energy gap could be found, just a reduced point-contact conductance persisting up to about 100 K and indicating reduced density of states. On the other hand within the ab plane two nodeless superconducting energy gaps DELTA{sub S}approx2-5 meV and DELTA{sub L}approx9-11 meV are detected.

  13. Materials and mechanisms of hole superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, J.E., E-mail: jhirsch@ucsd.edu [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319 (United States)

    2012-01-15

    We study the applicability of the model of hole superconductivity to materials. Both conventional and unconventional materials are considered. Many different classes of materials are discussed. The theory is found suitable to describe all of them. No other theory of superconductivity can describe all these classes of materials. The theory of hole superconductivity proposes that there is a single mechanism of superconductivity that applies to all superconducting materials. This paper discusses several material families where superconductivity occurs and how they can be understood within this theory. Materials discussed include the elements, transition metal alloys, high T{sub c} cuprates both hole-doped and electron-doped, MgB{sub 2}, iron pnictides and iron chalcogenides, doped semiconductors, and elements under high pressure.

  14. Color superconductivity

    International Nuclear Information System (INIS)

    Wilczek, F.

    1997-01-01

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken

  15. Color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Wilczek, F. [Institute for Advanced Study, Princeton, NJ (United States)

    1997-09-22

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken.

  16. Optimal pole shifting controller for interconnected power system

    International Nuclear Information System (INIS)

    Yousef, Ali M.; Kassem, Ahmed M.

    2011-01-01

    Research highlights: → Mathematical model represents a power system which consists of synchronous machine connected to infinite bus through transmission line. → Power system stabilizer was designed based on optimal pole shifting controller. → The system performances was tested through load disturbances at different operating conditions. → The system performance with the proposed optimal pole shifting controller is compared with the conventional pole placement controller. → The digital simulation results indicated that the proposed controller has a superior performance. -- Abstract: Power system stabilizer based on optimal pole shifting is proposed. An approach for shifting the real parts of the open-loop poles to any desired positions while preserving the imaginary parts is presented. In each step of this approach, it is required to solve a first-order or a second-order linear matrix Lyapunov equation for shifting one real pole or two complex conjugate poles, respectively. This presented method yields a solution, which is optimal with respect to a quadratic performance index. The attractive feature of this method is that it enables solutions of the complex problem to be easily found without solving any non-linear algebraic Riccati equation. The present power system stabilizer is based on Riccati equation approach. The control law depends on finding the feedback gain matrix, and then the control signal is synthesized by multiplying the state variables of the power system with determined gain matrix. The gain matrix is calculated one time only, and it works over wide range of operating conditions. To validate the power of the proposed PSS, a linearized model of a simple power system consisted of a single synchronous machine connected to infinite bus bar through transmission line is simulated. The studied power system is subjected to various operating points and power system parameters changes.

  17. Optimal pole shifting controller for interconnected power system

    Energy Technology Data Exchange (ETDEWEB)

    Yousef, Ali M., E-mail: drali_yousef@yahoo.co [Electrical Eng. Dept., Faculty of Engineering, Assiut University (Egypt); Kassem, Ahmed M., E-mail: kassem_ahmed53@hotmail.co [Control Technology Dep., Industrial Education College, Beni-Suef University (Egypt)

    2011-05-15

    Research highlights: {yields} Mathematical model represents a power system which consists of synchronous machine connected to infinite bus through transmission line. {yields} Power system stabilizer was designed based on optimal pole shifting controller. {yields} The system performances was tested through load disturbances at different operating conditions. {yields} The system performance with the proposed optimal pole shifting controller is compared with the conventional pole placement controller. {yields} The digital simulation results indicated that the proposed controller has a superior performance. -- Abstract: Power system stabilizer based on optimal pole shifting is proposed. An approach for shifting the real parts of the open-loop poles to any desired positions while preserving the imaginary parts is presented. In each step of this approach, it is required to solve a first-order or a second-order linear matrix Lyapunov equation for shifting one real pole or two complex conjugate poles, respectively. This presented method yields a solution, which is optimal with respect to a quadratic performance index. The attractive feature of this method is that it enables solutions of the complex problem to be easily found without solving any non-linear algebraic Riccati equation. The present power system stabilizer is based on Riccati equation approach. The control law depends on finding the feedback gain matrix, and then the control signal is synthesized by multiplying the state variables of the power system with determined gain matrix. The gain matrix is calculated one time only, and it works over wide range of operating conditions. To validate the power of the proposed PSS, a linearized model of a simple power system consisted of a single synchronous machine connected to infinite bus bar through transmission line is simulated. The studied power system is subjected to various operating points and power system parameters changes.

  18. Superconducting magnet

    Science.gov (United States)

    1985-01-01

    Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.

  19. Melt formed superconducting joint between superconducting tapes

    International Nuclear Information System (INIS)

    Benz, M.G.; Knudsen, B.A.; Rumaner, L.E.; Zaabala, R.J.

    1992-01-01

    This patent describes a superconducting joint between contiguous superconducting tapes having an inner laminate comprised of a parent-metal layer selected from the group niobium, tantalum, technetium, and vanadium, a superconductive intermetallic compound layer on the parent-metal layer, a reactive-metal layer that is capable of combining with the parent-metal and forming the superconductive intermetallic compound, the joint comprising: a continuous precipitate of the superconductive intermetallic compound fused to the tapes forming a continuous superconducting path between the tapes

  20. Preliminary magnet design for a superconducting separated sector cyclotron

    International Nuclear Information System (INIS)

    Bertrand, P.; Chabert, A.; Duval, M.; Ripouteau, F.

    1992-01-01

    This paper reports that in order to increase the energies available at GANIL, studies on a superconducting separated six straight sector cyclotron for heavy ions with energy up to 500 MeV/A (ions with Q/A = 0.5) have been performed. With a mean injection radius of 2.5 m and an extraction radius of 5 m, the maximum magnetic field on a sector has to be 5T. Each of the six sectors consists of two superconducting main coils (wound around the poles), room temperature iron pole pieces and a large yoke. Due to the broad ranges of energy and ion species, the required field laws are very different and for the most difficult operating point, the induction difference between the injection and ejection radii is about one Tesla. As a consequence, correcting coils have to provide a high field and one unusual point is that the machine will be operated with superconducting trim coils

  1. INNOVATIVE CLUSTER OR COMPETITIVENESS POLE?

    Directory of Open Access Journals (Sweden)

    Liliana Scutaru

    2015-02-01

    Full Text Available The paper analyzes the situation of clusters in Romania and their areas of activity and innovation in entrepreneurship Romanian state. It is made also a territorial distribution of clusters on the eight regions. The findings lead to the conclusion that there are some clusters that have the vocation to become poles of competitiveness in areas such as renewable energy, automotive, electronics, health, biotechnology, mechatronics or ICT (Information and Communication Technology which represent the resources for future of the Romanian economy. Regarding the degree of innovation of Romanian Small and Medium Enterprises (SMEs, the level is relatively modest, 30.8% of all enterprises being innovative. If we were to answer the question the title suggests, we would say "yes" to both since the innovative cluster as well as the competitiveness pole promotes par excellence, innovation through study, research and stimulation of creativity. And this is more than enough to support economic growth of Romania and maintain the competitiveness worldwide.

  2. Pole counting and resonance classification

    International Nuclear Information System (INIS)

    Morgan, D.

    1992-01-01

    S-wave resonances occurring close to an inelastic threshold can be classified according to the number of nearby poles they possess. One then has a useful possibility of distinguishing dynamical alternatives by objective appeal to data. Making this quantitative entails developing suitable effective range expansions for various realizations of potential scattering. A key application is deciding the make-up of f 0 (976) (S*). (author)

  3. Development of a multi-pole magnetorheological brake

    International Nuclear Information System (INIS)

    Shiao, Yaojung; Nguyen, Quang-Anh

    2013-01-01

    This paper presents a new approach in the design and optimization of a novel multi-pole magnetorheological (MR) brake that employs magnetic flux more effectively on the surface of the rotor. MR brakes with conventional single ring-type electromagnetic poles have reached the limits of torque enhancement. One major reason is the limitation of the magnetic field strength within the active area of the MR fluid due to the geometric constraints of the coil. The multi-pole MR brake design features multiple electromagnetic poles surrounded by several coils. As a result, the active chaining areas for the MR fluid are greatly increased, and significant brake torque improvement is achieved. The coil structure, as a part of the stator, becomes flexible and customizable in terms of space usage for the winding and bobbin design. In addition, this brake offers extra options in its dimensions for torque enhancement because either the radial or the axial dimensions of the rotor can be increased. Magnetic circuit analysis was conducted to analyze the effects of the design parameters on the field torque. After that, simulations were done to find the optimal design under all major geometric constraints with a given power supply. The results show that the multi-pole MR brake provides a considerable braking torque increase while maintaining a compact and solid design. This is confirmation of its feasibility in actual braking applications. (paper)

  4. Superconducting six-axis accelerometer

    Science.gov (United States)

    Paik, H. J.

    1990-01-01

    A new superconducting accelerometer, capable of measuring both linear and angular accelerations, is under development at the University of Maryland. A single superconducting proof mass is magnetically levitated against gravity or any other proof force. Its relative positions and orientations with respect to the platform are monitored by six superconducting inductance bridges sharing a single amplifier, called the Superconducting Quantum Interference Device (SQUID). The six degrees of freedom, the three linear acceleration components and the three angular acceleration components, of the platform are measured simultaneously. In order to improve the linearity and the dynamic range of the instrument, the demodulated outputs of the SQUID are fed back to appropriate levitation coils so that the proof mass remains at the null position for all six inductance bridges. The expected intrinsic noise of the instrument is 4 x 10(exp -12)m s(exp -2) Hz(exp -1/2) for linear acceleration and 3 x 10(exp -11) rad s(exp -2) Hz(exp -1/2) for angular acceleration in 1-g environment. In 0-g, the linear acceleration sensitivity of the superconducting accelerometer could be improved by two orders of magnitude. The design and the operating principle of a laboratory prototype of the new instrument is discussed.

  5. Heat Capacity and Thermal Conductance Measurements of a Superconducting-Normal Mixed State by Detection of Single 3 eV Photons in a Magnetic Penetration Thermometer

    Science.gov (United States)

    Stevenson, T. R.; Balvin, M. A.; Bandler, S. R.; Denis, K. L.; Lee, S.-J.; Nagler, P. C.; Smith, S. J.

    2015-01-01

    We report on measurements of the detected signal pulses in a molybdenum-gold Magnetic Penetration Thermometer (MPT) in response to absorption of one or more 3 eV photons. We designed and used this MPT sensor for x-ray microcalorimetry. In this device, the diamagnetic response of a superconducting MoAu bilayer is used to sense temperature changes in response to absorbed photons, and responsivity is enhanced by a Meissner transition in which the magnetic flux penetrating the sensor changes rapidly to minimize free energy in a mixed superconducting normal state. We have previously reported on use of our MPT to study a thermal phonon energy loss to the substrate when absorbing x-rays. We now describe results of extracting heat capacity C and thermal conductance G values from pulse height and decay time of MPT pulses generated by 3 eV photons. The variation in C and G at temperatures near the Meissner transition temperature (set by an internal magnetic bias field) allow us to probe the behavior in superconducting normal mixed state of the condensation energy and the electron cooling power resulting from quasi-particle recombination and phonon emission. The information gained on electron cooling power is also relevant to the operation of other superconducting detectors, such as Microwave Kinetic Inductance Detectors.

  6. Two-pole microring weight banks.

    Science.gov (United States)

    Tait, Alexander N; Wu, Allie X; Ferreira de Lima, Thomas; Nahmias, Mitchell A; Shastri, Bhavin J; Prucnal, Paul R

    2018-05-15

    Weighted addition is an elemental multi-input to single-output operation that can be implemented with high-performance photonic devices. Microring (MRR) weight banks bring programmable weighted addition to silicon photonics. Prior work showed that their channel limits are affected by coherent inter-channel effects that occur uniquely in weight banks. We fabricate two-pole designs that exploit this inter-channel interference in a way that is robust to dynamic tuning and fabrication variation. Scaling analysis predicts a channel count improvement of 3.4-fold, which is substantially greater than predicted by incoherent analysis used in conventional MRR devices. Advances in weight bank design expand the potential of reconfigurable analog photonic networks and multivariate microwave photonics.

  7. Superconducting plasmas

    International Nuclear Information System (INIS)

    Ohnuma, Toshiro; Ohno, J.

    1994-01-01

    Superconducting (SC) plasmas are proposed and investigated. The SC plasmas are not yet familiar and have not yet been studied. However, the existence and the importance of SC plasmas are stressed in this report. The existence of SC plasmas are found as follows. There is a fundamental property of Meissner effect in superconductors, which shows a repulsive effect of magnetic fields. Even in that case, in a microscopic view, there is a region of magnetic penetration. The penetration length λ is well-known as London's penetration depth, which is expressed as δ = (m s /μ 0 n s q s 2 ) 1/2 where m s , n s , q s and μ o show the mass, the density, the charge of SC electron and the permeability in free space, respectively. Because this expression is very simple, no one had tried it into more simple and meaningful form. Recently, one of the authors (T.O.) has found that the length can be expressed into more simple and understandable fundamental form as λ = c/ω ps where c = (ε 0 μ 0 ) -1/2 and ω ps = (n s q s 2 /m s ε 0 ) 1/2 are the light velocity and the superconducting plasma frequency. From this simple expression, the penetration depth of the magnetic field to SC is found as a SC plasma skin depth, that is, the fundamental property of SC can be expressed by the SC plasmas. This discovery indicates an importance of the studies of superconducting plasmas. From these points, several properties (propagating modes et al) of SC plasmas, which consist of SC electrons, normal electrons and lattice ions, are investigated in this report. Observations of SC plasma frequency is also reported with a use of Terahertz electromagnet-optical waves

  8. Monolayer Superconductivity in WS2

    NARCIS (Netherlands)

    Zheliuk, Oleksandr; Lu, Jianming; Yang, Jie; Ye, Jianting

    Superconductivity in monolayer tungsten disulfide (2H-WS2) is achieved by strong electrostatic electron doping of an electric double-layer transistor (EDLT). Single crystals of WS2 are grown by a scalable method - chemical vapor deposition (CVD) on standard Si/SiO2 substrate. The monolayers are

  9. Method and apparatus for assembling a permanent magnet pole assembly

    Science.gov (United States)

    Carl, Jr., Ralph James; Bagepalli, Bharat Sampathkumaran [Niskayuna, NY; Jansen, Patrick Lee [Scotia, NY; Dawson, Richard Nils [Voorheesville, NY; Qu, Ronghai [Clifton Park, NY; Avanesov, Mikhail Avramovich [Moscow, RU

    2009-08-11

    A pole assembly for a rotor, the pole assembly includes a permanent magnet pole including at least one permanent magnet block, a plurality of laminations including a pole cap mechanically coupled to the pole, and a plurality of laminations including a base plate mechanically coupled to the pole.

  10. Superconducting ac cable

    Science.gov (United States)

    Schmidt, F.

    1980-11-01

    The components of a superconducting 110 kV ac cable for power ratings or = 2000 MVA were developed. The cable design is of the semiflexible type, with a rigid cryogenic envelope containing a flexible hollow coaxial cable core. The cable core consists of spirally wound Nb-A1 composite wires electrically insulated by high pressure polyethylene tape wrappings. A 35 m long single phase test cable with full load terminals rated at 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of this cable design.

  11. Superconducting ac cable

    International Nuclear Information System (INIS)

    Schmidt, F.

    1980-01-01

    The components of a superconducting 110 kV ac cable for power ratings >= 2000 MVA have been developed. The cable design especially considered was of the semiflexible type, with a rigid cryogenic envelope and flexible hollow coaxial cable cores pulled into the former. The cable core consists of spirally wound Nb-Al composite wires and a HDPE-tape wrapped electrical insulation. A 35 m long single phase test cable with full load terminations for 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of our cable design. (orig.) [de

  12. The state of superconductivity

    International Nuclear Information System (INIS)

    Clark, T.D.

    1981-01-01

    The present status of applications based on the phenomena of superconductivity are reviewed. Superconducting materials, large scale applications, the Josephson effect and its applications, and superconductivity in instrumentation, are considered. The influence that superconductivity has had on modern theories of elementary particles, such as gauge symmetry breaking, is discussed. (U.K.)

  13. Four-junction superconducting circuit

    Science.gov (United States)

    Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.

    2016-01-01

    We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit. PMID:27356619

  14. A 15-pole high temperature superconductor filter for radar applications

    Science.gov (United States)

    Yu, Xiao; Xi, Weibin; Wu, Songtao

    2018-06-01

    This paper presents a compact and high first harmonic frequency resonator. The characteristics of this resonator are theoretically analyzed. A highly selective 15-pole Chebyshev high temperature superconducting ultra-high frequency narrowband filter for radar applications was fabricated by using this resonator. The filter has a center frequency of 495 MHz and a fractional bandwidth of 1%. The first harmonic frequency is more than 3.3 times the fundamental frequency. The measured filter shows excellent selectivity, better than 85 dB/1 MHz skirt slopes, and more than 85 dB of rejection at 497.5 MHz from the band edge. The filter was fabricated on a 2 inch YBCO thin film with a 0.5 mm thick MgO substrate. The experimental results are consistent with the simulations.

  15. 100 years of superconductivity

    CERN Document Server

    Rogalla, Horst

    2011-01-01

    Even a hundred years after its discovery, superconductivity continues to bring us new surprises, from superconducting magnets used in MRI to quantum detectors in electronics. 100 Years of Superconductivity presents a comprehensive collection of topics on nearly all the subdisciplines of superconductivity. Tracing the historical developments in superconductivity, the book includes contributions from many pioneers who are responsible for important steps forward in the field.The text first discusses interesting stories of the discovery and gradual progress of theory and experimentation. Emphasizi

  16. High-temperature superconductivity

    International Nuclear Information System (INIS)

    Ginzburg, V.L.

    1987-07-01

    After a short account of the history of experimental studies on superconductivity, the microscopic theory of superconductivity, the calculation of the control temperature and its possible maximum value are presented. An explanation of the mechanism of superconductivity in recently discovered superconducting metal oxide ceramics and the perspectives for the realization of new high-temperature superconducting materials are discussed. 56 refs, 2 figs, 3 tabs

  17. Superconducting accelerator technology

    International Nuclear Information System (INIS)

    Grunder, H.A.; Hartline, B.K.

    1986-01-01

    Modern and future accelerators for high energy and nuclear physics rely increasingly on superconducting components to achieve the required magnetic fields and accelerating fields. This paper presents a practical overview of the phenomenon of superconductivity, and describes the design issues and solutions associated with superconducting magnets and superconducting rf acceleration structures. Further development and application of superconducting components promises increased accelerator performance at reduced electric power cost

  18. Transport currents along c-axis and (a,b) planes in YBCO single domain materials. Critical current densities and normal-superconducting transitions

    International Nuclear Information System (INIS)

    Porcar, L.; Bourgault, D.; Chaud, X.; Noudem, J.G.; Tournier, R.; Tixador, P.

    1998-01-01

    High transport currents along the (a,b) planes and along the c-axis have been measured in pulsed current of different pseudo-frequencies. Self field losses and transport current of 8000 A (20000 A cm -2 ) have been measured in Y 1 Ba 2 Cu 3 O 7-δ bars textured by the melting zone technique. Critical currents as high as 500 A (90000 A cm -2 ) along the (a,b) planes or 3000 A (7500 A cm -2 ) along the c-axis have been measured. For both orientations, the transition from the normal state to the superconducting state has been observed. Electric field of 1000 V m -1 and study of the superconducting state recovery are reported. (orig.)

  19. Radiofrequency amplifier based on a DC superconducting quantum interference device

    International Nuclear Information System (INIS)

    Martinis, J.M.; Hilbert, C.; Clarke, J.

    1986-01-01

    A method is described of amplifying a radiofrequency signal consisting of: disposing a single symmetrically biased dc SQUID and an input coil within a superconducting shield, the dc SQUID having a superconducting ring interrupted by two shunted Josephson junctions, and the input coil being inductively coupled solely to the ring of the single SQUID, establishing a constant magnetic flux threading the SQUID ring, applying the radiofrequency signal to the input coil from outside of the superconducting shield, obtaining an amplified radiofrequency signal solely from across the ring of the single SQUID, transmitting the amplified radiofrequency signal from across the SQUID ring to the outside of the superconducting shield

  20. Coexistence of spin-triplet superconductivity with magnetism within a single mechanism for orbitally degenerate correlated electrons: statistically consistent Gutzwiller approximation

    International Nuclear Information System (INIS)

    Zegrodnik, M; Spałek, J; Bünemann, J

    2013-01-01

    An orbitally degenerate two-band Hubbard model is analyzed with the inclusion of the Hund's rule-induced spin-triplet even-parity paired states and their coexistence with magnetic ordering. The so-called statistically consistent Gutzwiller approximation (SGA) has been applied to the case of a square lattice. The superconducting gaps, the magnetic moment and the free energy are analyzed as a function of the Hund's rule coupling strength and the band filling. Also, the influence of the intersite hybridization on the stability of paired phases is discussed. In order to examine the effect of correlations the results are compared with those calculated earlier within the Hartree–Fock (HF) approximation combined with the Bardeen–Cooper–Schrieffer (BCS) approach. Significant differences between the two methods used (HF + BCS versus SGA + real-space pairing) appear in the stability regions of the considered phases. Our results supplement the analysis of this canonical model used widely in the discussions of pure magnetic phases with the detailed elaboration of the stability of the spin-triplet superconducting states and the coexistent magnetic-superconducting states. At the end, we briefly discuss qualitatively the factors that need to be included for a detailed quantitative comparison with the corresponding experimental results. (paper)

  1. The effect of nano-size ZrO2 powder addition on the microstructure and superconducting properties of single-domain Y-Ba-Cu-O bulk superconductors

    International Nuclear Information System (INIS)

    Iida, K; Babu, N H; Reddy, E S; Shi, Y-H; Cardwell, D A

    2005-01-01

    The effect of nano-size ZrO 2 powder addition on the microstructure and superconducting properties of Y-Ba-Cu-O single grain bulk superconductors has been investigated. Significant pushing phenomena of Y 2 BaCuO 5 (Y-211) particles, particularly in the c growth sector, were observed even with a small amount of ZrO 2 added to the precursor powder. An increase in Y-211 particle pushing was observed with increasing ZrO 2 content, leading to an inhomogeneous bulk microstructure. In addition, a growth cycle consisting of a Y-211 free layer-porous narrow layer-Y-211 high concentration layer was observed for samples prepared with 0.25 wt% ZrO 2 in both the a and c growth sectors. The extent of the growth of single grain Y-Ba-Cu-O (YBCO) decreased with increasing ZrO 2 content due to increased pushing of Y-211 particles towards molten liquid. The superconducting transition temperature, T c , of the ZrO 2 containing YBCO samples was sharp but depressed slightly (by up to 1 K) compared with an undoped YBCO grain, indicating a relative insensitivity of T c to ZrO 2 content. Finally, the sensitivity of critical current density, J c , to applied magnetic field in large grain bulk YBCO containing ZrO 2 was observed to depend critically on position due to the inhomogeneous sample microstructure

  2. 2D Stabilised analytic signal method in DC pole-pole potential data ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    synthetic error prone secondary pole-pole potential data. 1. Introduction. Analytical signal .... The meaning of the rest of the parameters is self- evident. The three ..... interpretation using 3-D analytic signal; Geophysics 57. 116–125. Starostenko ...

  3. High field superconducting magnets

    Science.gov (United States)

    Hait, Thomas P. (Inventor); Shirron, Peter J. (Inventor)

    2011-01-01

    A superconducting magnet includes an insulating layer disposed about the surface of a mandrel; a superconducting wire wound in adjacent turns about the mandrel to form the superconducting magnet, wherein the superconducting wire is in thermal communication with the mandrel, and the superconducting magnet has a field-to-current ratio equal to or greater than 1.1 Tesla per Ampere; a thermally conductive potting material configured to fill interstices between the adjacent turns, wherein the thermally conductive potting material and the superconducting wire provide a path for dissipation of heat; and a voltage limiting device disposed across each end of the superconducting wire, wherein the voltage limiting device is configured to prevent a voltage excursion across the superconducting wire during quench of the superconducting magnet.

  4. Understanding and application of superconducting materials

    International Nuclear Information System (INIS)

    Moon, Byeong Mu; Lee, Chun Heung

    1997-02-01

    This book deals with superconducting materials, which contains from basic theory to application of superconducting materials. The contents of this book are mystery of superconducting materials, properties of superconducting materials, thermodynamics of superconducting materials, theoretical background of superconducting materials, tunnelling and quantum interference, classification and properties of superconducting materials, high temperature superconducting materials, production and analysis of superconducting materials and application of superconducting materials.

  5. Development of a superconducting elliptically polarized undulator

    International Nuclear Information System (INIS)

    Chen, S D; Liang, K S; Jan, J C; Hwang, C S

    2010-01-01

    A superconducting, elliptically polarized undulator (SEPU24) with a period of length 24 mm was developed to provide first-harmonic photons from a 0.8 GeV storage ring for extreme-ultraviolet (EUV) lithography experiment. In SEPU24, two layers of a magnet array structure - with and without rotated magnet arrays - are combined to generate a helical field that provides radiation with wavelength 13.5 nm in the in-band energy. The arrays of iron and aluminium poles were wound with a racetrack coil vertically as for the magnet pole array. The elliptical field is created when the up and down magnet-pole arrays pass excitation currents in alternate directions. SEPU24 is designed with a magnet of gap 6.8 mm, yielding magnetic flux density B x =B z =0.61 T of the helical field. A prototype magnet was fabricated with a diode for quench protection, and assembled in a test dewar to test the magnet performance. A cryogenic Hall-probe system with a precise linear stage was used to measure the distribution of the magnetic field. We describe the design concept and algorithm, the engineering design, the calculation of the magnetic field, the construction and testing of the 10-pole prototype magnet and related issues.

  6. A high gradient superconducting quadrupole for a low charge state ion linac

    International Nuclear Information System (INIS)

    Kim, J.W.; Shepard, K.W.; Nolen, J.A.

    1995-01-01

    A superconducting quadrupole magnet has been designed for use as the focusing element in a low charge state linac proposed at Argonne. The expected field gradient is 350 T/m at an operating current of 53 A, and the bore diameter is 3 cm. The use of rare earth material holmium for pole tips provides about 10% more gradient then iron pole tips. The design and the status of construction of a prototype singlet magnet is described

  7. ac superconducting articles

    International Nuclear Information System (INIS)

    Meyerhoff, R.W.

    1977-01-01

    A noval ac superconducting cable is described. It consists of a composite structure having a superconducting surface along with a high thermally conductive material wherein the superconducting surface has the desired physical properties, geometrical shape and surface finish produced by the steps of depositing a superconducting layer upon a substrate having a predetermined surface finish and shape which conforms to that of the desired superconducting article, depositing a supporting layer of material on the superconducting layer and removing the substrate, the surface of the superconductor being a replica of the substrate surface

  8. Superconducting detectors for semiconductor quantum photonics

    International Nuclear Information System (INIS)

    Reithmaier, Guenther M.

    2015-01-01

    In this thesis we present the first successful on-chip detection of quantum light, thereby demonstrating the monolithic integration of superconducting single photon detectors with individually addressable semiconductor quantum dots in a prototypical quantum photonic circuit. Therefore, we optimized both the deposition of high quality superconducting NbN thin films on GaAs substrates and the fabrication of superconducting detectors and successfully integrated these novel devices with GaAs/AlGaAs ridge waveguides loaded with self-assembled InGaAs quantum dots.

  9. RF Design and Operating Performance of the BNL/AES 1.3 GHz Single Cell Superconducting RF Photocathode Electron Gun

    International Nuclear Information System (INIS)

    Cole, Michael; Kneisel, Peter; Ben-Zvi, Ilan; Burrill, Andrew; Hahn, H.; Rao, Triveni; Zhao, Y.

    2005-01-01

    Over the past several years Advanced Energy Systems and BNL have been collaborating on the development and testing of a fully superconducting photocathode electron gun. Over the past year we have begun to realize significant results which have been published elsewhere (1). This paper will review the RF design of the gun under test and present results of its performance under various operating conditions. Results for cavity quality factor will be presented for various operating temperatures and cavity field gradients. We will also discuss future plans for testing using this gun.

  10. Prototype Superconducting Quadrupole for the ISR high-luminosity (low beta)insertion:end view.

    CERN Multimedia

    CERN PhotoLab

    1977-01-01

    In this picture, taken before the insertion of the inner vacuum chamber with inbedded 6-pole superconducting windings, one can see the main components of the magnet structure: (from inside outwards) the superconducting quadrupole coils surronded by glass epoxy bandage rings and stainless steel spacers, the low-carbon steel yoke quadrants and the aluminium alloy shrinking rings. See also photos 7702307, 7702688X, 7702690X.

  11. Superconducting transition and low-field magnetoresistance of a niobium single crystal at 4.2 deg. K; Transition supraconductrice et magnetoresistance en champ faible d'un echantillon monocristallin de niobium a 4.2 deg. K

    Energy Technology Data Exchange (ETDEWEB)

    Perriot, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires. Service de physique du solide et de resonnance magnetique

    1967-01-01

    We report the study of the electrical resistance of a niobium single crystal, at 4.2 deg. K, from the beginning of the superconductive transition to 80 kilo oersteds. Critical fieldsH{sub c2} and H{sub c3} have been determined. Influences on superconductive transition of current density, field-current angle, crystal orientation and magnetoresistance have been studied. Variation laws of low-field transverse and longitudinal magneto-resistances have been determined. (author) [French] La variation de la resistance electrique d'un monocristal cylindrique de niobium a ete etudiee, a 4,2 deg. K, depuis le debut de la transition supraconductrice jusqu'a 80 kilooersteds. Les champs critiques H{sub c2} et H{sub c3} ont ete determines. On a etudie l'influence de la densite de courant, de l'angle champ-courant, de l'anisotropie cristalline et de la magnetoresistance sur la transition supraconductrice. Les lois de variation des magnetoresistances transversale et longitudinale ont ete determinees dans le domaine des champs faibles. (auteur)

  12. Anomalous reduction in the long-time flux creep relaxation in superconducting Ca10(Pt4As8)((Fe1‑x Pt x )2As2)5 (x ≈ 0.05) single crystals

    Science.gov (United States)

    Haberkorn, N.; Huang, Silu; Jin, R.

    2018-06-01

    We report the vortex dynamics of superconducting a Ca10(Pt4As8)((Fe1‑x Pt x )2As2)5 (x ≈ 0.05) single crystal with T c = 26 K investigated by performing magnetic measurements. The field dependence of the magnetization displays a second peak (SPM), typically related to a crossover between elastic and plastic vortex relaxation in a weak pinning scenario. Long-time flux creep relaxation measurements for fields smaller that of the SPM show that the vortex dynamics can be separated in two different regions. For magnetic fields smaller than the lower end of the SPM, glassy relaxation (with a characteristic glassy exponent μ) is observed. For magnetic fields between the lower end and the SPM, the flux creep rate decreases systematically to values below to the ones predicted by the collective theory. This effect can be understood by considering a stable vortex lattice configuration. As the field position of the SPM can be adjusted by modifying the quenched potential, our results suggest that extremely low flux creep relaxation rate may be tuned in many other superconducting materials.

  13. Anisotropic two-gap superconductivity and the absence of a Pauli paramagnetic limit in single-crystalline LaO0.5F0.5BiS2

    Science.gov (United States)

    Chan, Y. C.; Yip, K. Y.; Cheung, Y. W.; Chan, Y. T.; Niu, Q.; Kajitani, J.; Higashinaka, R.; Matsuda, T. D.; Yanase, Y.; Aoki, Y.; Lai, K. T.; Goh, Swee K.

    2018-03-01

    Ambient-pressure-grown LaO0.5F0.5BiS2 with a superconducting transition temperature Tc˜3 K possesses a highly anisotropic normal state. By a series of electrical resistivity measurements with a magnetic-field direction varying between the crystalline c axis and the a b plane, we present datasets displaying the temperature dependence of the out-of-plane upper critical field Hc2 ⊥(T ) , the in-plane upper critical field Hc2 ∥(T ) , as well as the angular dependence of Hc 2 at fixed temperatures for ambient-pressure-grown LaO0.5F0.5BiS2 single crystals. The anisotropy of the superconductivity, Hc2 ∥/Hc2 ⊥ , reaches ˜16 on approaching 0 K, but it decreases significantly near Tc. A pronounced upward curvature of Hc2 ∥(T ) is observed near Tc, which we analyze using a two-gap model. Moreover, Hc2 ∥(0 ) is found to exceed the Pauli paramagnetic limit, which can be understood by considering the strong spin-orbit coupling associated with Bi as well as the breaking of the local inversion symmetry at the electronically active BiS2 bilayers. Hence, LaO0.5F0.5BiS2 with a centrosymmetric lattice structure is a unique platform to explore the physics associated with local parity violation in the bulk crystal.

  14. Superconducting transition and low-field magnetoresistance of a niobium single crystal at 4.2 deg. K; Transition supraconductrice et magnetoresistance en champ faible d'un echantillon monocristallin de niobium a 4.2 deg. K

    Energy Technology Data Exchange (ETDEWEB)

    Perriot, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires. Service de physique du solide et de resonnance magnetique

    1967-01-01

    We report the study of the electrical resistance of a niobium single crystal, at 4.2 deg. K, from the beginning of the superconductive transition to 80 kilo oersteds. Critical fieldsH{sub c2} and H{sub c3} have been determined. Influences on superconductive transition of current density, field-current angle, crystal orientation and magnetoresistance have been studied. Variation laws of low-field transverse and longitudinal magneto-resistances have been determined. (author) [French] La variation de la resistance electrique d'un monocristal cylindrique de niobium a ete etudiee, a 4,2 deg. K, depuis le debut de la transition supraconductrice jusqu'a 80 kilooersteds. Les champs critiques H{sub c2} et H{sub c3} ont ete determines. On a etudie l'influence de la densite de courant, de l'angle champ-courant, de l'anisotropie cristalline et de la magnetoresistance sur la transition supraconductrice. Les lois de variation des magnetoresistances transversale et longitudinale ont ete determinees dans le domaine des champs faibles. (auteur)

  15. WORKSHOPS: Radiofrequency superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    In the continual push towards higher energy particle beams, superconducting radiofrequency techniques now play a vital role, highlighted in the fifth workshop on radiofrequency superconductivity, held at DESY from 19 - 24 August 1991

  16. WORKSHOPS: Radiofrequency superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1992-01-15

    In the continual push towards higher energy particle beams, superconducting radiofrequency techniques now play a vital role, highlighted in the fifth workshop on radiofrequency superconductivity, held at DESY from 19 - 24 August 1991.

  17. Experimental evidence for s-wave pairing symmetry in superconducting Cu(x)Bi2Se3 single crystals using a scanning tunneling microscope.

    Science.gov (United States)

    Levy, Niv; Zhang, Tong; Ha, Jeonghoon; Sharifi, Fred; Talin, A Alec; Kuk, Young; Stroscio, Joseph A

    2013-03-15

    Topological superconductors represent a newly predicted phase of matter that is topologically distinct from conventional superconducting condensates of Cooper pairs. As a manifestation of their topological character, topological superconductors support solid-state realizations of Majorana fermions at their boundaries. The recently discovered superconductor Cu(x)Bi(2)Se(3) has been theoretically proposed as an odd-parity superconductor in the time-reversal-invariant topological superconductor class, and point-contact spectroscopy measurements have reported the observation of zero-bias conductance peaks corresponding to Majorana states in this material. Here we report scanning tunneling microscopy measurements of the superconducting energy gap in Cu(x)Bi(2)Se(3) as a function of spatial position and applied magnetic field. The tunneling spectrum shows that the density of states at the Fermi level is fully gapped without any in-gap states. The spectrum is well described by the Bardeen-Cooper-Schrieffer theory with a momentum independent order parameter, which suggests that Cu(x)Bi(2)Se(3) is a classical s-wave superconductor contrary to previous expectations and measurements.

  18. Metrópoles desgovernadas

    Directory of Open Access Journals (Sweden)

    Erminia Maricato

    2011-04-01

    Full Text Available Apesar de sua importância econômica, política, social, demográfica, cultural, territorial e ambiental, há, nas metrópoles brasileiras, uma significativa falta de governo, evidenciada pelas incipientes iniciativas de cooperação administrativa intermunicipal e federativa. Este artigo aborda as mudanças estruturais - no processo de urbanização/ metropolização - devidas à reestruturação produtiva do capitalismo global, e, na escala nacional, trata da mudança no marco institucional - jurídico/político - que passou de concentrador e centralizador, durante o regime militar, para descentralizador e esvaziado, após a Constituição de 1988. O recuo verificado nas políticas sociais durante os anos 1980 e 1990, notadamente em transporte, habitação e saneamento, além do desmonte dos organismos metropolitanos, conduziu nossas metrópoles a um destino de banalização das tragédias urbanas. Em que pese sua urgência, a questão metropolitana não sensibiliza nenhuma força política ou instituição que lhe atribua lugar de destaque na agenda nacional.Despite its economic, political, social, demographic, cultural, territorial and environmental importance, there is a significant lack of government in the brazilian metropolises, evidenced by the incipient initiatives of intermunicipal and federative administrative cooperation. This article analyses the structural changes - in the process of urbanization/metropolization - due to the productive restructuring of global capitalism, and, in a national scale, analyses the change in the institutional mark - legal/political - which passed from concentrator and centralizer, during the Military Regimen, to decentralized and emptied, after 1988 Constitution. The downturn verified in social policies during the years 1980 and 1990, notably in transport, housing and sanitation, besides the dismantling of the metropolitan agencies, has led our cities to the trivialization of urban tragedies. Despite

  19. Superconductivity and future accelerators

    International Nuclear Information System (INIS)

    Danby, G.T.; Jackson, J.W.

    1963-01-01

    For 50 years particle accelerators employing accelerating cavities and deflecting magnets have been developed at a prodigious rate. New accelerator concepts and hardware ensembles have yielded great improvements in performance and GeV/$. The great idea for collective acceleration resulting from intense auxiliary charged-particle beams or laser light may or may not be just around the corner. In its absence, superconductivity (SC) applied both to rf cavities and to magnets opened up the potential for very large accelerators without excessive energy consumption and with other economies, even with the cw operation desirable for colliding beams. HEP has aggressively pioneered this new technology: the Fermilab single ring 1 TeV accelerator - 2 TeV collider is near the testing stage. Brookhaven National Laboratory's high luminosity pp 2 ring 800 GeV CBA collider is well into construction. Other types of superconducting projects are in the planning stage with much background R and D accomplished. The next generation of hadron colliders under discussion involves perhaps a 20 TeV ring (or rings) with 40 TeV CM energy. This is a very large machine: even if the highest practical field B approx. 10T is used, the radius is 10x that of the Fermilab accelerator. An extreme effort to get maximum GeV/$ may be crucial even for serious consideration of funding

  20. Laminated wood as an alternative to wood poles : Engineered wood structures for electric utility and telecommunications industries

    Energy Technology Data Exchange (ETDEWEB)

    Reisdorff, R. [Laminated Wood Systems Inc., Seward, NE (United States)

    2002-07-01

    In this PowerPoint presentation, the author discusses the major advantages of laminated structures, for both the electric and telecommunication industries. The advantages include economy, quick delivery, climbing and field modifications, dimensional uniformity and stability. A series of pictures was displayed which showed the manufacturing process. Laminated structures have a proven history. They were developed in Europe in 1890, and introduced to the United States in 1934. Framing members were introduced in the late 1940s, while poles were introduced in 1963, two years ahead of steel poles. Some of the electrical utility applications include: (1) distribution structures, (2) transmission structures such as single-pole, phase over phase switch structures, tangent structures, and H-Frame construction. The applications for the telecommunication industry consist of joint use structures, such as electric and telecommunication, lighting and telecommunication, overhead telephone and wireless; mono-pole applications; three-pole Bell Towers; and tree poles. Examples of each type were shown. figs.

  1. Superconducting current in a bisoliton superconductivity model

    International Nuclear Information System (INIS)

    Ermakov, V.N.; Kruchinin, S.P.; Ponezha, E.A.

    1991-01-01

    It is shown that the transition into a superconducting state with the current which is described by a bisoliton superconductivity model is accompanied by the deformation of the spectrum of one-particle states of the current carriers. The deformation value is proportional to the conducting current force. The residuaby resistance in such state is absent

  2. Holography with a Landau pole

    Energy Technology Data Exchange (ETDEWEB)

    Faedo, Antón F. [Departament de Física Quántica i Astrofísica and Institut de Ciències del Cosmos (ICC), Universitat de Barcelona, Martí i Franquès 1, ES-08028, Barcelona (Spain); Mateos, David [Departament de Física Quántica i Astrofísica and Institut de Ciències del Cosmos (ICC), Universitat de Barcelona, Martí i Franquès 1, ES-08028, Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, ES-08010, Barcelona (Spain); Pantelidou, Christiana [Departament de Física Quántica i Astrofísica and Institut de Ciències del Cosmos (ICC), Universitat de Barcelona, Martí i Franquès 1, ES-08028, Barcelona (Spain); Tarrío, Javier [Physique Théorique et Mathématique, Université Libre de Bruxelles (ULB), and International Solvay Institutes, Campus de la Plaine CP 231, B-1050, Brussels (Belgium)

    2017-02-08

    Holography for UV-incomplete gauge theories is important but poorly understood. A paradigmatic example is d=4, N=4 super Yang-Mills coupled to N{sub f} quark flavors, which possesses a Landau pole at a UV scale Λ{sub LP}. The dual gravity solution exhibits a UV singularity at a finite proper distance along the holographic direction. Despite this, holographic renormalization can be fully implemented via analytic continuation to an AdS solution. The presence of a UV cut-off manifests itself in several interesting ways. At energies E≪Λ{sub LP} no pathologies appear, as expected from effective field theory. In contrast, at scales E≲Λ{sub LP} the gravitational potential becomes repulsive, and at temperatures T≲Λ{sub LP} the specific heat becomes negative. Although we focus on N=4 super Yang-Mills with flavor, our qualitative results apply to a much more general class of theories, since they only depend on the fact that the metric near the UV singularity is a hyper-scaling violating metric with exponent θ>d−1.

  3. Holography with a Landau pole

    International Nuclear Information System (INIS)

    Faedo, Antón F.; Mateos, David; Pantelidou, Christiana; Tarrío, Javier

    2017-01-01

    Holography for UV-incomplete gauge theories is important but poorly understood. A paradigmatic example is d=4, N=4 super Yang-Mills coupled to N f quark flavors, which possesses a Landau pole at a UV scale Λ LP . The dual gravity solution exhibits a UV singularity at a finite proper distance along the holographic direction. Despite this, holographic renormalization can be fully implemented via analytic continuation to an AdS solution. The presence of a UV cut-off manifests itself in several interesting ways. At energies E≪Λ LP no pathologies appear, as expected from effective field theory. In contrast, at scales E≲Λ LP the gravitational potential becomes repulsive, and at temperatures T≲Λ LP the specific heat becomes negative. Although we focus on N=4 super Yang-Mills with flavor, our qualitative results apply to a much more general class of theories, since they only depend on the fact that the metric near the UV singularity is a hyper-scaling violating metric with exponent θ>d−1.

  4. Utility poles not affected by CCA decision

    Energy Technology Data Exchange (ETDEWEB)

    De Venzio, H. [Arch Wood Protection Canada, Mississauga, ON (Canada)

    2002-08-01

    A voluntary decision by industry to move non-industrial use of treated lumber products away from pressure-treated wood containing chromated copper arsenate (CCA) preservative was announced by the Environmental Protection Agency on February 12, 2002. Although new alternative wood preservatives would be used, this decision does not affect utility poles, which will continue to be sold and installed. The author provides a brief historical outline concerning the creation of CCA in 1933 and its subsequent uses. CCA has many advantages, including clean surface of the poles, ground line treatment that is not required thus eliminating the requirement to rotate the poles during extended storage periods. Conductivity is low, as is corrosivity without affecting the bending characteristics of the wood. The injection of a refined hydrocarbon oil emulsion in the outer layer of the pole after the treatment with CCA is offered by some pole producers to facilitate gaff penetration. Sawing, drilling and nailing are also made easier. Water repellents can be added to the treating solution to improve climbability, slowing down the absorption and release of moisture. Warranties, extending for 50-year periods, are offered by some companies against wood-destroying organisms. The North American Wood Pole Coalition (NAWPC) was formed in 1998 to promote the use of wood poles, and publishes brochures and technical bulletins to that effect.

  5. Geometric Modelling of Octagonal Lamp Poles

    Science.gov (United States)

    Chan, T. O.; Lichti, D. D.

    2014-06-01

    Lamp poles are one of the most abundant highway and community components in modern cities. Their supporting parts are primarily tapered octagonal cones specifically designed for wind resistance. The geometry and the positions of the lamp poles are important information for various applications. For example, they are important to monitoring deformation of aged lamp poles, maintaining an efficient highway GIS system, and also facilitating possible feature-based calibration of mobile LiDAR systems. In this paper, we present a novel geometric model for octagonal lamp poles. The model consists of seven parameters in which a rotation about the z-axis is included, and points are constrained by the trigonometric property of 2D octagons after applying the rotations. For the geometric fitting of the lamp pole point cloud captured by a terrestrial LiDAR, accurate initial parameter values are essential. They can be estimated by first fitting the points to a circular cone model and this is followed by some basic point cloud processing techniques. The model was verified by fitting both simulated and real data. The real data includes several lamp pole point clouds captured by: (1) Faro Focus 3D and (2) Velodyne HDL-32E. The fitting results using the proposed model are promising, and up to 2.9 mm improvement in fitting accuracy was realized for the real lamp pole point clouds compared to using the conventional circular cone model. The overall result suggests that the proposed model is appropriate and rigorous.

  6. Frequency dispersion of longitudinal ultrasonic velocity and attenuation in [001]c-poled 0.24Pb(In₁/₂Nb₁/₂O₃- 0.45Pb(Mg₁/₃Nb₂/₃)O₃-0.31PbTiO₃ single crystal.

    Science.gov (United States)

    Sun, Enwei; Cao, Wenwu; Han, Pengdi

    2011-08-01

    The frequency dispersion of ultrasonic velocity and attenuation in [001](c)-poled 0.24Pb(in(1/2)Nb(1/2))O(3)-0.45Pb(Mg(1/3)Nb(2/3))o(3)-0.31PbTio(3) (PIN-0.45PMN-0.31PT) ternary single crystal were measured by ultrasonic spectroscopy from 25 to 100 MHz for the longitudinal wave. It was found that the velocity has a linear relationship with the frequency f, but the attenuation has a quadratic relation with f. The attenuation and frequency dispersion of the ternary system are lower than that of the (1-x)Pb(Mg(1/3)Nb(2/3))O(3)-xPbTiO(3) (PMN-PT) binary system and the coercive field also increased by a factor of 2.5, hence, the ternary single system is superior to the corresponding binary single-crystal system for high-frequency and high-power transducer applications.

  7. Multigap superconductivity and strong electron-boson coupling in Fe-based superconductors: a point-contact Andreev-reflection study of Ba(Fe(1-x)Co(x))2As2 single crystals.

    Science.gov (United States)

    Tortello, M; Daghero, D; Ummarino, G A; Stepanov, V A; Jiang, J; Weiss, J D; Hellstrom, E E; Gonnelli, R S

    2010-12-03

    Directional point-contact Andreev-reflection measurements in Ba(Fe(1-x)Co(x))2As2 single crystals (T(c) = 24.5 K) indicate the presence of two superconducting gaps with no line nodes on the Fermi surface. The point-contact Andreev-reflection spectra also feature additional structures related to the electron-boson interaction, from which the characteristic boson energy Ω(b)(T) is obtained, very similar to the spin-resonance energy observed in neutron scattering experiments. Both the gaps and the additional structures can be reproduced within a three-band s ± Eliashberg model by using an electron-boson spectral function peaked at Ω(0) = 12 meV ≃ Ω(b)(0).

  8. Spectral investigation of hot-spot and cavity resonance effects on the terahertz radiation emitted from high-Tc superconducting Bi2Sr2CaCu2O8+δ single crystal mesa structures

    Science.gov (United States)

    Kadowaki, Kazuo; Watanabe, Chiharu; Minami, Hidetoshi; Yamamoto, Takashi; Kashiwagi, Takanari; Klemm, Richard

    2014-03-01

    Terahertz (THz) electromagnetic radiation emitted from high-Tc superconducting Bi2Sr2CaCu2O8+δ mesa structures in the case of single mesa and series-connected mesas is investigated by the FTIR spectroscopic technique while observing its temperature distribution simultaneously by a SiC photoluminescence technique. Changing the bias level, sudden jumps of the hot-spot position were clearly observed. Although the radiation intensity changes drastically associated with the jump of the hot spot position, the frequency is unaffected as long as the voltage per junction is kept constant. Since the frequency of the intense radiation satisfies the cavity resonance condition, we confirmed that the cavity resonance is of primarily importance for the synchronization of whole intrinsic Josephson junctions in the mesa for high power radiation. This work was supported in part by the Grant-in-Aid for challenging Exploratory Research, the Ministry of Education, Culture, Sports, Science & Technology (MEXT).

  9. A superconducting nanowire can be modeled by using SPICE

    Science.gov (United States)

    Berggren, Karl K.; Zhao, Qing-Yuan; Abebe, Nathnael; Chen, Minjie; Ravindran, Prasana; McCaughan, Adam; Bardin, Joseph C.

    2018-05-01

    Modeling of superconducting nanowire single-photon detectors typically requires custom simulations or finite-element analysis in one or two dimensions. Here, we demonstrate two simplified one-dimensional SPICE models of a superconducting nanowire that can quickly and efficiently describe the electrical characteristics of a superconducting nanowire. These models may be of particular use in understanding alternative architectures for nanowire detectors and readouts.

  10. Fabrication and characterization of aluminum airbridges for superconducting microwave circuits

    International Nuclear Information System (INIS)

    Chen, Zijun; Kelly, J.; Barends, R.; Bochmann, J.; Chen, Yu; Chiaro, B.; Dunsworth, A.; Jeffrey, E.; Mutus, J. Y.; O'Malley, P. J. J.; Neill, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Megrant, A.; Cleland, A. N.; Martinis, John M.

    2014-01-01

    Superconducting microwave circuits based on coplanar waveguides (CPW) are susceptible to parasitic slotline modes which can lead to loss and decoherence. We motivate the use of superconducting airbridges as a reliable method for preventing the propagation of these modes. We describe the fabrication of these airbridges on superconducting resonators, which we use to measure the loss due to placing airbridges over CPW lines. We find that the additional loss at single photon levels is small, and decreases at higher drive powers

  11. Enhanced superconductivity of fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Washington, II, Aaron L.; Teprovich, Joseph A.; Zidan, Ragaiy

    2017-06-20

    Methods for enhancing characteristics of superconductive fullerenes and devices incorporating the fullerenes are disclosed. Enhancements can include increase in the critical transition temperature at a constant magnetic field; the existence of a superconducting hysteresis over a changing magnetic field; a decrease in the stabilizing magnetic field required for the onset of superconductivity; and/or an increase in the stability of superconductivity over a large magnetic field. The enhancements can be brought about by transmitting electromagnetic radiation to the superconductive fullerene such that the electromagnetic radiation impinges on the fullerene with an energy that is greater than the band gap of the fullerene.

  12. Superconductivity in Medicine

    Science.gov (United States)

    Alonso, Jose R.; Antaya, Timothy A.

    2012-01-01

    Superconductivity is playing an increasingly important role in advanced medical technologies. Compact superconducting cyclotrons are emerging as powerful tools for external beam therapy with protons and carbon ions, and offer advantages of cost and size reduction in isotope production as well. Superconducting magnets in isocentric gantries reduce their size and weight to practical proportions. In diagnostic imaging, superconducting magnets have been crucial for the successful clinical implementation of magnetic resonance imaging. This article introduces each of those areas and describes the role which superconductivity is playing in them.

  13. The LHC superconducting cavities

    CERN Document Server

    Boussard, Daniel; Häbel, E; Kindermann, H P; Losito, R; Marque, S; Rödel, V; Stirbet, M

    1999-01-01

    The LHC RF system, which must handle high intensity (0.5 A d.c.) beams, makes use of superconducting single-cell cavities, best suited to minimizing the effects of periodic transient beam loading. There will be eight cavities per beam, each capable of delivering 2 MV (5 MV/m accelerating field) at 400 MHz. The cavities themselves are now being manufactured by industry, using niobium-on-copper technology which gives full satisfaction at LEP. A cavity unit includes a helium tank (4.5 K operating temperature) built around a cavity cell, RF and HOM couplers and a mechanical tuner, all housed in a modular cryostat. Four-unit modules are ultimately foreseen for the LHC (two per beam), while at present a prototype version with two complete units is being extensively tested. In addition to a detailed description of the cavity and its ancillary equipment, the first test results of the prototype will be reported.

  14. Cold Hole Over Jupiter's Pole

    Science.gov (United States)

    2002-01-01

    Observations with two NASA telescopes show that Jupiter has an arctic polar vortex similar to a vortex over Earth's Antarctica that enables depletion of Earth's stratospheric ozone.These composite images of Jupiter's north polar region from the Hubble Space Telescope (right) and the Infrared Telescope Facility (left) show a quasi-hexagonal shape that extends vertically from the stratosphere down into the top of the troposphere. A sharp temperature drop, compared to surrounding air masses, creates an eastward wind that tends to keep the polar atmosphere, including the stratospheric haze, isolated from the rest of the atmosphere.The linear striations in the composite projections are artifacts of the image processing. The area closest to the pole has been omitted because it was too close to the edge of the planet in the original images to represent the planet reliably.The composite on the right combines images from the Wide Field and Planetary Camera 2 of the Hubble Space Telescope taken at a wavelength of 890 nanometers, which shows stratospheric haze particles.The sharp boundary and wave-like structure of the haze layer suggest a polar vortex and a similarity to Earth's stratospheric polar clouds. Images of Jupiter's thermal radiation clinch that identification. The composite on the left, for example, is made from images taken with Jet Propulsion Laboratory's Mid-Infrared Large-Well Imager at NASA's Infrared Telescope Facility at a wavelength of 17 microns. It shows polar air mass that is 5 to 6 degrees Celsius (9 to 10 degrees Fahrenheit) colder than its surroundings, with the same border as the stratospheric haze. Similar observations at other infrared wavelengths show the cold air mass extends at least as high as the middle stratosphere down to the top of the troposphere.These images were taken Aug. 11 through Aug. 13, 1999, near a time when Jupiter's north pole was most visible from Earth. Other Infrared Telescope Facility images at frequencies sensitive to the

  15. Superconductivity in transition metals.

    Science.gov (United States)

    Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P

    2015-03-13

    A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  16. VT Green Mountain Power Pole Data

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) Green Mountain Power (GMP) pole and OVERHEAD linear distribution/sub-transmission model data. THE LINEAR DISTRIBUTION LAYER ONLY INCLUDES OVERHEAD...

  17. The pole tide in deep oceans

    Science.gov (United States)

    Dickman, S. R.

    1990-01-01

    The fluid-dynamical theory of the pole tide is examined by describing the oceanic response to the Chandler wobble and assessing its implications for mantle anelasticity and low-frequency ocean dynamics. The Laplace tide equations accounting for bottom friction are given, and a spherical harmonic approach is delineated in which the time-independent portion of the tide height is expanded. Pole-tide height and related inertia products are linearly proportional to wobble amplitude, and the final equations are modified to account for mantle elasticity and oceanic loading. Results for pole tide effects are given for various earth models with attention to the role of boundary constraints. A dynamic effect is identified which lengthens the Chandler period by about 1 day more than static lengthening, a contribution that suggests a vigorous low-frequency response. The values derived are shown to agree with previous models that do not incorporate the effects of the pole tide.

  18. Synthetic focused array of electrical prospecting using pole-pole array potential data; Sanjigen denki tansaho ni okeru nikyokuho den`i data wo mochiita denryu shusoku haichi no goseiho

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, K [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1997-10-22

    Various methods have been put into practice for the conventional two-dimensional pole configuration using a single line in three-dimensional electrical prospecting. Pole configuration effective for the three-dimensional exploration has not been investigated. This paper describes synthetic focused array using four pairs of guarded poles based on pole-pole array potential data in the case of arrangement of measuring points on a grid. Results of the numerical simulation are also described. For the focused array, laterolog of electrical logging is applied to the surface prospecting. Directivity can be given to the current from the main pole by controlling the current from guarded pole. It was found from the simulation that the resistivity anomaly is concentrated directly on the embedded ball for the focused array rather than for the pole-pole array. It was also found that two conductive balls can be clearly separated for the focused array rather than for the dipole-dipole array. Accordingly, it was considered that results approximating the original structures can be obtained by analyzing using the both arrays. 5 refs., 6 figs.

  19. On pole structure assignment in linear systems

    Czech Academy of Sciences Publication Activity Database

    Loiseau, J.-J.; Zagalak, Petr

    2009-01-01

    Roč. 82, č. 7 (2009), s. 1179-1192 ISSN 0020-7179 R&D Projects: GA ČR(CZ) GA102/07/1596 Institutional research plan: CEZ:AV0Z10750506 Keywords : linear systems * linear state feedback * pole structure assignment Subject RIV: BC - Control Systems Theory Impact factor: 1.124, year: 2009 http://library.utia.cas.cz/separaty/2009/AS/zagalak-on pole structure assignment in linear systems.pdf

  20. Nonlinear performance characterization in an eight-pole quasi-elliptic bandpass filter

    International Nuclear Information System (INIS)

    Mateu, J; Collado, C; Menendez, O; O'Callaghan, J M

    2004-01-01

    In this work we predict the nonlinear behaviour of an eight-pole quasi-elliptic bandpass high temperature superconducting (HTS) filter with an equivalent circuit extracted from intermodulation measurements performed at the centre of the filter passband. We present measurements that show that the equivalent circuit is able to predict the intermodulation products produced by the filter when driven by two in-band or out-of-band sinusoidal signals. Numerical techniques based on harmonic balance are used to extract the elements of the equivalent circuit and to simulate its nonlinear performance

  1. RHEED transmission mode and pole figures thin film and nanostructure texture analysis

    CERN Document Server

    Wang, Gwo-Ching

    2014-01-01

    This unique book covers the fundamental principle of electron diffraction, basic instrumentation of RHEED, definitions of textures in thin films and nanostructures, mechanisms and control of texture formation, and examples of RHEED transmission mode measurements of texture and texture evolution of thin films and nanostructures. Also presented is a new application of RHEED in the transmission mode called RHEED pole figure technique that can be used to monitor the texture evolution in thin film growth and nanostructures and is not limited to single crystal epitaxial film growth. Details of the construction of RHEED pole figures and the interpretation of observed pole figures are presented.  Materials covered include metals, semiconductors, and thin insulators. This book also: Presents a new application of RHEED in the transmission mode Introduces a variety of textures from metals, semiconductors, compound semiconductors, and their characteristics in RHEED pole figures Provides examples of RHEED measurements o...

  2. Design study of 10 kW superconducting generator for wind turbine applications

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Mijatovic, Nenad; Seiler, Eugen

    2009-01-01

    = 1 Tesla to be similar to the performance of permanent magnets and to represent a layout, which can be scaled up in future off-shore wind turbines. The proposed generator is a 8 pole synchronous machine based on race-track coils of high temperature superconducting tapes and an air cored copper stator...

  3. Status of the Chalk River superconducting heavy-ion cyclotron

    International Nuclear Information System (INIS)

    Ormrod, J.H.; Bigham, C.B.; Heighway, E.A.; Hoffmann, C.R.; Hulbert, J.A.; Schneider, H.R.

    1982-01-01

    The Chalk River four-sector K=520 superconducting cyclotron is designed to accelerate all ions from lithium (to 50 MeV/u) to uranium (to 10 MeV/u) using a 13 MV tandem Van de Graaff as injector. After an extended shutdown the magnet has been reassembled and field measurements resumed. During the shutdown a ground fault between the superconducting coil and its container was removed, the flutter poles were shimmed and the remaining trim rod holes were bored in them, the 104 trim rods with their holders were installed and the cryostat inner wall was modified to accept the radiofrequency accelerating structure. Experiments on the radiofrequency accelerating system, cryopumps, electrostatic deflector and superconducting windings for the magnetic channel are done in separate test chambers. Recent results and the status of all subsystems are given

  4. Investigation of superconducting properties of nanowires prepared by template synthesis

    DEFF Research Database (Denmark)

    Michotte, S.; Mátéfi-Tempfli, Stefan; Piraux, L.

    2003-01-01

    of the nanowires is small enough to ensure a one-dimensional superconducting regime in a wide temperature range below T. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied......We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have a uniform diameter of ∼40 nm and a very large aspect ratio (∼500). The diameter...

  5. Permanent magnet design for high-speed superconducting bearings

    Science.gov (United States)

    Hull, John R.; Uherka, Kenneth L.; Abdoud, Robert G.

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

  6. Permanent magnet design for high-speed superconducting bearings

    International Nuclear Information System (INIS)

    Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing. 9 figs

  7. Clusters of cyclones encircling Jupiter’s poles

    Science.gov (United States)

    Adriani, A.; Mura, A.; Orton, G.; Hansen, C.; Altieri, F.; Moriconi, M. L.; Rogers, J.; Eichstädt, G.; Momary, T.; Ingersoll, A. P.; Filacchione, G.; Sindoni, G.; Tabataba-Vakili, F.; Dinelli, B. M.; Fabiano, F.; Bolton, S. J.; Connerney, J. E. P.; Atreya, S. K.; Lunine, J. I.; Tosi, F.; Migliorini, A.; Grassi, D.; Piccioni, G.; Noschese, R.; Cicchetti, A.; Plainaki, C.; Olivieri, A.; O’Neill, M. E.; Turrini, D.; Stefani, S.; Sordini, R.; Amoroso, M.

    2018-03-01

    The familiar axisymmetric zones and belts that characterize Jupiter’s weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes. Two-dimensional turbulence in combination with the Coriolis β-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows. The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur. Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles. Jovian polar regions are not visible from Earth owing to Jupiter’s low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter’s equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis β-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn’s polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.

  8. Correlation effects in superconducting quantum dot systems

    Science.gov (United States)

    Pokorný, Vladislav; Žonda, Martin

    2018-05-01

    We study the effect of electron correlations on a system consisting of a single-level quantum dot with local Coulomb interaction attached to two superconducting leads. We use the single-impurity Anderson model with BCS superconducting baths to study the interplay between the proximity induced electron pairing and the local Coulomb interaction. We show how to solve the model using the continuous-time hybridization-expansion quantum Monte Carlo method. The results obtained for experimentally relevant parameters are compared with results of self-consistent second order perturbation theory as well as with the numerical renormalization group method.

  9. Nano-fabricated superconducting radio-frequency composites, method for producing nano-fabricated superconducting rf composites

    Science.gov (United States)

    Norem, James H.; Pellin, Michael J.

    2013-06-11

    Superconducting rf is limited by a wide range of failure mechanisms inherent in the typical manufacture methods. This invention provides a method for fabricating superconducting rf structures comprising coating the structures with single atomic-layer thick films of alternating chemical composition. Also provided is a cavity defining the invented laminate structure.

  10. The potential of wood-based composite poles

    Science.gov (United States)

    Todd F. Shupe; Cheng Piao; Chung Y. Hse

    2009-01-01

    Wood-based composite utility poles are receiving increasing attention in the North American pole market. This interest is being driven by many increasing factors such as increasing: (1) disposal costs of solid wood poles, (2) liability and environmental concerns with traditional means of disposal of solid wood poles, (3) cost and concerns of long-term...

  11. Laser activated superconducting switch

    International Nuclear Information System (INIS)

    Wolf, A.A.

    1976-01-01

    A superconducting switch or bistable device is described consisting of 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

  12. Modeling of the free space and focused magnetic field profiles of the ORNL superconducting motor

    International Nuclear Information System (INIS)

    Bailey, J.M.; Rader, M.; Sohns, C.W.; McKeever, J.; Schwenterly, S.W.

    1992-01-01

    The ORNL superconducting motor, is a device consisting of 4 DC superconducting magnets in a square cross section. These coils are arranged in a N-S-N-S configuration and at present have no iron flux return paths. Experimentally the device has been operated and has been shown to produce 102.3 kg-m of locked rotor torque at 100 Ampers winding current. The superconductors were operating at 40 Kelvin. The peak magnetic field at 2,100 amperes operating current was 2 Tesla on the cryostat face. Recently there has been an effort under way to improve the operating parameters of the device by improving the flux utilization of the device. This was to be accomplished by the use of flux focusing pole pieces. The effects of the pole pieces and the vacuum magnetic field have been modeled with the MSC EMAS code to see the possible benefit of adding pole pieces to the in situ experiment

  13. Effect of the wire width and magnetic field on the detection efficiency of superconducting nanowire single-photon detectors; Einfluss von Geometrie und magnetischem Feld auf die Effizienz supraleitender Nanodraht-Einzelphotonendetektoren

    Energy Technology Data Exchange (ETDEWEB)

    Lusche, Robert

    2015-06-24

    The aim of this thesis is to a gain deeper understanding of the single photon detection process in superconducting nanowire single-photon detectors (SNSPDs). A detailed knowledge of the physical principles and mechanisms which the detection process is based on helps to improve specific detector parameters and hence the suitability of such detectors for various applications. Several theoretical models of the detection process have been compared to the results of measurements of photon and dark count rates in meander-type TaN- and NbN-SNSPDs with different wire-widths in a broad range of wavelengths, transport currents and magnetic fields. In the first part of the thesis, measurements of the photon and dark count rates of TaN- and NbN-SNSPDs with varying wire width are described. For each meander spectra of the intrinsic detection efficiency (IDE) were derived. The IDE represents the probability that the SNSPD generates a measurable voltage pulse upon absorption of a photon. The recorded IDE spectra have shown a characteristic cut-off wavelength up to which photons were detected with a probability of 100 per cent. Furthermore it was found that the cut-off wavelengths increases linearly with the increase in the inverse wire width. This observation is best explained by the refined hot spot model. The second part of the thesis describes the influence of magnetic field on the photon and dark count rates of NbN-SNSPDs. In order to apply magnetic fields to the meanders a continuous-flow inset for mobile 4He storage dewars was constructed. It was shown for the first time, that the photon count rate exhibits a magnetic field dependence. Furthermore it could be shown that the measured dependence of the photon and dark count rate on the magnetic field is in good agreement with the theoretical model of vortex-assisted photon detection in narrow superconducting lines. Hence, within this thesis it could be confirmed that magnetic vortices are involved in the single photon

  14. Frontiers in Superconducting Materials

    CERN Document Server

    Narlikar, Anant V

    2005-01-01

    Frontiers in Superconducting Materials gives a state-of-the-art report of the most important topics of the current research in superconductive materials and related phenomena. It comprises 30 chapters written by renowned international experts in the field. It is of central interest to researchers and specialists in Physics and Materials Science, both in academic and industrial research, as well as advanced students. It also addresses electronic and electrical engineers. Even non-specialists interested in superconductivity might find some useful answers.

  15. Superconductivity and their applications

    OpenAIRE

    Roque, António; Sousa, Duarte M.; Fernão Pires, Vítor; Margato, Elmano

    2017-01-01

    Trabalho apresentado em International Conference on Renewable Energies and Power Quality (ICREPQ’17), 4 a 6 de Abril de 2017, Málaga, Espanha The research in the field of superconductivity has led to the synthesis of superconducting materials with features that allow you to expand the applicability of this kind of materials. Among the superconducting materials characteristics, the critical temperature of the superconductor is framing the range and type of industrial applications that can b...

  16. Superconducting machines. Chapter 4

    International Nuclear Information System (INIS)

    Appleton, A.D.

    1977-01-01

    A brief account is given of the principles of superconductivity and superconductors. The properties of Nb-Ti superconductors and the method of flux stabilization are described. The basic features of superconducting d.c. machines are illustrated by the use of these machines for ship propulsion, steel-mill drives, industrial drives, aluminium production, and other d.c. power supplies. Superconducting a.c. generators and their design parameters are discussed. (U.K.)

  17. Superconductivity in the actinides

    International Nuclear Information System (INIS)

    Smith, J.L.; Lawson, A.C.

    1985-01-01

    The trends in the occurrence of superconductivity in actinide materials are discussed. Most of them seem to show simple transition metal behavior. However, the superconductivity of americium proves that the f electrons are localized in that element and that ''actinides'' is the correct name for this row of elements. Recently the superconductivity of UBe 13 and UPt 3 has been shown to be extremely unusual, and these compounds fall in the new class of compounds now known as heavy fermion materials

  18. WORKSHOP: Radiofrequency superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1984-10-15

    The Second Workshop on Radiofrequency Superconductivity was held at CERN from 23-27 July, four years after the first, organized at Karlsruhe. 35 invited talks were presented to the about 80 participants from Australia, Brazil, Europe, Japan and the United States. For the first time, ten Laboratories operating or planning superconducting accelerators for heavy ions participated and shared their experience with the community proposing the use of superconducting accelerating sections for electron accelerators.

  19. WORKSHOP: Radiofrequency superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1984-01-01

    The Second Workshop on Radiofrequency Superconductivity was held at CERN from 23-27 July, four years after the first, organized at Karlsruhe. 35 invited talks were presented to the about 80 participants from Australia, Brazil, Europe, Japan and the United States. For the first time, ten Laboratories operating or planning superconducting accelerators for heavy ions participated and shared their experience with the community proposing the use of superconducting accelerating sections for electron accelerators

  20. Superconductivity in power engineering

    International Nuclear Information System (INIS)

    1989-01-01

    This proceedings volume presents 24 conference papers and 15 posters dealing with the following aspects: 1) Principles and elementary aspects of high-temperature superconductivity (3 plenary lectures); 2) Preparation, properties and materials requirements of metallic or oxide superconductors (critical current behaviour, soldered joints, structural studies); 3) Magnet technology (large magnets for thermonuclear fusion devices; magnets for particle accelerators and medical devices); 4) Magnetic levitation and superconductivity; 5) Cryogenics; 6) Energy storage systems using superconducting coils (SMES); 7) Superconducting power transmission cables, switches, transformers, and generator systems for power plant; 8) Supporting activities, industrial aspects, patents. There are thirty-eight records in the ENERGY database relating to individual conference papers. (MM) [de

  1. Superconductivity and its application

    International Nuclear Information System (INIS)

    Spadoni, M.

    1988-01-01

    This paper, after a short introduction to superconductivity and to multifilamentary superconducting composites is aiming to review the state of the art and the future perspective of some of the applications of the superconducting materials. The main interest is focussed to large scale applications like, for istance, magnets for accelerators or fusion reactors, superconducting system for NMR thomography, etc. A short paragraph is dedicated to applications for high sensitivity instrumentation. The paper is then concluded by some considerations about the potentialities of the newly discovered high critical temperature materials

  2. Superconducting quantum electronics

    International Nuclear Information System (INIS)

    Kose, V.

    1989-01-01

    This book reviews recent accomplishments, presents new results and discusses possible future developments of superconducting quantum electronics and high T c superconductivity. The three main parts of the book deal with fundamentals, sensitive detectors, and precision metrology. New results reported include: correct equivalent circuits modelling superconducting electronic devices; exact solution of the Mattis-Bardeen equations describing various experiments for thin films; complete theoretical description and experimental results for a new broad band spectrum analyzer; a new Josephson junction potentiometer allowing tracing of unknown voltage ratios back to well-known frequency ratios; and fast superconducting SQUID shift registers enabling the production of calculable noise power spectra in the microwave region

  3. Superconducting linear accelerator cryostat

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Elkonin, B.V.; Sokolowski, J.S.

    1984-01-01

    A large vertical cryostat for a superconducting linear accelerator using quarter wave resonators has been developed. The essential technical details, operational experience and performance are described. (author)

  4. Basic Study of Superconductive Actuator

    OpenAIRE

    涌井, 和也; 荻原, 宏康

    2000-01-01

    There are two kinds of electromagnetic propulsion ships : a superconductive electromagnetic propulsion ship and a superconductive electricity propulsion ship. A superconductive electromagnetic propulsion ship uses the electromagnetic force (Lorenz force) by the interaction between a magnetic field and a electric current. On the other hand, a superconductive electricity propulsion ship uses screws driven by a superconductive motor. A superconductive propulsion ship technique has the merits of ...

  5. Pole shifting with constrained output feedback

    International Nuclear Information System (INIS)

    Hamel, D.; Mensah, S.; Boisvert, J.

    1984-03-01

    The concept of pole placement plays an important role in linear, multi-variable, control theory. It has received much attention since its introduction, and several pole shifting algorithms are now available. This work presents a new method which allows practical and engineering constraints such as gain limitation and controller structure to be introduced right into the pole shifting design strategy. This is achieved by formulating the pole placement problem as a constrained optimization problem. Explicit constraints (controller structure and gain limits) are defined to identify an admissible region for the feedback gain matrix. The desired pole configuration is translated into an appropriate cost function which must be closed-loop minimized. The resulting constrained optimization problem can thus be solved with optimization algorithms. The method has been implemented as an algorithmic interactive module in a computer-aided control system design package, MVPACK. The application of the method is illustrated to design controllers for an aircraft and an evaporator. The results illustrate the importance of controller structure on overall performance of a control system

  6. POLE somatic mutations in advanced colorectal cancer.

    Science.gov (United States)

    Guerra, Joana; Pinto, Carla; Pinto, Diana; Pinheiro, Manuela; Silva, Romina; Peixoto, Ana; Rocha, Patrícia; Veiga, Isabel; Santos, Catarina; Santos, Rui; Cabreira, Verónica; Lopes, Paula; Henrique, Rui; Teixeira, Manuel R

    2017-12-01

    Despite all the knowledge already gathered, the picture of somatic genetic changes in colorectal tumorigenesis is far from complete. Recently, germline and somatic mutations in the exonuclease domain of polymerase epsilon, catalytic subunit (POLE) gene have been reported in a small subset of microsatellite-stable and hypermutated colorectal carcinomas (CRCs), affecting the proofreading activity of the enzyme and leading to misincorporation of bases during DNA replication. To evaluate the role of POLE mutations in colorectal carcinogenesis, namely in advanced CRC, we searched for somatic mutations by Sanger sequencing in tumor DNA samples from 307 cases. Microsatellite instability and mutation analyses of a panel of oncogenes were performed in the tumors harboring POLE mutations. Three heterozygous mutations were found in two tumors, the c.857C>G, p.Pro286Arg, the c.901G>A, p.Asp301Asn, and the c.1376C>T, p.Ser459Phe. Of the POLE-mutated CRCs, one tumor was microsatellite-stable and the other had low microsatellite instability, whereas KRAS and PIK3CA mutations were found in one tumor each. We conclude that POLE somatic mutations exist but are rare in advanced CRC, with further larger studies being necessary to evaluate its biological and clinical implications. © 2017 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

  7. Influence of the absorptive part of the complex potential on the S-Matrix poles

    International Nuclear Information System (INIS)

    Grama, C.; Grama, N.; Zamfirescu, I

    2001-01-01

    Although the polology of the S-matrix has been extensively studied, it occurred that some aspects remained disputable in the case of complex central potential V(r)=gV(r), g in C . These aspects are related to the origin of the observed narrow Σ-hypernuclear states that have been interpreted by Gal, Toker and Alexander as states which correspond to S-matrix poles situated in the second k-plane quadrant. From the analytical properties of the S-matrix for a real potential it results that there is no pole in the first and second k-plane quadrants, except for the imaginary k-axis. By switching on the absorption the S-matrix poles for real potential can evolve into the second quadrant of the k-plane. A critical study of the Σ-hypernuclear states needs the analysis of the motion of the S-matrix poles in the k-plane for variable complex coupling strength g. Recently contradictory opinions relative to the S-matrix poles trajectories in the complex k-plane for a complex square potential occurred. According to some authors the poles in the second quadrant can occur either from bound state poles moving anticlockwise, or from virtual state poles and capture resonant state poles moving clockwise as the absorption is switched on. Dabrowski argues that the statement made by Gal et al, Bonetti et al and Oset et al concerning the movement of the virtual poles with increasing absorptive potential is in general not correct. Dabrowski relates the direction in which the pole moves when the potential absorption increases to the direction in which the pole moves with increasing the real part of the potential, without clarifying this last question. For example, two poles moving in opposite directions along the imaginary k-axis are associated by Dabrowski to the same state. This is a wrong result, because one should associate a single pole to each quantum state. The aim of our work is to study the influence of the absorptive part of the potential on the S-matrix poles for the non

  8. Endoscopic extradural supraorbital approach to the temporal pole and adjacent area: technical note.

    Science.gov (United States)

    Komatsu, Fuminari; Imai, Masaaki; Shigematsu, Hideaki; Aoki, Rie; Oda, Shinri; Shimoda, Masami; Matsumae, Mitsunori

    2017-08-25

    The authors' initial experience with the endoscopic extradural supraorbital approach to the temporal pole and adjacent area is reported. Fully endoscopic surgery using the extradural space via a supraorbital keyhole was performed for tumors in or around the temporal pole, including temporal pole cavernous angioma, sphenoid ridge meningioma, and cavernous sinus pituitary adenoma, mainly using 4-mm, 0° and 30° endoscopes and single-shaft instruments. After making a supraorbital keyhole, a 4-mm, 30° endoscope was advanced into the extradural space of the anterior cranial fossa during lifting of the dura mater. Following identification of the sphenoid ridge, orbital roof, and anterior clinoid process, the bone lateral to the orbital roof was drilled off until the dura mater of the anterior aspect of the temporal lobe was exposed. The dura mater of the temporal lobe was incised and opened, exposing the temporal pole under a 4-mm, 0° endoscope. Tumors in or around the temporal pole were safely removed under a superb view through the extradural corridor. The endoscopic extradural supraorbital approach was technically feasible and safe. The anterior trajectory to the temporal pole using the extradural space under endoscopy provided excellent visibility, allowing minimally invasive surgery. Further surgical experience and development of specialized instruments would promote this approach as an alternative surgical option.

  9. Superconducting Coil of Po Dipole

    CERN Multimedia

    1983-01-01

    The Po superconducting dipole was built as a prototype beam transport magnet for the SPS extracted proton beam P0. Its main features were: coil aperture 72 mm, length 5 m, room-temperature yoke, NbTi cable conductor impregnated with solder, nominal field 4.2 T at 4.7 K (87% of critical field). It reached its nominal field without any quench.After this successful test up to its nominal field of 4.2 T, the power was not raised to reach a quench. The magnet was not installed in a beam and had no other further use. Nevertheless its construction provided knowledges and experience which became useful in the design and construction of the LHC magnets. The photo shows a detail of the inner layer winding before superposing the outer layer to form the complete coil of a pole. Worth noticing is the interleaved glass-epoxy sheet (white) with grooved channels for the flow of cooling helium. See also 8211532X.

  10. PolyPole-1: An accurate numerical algorithm for intra-granular fission gas release

    International Nuclear Information System (INIS)

    Pizzocri, D.; Rabiti, C.; Luzzi, L.; Barani, T.; Van Uffelen, P.; Pastore, G.

    2016-01-01

    The transport of fission gas from within the fuel grains to the grain boundaries (intra-granular fission gas release) is a fundamental controlling mechanism of fission gas release and gaseous swelling in nuclear fuel. Hence, accurate numerical solution of the corresponding mathematical problem needs to be included in fission gas behaviour models used in fuel performance codes. Under the assumption of equilibrium between trapping and resolution, the process can be described mathematically by a single diffusion equation for the gas atom concentration in a grain. In this paper, we propose a new numerical algorithm (PolyPole-1) to efficiently solve the fission gas diffusion equation in time-varying conditions. The PolyPole-1 algorithm is based on the analytic modal solution of the diffusion equation for constant conditions, combined with polynomial corrective terms that embody the information on the deviation from constant conditions. The new algorithm is verified by comparing the results to a finite difference solution over a large number of randomly generated operation histories. Furthermore, comparison to state-of-the-art algorithms used in fuel performance codes demonstrates that the accuracy of PolyPole-1 is superior to other algorithms, with similar computational effort. Finally, the concept of PolyPole-1 may be extended to the solution of the general problem of intra-granular fission gas diffusion during non-equilibrium trapping and resolution, which will be the subject of future work. - Highlights: • A new numerical algorithm (PolyPole-1) for intra-granular fission gas release in time-varying conditions is developed. • The concept combines the modal analytic solution for constant conditions and a polynomial correction. • PolyPole-1 is extensively verified and compared to other state-of-the-art algorithms. • PolyPole-1 exhibits a superior accuracy and a similar computational time relative to other algorithms. • The PolyPole-1 algorithm can be

  11. PolyPole-1: An accurate numerical algorithm for intra-granular fission gas release

    Energy Technology Data Exchange (ETDEWEB)

    Pizzocri, D. [Politecnico di Milano, Department of Energy, Nuclear Engineering Division, Via La Masa 34, 20156 Milano (Italy); Rabiti, C. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-3840 (United States); Luzzi, L.; Barani, T. [Politecnico di Milano, Department of Energy, Nuclear Engineering Division, Via La Masa 34, 20156 Milano (Italy); Van Uffelen, P. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Pastore, G., E-mail: giovanni.pastore@inl.gov [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-3840 (United States)

    2016-09-15

    The transport of fission gas from within the fuel grains to the grain boundaries (intra-granular fission gas release) is a fundamental controlling mechanism of fission gas release and gaseous swelling in nuclear fuel. Hence, accurate numerical solution of the corresponding mathematical problem needs to be included in fission gas behaviour models used in fuel performance codes. Under the assumption of equilibrium between trapping and resolution, the process can be described mathematically by a single diffusion equation for the gas atom concentration in a grain. In this paper, we propose a new numerical algorithm (PolyPole-1) to efficiently solve the fission gas diffusion equation in time-varying conditions. The PolyPole-1 algorithm is based on the analytic modal solution of the diffusion equation for constant conditions, combined with polynomial corrective terms that embody the information on the deviation from constant conditions. The new algorithm is verified by comparing the results to a finite difference solution over a large number of randomly generated operation histories. Furthermore, comparison to state-of-the-art algorithms used in fuel performance codes demonstrates that the accuracy of PolyPole-1 is superior to other algorithms, with similar computational effort. Finally, the concept of PolyPole-1 may be extended to the solution of the general problem of intra-granular fission gas diffusion during non-equilibrium trapping and resolution, which will be the subject of future work. - Highlights: • A new numerical algorithm (PolyPole-1) for intra-granular fission gas release in time-varying conditions is developed. • The concept combines the modal analytic solution for constant conditions and a polynomial correction. • PolyPole-1 is extensively verified and compared to other state-of-the-art algorithms. • PolyPole-1 exhibits a superior accuracy and a similar computational time relative to other algorithms. • The PolyPole-1 algorithm can be

  12. Pole lengths influence O2-cost during double poling in highly trained cross-country skiers.

    Science.gov (United States)

    Carlsen, Camilla Høivik; Rud, Bjarne; Myklebust, Håvard; Losnegard, Thomas

    2018-02-01

    In elite cross-country skiing, double poling is used in different terrain. This study compared O 2 -cost and kinematics during double poling with four different pole lengths [self-selected (SS), SS - 5 cm, SS + 5 cm, SS + 10 cm] at Low versus Moderate incline. Thirteen highly trained male cross-country skiers (mean ± SD 23 ± 3 years; 182 ± 4 cm; 77 ± 6 kg) completed eight submaximal trials with roller skis on a treadmill at two conditions: "Low incline" (1.7°; 4.5 m s -1 ) and "Moderate incline" (4.5°; 2.5 m s -1 ) with each of the four pole lengths. O 2 -cost and 3D body kinematics were assessed in each trial. In Low incline, SS + 10 cm induced a lower O 2 -cost than all the other pole lengths [P size (ES) 0.5-0.8], whereas no differences were found between the remaining pole lengths (P > 0.05; ES 0.2-0.4). In Moderate incline, significant differences between all pole lengths were found for O 2 -cost, with SS - 5 cm > SS > SS + 5 cm > SS + 10 cm (P differences in O 2 -cost between SS and the other pole lengths were greater in Moderate incline than Low incline (SS - 5 cm; 1.5%, ES 0.8, SS + 5 cm; 1.3%, ES 1.0, and SS + 10 cm; 1.9%, ES 1.0, all P difference was found in cycle, poling or reposition times between pole lengths. However, at both conditions a smaller total vertical displacement of center of mass was observed with SS + 10 cm compared to the other pole lengths. Increasing pole length from SS - 5 cm to SS + 10 cm during double poling induced lower O 2 -cost and this advantage was greater in Moderate compared to Low incline.

  13. Pole solutions for flame front propagation

    CERN Document Server

    Kupervasser, Oleg

    2015-01-01

    This book deals with solving mathematically the unsteady flame propagation equations. New original mathematical methods for solving complex non-linear equations and investigating their properties are presented. Pole solutions for flame front propagation are developed. Premixed flames and filtration combustion have remarkable properties: the complex nonlinear integro-differential equations for these problems have exact analytical solutions described by the motion of poles in a complex plane. Instead of complex equations, a finite set of ordinary differential equations is applied. These solutions help to investigate analytically and numerically properties of the flame front propagation equations.

  14. PNRA. South-pole directory listing

    OpenAIRE

    Biagioni, Stefania; Carlesi, Carlo; Carpen?, Andrea; Ramorino, Chiara; Rossi, Lucio

    1992-01-01

    In the following all DATA-SET descriptors (DSD) contained in the "South-Pole Directory" (vers. 1992) are listed. The "South-Pole Directory" was a joint project between ENEA and CNR. The IEI/CNR took care of the data digitalization and check and of the english translation (where necessary). The ARF/CNR and the Progetto Antartide/ENEA joined the IEI/CNR in defining the acronyms of the Sensor_Names and of the Source_Names, together with the short and long names for the Data_Centers. Finally, the...

  15. Ballistic superconductivity in semiconductor nanowires

    Science.gov (United States)

    Zhang, Hao; Gül, Önder; Conesa-Boj, Sonia; Nowak, Michał P.; Wimmer, Michael; Zuo, Kun; Mourik, Vincent; de Vries, Folkert K.; van Veen, Jasper; de Moor, Michiel W. A.; Bommer, Jouri D. S.; van Woerkom, David J.; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P.A.M.; Quintero-Pérez, Marina; Cassidy, Maja C.; Koelling, Sebastian; Goswami, Srijit; Watanabe, Kenji; Taniguchi, Takashi; Kouwenhoven, Leo P.

    2017-01-01

    Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of superconductors with the possibility to control charges down to a single electron. These advances brought semiconductor nanowires to the forefront of efforts to realize topological superconductivity and Majorana modes. A prime challenge to benefit from the topological properties of Majoranas is to reduce the disorder in hybrid nanowire devices. Here we show ballistic superconductivity in InSb semiconductor nanowires. Our structural and chemical analyses demonstrate a high-quality interface between the nanowire and a NbTiN superconductor that enables ballistic transport. This is manifested by a quantized conductance for normal carriers, a strongly enhanced conductance for Andreev-reflecting carriers, and an induced hard gap with a significantly reduced density of states. These results pave the way for disorder-free Majorana devices. PMID:28681843

  16. Radiation effects on superconductivity

    International Nuclear Information System (INIS)

    Brown, B.S.

    1975-01-01

    The effect of radiation on the superconducting transition temperature (T/sub c/), upper critical field (H/sub c2/), and volume-pinning-force density (F/sub p/) were discussed for the three kinds of superconducting material (elements, alloys, and compounds). 11 figures, 3 tables, 86 references

  17. Superconducting elliptical cavities

    CERN Document Server

    Sekutowicz, J K

    2011-01-01

    We give a brief overview of the history, state of the art, and future for elliptical superconducting cavities. Principles of the cell shape optimization, criteria for multi-cell structures design, HOM damping schemes and other features are discussed along with examples of superconducting structures for various applications.

  18. Superconductivity in technology

    International Nuclear Information System (INIS)

    Komarek, P.

    1976-01-01

    Physics, especially high energy physics and solid state physics was the first area in which superconducting magnets were used but in the long run, the most extensive application of superconductivity will probably be in energy technology. Superconducting power transmission cables, magnets for energy conversion in superconducting electrical machines, MHD-generators and fusion reactors and magnets for energy storage are being investigated. Magnets for fusion reactors will have particularly large physical dimensions, which means that much development effort is still needed, for there is no economic alternative. Superconducting surfaces in radio frequency cavities can give Q-values up to a factor of 10 6 higher than those of conventional resonators. Particle accelerators are the important application. And for telecommunication, simple coaxial superconducting radio frequency cables seem promising. The tunnel effect in superconducting junctions is now being developed commercially for sensitive magnetometers and may soon possibly feature in the memory cells of computer devices. Hence superconductivity can play an important role in the technological world, solving physical and technological problems and showing economic advantages as compared with possible conventional techniques, bearing also in mind the importance of reliability and safety. (author)

  19. Academic training: Applied superconductivity

    CERN Multimedia

    2007-01-01

    LECTURE SERIES 17, 18, 19 January from 11.00 to 12.00 hrs Council Room, Bldg 503 Applied Superconductivity : Theory, superconducting Materials and applications E. PALMIERI/INFN, Padova, Italy When hearing about persistent currents recirculating for several years in a superconducting loop without any appreciable decay, one realizes that we are dealing with a phenomenon which in nature is the closest known to the perpetual motion. Zero resistivity and perfect diamagnetism in Mercury at 4.2 K, the breakthrough during 75 years of several hundreds of superconducting materials, the revolution of the "liquid Nitrogen superconductivity"; the discovery of still a binary compound becoming superconducting at 40 K and the subsequent re-exploration of the already known superconducting materials: Nature discloses drop by drop its intimate secrets and nobody can exclude that the last final surprise must still come. After an overview of phenomenology and basic theory of superconductivity, the lectures for this a...

  20. Superconducting rotating machines

    International Nuclear Information System (INIS)

    Smith, J.L. Jr.; Kirtley, J.L. Jr.; Thullen, P.

    1975-01-01

    The opportunities and limitations of the applications of superconductors in rotating electric machines are given. The relevant properties of superconductors and the fundamental requirements for rotating electric machines are discussed. The current state-of-the-art of superconducting machines is reviewed. Key problems, future developments and the long range potential of superconducting machines are assessed

  1. Superconductivity in bad metals

    International Nuclear Information System (INIS)

    Emery, V.J.; Kivelson, S.A.

    1995-01-01

    It is argued that many synthetic metals, including high temperature superconductors are ''bad metals'' with such a poor conductivity that the usual mean-field theory of superconductivity breaks down because of anomalously large classical and quantum fluctuations of the phase of the superconducting order parameter. Some consequences for high temperature superconductors are described

  2. Superconductivity and electronic structure in single-layer FeSe on SrTiO{sub 3} probed by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jandke, Jasmin; Dressner, Jonas; Wulfhekel, Wulf [Physikalisches Institut, Karlsruhe Institute of Technology (Germany); Yang, Fang; Gao, Chunlei [Fudan Universitaet, Shanghai (China)

    2016-07-01

    We use high-resolution scanning tunneling spectroscopy (STS) to study single-layer FeSe on Nb-doped SrTiO{sub 3} (001). Features of bosonic excitations were observed in the measured quasiparticle density of states. Furthermore, using STS, quasiparticle interference (QPI) imaging was performed in order to map the multiband electronic structure of FeSe. Compared to previous measurements, an additional feature is visible in our measured QPI maps on a single-layer FeSe/SrTiO{sub 3}. The origin of this feature will be discussed.

  3. Submicron superconducting structures

    International Nuclear Information System (INIS)

    Golovashkin, A.I.; Lykov, A.N.

    1986-01-01

    An overview of works concerning superconducting structures of submicron dimensions and a system of such structures is given. It is noted that usage of the above structures in superconducting microelectronics permits, first, to increase the element packing density, to decrease the signal transmission time, capacity, power dissipated in high-frequency applications. Secondly, negligible coherence length in transition metals, their alloys and high-temperature compounds also restrict the dimensions of superconducting weak couplings when the 'classical' Josephson effect is displayed. The most effective methods for production of submicron superconducting structures are the following: lithography, double scribering. Recently the systems of superconducting submicron elements are extensively studied. It is shown that such systems can be phased by magnetic field

  4. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Mijatovic, Nenad; Seiler, Eugen

    2010-01-01

    , the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10......We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future...... offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However...

  5. Superconducting Wind Turbine Generators

    Directory of Open Access Journals (Sweden)

    Yunying Pan

    2016-08-01

    Full Text Available Wind energy is well known as a renewable energy because its clean and less polluted characteristic, which is the foundation of development modern wind electricity. To find more efficient wind turbine is the focus of scientists around the world. Compared from conventional wind turbines, superconducting wind turbine generators have advantages at zero resistance, smaller size and lighter weight. Superconducting wind turbine will inevitably become the main trends in this area. This paper intends to introduce the basic concept and principle of superconductivity, and compare form traditional wind turbine to obtain superiority, then to summary three proposed machine concept.While superconductivity have difficulty  in modern technology and we also have proposed some challenges in achieving superconducting wind turbine finally.

  6. A Visit to the South Pole

    Indian Academy of Sciences (India)

    IAS Admin

    For these reasons, I could not buy many of the essential things .... Geomagnetic South Pole at 78° 27' S, 106° 48' E at an altitude of 3,488 metres on approximately .... Smokers at the station were often found searching for used cigarette butts.

  7. Recent advances in poled optical fibres

    DEFF Research Database (Denmark)

    Pruneri, V.; Margulis, W.; Myrén, N.

    2005-01-01

    A second-order nonlinearity can be induced in optical fibres through poling. We describe accomplishments of the EU project GLAMOROUS in making low-cost high performance electrooptic and nonlinear optical fibre- and waveguide-based components. In particular a comparison with more traditional...

  8. Stabilization, pole placement, and regular implementability

    NARCIS (Netherlands)

    Belur, MN; Trentelman, HL

    In this paper, we study control by interconnection of linear differential systems. We give necessary and sufficient conditions for regular implementability of a-given linear, differential system. We formulate the problems of stabilization and pole placement as problems of finding a suitable,

  9. Pole masses of quarks in dimensional reduction

    International Nuclear Information System (INIS)

    Avdeev, L.V.; Kalmykov, M.Yu.

    1997-01-01

    Pole masses of quarks in quantum chromodynamics are calculated to the two-loop order in the framework of the regularization by dimensional reduction. For the diagram with a light quark loop, the non-Euclidean asymptotic expansion is constructed with the external momentum on the mass shell of a heavy quark

  10. Rotor pole refurbishment for hydrogenerators: insulation problems and solutions

    International Nuclear Information System (INIS)

    Reynolds, R.R.; Rux, L.

    2005-01-01

    Rotor poles for Unit 1 at Lower Granite Powerhouse were removed from the rotor and shipped to a repair facility for refurbishment. Upon inspection, it was found that all of the pole bodies exhibited a distinct bow, center to end, on the pole mounting surface. In some cases, the deflection was as much as 0.106 inch. Concerns were raised about how this condition might affect the ability to properly insulate and/or re-seat the poles. This paper presents details of the rotor pole and field winding evaluation, the problems encountered, and the solutions implemented to successfully refurbish the rotor poles and field winding. (author)

  11. Superconducting magnet safety

    International Nuclear Information System (INIS)

    Arendt, F.; Komarek, P.

    1983-01-01

    One of the major components in a fusion reactor for which a safety analysis must be carried out is the magnet system. Most of the possible disturbances influencing the operation of superconducting magnets lead only to a quench, defined as an ''abnormal operating condition'' which causes just a temporary shut down of the magnet system without damage, if the system is well designed. More unlikely are accidental events which are associated with the generation of high power arcs. In these cases, single current arcs, e.g. at broken current leads, will lead to moderate damage only, but with the necessity of a longer shut down period for repair or replacing. Severe damage can only occur if in a multiple current arcing, starting by broken conductors, a wide-spread rupture of the winding occurs and the final high power arc burns through the coil case damaging other coils and reactor components. In a very hypothetical event the simultaneous rupture of the complete winding at two locations at least 1 m apart leads to missile generation due to the electromagnetic forces in the background field. The kinetic energy which the flying piece can get will be less than the values assumed for airplane crashes with the containment of modern fission power plants. (author)

  12. Superconductivity and electron microscopy

    International Nuclear Information System (INIS)

    Hawkes, P.W.; Valdre, U.

    1977-01-01

    In this review article, two aspects of the role of superconductivity in electron microscopy are examined: (i) the development of superconducting devices (mainly lenses) and their incorporation in electron microscopes; (ii) the development of electron microscope techniques for studying fundamental and technological problems associated with superconductivity. The first part opens with a brief account of the relevant properties of conventional lenses, after which the various types of superconducting lenses are described and their properties compared. The relative merits and inconveniences of superconducting and conventional lenses are examined, particular attention being paid to the spherical and chromatic aberration coefficients at accelerating voltages above a megavolt. This part closes with a survey of the various microscope designs that have been built or proposed, incorporating superconducting components. In the second part, some methods that have been or might be used in the study of superconductivity in the electron microscope are described. A brief account of the types of application for which they are suitable is given. (author)

  13. Superconducting materials and magnets

    International Nuclear Information System (INIS)

    1991-04-01

    The Technical Committee Meeting on Superconducting Materials and Magnets was convened by the IAEA and held by invitation of the Japanese government on September 4-6, 1989 in Tokyo. The meeting was hosted by the National Research Institute for Metals. Topics of the conference related to superconducting magnets and technology with particular application to fusion and the superconducting supercollider. Technology using both high and low-temperature superconductors was discussed. This document is a compendium of the papers presented at the meeting. Refs, figs and tabs

  14. Superconducting tin core fiber

    International Nuclear Information System (INIS)

    Homa, Daniel; Liang, Yongxuan; Hill, Cary; Kaur, Gurbinder; Pickrell, Gary

    2015-01-01

    In this study, we demonstrated superconductivity in a fiber with a tin core and fused silica cladding. The fibers were fabricated via a modified melt-draw technique and maintained core diameters ranging from 50-300 microns and overall diameters of 125-800 microns. Superconductivity of this fiber design was validated via the traditional four-probe test method in a bath of liquid helium at temperatures on the order of 3.8 K. The synthesis route and fiber design are perquisites to ongoing research dedicated all-fiber optoelectronics and the relationships between superconductivity and the material structures, as well as corresponding fabrication techniques. (orig.)

  15. Superconductivity in doped insulators

    International Nuclear Information System (INIS)

    Emery, V.J.; Kivelson, S.A.

    1995-01-01

    It is shown that many synthetic metals, including high temperature superconductors are ''bad metals'', with such a poor conductivity that the usual meanfield theory of superconductivity breaks down because of anomalously large classical and quantum fluctuations of the phase of the superconducting order parameter. It is argued that the supression of a first order phase transition (phase separation) by the long-range Coulomb interaction leads to high temperature superconductivity accompanied by static or dynamical charge inhomogeneIty. Evidence in support of this picture for high temperature superconductors is described

  16. Superconducting active impedance converter

    International Nuclear Information System (INIS)

    Ginley, D.S.; Hietala, V.M.; Martens, J.S.

    1993-01-01

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductors allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology. 12 figures

  17. Introduction to superconductivity

    CERN Document Server

    Darriulat, Pierre

    1998-01-01

    The lecture series will address physicists, such as particle and nuclear physicists, familiar with non-relativistic quantum mechanics but not with solid state physics. The aim of this introduction to low temperature superconductivity is to give sufficient bases to the student for him/her to be able to access the scientific literature on this field. The five lectures will cover the following topics : 1. Normal metals, free electron gas, chambers equation. 2. Cooper pairs, the BCS ground state, quasi particle excitations. 3. DC superconductivity, Meissner state, dirty superconductors.4. Self consistent approach, Ginsburg Landau equations, Abrikosov fluxon lattice. 5. Josephson effects, high temperature superconductivity.

  18. Hybrid quantum systems: Outsourcing superconducting qubits

    Science.gov (United States)

    Cleland, Andrew

    Superconducting qubits offer excellent prospects for manipulating quantum information, with good qubit lifetimes, high fidelity single- and two-qubit gates, and straightforward scalability (admittedly with multi-dimensional interconnect challenges). One interesting route for experimental development is the exploration of hybrid systems, i.e. coupling superconducting qubits to other systems. I will report on our group's efforts to develop approaches that will allow interfacing superconducting qubits in a quantum-coherent fashion to spin defects in solids, to optomechanical devices, and to resonant nanomechanical structures. The longer term goals of these efforts include transferring quantum states between different qubit systems; generating and receiving ``flying'' acoustic phonon-based as well as optical photon-based qubits; and ultimately developing systems that can be used for quantum memory, quantum computation and quantum communication, the last in both the microwave and fiber telecommunications bands. Work is supported by Grants from AFOSR, ARO, DOE and NSF.

  19. Interplay between superconductivity and Coulomb blockade

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Thomas; Sprenger, Susanne; Scheer, Elke [Universitaet Konstanz (Germany)

    2016-07-01

    Studying the interplay between superconductivity and Coulomb blockade (CB) can be achieved by investigating an all superconducting single electron transistor (SSET) consisting of an island coupled to the leads by two tunneling contacts. The majority of experiments performed so far were using superconducting tunnel contacts made from oxide layers, in which multiple Andreev reflections (MAR) can be excluded. Using a mechanically controlled break junction (MCBJ) made of aluminum enables tuning the contributions of MAR in one junction continuously and thereby addressing different transport regimes within the same sample. Our results offer the possibility to attribute particular features in the transport characteristics to the transmission probabilities of individual modes in the MCBJ contact. We discuss our findings in terms of dynamical CB, SSET behaviour and MAR when continuously opening the MCBJ from the fully closed state to a tunneling contact.

  20. Textured dysprosium and gadolinium poles for high-field, short-period hybrid undulators

    International Nuclear Information System (INIS)

    Murokh, Alex; Solovyov, Vyacheslav; Agustsson, Ron; O'Shea, Finn H.; Chubar, Oleg; Chen, Yung; Grandsaert, Thomas

    2014-01-01

    We discuss the feasibility of enhancement of the gap field in a short-period hybrid undulator by using pole inserts with the saturation inductance B s , over that of iron, 2 T. Dysprosium metal, with the saturation inductance of 3.4 T below 90 K, and Gadolinium with B s =2.7 T, appear as good candidates as the optimized pole material. However, due to the high magnetic anisotropy of Dy, such a high level of magnetization can only be realized when the external field lies in the basal plane. This implies that the pole has to be single-crystalline or highly textured. Considering that growing large, >10mm, Dy single crystals is difficult, we propose secondary recrystallization as a method to induce the required texture in thin Dy and Gd foils. The textured foils can be stacked to produce pole inserts of the desired geometry and orientation. Results of small-scale processing and magnetic measurements of thin (20–60 μ) foils provide evidence that the required texture quality can be achieved by a relatively simple sequence of heat-treatments and cold rolling. The advantage of textured Dy and Gd poles is demonstrated in a several period test undulator. -- Highlights: • Textured rare-earth materials for use as undulator pole materials. • We measure the development of texture in Dy and Gd. • We compare the rare-earth materials with high saturation steel in undulators. • Thin sheets of Dy and Gd materials perform similar to single crystals

  1. Development of innovative superconducting DC power cable

    Energy Technology Data Exchange (ETDEWEB)

    Matsushita, Teruo; Kiuchi, Masaru [Dept. of Computer Science and Electronics Kyushu Institute of Technology, Iizuka (Japan)

    2017-09-15

    It is required to reduce the cost of superconducting cable to realize a superconducting DC power network that covers a wide area in order to utilize renewable energy. In this paper a new concept of innovative cable is introduced that can enhance the current-carrying capacity even though the same superconducting tape is used. Such a cable can be realized by designing an optimal winding structure in such a way that the angle between the tape and magnetic field becomes small. This idea was confirmed by preliminary experiments for a single layer model cable made of Bi-2223 tapes and REBCO coated conductors. Experiments of three and four layer cables of practical sizes were also done and it was found that the current-carrying capacity increased as theoretically predicted. If the critical current properties of commercial superconducting tapes are further improved in a parallel magnetic field, the enhancement will become pronounced and this technology will surely contribute to realization of superconducting DC power network.

  2. Fatigue failure and cracking in high mast poles.

    Science.gov (United States)

    2012-03-01

    This report presents the findings of a comprehensive research project to investigate the fatigue : cracking and failure of galvanized high mast illumination poles (HMIP). Ultrasonic inspection of : poles throughout the state has revealed the presence...

  3. Superconducting qubits can be coupled and addressed as trapped ions

    Science.gov (United States)

    Liu, Y. X.; Wei, L. F.; Johansson, J. R.; Tsai, J. S.; Nori, F.

    2009-03-01

    Exploiting the intrinsic nonlinearity of superconducting Josephson junctions, we propose a scalable circuit with superconducting qubits (SCQs) which is very similar to the successful one now being used for trapped ions. The SCQs are coupled to the ``vibrational'' mode provided by a superconducting LC circuit or its equivalent (e.g., a superconducting quantum interference device). Both single-qubit rotations and qubit-LC-circuit couplings and/or decouplings can be controlled by the frequencies of the time-dependent magnetic fluxes. The circuit is scalable since the qubit-qubit interactions, mediated by the LC circuit, can be selectively performed, and the information transfer can be realized in a controllable way. [4pt] Y.X. Liu, L.F. Wei, J.R. Johansson, J.S. Tsai, F. Nori, Superconducting qubits can be coupled and addressed as trapped ions, Phys. Rev. B 76, 144518 (2007). URL: http://link.aps.org/abstract/PRB/v76/e144518

  4. Modern aspects of Josephson dynamics and superconductivity electronics

    CERN Document Server

    Askerzade, Iman; Cantürk, Mehmet

    2017-01-01

    In this book new experimental investigations of properties of Josephson junctions and systems are explored with the help of recent developments in superconductivity. The theory of the Josephson effect is presented taking into account the influence of multiband and anisotropy effects in new superconducting compounds. Anharmonicity effects in current-phase relation on Josephson junctions dynamics are discussed. Recent studies in analogue and digital superconductivity electronics are presented. Topics of special interest include resistive single flux quantum logic in digital electronics. Application of Josephson junctions in quantum computing as superconducting quantum bits are analyzed. Particular attention is given to understanding chaotic behaviour of Josephson junctions and systems. The book is written for graduate students and researchers in the field of applied superconductivity.

  5. Development of the experimental setup for investigation of latching of superconducting single-photon detector caused by blinding attack on the quantum key distribution system

    Directory of Open Access Journals (Sweden)

    Elezov M.S.

    2017-01-01

    Full Text Available Recently bright-light control of the SSPD has been demonstrated. This attack employed a “backdoor” in the detector biasing scheme. Under bright-light illumination, SSPD becomes resistive and remains “latched” in the resistive state even when the light is switched off. While the SSPD is latched, Eve can simulate SSPD single-photon response by sending strong light pulses, thus deceiving Bob. We developed the experimental setup for investigation of a dependence on latching threshold of SSPD on optical pulse length and peak power. By knowing latching threshold it is possible to understand essential requirements for development countermeasures against blinding attack on quantum key distribution system with SSPDs.

  6. An improved torque density Modulated Pole Machine for low speed high torque applications

    DEFF Research Database (Denmark)

    Washington, J. G.; Atkinson, G. J.; Baker, N. J.

    2012-01-01

    This paper presents a new topology for three-phase Modulated Pole Machines. This new topology the “Combined Phase Modulated Pole Machine” is analysed and compared to the more traditional technology of three separate single phase units stacked axially with a separation between phases. Three......- dimensional Finite Element calculations are used to compare performance of the machines under the same conditions, it is shown that the new Combined Phase topology produces a greater torque whilst reducing the number of components required to assemble the machine and increasing its mechanical integrity....

  7. Hybrid superconducting magnetic suspensions

    International Nuclear Information System (INIS)

    Tixador, P.; Hiebel, P.; Brunet, Y.; Chaud, X.; Gautier-Picard, P.

    1996-01-01

    Superconductors, especially high T c ones, are the most attractive materials to design stable and fully passive magnetic suspensions which have to control five degrees of freedom. The hybrid superconducting magnetic suspensions present high performances and a simple cooling mode. They consist of a permanent magnet bearing, stabilized by a suitable magnet-superconductor structure. Several designs are given and compared in terms of forces and stiffnesses. The design of the magnet bearing plays an important part. The superconducting magnetic bearing participates less in levitation but must provide a high stabilizing stiffness. This is achieved by the magnet configuration, a good material in term of critical current density and field cooling. A hybrid superconducting suspension for a flywheel is presented. This system consists of a magnet thrust bearing stabilized by superconductors interacting with an alternating polarity magnet structure. First tests and results are reported. Superconducting materials are magnetically melt-textured YBaCuO

  8. Superconducting Technology Assessment

    National Research Council Canada - National Science Library

    2005-01-01

    This Superconducting Technology Assessment (STA) has been conducted by the National Security Agency to address the fundamental question of a potential replacement for silicon complementary metal oxide semiconductor (CMOS...

  9. Superconductivity: materials and applications

    International Nuclear Information System (INIS)

    Duchateau, J.L.; Kircher, F.; Leveque, J.; Tixador, P.

    2008-01-01

    This digest paper presents the different types of superconducting materials: 1 - the low-TC superconductors: the multi-filament composite as elementary constituent, the world production of NbTi, the superconducting cables of the LHC collider and of the ITER tokamak; 2 - the high-TC superconductors: BiSrCaCuO (PIT 1G) ribbons and wires, deposited coatings; 3 - application to particle physics: the the LHC collider of the CERN, the LHC detectors; 4 - applications to thermonuclear fusion: Tore Supra and ITER tokamaks; 5 - NMR imaging: properties of superconducting magnets; 6 - applications in electrotechnics: cables, motors and alternators, current limiters, transformers, superconducting energy storage systems (SMES). (J.S.)

  10. Superconductivity and its devices

    International Nuclear Information System (INIS)

    Forbes, D.S.

    1981-01-01

    Among the more important developments that are discussed are cryotrons, superconducting motors and generators, and high-field magnets. Cryotrons will create faster and more economical computer systems. Superconducting motors and generators will cost much less to build than conventional electric generators and cut fuel consumption. Moreover, high-field magnets are being used to confine plasma in connection with nuclear fusion. Superconductors have a vital role to play in all of these developments. Most importantly, though, are the magnetic properties of superconductivity. Superconducting magnets are an integral part of nuclear fusion. In addition, high-field magnets are necessary in the use of accelerators, which are needed to study the interactions between elementary particles

  11. Superconductivity: Heike's heritage

    NARCIS (Netherlands)

    van der Marel, D.; Golden, M.

    2011-01-01

    A century ago, Heike Kamerlingh Onnes discovered superconductivity. And yet, despite the conventional superconductors being understood, the list of unconventional superconductors is growing — for which unconventional theories may be required.

  12. Theoretical modeling and experimental analyses of laminated wood composite poles

    Science.gov (United States)

    Cheng Piao; Todd F. Shupe; Vijaya Gopu; Chung Y. Hse

    2005-01-01

    Wood laminated composite poles consist of trapezoid-shaped wood strips bonded with synthetic resin. The thick-walled hollow poles had adequate strength and stiffness properties and were a promising substitute for solid wood poles. It was necessary to develop theoretical models to facilitate the manufacture and future installation and maintenance of this novel...

  13. Second-harmonic imaging of poled silica waveguides

    DEFF Research Database (Denmark)

    Arentoft, Jesper; Pedersen, Kjeld; Bozhevolnyi, Sergey I.

    2000-01-01

    Electric-field poled silica-based waveguides are characterized by measurements of second-harmonic generation (SHG) and of the linear electro-optic effect (LEO). A SHG scanning technique allowing for high-resolution imaging of poled devices is demonstrated. Scans along the direction of the poling...

  14. Superconducting Undulator with Variably Polarized Light

    CERN Document Server

    Hwang, Ching Shiang; Ching Fan, Tai; Li, W P; Lin, P H

    2004-01-01

    This study investigates planar in-vacuo superconducting undulators with periodic length of 5 cm (IVSU5) producing linearly and circularly polarized infrared rays or xrays source. The vertically wound racetrack coil is selected for the coil and pole fabrication of the IVSU5. When the up and down magnetic pole arrays with alternative directions rotated wires in the horizontal plane, a helical field radiates circularly polarized light in the electron storage ring, the free electron laser (FEL), and the energy recovery linac (ERL) facilities. Meanwhile, an un-rotated wire is constructed together with the rotated wire on the same undulator is used to switch the linear horizontal and vertical, the right- and left-circular polarization radiation. Given a periodic length of 5 cm and a gap of 23 mm, the maximum magnetic flux density in the helical undulator are Bz = 1.5 T and Bx = 0.5 T when the wires rotated by 20°. This article describes the main factors of the planar and helical undulator design for FEL and...

  15. RADIOFREQUENCY SUPERCONDUCTIVITY: Workshop

    International Nuclear Information System (INIS)

    Lengeler, Herbert

    1989-01-01

    Superconducting radiofrequency is already playing an important role in the beam acceleration system for the TRISTAN electron-positron collider at the Japanese KEK Laboratory and new such systems are being prepared for other major machines. Thus the fourth Workshop on Radiofrequency Superconductivity, organized by KEK under the chairmanship of local specialist Yuzo Kojima and held just before the International Conference on High Energy Accelerators, had much progress to review and even more to look forward to

  16. Stacked magnet superconducting bearing

    International Nuclear Information System (INIS)

    Rigney, T.K. II; Saville, M.P.

    1993-01-01

    A superconducting bearing is described, comprising: a plurality of permanent magnets magnetized end-to-end and stacked side-by-side in alternating polarity, such that flux lines flow between ends of adjacent magnets; isolating means, disposed between said adjacent magnets, for reducing flux leakage between opposing sides of said adjacent magnets; and a member made of superconducting material having at least one surface in communication with said flux lines

  17. Superconductivity at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, N B; Ginzburg, N I

    1969-07-01

    Work published during the last 3 or 4 yrs concerning the effect of pressure on superconductivity is reviewed. Superconducting modifications of Si, Ge, Sb, Te, Se, P and Ce. Change of Fermi surface under pressure for nontransition metals. First experiments on the influence of pressure on the tunneling effect in superconductors provide new information on the nature of the change in phonon and electron energy spectra of metals under hydrostatic compression. 78 references.

  18. Superconductivity: A critical analysis

    International Nuclear Information System (INIS)

    Sacchetti, Nicola

    1997-01-01

    It is some forty years now that superconductivity has entered into the field of applied Physics. Countless applications have been proposed some of which have been successfully tested in the form of prototypes and relatively few have become widely used products. This article offers an objective examination of what applied superconductivity represents in the area of modern technology highlighting its exclusive advantages and its inevitable limitations

  19. Generalized Superconductivity. Generalized Levitation

    International Nuclear Information System (INIS)

    Ciobanu, B.; Agop, M.

    2004-01-01

    In the recent papers, the gravitational superconductivity is described. We introduce the concept of generalized superconductivity observing that any nongeodesic motion and, in particular, the motion in an electromagnetic field, can be transformed in a geodesic motion by a suitable choice of the connection. In the present paper, the gravitoelectromagnetic London equations have been obtained from the generalized Helmholtz vortex theorem using the generalized local equivalence principle. In this context, the gravitoelectromagnetic Meissner effect and, implicitly, the gravitoelectromagnetic levitation are given. (authors)

  20. Superconducting magnets for accelerators

    International Nuclear Information System (INIS)

    Denisov, Yu.N.

    1979-01-01

    Expediency of usage and possibilities arising in application of superconducting devices in magnetic systems of accelerators and experimental nuclear-physical devices are studied. Parameters of specific devices are given. It is emphasized that at the existing level of technological possibilities, construction and usage of superconducting magnetic systems in experimental nuclear physics should be thought of as possible, from the engineering, and expedient, from the economical viewpoints [ru

  1. Permanent magnet machine and method with reluctance poles and non-identical PM poles for high density operation

    Science.gov (United States)

    Hsu, John S.

    2010-05-18

    A method and apparatus in which a stator (11) and a rotor (12) define a primary air gap (20) for receiving AC flux and at least one source (23, 40), and preferably two sources (23, 24, 40) of DC excitation are positioned for inducing DC flux at opposite ends of the rotor (12). Portions of PM material (17, 17a) are provided as boundaries separating PM rotor pole portions from each other and from reluctance poles. The PM poles (18) and the reluctance poles (19) can be formed with poles of one polarity having enlarged flux paths in relation to flux paths for pole portions of an opposite polarity, the enlarged flux paths communicating with a core of the rotor (12) so as to increase reluctance torque produced by the electric machine. Reluctance torque is increased by providing asymmetrical pole faces. The DC excitation can also use asymmetric poles and asymmetric excitation sources. Several embodiments are disclosed with additional variations.

  2. Groebner Basis Solutions to Satellite Trajectory Control by Pole Placement

    Science.gov (United States)

    Kukelova, Z.; Krsek, P.; Smutny, V.; Pajdla, T.

    2013-09-01

    Satellites play an important role, e.g., in telecommunication, navigation and weather monitoring. Controlling their trajectories is an important problem. In [1], an approach to the pole placement for the synthesis of a linear controller has been presented. It leads to solving five polynomial equations in nine unknown elements of the state space matrices of a compensator. This is an underconstrained system and therefore four of the unknown elements need to be considered as free parameters and set to some prior values to obtain a system of five equations in five unknowns. In [1], this system was solved for one chosen set of free parameters with the help of Dixon resultants. In this work, we study and present Groebner basis solutions to this problem of computation of a dynamic compensator for the satellite for different combinations of input free parameters. We show that the Groebner basis method for solving systems of polynomial equations leads to very simple solutions for all combinations of free parameters. These solutions require to perform only the Gauss-Jordan elimination of a small matrix and computation of roots of a single variable polynomial. The maximum degree of this polynomial is not greater than six in general but for most combinations of the input free parameters its degree is even lower. [1] B. Palancz. Application of Dixon resultant to satellite trajectory control by pole placement. Journal of Symbolic Computation, Volume 50, March 2013, Pages 79-99, Elsevier.

  3. Physics on the Z-pole

    International Nuclear Information System (INIS)

    Omori, Tsunehiko; Kurihara, Yoshimasa; Sugimoto, Yasuhiro; Fujii, Yoshiaki; Fujii, Keisuke

    1994-01-01

    JLC will provide a high luminosity of 2.0 x 10 33 cm -2 s -1 on the Z-pole. To realize the Z-pole running we need to add a transport line to bypass unnecessary part of the main linac. With this high luminosity, the third angle of the unitality triangle (sin 2φ 3 ) can be measured in B s (B s ) → pK s channel with 3σ sensitivity in 1 year when sin 2φ 3 = -0.5, Xs = 10, and the branching ratio of the channel is 2 x 10 -5 . Also sin 2 θw can be measured with accuracy of Δsin 2 θw/sin 2 θw = 0.1%. (J.P.N.)

  4. Sun's pole-equator flux differences

    Energy Technology Data Exchange (ETDEWEB)

    Belvedere, G [Istituto di Astronomia dell' Universita di Catania, Italy; Paterno, L [Osservatorio Astrofisico di Catania, Italy

    1977-04-01

    The possibility that large flux differences between the poles and the equator at the bottom of the solar convective zone are compatible with the small differences observed at the surface is studied. The consequences of increasing the depth of the convective zone due to overshooting are explored. A Boussinesq model is used for the convective zone and it is assumed that the interaction of the global convection with rotation is modelled through a convective flux coefficient whose perturbed part is proportional to the local Taylor number. The numerical integration of the equations of motion and energy shows that coexistence between large pole-equator flux differences at the bottom and small ones at the surface is possible if the solar convective zone extends to a depth of 0.4 R(Sun). The angular velocity distribution inside the convective zone is in agreement with the ..cap alpha omega..-dynamo theories of the solar cycle.

  5. Emergent Higgsless Superconductivity

    Directory of Open Access Journals (Sweden)

    Cristina Diamantini M.

    2017-01-01

    Full Text Available We present a new Higgsless model of superconductivity, inspired from anyon superconductivity but P- and T-invariant and generalizable to any dimension. While the original anyon superconductivity mechanism was based on incompressible quantum Hall fluids as average field states, our mechanism involves topological insulators as average field states. In D space dimensions it involves a (D-1-form fictitious pseudovector gauge field which originates from the condensation of topological defects in compact lowenergy effective BF theories. There is no massive Higgs scalar as there is no local order parameter. When electromagnetism is switched on, the photon acquires mass by the topological BF mechanism. Although the charge of the gapless mode (2 and the topological order (4 are the same as those of the standard Higgs model, the two models of superconductivity are clearly different since the origins of the gap, reflected in the high-energy sectors are totally different. In 2D thi! s type of superconductivity is explicitly realized as global superconductivity in Josephson junction arrays. In 3D this model predicts a possible phase transition from topological insulators to Higgsless superconductors.

  6. Superconducting Fullerene Nanowhiskers

    Directory of Open Access Journals (Sweden)

    Yoshihiko Takano

    2012-04-01

    Full Text Available We synthesized superconducting fullerene nanowhiskers (C60NWs by potassium (K intercalation. They showed large superconducting volume fractions, as high as 80%. The superconducting transition temperature at 17 K was independent of the K content (x in the range between 1.6 and 6.0 in K-doped C60 nanowhiskers (KxC60NWs, while the superconducting volume fractions changed with x. The highest shielding fraction of a full shielding volume was observed in the material of K3.3C60NW by heating at 200 °C. On the other hand, that of a K-doped fullerene (K-C60 crystal was less than 1%. We report the superconducting behaviors of our newly synthesized KxC60NWs in comparison to those of KxC60 crystals, which show superconductivity at 19 K in K3C60. The lattice structures are also discussed, based on the x-ray diffraction (XRD analyses.

  7. Upper critical field and superconducting anisotropy of BaFe2-xRuxAs2 (x=0.48 and 0.75) single crystals

    International Nuclear Information System (INIS)

    Jo, Youn Jung; Eom, Man Jin; Kim, Jun Sung; Kang, W.

    2014-01-01

    The upper critical field (H c 2 ) was determined by applying a magnetic field along the ab plane and c axis for two single crystals of BaFe 2-x Ru x As 2 (x=0.48 and 0.75). The anisotropy of the H c 2 (0), γ(0)=H c 2 ab (0)/H c 2 c (0), was ∼1.6 for x=0.48 and ∼2.3 for x=0.75. The angle-dependent resistance measured below T c allowed perfect scaling features based on anisotropic Ginzburg-Landau theory, leading to consistent anisotropy values. Because only one fitting parameter γ is used in the scaling for each temperature, the validity of the γ value was compared with that determined from γ=H c 2 ab /H c 2 c . The γ obtained at a temperature close to Tc was 3.0 and decreased to 2.0 at low temperatures. Comparing to the anisotropy determined for electron- or hole-doped BaFe 2 As 2 using the same method, the present results point to consistent anisotropy in Ru-doped BaFe 2 As 2 with other electron- or hole-doped BaFe 2 As 2 .

  8. The South Pole and the Ross Sea

    Science.gov (United States)

    2002-01-01

    This image shows a rare clear view of the South Pole (lower right) and the Ross Sea, Antarctica. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) acquired the scene on December 26, 2001. The geographic South Pole is located in the center of Antarctica, at an altitude of 2,900 meters (9,300 feet). It rests on a continent-wide ice sheet that is 2,870 m thick, with the underlying bedrock only 30 m (98 feet) above sea level. The ice underlying the South Pole is as much as 140,000 years old, and is currently accumulating at about 82 cm (32 inches) per year. Roughly 2,500 km (1,550 miles) away is the green water of the Ross Sea, which indicates the presence of large numbers of phytoplankton. This is a highly productive part of the world's oceans. Also note the ice gathered around McMurdo Sound, seen toward the lefthand shoreline of the Ross Sea, at the edge of the Ross Ice Shelf. According to National Science Foundation researchers, this ice is making it difficult for penguins to reach their food supply. Separating the continental Antarctic ice sheet from the Ross Sea are the Queen Maud Mountains and the Ross Ice Shelf. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  9. High-current applications of superconductivity

    International Nuclear Information System (INIS)

    Komarek, P.

    1995-01-01

    The following topics were dealt with: superconducting materials, design principles of superconducting magnets, magnets for research and engineering, superconductivity for power engineering, superconductivity in nuclear fusion technology, economical considerations

  10. Po Superconducting Magnet:detail of the windings

    CERN Multimedia

    1982-01-01

    The Po superconducting dipole was built as a prototype beam transport magnet for the SPS extracted proton beam Po. Its main features were: coil aperture 72 mm, length 5 m, room-temperature yoke, NbTi cable conductor impregnated with solder, nominal field 4.2 T at 4.7 K (87% of critical field). It reached its nominal field without any quench. The photo shows a detail of the inner layer winding before superposing the outer layer to form the complete coil of a pole. Worth noticing is the interleaved glass-epoxy sheet (white) with grooved channels for the flow of cooling helium. See also 8307552X.

  11. Superconducting sector magnet for the deuteron cyclotron DC-1

    International Nuclear Information System (INIS)

    Alenitskij, Y.G.; Vasilenko, A.T.; Zaplatin, N.L.; Mironov, S.V.; Morozov, N.A.; Pryanichnikov, V.I.; Samsonov, E.V.; Sukhanov, V.I.; Chesnov, A.F.; Chesnova, S.I.

    1992-01-01

    In this paper the results of calculations of a superconducting magnet with a cold pole for a cyclotron to deuteron energy 100 MeV are presented. The maximum induction in the magnet is 4.5 T, stored energy 5 MJ, mean current density in coil 9 · 10 7 A/m 2 . The scheme and main parameters of the magnet protection system and cryogenic provision system are described. The results of calculation of magnetic and thermal forces acting on the coil and its case are presented. The status of the manufacture of the magnetic system elements is considered

  12. 3D Magnetic field modeling of a new superconducting synchronous machine using reluctance network method

    Science.gov (United States)

    Kelouaz, Moussa; Ouazir, Youcef; Hadjout, Larbi; Mezani, Smail; Lubin, Thiery; Berger, Kévin; Lévêque, Jean

    2018-05-01

    In this paper a new superconducting inductor topology intended for synchronous machine is presented. The studied machine has a standard 3-phase armature and a new kind of 2-poles inductor (claw-pole structure) excited by two coaxial superconducting coils. The air-gap spatial variation of the radial flux density is obtained by inserting a superconducting bulk, which deviates the magnetic field due to the coils. The complex geometry of this inductor usually needs 3D finite elements (FEM) for its analysis. However, to avoid a long computational time inherent to 3D FEM, we propose in this work an alternative modeling, which uses a 3D meshed reluctance network. The results obtained with the developed model are compared to 3D FEM computations as well as to measurements carried out on a laboratory prototype. Finally, a 3D FEM study of the shielding properties of the superconducting screen demonstrates the suitability of using a diamagnetic-like model of the superconducting screen.

  13. Ideal of the perfect magnet-superconducting systems

    International Nuclear Information System (INIS)

    Shoaee, H.; Spencer, J.E.

    1983-04-01

    In this report, we study an iron-free, superconducting, elliptical coil quadrupole which has been proposed by General Atomics for use in the SLC final focus system. Beth has shown that such coils might provide a pure quadrupole field ignoring 3-D effects. Similarly, recent studies of rare earth permanent magnets have shown that, at least in principle, these magnets can also be made arbitrarily pure. Since similar claims can be made for conventional iron-core electromagnets either by demanding pure hyperbolic pole contours or using tricks, it is interesting to consider just how wide the gulf between principle and practice really is for each type of magnet and what it takes to bridge it (and where one is most likely to fall off). Here we consider only the superconducting option because its greater strength, variability and linearity make it potentially useful for the SLC and the low-beta insertions of the high energy storage rings such as PEP

  14. Numerical calculation of transient field effects in quenching superconducting magnets

    CERN Document Server

    Schwerg, Nikolai; Russenschuck, Stephan

    2009-01-01

    The maximum obtainable magnetic induction of accelerator magnets, relying on normal conducting cables and iron poles, is limited to around 2 T because of ohmic losses and iron saturation. Using superconducting cables, and employing permeable materials merely to reduce the fringe field, this limit can be exceeded and fields of more than 10 T can be obtained. A quench denotes the sudden transition from the superconducting to the normal conducting state. The drastic increase in electrical resistivity causes ohmic heating. The dissipated heat yields a temperature rise in the coil and causes the quench to propagate. The resulting high voltages and excessive temperatures can result in an irreversible damage of the magnet - to the extend of a cable melt-down. The quench behavior of a magnet depends on numerous factors, e.g. the magnet design, the applied magnet protection measures, the external electrical network, electrical and thermal material properties, and induced eddy current losses. The analysis and optimizat...

  15. Straight ends for superconducting dipole magnet using constant perimeter geometry

    International Nuclear Information System (INIS)

    Royet, J.

    1989-01-01

    The ends of the SSC Dipole magnets are a very critical aspect of the superconducting cable windings needed for this large project. The internal coils, where the radius at the pole is as small as 3/10 of an inch for the first turn, are difficult to form with the very stiff cable, and a high tension is needed. The curing operation on the coils is performed in a heated forming press which applies an important additional stress on the superconducting wire and insulation. A new design of this sensitive region of the magnets was performed at LBL, and several prototypes were built and tested. In this paper the construction method used to solve some of the most critical problems is exposed along with a description of the experimental work in progress. 3 refs., 2 figs

  16. Current superimposition variable flux reluctance motor with 8 salient poles

    Science.gov (United States)

    Takahara, Kazuaki; Hirata, Katsuhiro; Niguchi, Noboru; Kohara, Akira

    2017-12-01

    We propose a current superimposition variable flux reluctance motor for a traction motor of electric vehicles and hybrid electric vehicles, which consists of 10 salient poles in the rotor and 12 slots in the stator. However, iron losses of this motor in high rotation speed ranges is large because the number of salient poles is large. In this paper, we propose a current superimposition variable flux reluctance motor that consists of 8 salient poles and 12 slots. The characteristics of the 10-pole-12-slot and 8-pole-12-slot current superimposition variable flux reluctance motors are compared using finite element analysis under vector control.

  17. Current superimposition variable flux reluctance motor with 8 salient poles

    Directory of Open Access Journals (Sweden)

    Takahara Kazuaki

    2017-12-01

    Full Text Available We propose a current superimposition variable flux reluctance motor for a traction motor of electric vehicles and hybrid electric vehicles, which consists of 10 salient poles in the rotor and 12 slots in the stator. However, iron losses of this motor in high rotation speed ranges is large because the number of salient poles is large. In this paper, we propose a current superimposition variable flux reluctance motor that consists of 8 salient poles and 12 slots. The characteristics of the 10-pole-12-slot and 8-pole-12-slot current superimposition variable flux reluctance motors are compared using finite element analysis under vector control.

  18. Color symmetrical superconductivity in a schematic nuclear quark model

    DEFF Research Database (Denmark)

    Bohr, Henrik; Providencia, C.; da Providencia, J.

    2010-01-01

    In this letter, a novel BCS-type formalism is constructed in the framework of a schematic QCD inspired quark model, having in mind the description of color symmetrical superconducting states. In the usual approach to color superconductivity, the pairing correlations affect only the quasi-particle...... states of two colors, the single-particle states of the third color remaining unaffected by the pairing correlations. In the theory of color symmetrical superconductivity here proposed, the pairing correlations affect symmetrically the quasi-particle states of the three colors and vanishing net color...

  19. On the superconducting phase diagram of high Tc superconductors

    International Nuclear Information System (INIS)

    de la Cruz, F.

    1990-01-01

    The tendency of oxide superconductors to show granularity has been pointed out since the beginning of research on superconductivity in this type of materials. Nevertheless, only very recently the full phase diagram and characteristics of the grains have been determined. In this paper, the authors review and discuss the different critical fields and their relation to the transport of superconducting current. The superconducting response of single crystals of High Tc superconductors is discussed. Special attention is devoted to the behavior of the vortex lattice and, in particular, to the recent discovery of the quenching of H c1 in YBaCuO, several degrees below Tc

  20. Electromagnetic force analysis on the stator and rotor windings of a superconducting generator

    International Nuclear Information System (INIS)

    Colovini, L.; Martinelli, G.; Morini, A.

    1985-01-01

    The determination of values and distribution of the forces acting on the components of a superconducting generator is important when designing the machine, particularly in the choice of materials. The paper analyses the electromagnetic forces acting on the field and armature windings; for this purpose, with reference to the preliminary design of a two-pole 300 MVA superconducting generator, a two-dimensional analytical method set up by the authors is utilized to calculate the forces on the windings under steady state operation and results are compared with those obtained by means of a numerical method

  1. Superconducting nanostructured materials

    International Nuclear Information System (INIS)

    Metlushko, V.

    1998-01-01

    Within the last year it has been realized that the remarkable properties of superconducting thin films containing a periodic array of defects (such as sub-micron sized holes) offer a new route for developing a novel superconducting materials based on precise control of microstructure by modern photolithography. A superconductor is a material which, when cooled below a certain temperature, loses all resistance to electricity. This means that superconducting materials can carry large electrical currents without any energy loss--but there are limits to how much current can flow before superconductivity is destroyed. The current at which superconductivity breaks down is called the critical current. The value of the critical current is determined by the balance of Lorentz forces and pinning forces acting on the flux lines in the superconductor. Lorentz forces proportional to the current flow tend to drive the flux lines into motion, which dissipates energy and destroys zero resistance. Pinning forces created by isolated defects in the microstructure oppose flux line motion and increase the critical current. Many kinds of artificial pinning centers have been proposed and developed to increase critical current performance, ranging from dispersal of small non-superconducting second phases to creation of defects by proton, neutron or heavy ion irradiation. In all of these methods, the pinning centers are randomly distributed over the superconducting material, causing them to operate well below their maximum efficiency. We are overcome this drawback by creating pinning centers in aperiodic lattice (see Fig 1) so that each pin site interacts strongly with only one or a few flux lines

  2. Superconducting wind turbine generators

    International Nuclear Information System (INIS)

    Abrahamsen, A B; Seiler, E; Zirngibl, T; Andersen, N H; Mijatovic, N; Traeholt, C; Pedersen, N F; Oestergaard, J; Noergaard, P B

    2010-01-01

    We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10 MW is suggested to secure the accumulation of reliability experience. Finally, the quantities of high temperature superconducting tape needed for a 10 kW and an extreme high field 10 MW generator are found to be 7.5 km and 1500 km, respectively. A more realistic estimate is 200-300 km of tape per 10 MW generator and it is concluded that the present production capacity of coated conductors must be increased by a factor of 36 by 2020, resulting in a ten times lower price of the tape in order to reach a realistic price level for the superconducting drive train.

  3. High-efficiency and low-cost permanent magnet guideway consideration for high-Tc superconducting Maglev vehicle practical application

    International Nuclear Information System (INIS)

    Deng, Z; Wang, J; Zheng, J; Jing, H; Lu, Y; Ma, G; Liu, L; Liu, W; Zhang, Y; Wang, S

    2008-01-01

    In order to improve the cost performance of the present high-T c superconducting (HTS) Maglev vehicle system for practical application, the multi-pole permanent magnet guideway (PMG) concept was introduced. A well-known double-pole Halbach PMG was chosen as a representative of multi-pole PMGs to compare with traditional monopole PMGs from the point of view of levitation efficiency and cost. Experimental results show that YBCO bulks above the double-pole Halbach PMG can exhibit better load capability and guidance performance as well as dynamics stability at the applied working height between the bulk HTSC and the PMG due to a more reasonable magnetic field distribution at the working range of bulk HTSC. Furthermore, the double-pole PMG configuration can play a more important role in improving guidance performance due to the potential-well field configuration. By comparing with former 'century' PMGs, the double-pole Halbach PMG shows another remarkable advantage in reducing the cost of levitation. As another necessary issue, magnetic field homogeneity and the corresponding magnetic drag force of a double-pole Halbach PMG has been considered by experiment in spite of the above highlights. Synthetically, the multi-pole Halbach PMG design is concluded to be one important choice for future HTS Maglev vehicle applications because of its high efficiency and low cost.

  4. Superconductivity and macroscopic quantum phenomena

    International Nuclear Information System (INIS)

    Rogovin, D.; Scully, M.

    1976-01-01

    It is often asserted that superconducting systems are manifestations of quantum mechanics on a macroscopic scale. In this review article it is demonstrated that this quantum assertion is true within the framework of the microscopic theory of superconductivity. (Auth.)

  5. Superconducting state mechanisms and properties

    CERN Document Server

    Kresin, Vladimir Z; Wolf, Stuart A

    2014-01-01

    'Superconducting State' provides a very detailed theoretical treatment of the key mechanisms of superconductivity, including the current state of the art (phonons, magnons, and plasmons). A very complete description is given of the electron-phonon mechanism responsible for superconductivity in the majority of superconducting systems, and the history of its development, as well as a detailed description of the key experimental techniques used to study the superconducting state and determine the mechanisms. In addition, there are chapters describing the discovery and properties of the key superconducting compounds that are of the most interest for science, and applications including a special chapter on the cuprate superconductors. It provides detailed treatments of some very novel aspects of superconductivity, including multiple bands (gaps), the "pseudogap" state, novel isotope effects beyond BCS, and induced superconductivity.

  6. Fullerides - Superconductivity at the limit

    NARCIS (Netherlands)

    Palstra, Thomas T. M.

    The successful synthesis of highly crystalline Cs3C60, exhibiting superconductivity up to a record temperature for fullerides of 38 K, demonstrates a powerful synthetic route for investigating the origin of superconductivity in this class of materials.

  7. Rf superconducting devices

    International Nuclear Information System (INIS)

    Hartwig, W.H.; Passow, C.

    1975-01-01

    Topics discussed include (1) the theory of superconductors in high-frequency fields (London surface impedance, anomalous normal surface resistance, pippard nonlocal theory, quantum mechanical model, superconductor parameters, quantum mechanical calculation techniques for the surface, impedance, and experimental verification of surface impedance theories); (2) residual resistance (separation of losses, magnetic field effects, surface resistance of imperfect and impure conductors, residual loss due to acoustic coupling, losses from nonideal surfaces, high magnetic field losses, field emission, and nonlinear effects); (3) design and performance of superconducting devices (design considerations, materials and fabrication techniques, measurement of performance, and frequency stability); (4) devices for particle acceleration and deflection (advantages and problems of using superconductors, accelerators for fast particles, accelerators for particles with slow velocities, beam optical devices separators, and applications and projects under way); (5) applications of low-power superconducting resonators (superconducting filters and tuners, oscillators and detectors, mixers and amplifiers, antennas and output tanks, superconducting resonators for materials research, and radiation detection with loaded superconducting resonators); and (6) transmission and delay lines

  8. Superconducting Ferromagnetic Nanodiamond.

    Science.gov (United States)

    Zhang, Gufei; Samuely, Tomas; Xu, Zheng; Jochum, Johanna K; Volodin, Alexander; Zhou, Shengqiang; May, Paul W; Onufriienko, Oleksandr; Kačmarčík, Jozef; Steele, Julian A; Li, Jun; Vanacken, Johan; Vacík, Jiri; Szabó, Pavol; Yuan, Haifeng; Roeffaers, Maarten B J; Cerbu, Dorin; Samuely, Peter; Hofkens, Johan; Moshchalkov, Victor V

    2017-06-27

    Superconductivity and ferromagnetism are two mutually antagonistic states in condensed matter. Research on the interplay between these two competing orderings sheds light not only on the cause of various quantum phenomena in strongly correlated systems but also on the general mechanism of superconductivity. Here we report on the observation of the electronic entanglement between superconducting and ferromagnetic states in hydrogenated boron-doped nanodiamond films, which have a superconducting transition temperature T c ∼ 3 K and a Curie temperature T Curie > 400 K. In spite of the high T Curie , our nanodiamond films demonstrate a decrease in the temperature dependence of magnetization below 100 K, in correspondence to an increase in the temperature dependence of resistivity. These anomalous magnetic and electrical transport properties reveal the presence of an intriguing precursor phase, in which spin fluctuations intervene as a result of the interplay between the two antagonistic states. Furthermore, the observations of high-temperature ferromagnetism, giant positive magnetoresistance, and anomalous Hall effect bring attention to the potential applications of our superconducting ferromagnetic nanodiamond films in magnetoelectronics, spintronics, and magnetic field sensing.

  9. Jupiter's interior and deep atmosphere: The initial pole-to-pole passes with the Juno spacecraft

    DEFF Research Database (Denmark)

    Bolton, S. J.; Adriani, Alberto; Adumitroaie, V.

    2017-01-01

    On 27 August 2016, the Juno spacecraft acquired science observations of Jupiter, passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter's poles show a chaotic scene, unlike Saturn's poles. Microwave sounding reveals weather features at pressures deeper than 100 bars,...... of magnitude more precise. This has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter's core. The observed magnetic field exhibits smaller spatial variations than expected, indicative of a rich harmonic content....

  10. Characterization of superconducting multilayers samples

    CERN Document Server

    Antoine, C Z; Berry, S; Bouat, S; Jacquot, J F; Villegier, J C; Lamura, G; Gurevich, A

    2009-01-01

    Best RF bulk niobium accelerating cavities have nearly reached their ultimate limits at rf equatorial magnetic field H  200 mT close to the thermodynamic critical field Hc. In 2006 Gurevich proposed to use nanoscale layers of superconducting materials with high values of Hc > HcNb for magnetic shielding of bulk niobium to increase the breakdown magnetic field inside SC RF cavities [1]. Depositing good quality layers inside a whole cavity is rather difficult but we have sputtered high quality samples by applying the technique used for the preparation of superconducting electronics circuits and characterized these samples by X-ray reflectivity, dc resistivity (PPMS) and dc magnetization (SQUID). Dc magnetization curves of a 250 nm thick Nb film have been measured, with and without a magnetron sputtered coating of a single or multiple stack of 15 nm MgO and 25 nm NbN layers. The Nb samples with/without the coating clearly exhibit different behaviors. Because SQUID measurements are influenced by edge an...

  11. The LHC Superconducting RF System

    CERN Document Server

    Boussard, Daniel

    1999-01-01

    The European Laboratory for Particle Physics (CERN), the largest high energy physics laboratory worldwide, is constructing the Large Hadron Collider (LHC) in the existing 27 km circumference LEP (Large Electron Positron) collider tunnel. For the LHC, superconducting cavities, operating at 4.5 K, will provide the required acceleration field for ramping the beam energy up to 7 TeV and for keeping the colliding proton beams tightly bunched. Superconducting cavities were chosen, not only because of their high acceleration field leading to a small contribution to the machine impedance, but also because of their high stored energy which minimises the effects of periodic transient beam loading associated with the high beam intensity (0.5 A). There will be eight single-cell cavities per beam, each delivering 2 MV (5.3 MV/m) at 400 MHz. The cavities themselves are now being manufactured by industrial firms, using niobium on copper technology which gives full satisfaction at LEP. A complete cavity prototype assembly in...

  12. Hydrostatic pressure study of the structural phase transitions and superconductivity in single crystals of (Ba1-xKx)Fe2As2 (x=0 and 0.45) and CaFe2As2

    International Nuclear Information System (INIS)

    Torikachvili, M.S.; Bud'ko, S.L.; Ni Ni; Canfield, P.C.

    2009-01-01

    We studied the effect of hydrostatic pressure (P) on the structural phase transitions and superconductivity in the ternary and pseudo-ternary iron arsenides CaFe 2 As 2 , BaFe 2 As 2 , and (Ba 0.55 K 0.45 )Fe 2 As 2 , by means of measurements of electrical resistivity (ρ) in the 1.8-300 K temperature (T) range, pressures up to 20 kbar, and magnetic fields up to 9 T. CaFe 2 As 2 and BaFe 2 As 2 (lightly doped with Sn) display structural phase transitions near 170 and 85 K, respectively, and do not exhibit superconductivity in ambient pressure, while K-doped (Ba 0.55 K 0.45 )Fe 2 As 2 is superconducting for T 2 As 2 is to shift the onset of the crystallographic transformation down in temperature at the rate of ∼-1.04 K/kbar, while shifting the whole ρ(T) curves downward, whereas its effect on superconducting (Ba 0.55 K 0.45 )Fe 2 As 2 is to shift the onset of superconductivity to lower temperatures at the rate of ∼-0.21 K/kbar. The effect of pressure on CaFe 2 As 2 is first to suppress the crystallographic transformation and induce superconductivity with onset near 12 K very rapidly, i.e., for P c2 ) data in (Ba 0.55 K 0.45 )Fe 2 As 2 and CaFe 2 As 2 are discussed.

  13. Tent-Poles of the Bestseller

    DEFF Research Database (Denmark)

    Jensen, Thessa; Vistisen, Peter

    2013-01-01

    This article proposes a framework for understanding and analysing how the passive audience of a media event turns into active stakeholders. The starting point is the cross-media content quadrant (Jensen and Vistisen, 2012), which shows how the producer’s control is distributed on social media...... platforms, while storytelling evolves around a tent-pole, for example, a bestseller or blockbuster. To further explain how the audience engages, a three-step rhetoric model largely based on Bitzer (1998) and Tolkien (1971) is developed and explained....

  14. Infrared solar physics from the South Pole

    Science.gov (United States)

    Deming, Drake

    1989-01-01

    Infrared (IR) observations of the sun could greatly benefit from the quality of the South Pole as an IR site, and the potential for multi-day sequences of uninterrupted observations. A nearly continuous picture of the evolution of the magnetic field in solar active regions could be obtained using vector magnetographs, especially vector magnetographs which incorporate IR array detectors. Observations of the sun over a range of wavelengths in the IR continuum could also be used to study the vertical propagation characteristics of the solar p-mode oscillations.

  15. Complex conjugate poles and parton distributions

    International Nuclear Information System (INIS)

    Tiburzi, B.C.; Detmold, W.; Miller, G.A.

    2003-01-01

    We calculate parton and generalized parton distributions in Minkowski space using a scalar propagator with a pair of complex conjugate poles. Correct spectral and support properties are obtained only after careful analytic continuation from Euclidean space. Alternately the quark distribution function can be calculated from modified cutting rules, which put the intermediate state on its complex mass shells. Distribution functions agree with those resulting from the model's Euclidean space double distribution which we calculate via nondiagonal matrix elements of twist-two operators. Thus one can use a wide class of analytic parametrizations of the quark propagator to connect Euclidean space Green functions to light-cone dominated amplitudes

  16. Superconductive analogue of spin glasses

    International Nuclear Information System (INIS)

    Feigel'man, M.; Ioffe, L.; Vinokur, V.; Larkin, A.

    1987-07-01

    The properties of granular superconductors in magnetic fields, namely the existence of a new superconductive state analogue of the low-temperature superconductive state in spin glasses are discussed in the frame of the infinite-range model and the finite-range models. Experiments for elucidation of spin-glass superconductive state in real systems are suggested. 30 refs

  17. Quenches in large superconducting magnets

    International Nuclear Information System (INIS)

    Eberhard, P.H.; Alston-Garnjost, M.; Green, M.A.; Lecomte, P.; Smits, R.G.; Taylor, J.D.; Vuillemin, V.

    1977-08-01

    The development of large high current density superconducting magnets requires an understanding of the quench process by which the magnet goes normal. A theory which describes the quench process in large superconducting magnets is presented and compared with experimental measurements. The use of a quench theory to improve the design of large high current density superconducting magnets is discussed

  18. On anyon superconductivity--

    International Nuclear Information System (INIS)

    Chen, Y.-H.; Wilczek, F.; Witten, E.; Halperin, B.I.

    1989-01-01

    We investigate the statistical mechanics of a gas of fractional statistics particles in 2 + 1 dimensions. In the case of statistics very close to Fermi statistics (statistical parameter θ = π(1 - 1/n), for large n), the effect of the statistics is a weak attraction. Building upon earlier RPA calculation for the case n = 2, the authors argue that for large n perturbation theory is reliable and exhibits superfluidity (or superconductivity after coupling to electromagnetism). They describe the order parameter for this superconductng phase in terms of spontaneous breaking of commutativity of translations as opposed to the usual pairing order parameters. The vortices of the superconducting anyon gas are charged, and superconducting order parameters of the usual type vanish. They investigate the characteristic P and T violating phenomenology

  19. Connectivity and superconductivity

    CERN Document Server

    Rubinstein, Jacob

    2000-01-01

    The motto of connectivity and superconductivity is that the solutions of the Ginzburg--Landau equations are qualitatively influenced by the topology of the boundaries, as in multiply-connected samples. Special attention is paid to the "zero set", the set of the positions (also known as "quantum vortices") where the order parameter vanishes. The effects considered here usually become important in the regime where the coherence length is of the order of the dimensions of the sample. It takes the intuition of physicists and the awareness of mathematicians to find these new effects. In connectivity and superconductivity, theoretical and experimental physicists are brought together with pure and applied mathematicians to review these surprising results. This volume is intended to serve as a reference book for graduate students and researchers in physics or mathematics interested in superconductivity, or in the Schrödinger equation as a limiting case of the Ginzburg--Landau equations.

  20. Superconducting linac booster

    International Nuclear Information System (INIS)

    Srinivasan, B.; Betigeri, M.G.; Pandey, M.K.; Pillay, R.G.; Kurup, M.B.

    1997-01-01

    The report on superconducting LINAC booster, which is a joint project of Bhabha Atomic Research Centre (BARC) and Tata Institute of Fundamental Research (TIFR), brings out the work accomplished so far towards the development of the technology of superconducting LINAC to boost the energy of ions from the 14UD Pelletron. The LINAC is modular in construction with each module comprising of a helium cryostat housing four lead-plated quarter wave resonators. The resonators are superconducting for temperatures below 7.19K. An energy boost of 2 MeV/q per module is expected to be achieved. The first module and the post-tandem superbuncher have been fabricated and tested on the LINAC beam line. This report gives a summary of the technological achievements and also brings out the difficulties encountered during the R and D phase. (author)

  1. Superconducting accelerator magnet design

    International Nuclear Information System (INIS)

    Wolff, S.

    1994-01-01

    Superconducting dipoles, quadrupoles and correction magnets are necessary to achieve the high magnetic fields required for big accelerators presently in construction or in the design phase. Different designs of superconducting accelerator magnets are described and the designs chosen at the big accelerator laboratories are presented. The most frequently used cosθ coil configuration is discussed in detail. Approaches for calculating the magnetic field quality including coil end fields are presented. Design details of the cables, coils, mechanical structures, yokes, helium vessels and cryostats including thermal radiation shields and support structures used in superconducting magnets are given. Necessary material properties are mentioned. Finally, the main results of magnetic field measurements and quench statistics are presented. (orig.)

  2. Large Superconducting Magnet Systems

    CERN Document Server

    Védrine, P.

    2014-07-17

    The increase of energy in accelerators over the past decades has led to the design of superconducting magnets for both accelerators and the associated detectors. The use of Nb−Ti superconducting materials allows an increase in the dipole field by up to 10 T compared with the maximum field of 2 T in a conventional magnet. The field bending of the particles in the detectors and generated by the magnets can also be increased. New materials, such as Nb$_{3}$Sn and high temperature superconductor (HTS) conductors, can open the way to higher fields, in the range 13–20 T. The latest generations of fusion machines producing hot plasma also use large superconducting magnet systems.

  3. Superconducting super collider

    International Nuclear Information System (INIS)

    Limon, P.J.

    1987-01-01

    The Superconducting Super Collider is to be a 20 TeV per beam proton-proton accelerator and collider. Physically the SCC will be 52 miles in circumference and slightly oval in shape. The use of superconducting magnets instead of conventional cuts the circumference from 180 miles to the 52 miles. The operating cost of the SCC per year is estimated to be about $200-250 million. A detailed cost estimate of the project is roughly $3 billion in 1986 dollars. For the big collider ring, the technical cost are dominated by the magnet system. That is why one must focus on the cost and design of the magnets. Presently, the process of site selection is underway. The major R and D efforts concern superconducting dipoles. The magnets use niobium-titanium as a conductor stabilized in a copper matrix. 10 figures

  4. Crystalline color superconductivity

    International Nuclear Information System (INIS)

    Alford, Mark; Bowers, Jeffrey A.; Rajagopal, Krishna

    2001-01-01

    In any context in which color superconductivity arises in nature, it is likely to involve pairing between species of quarks with differing chemical potentials. For suitable values of the differences between chemical potentials, Cooper pairs with nonzero total momentum are favored, as was first realized by Larkin, Ovchinnikov, Fulde, and Ferrell (LOFF). Condensates of this sort spontaneously break translational and rotational invariance, leading to gaps which vary periodically in a crystalline pattern. Unlike the original LOFF state, these crystalline quark matter condensates include both spin-zero and spin-one Cooper pairs. We explore the range of parameters for which crystalline color superconductivity arises in the QCD phase diagram. If in some shell within the quark matter core of a neutron star (or within a strange quark star) the quark number densities are such that crystalline color superconductivity arises, rotational vortices may be pinned in this shell, making it a locus for glitch phenomena

  5. Large Superconducting Magnet Systems

    Energy Technology Data Exchange (ETDEWEB)

    Védrine, P [Saclay (France)

    2014-07-01

    The increase of energy in accelerators over the past decades has led to the design of superconducting magnets for both accelerators and the associated detectors. The use of Nb−Ti superconducting materials allows an increase in the dipole field by up to 10 T compared with the maximum field of 2 T in a conventional magnet. The field bending of the particles in the detectors and generated by the magnets can also be increased. New materials, such as Nb3Sn and high temperature superconductor (HTS) conductors, can open the way to higher fields, in the range 13–20 T. The latest generations of fusion machines producing hot plasma also use large superconducting magnet systems.

  6. Design of a portable CAT scanner for utility pole inspection

    International Nuclear Information System (INIS)

    Miller, W.H.

    1986-01-01

    Work is under way at the University of Missouri, Columbia (UMC) to design, build, and test a portable computerized axial tomography (CAT) device for the nondestructive, field imaging of wooden utility poles. CAT is a well-established medical technology that has recently been applied to a number of industrial applications. Wooden utility poles are prone to rot and decay at ground level; current techniques to assess this loss of strength are relatively primitive, i.e., tapping the pole (hitting the pole with a hammer) or boring into the pole for samples and then testing inside the bore hole with an electrical pulse device. The accuracy in identifying poles needing replacement using these techniques is ∼ 70%. Since the cost of replacing a pole ranges from hundreds to thousands of dollars, an accurate, nondestructive method is needed. CAT can accurately image a wooden utility pole (since the size, density, and atomic elements of a pole are similar to the human head to torso), as was confirmed by imaging poles using the UMC nuclear engineering EMI-1010 medical scanner. Detailed images have been produced showing the ring structure of the wood and voids due to rot or decay. Images approaching this quality have also been produced on living trees using semiportable systems by other researchers

  7. Synthesis and characterization of superconducting bismuthates

    International Nuclear Information System (INIS)

    Tang, Horngyi.

    1991-01-01

    A new electrosynthetic technique for low-temperature crystal growth of superconducting bismuthates was developed, and its utility demonstrated by growing various high-quality BiO 3 crystals. The crystals of Ba 1-x K x BiO 3 and Ba 1-x Rb x BiO 3 display their T c onset at 31.8k and 28k, respectively, using SQUID magnetometry. The structure of a KBiO 3 x H 2 O single crystal determined by single crystal x-ray diffraction confirms previous results from powder samples that it is isostructural with KSbO 3 . The crystals of Ba 1-x Cs x BiO 3 do not show superconductivity to 4k. Chemical vapor-transport experiments leading to the fabrication of MoS 2 /WSe 2 junctions were also performed and are described in detail

  8. Superconductivity in few-layer stanene

    Science.gov (United States)

    Liao, Menghan; Zang, Yunyi; Guan, Zhaoyong; Li, Haiwei; Gong, Yan; Zhu, Kejing; Hu, Xiao-Peng; Zhang, Ding; Xu, Yong; Wang, Ya-Yu; He, Ke; Ma, Xu-Cun; Zhang, Shou-Cheng; Xue, Qi-Kun

    2018-04-01

    A single atomic slice of α-tin—stanene—has been predicted to host the quantum spin Hall effect at room temperature, offering an ideal platform to study low-dimensional and topological physics. Although recent research has focused on monolayer stanene, the quantum size effect in few-layer stanene could profoundly change material properties, but remains unexplored. By exploring the layer degree of freedom, we discover superconductivity in few-layer stanene down to a bilayer grown on PbTe, while bulk α-tin is not superconductive. Through substrate engineering, we further realize a transition from a single-band to a two-band superconductor with a doubling of the transition temperature. In situ angle-resolved photoemission spectroscopy (ARPES) together with first-principles calculations elucidate the corresponding band structure. The theory also indicates the existence of a topologically non-trivial band. Our experimental findings open up novel strategies for constructing two-dimensional topological superconductors.

  9. Superconducting Quadrupole for the ISR High Luminosity insertion:end view

    CERN Multimedia

    1977-01-01

    Connection end view of the prototype quadrupole before insertion of the inner vacuum chamber with inbedded 6-pole windings. The main components of the structure can be seen: (from inside outwards) the superconducting quadrupole coils surrounded by glass epoxy bandage rings and stainless steel spacers, the low-carbon steel yoke quadrants and the aluminium alloy shrinking rings. See also photos 7702690X, 7702307, 7702308, 7812604X.

  10. Superconducting Quadrupoles for the ISR High Luminosity insertion Coil cross section

    CERN Multimedia

    1978-01-01

    This picture shows a cut out section of an ISR High Luminosity (low beta) Quadrupole. One can clearly see the distribution of conductors and spacers which produces the wanted quadrupolar field. The spacers are made of pure copper and the central pole of stainless steel.The superconducting wire may be seen in photo 8008591X. See also pictures 7702690X, 8008591X, 7702698X.

  11. Superconducting current generators

    International Nuclear Information System (INIS)

    Genevey, P.

    1970-01-01

    After a brief summary of the principle of energy storage and liberation with superconducting coils,two current generators are described that create currents in the range 600 to 1400 A, used for two storage experiments of 25 kJ and 50 kJ respectively. The two current generators are: a) a flux pump and b) a superconducting transformer. Both could be developed into more powerful units. The study shows the advantage of the transformer over the flux pump in order to create large currents. The efficiencies of the two generators are 95 per cent and 40 to 60 per cent respectively. (author) [fr

  12. Materials for superconducting cavities

    International Nuclear Information System (INIS)

    Bonin, B.

    1996-01-01

    The ideal material for superconducting cavities should exhibit a high critical temperature, a high critical field, and, above all, a low surface resistance. Unfortunately, these requirements can be conflicting and a compromise has to be found. To date, most superconducting cavities for accelerators are made of niobium. The reasons for this choice are discussed. Thin films of other materials such as NbN, Nb 3 Sn, or even YBCO compounds can also be envisaged and are presently investigated in various laboratories. It is shown that their success will depend critically on the crystalline perfection of these films. (author)

  13. Today's markets for superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    The worldwide market for superconductive products may exceed $1 billion in 1987. These products are expanding the frontiers of science, revolutionizing the art of medical diagnosis, and developing the energy technology of the future. In general, today's customers for superconductive equipment want the highest possible performance, almost regardless of cost. The products operate within a few degrees of absolute zero, and virtually all are fabricated from niobium or niobium alloys-so far the high-temperature superconductors discovered in 1986 and 1987 have had no impact on these markets. The industry shows potential and profound societal impact, even without the new materials

  14. Gambling with Superconducting Fluctuations

    Science.gov (United States)

    Foltyn, Marek; Zgirski, Maciej

    2015-08-01

    Josephson junctions and superconducting nanowires, when biased close to superconducting critical current, can switch to a nonzero voltage state by thermal or quantum fluctuations. The process is understood as an escape of a Brownian particle from a metastable state. Since this effect is fully stochastic, we propose to use it for generating random numbers. We present protocol for obtaining random numbers and test the experimentally harvested data for their fidelity. Our work is prerequisite for using the Josephson junction as a tool for stochastic (probabilistic) determination of physical parameters such as magnetic flux, temperature, and current.

  15. Superconducting cosmic strings

    International Nuclear Information System (INIS)

    Chudnovsky, E.M.; Field, G.B.; Spergel, D.N.; Vilenkin, A.

    1986-01-01

    Superconducting loops of string formed in the early Universe, if they are relatively light, can be an important source of relativistic particles in the Galaxy. They can be observed as sources of synchrotron radiation at centimeter wavelengths. We propose a string model for two recently discovered radio sources, the ''thread'' in the galactic center and the source G357.7-0.1, and predict that the filaments in these sources should move at relativistic speeds. We also consider superheavy superconducting strings, and the possibility that they be observed as extragalactic radio sources

  16. Superconducting Electronic Film Structures

    Science.gov (United States)

    1991-02-14

    Segmuller, A., Cooper, E.I., Chisholm, M.F., Gupta, A. Shinde, S., and Laibowitz, R.B. Lanthanum gallate substrates for epitaxial high-T superconducting thin...M. F. Chisholm, A. Gupta, S. Shinde, and R. B. Laibowitz, " Lanthanum Gallate Substrates for Epitaxial High-T c Superconducting Thin Films," Appl...G. Forrester and J. Talvacchio, " Lanthanum Copper Oxide Buffer Layers for Growth of High-T c Superconductor Films," Disclosure No. RDS 90-065, filed

  17. Superconductivity in doped semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bustarret, E., E-mail: Etienne.bustarret@neel.cnrs.fr

    2015-07-15

    A historical survey of the main normal and superconducting state properties of several semiconductors doped into superconductivity is proposed. This class of materials includes selenides, tellurides, oxides and column-IV semiconductors. Most of the experimental data point to a weak coupling pairing mechanism, probably phonon-mediated in the case of diamond, but probably not in the case of strontium titanate, these being the most intensively studied materials over the last decade. Despite promising theoretical predictions based on a conventional mechanism, the occurrence of critical temperatures significantly higher than 10 K has not been yet verified. However, the class provides an enticing playground for testing theories and devices alike.

  18. Technology of RF superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    This work has several parts, two of which are collaborative development projects with the majority of the work being performed at Argonne. The first is the development of a superconducting RFQ structure in collaboration with AccSys Technology Inc. of Pleasanton, California, funded as a Phase II SBIR grant. Another is a collaborative project with the Nuclear Science Centre, New Delhi, India (who are funding the work) to develop new superconducting ion accelerating structures. Other initiatives are developing various aspects of the technology required to utilize ATLAS as a secondary beam linac for radioactive beams

  19. Anomalous electron doping independent two-dimensional superconductivity

    Science.gov (United States)

    Zhou, Wei; Xing, Xiangzhuo; Zhao, Haijun; Feng, Jiajia; Pan, Yongqiang; Zhou, Nan; Zhang, Yufeng; Qian, Bin; Shi, Zhixiang

    2017-07-01

    Transition metal (Co and Ni) co-doping effects are investigated on an underdoped Ca0.94La0.06Fe2As2 compound. It is discovered that electron doping from substituting Fe with transition metal (TM = Co, Ni) can trigger high-{T}{{c}} superconductivity around 35 K, which emerges abruptly before the total suppression of the innate spin-density-wave/anti-ferromagnetism (SDW/AFM) state. Remarkably, the critical temperature for the high-{T}{{c}} superconductivity remains constant against a wide range of TM doping levels. And the net electron doping density dependence of the superconducting {T}{{c}} based on the rigid band model can be nicely scaled into a single curve for Co and Ni substitutions, in stark contrast to the case of Ba(Fe1-x TM x )2As2. This carrier density independent superconductivity and the unusual scaling behavior are presumably resulted from the interface superconductivity based on the similarity with the interface superconductivity in a La2-x Sr x CuO4-La2CuO4 bilayer. Evidence of the two-dimensional character of the superfluid by angle-resolved magneto-resistance measurements can further strengthen the interface nature of the high-{T}{{c}} superconductivity.

  20. The Pole Orientation, Pole Precession, and Moment of Inertia Factor of Saturn

    Science.gov (United States)

    Jacobson, R. A.; French, R. G.; Nicholson, P. D.; Hedman, M.; Colwell, J. E.; Marouf, E.; Rappaport, N.; McGhee, C.; Sepersky, T.; Lonergan, K.

    2011-01-01

    This paper discusses our determination of the Saturn's pole orientation and precession using a combination of Earthbased and spacecraft based observational data. From our model of the polar motion and the observed precession rate we obtain a value for Saturn's polar moment of inertia

  1. High Accelerating Field Superconducting Radio Frequency Cavities

    Science.gov (United States)

    Orr, R. S.; Saito, K.; Furuta, F.; Saeki, T.; Inoue, H.; Morozumi, Y.; Higo, T.; Higashi, Y.; Matsumoto, H.; Kazakov, S.; Yamaoka, H.; Ueno, K.; Sato, M.

    2008-06-01

    We have conducted a study of a series of single cell superconducting RF cavities at KEK. These tests were designed to investigate the effect of surface treatment on the maximum accelerating field attainable. All of these cavities are of the ICHIRO shape, based on the Low Loss shape. Our results indicate that accelerating fields as high as the theoretical maximum of 50MV/m are attainable.

  2. Superconducting niobium in high rf magnetic fields

    International Nuclear Information System (INIS)

    Mueller, G.

    1988-01-01

    The benefit of superconducting cavities for accelerator applications depends on the field and Q/sub 0/ levels which can be achieved reliably in mass producible multicell accelerating structures. The presently observed field and Q/sub 0/ limitations are caused by anomalous loss mechanisms which are not correlated with the intrinsic properties of the pure superconductor but rather due to defects or contaminants on the superconducting surface. The ultimate performance levels of clean superconducting cavities built from pure Nb will be given by the rf critical field and the surface resistance of the superconductor. In the first part of this paper a short survey is given of the maximum surface magnetic fields achieved in single-cell cavities. The results of model calculations for the thermal breakdown induced by very small defects and for the transition to the defect free case is discussed in part 2. In the last chapter, a discussion is given for the rf critical field of Nb on the basis of the Ginzburg-Landau Theory. It is shown that not only purity but also the homogeneity of the material should become important for the performance of superconducting Nb cavities at field levels beyond 100mT. Measurement results of the upper critical field for different grades of commercially available Nb sheet materials are given. 58 references, 20 figures, 1 table

  3. Design of a High-Throughput Biological Crystallography Beamline for Superconducting Wiggler

    International Nuclear Information System (INIS)

    Tseng, P.C.; Chang, C.H.; Fung, H.S.; Ma, C.I.; Huang, L.J.; Jean, Y.C.; Song, Y.F.; Huang, Y.S.; Tsang, K.L.; Chen, C.T.

    2004-01-01

    We are constructing a high-throughput biological crystallography beamline BL13B, which utilizes the radiation generated from a 3.2 Tesla, 32-pole superconducting multipole wiggler, for multi-wavelength anomalous diffraction (MAD), single-wavelength anomalous diffraction (SAD), and other related experiments. This beamline is a standard double crystal monochromator (DCM) x-ray beamline equipped with a collimating mirror (CM) and a focusing mirror (FM). Both the CM and FM are one meter long and made of Si substrate, and the CM is side-cooled by water. Based on detailed thermal analysis, liquid nitrogen (LN2) cooling for both crystals of the DCM has been adopted to optimize the energy resolution and photon beam throughput. This beamline will deliver, through a 100 μm diameter pinhole, photon flux of greater than 1011 photons/sec in the energy range from 6.5 keV to 19 keV, which is comparable to existing protein crystallography beamlines from bending magnet source at high energy storage rings

  4. 5.7  W cw single-frequency laser at 671  nm by single-pass second harmonic generation of a 17.2  W injection-locked 1342  nm Nd : YVO4 ring laser using periodically poled MgO : LiNbO3.

    Science.gov (United States)

    Koch, Peter; Ruebel, Felix; Bartschke, Juergen; L'huillier, Johannes A

    2015-11-20

    We demonstrate a continuous wave single-frequency laser at 671.1 nm based on a high-power 888 nm pumped Nd:YVO4 ring laser at 1342.2 nm. Unidirectional operation of the fundamental ring laser is achieved with the injection-locking technique. A Nd:YVO4 microchip laser serves as the injecting seed source, providing a tunable single-frequency power of up to 40 mW. The ring laser emits a single-frequency power of 17.2 W with a Gaussian beam profile and a beam propagation factor of M2beam profile and a beam propagation factor of M2lasers. This work opens possibilities in cold atoms experiments with lithium, allowing the use of larger ensembles in magneto-optical traps or higher diffraction orders in atomic beam interferometers.

  5. Superconducting flux flow digital circuits

    International Nuclear Information System (INIS)

    Martens, J.S.; Zipperian, T.E.; Hietala, V.M.; Ginley, D.S.; Tigges, C.P.; Phillips, J.M.; Siegal, M.P.

    1993-01-01

    The authors have developed a family of digital logic circuits based on superconducting flux flow transistors that show high speed, reasonable signal levels, large fan-out, and large noise margins. The circuits are made from high-temperature superconductors (HTS) and have been shown to operate at over 90 K. NOR gates have been demonstrated with fan-outs of more than 5 and fully loaded switching times less than a fixture-limited 50 ps. Ring-oscillator data suggest inverter delay times of about 40ps when using a 3-μm linewidths. Simple flip-flops have also been demonstrated showing large noise margins, response times of less than 30 ps, and static power dissipation on the order of 30 nW. Among other uses, this logic family is appropriate as an interface between logic families such as single flux quantum and conventional semiconductor logic

  6. Design study of high-temperature superconducting generators for wind power systems

    Energy Technology Data Exchange (ETDEWEB)

    Maki, N [Technova Inc. 13th Fl. Imperial Hotel Tower, 1-chome, Chiyoda-ku, Tokyo 100-0011 (Japan)], E-mail: naokmaki@technova.co.jp

    2008-02-15

    Design study on high-temperature superconducting machines (HTSM) for wind power systems was carried out using specially developed design program. Outline of the design program was shown and the influence of machine parameters such as pole number, rotor outer diameter and synchronous reactance on the machine performance was clarified. Three kinds of generator structure are considered for wind power systems and the HTSM operated under highly magnetic saturated conditions with conventional rotor and stator has better performance than the other types of HTSM. Furthermore, conceptual structure of 8 MW, 20 pole HTSM adopting salient-pole rotor as in the case of water turbine generators and race-truck shaped HTS field windings like Japanese Maglev was shown.

  7. Design study of high-temperature superconducting generators for wind power systems

    International Nuclear Information System (INIS)

    Maki, N

    2008-01-01

    Design study on high-temperature superconducting machines (HTSM) for wind power systems was carried out using specially developed design program. Outline of the design program was shown and the influence of machine parameters such as pole number, rotor outer diameter and synchronous reactance on the machine performance was clarified. Three kinds of generator structure are considered for wind power systems and the HTSM operated under highly magnetic saturated conditions with conventional rotor and stator has better performance than the other types of HTSM. Furthermore, conceptual structure of 8 MW, 20 pole HTSM adopting salient-pole rotor as in the case of water turbine generators and race-truck shaped HTS field windings like Japanese Maglev was shown

  8. Multiple pole in the electron--hydrogen-atom scattering amplitude

    International Nuclear Information System (INIS)

    Amusia, M.Y.; Kuchiev, M.Y.

    1982-01-01

    It is demonstrated that the amplitude for electron--hydrogen-atom forward scattering has the third-order pole at the point E = -13.6 eV, E being the energy of the incident electron. The coefficients which characterize the pole are calculated exactly. The invalidity of the Born approximation is proved. The contribution of the pole singularity to the dispersion relation for the scattering amplitude is discussed

  9. Inhomogeneous superconductivity in a ferromagnet

    International Nuclear Information System (INIS)

    Kontos, T.; Aprili, M.; Lesueur, J.; Genet, F.; Boursier, R.; Grison, X.

    2003-01-01

    We have studied a new superconducting state where the condensate wave function resulting from conventional pairing, is modified by an exchange field. Superconductivity is induced into a ferromagnetic thin film (F) by the proximity effect with a superconducting reservoir (S). We observed oscillations of the superconducting order parameter induced in F as a function of the distance from the S/F interface. They originate from the finite momentum transfer provided to Cooper pairs by the splitting of the spin up and down bands. We measured the superconducting density of states in F by tunneling spectroscopy and the Josephson critical current when F is coupled with a superconducting counter-electrode. Negative values of the superconducting order parameter are revealed by capsized tunneling spectra in F and a negative Josephson coupling (π-junction)

  10. Superconductivity and magnet technology

    International Nuclear Information System (INIS)

    Lubell, M.S.

    1975-01-01

    The background theory of superconducting behavior is reviewed. Three parameters that characterize superconducting materials with values of commercial materials as examples are discussed. More than 1000 compounds and alloy systems and 26 elements are known to exhibit superconducting properties under normal conditions at very low temperatures. A wide variety of crystal structures are represented among the known superconductors. The most important ones do seem to have cubic symmetry such as the body-centered cubic (NbZr and NbTi), face-centered cubic (NbN), and the A15 or β-tungsten structures (Nb 3 Sn), V 3 Ga, Nb 3 Ge, Nb 3 Al, and V 3 Si). Attempts to understand some of the particular phenomena associated with superconductors as a necessary prelude to constructing superconducting magnets are discussed by the author. The origin of degradation is briefly discussed and methods to stabilize magnets are illustrated. The results of Oak Ridge National Laboratory design studies of toroidal magnet systems for fusion reactors are described

  11. Forecasting of superconducting compounds

    International Nuclear Information System (INIS)

    Savitskii, E.M.; Gribulya, V.G.; Kiseleva, N.N.

    1981-01-01

    In forecasting new superconducting intermetallic compounds of the A15 and Mo 3 Se types most promising from the viewpoint of high critical temperature Tsub(c), high critical magnetic fields Hsub(c), and high critical currents and in estimating their transition temperature it is proposed to apply cybernetic methods of computer learning

  12. Superconducting Super Collider project

    International Nuclear Information System (INIS)

    Perl, M.L.

    1986-04-01

    The scientific need for the Superconducting Super Collider (SSC) is outlined, along with the history of the development of the SSC concept. A brief technical description is given of each of the main points of the SSC conceptual design. The construction cost and construction schedule are discussed, followed by issues associated with the realization of the SSC. 8 refs., 3 figs., 3 tabs

  13. Checking BEBC superconducting magnet

    CERN Multimedia

    CERN PhotoLab

    1974-01-01

    The superconducting coils of the magnet for the 3.7 m Big European Bubble Chamber (BEBC) had to be checked, see Annual Report 1974, p. 60. The photo shows a dismantled pancake. By December 1974 the magnet reached again the field design value of 3.5 T.

  14. Niobium superconducting cavity

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.

  15. Superconducting magnets 1992

    International Nuclear Information System (INIS)

    1993-06-01

    This report discusses the following topics on Superconducting Magnets; SSC Magnet Industrialization; Collider Quadrupole Development; A Record-Setting Magnet; D20: The Push Beyond 10T; Nonaccelerator Applications; APC Materials Development; High-T c at Low Temperature; Cable and Cabling-Machine Development; and Analytical Magnet Design

  16. LHC superconducting strand

    CERN Multimedia

    Patrice Loiez

    1999-01-01

    This cross-section through a strand of superconducting matieral as used in the LHC shows the 8000 Niobium-Titanium filaments embedded like a honeycomb in copper. When cooled to 1.9 degrees above absolute zero in the LHC accelerator, these filaments will have zero resistance and so will carry a high electric current with no energy loss.

  17. Electrical Conduction and Superconductivity

    Indian Academy of Sciences (India)

    When an electric field is applied, this electron can be lifted to this higher energy ... By such a virtual process two electrons .... using superconducting coils has come to be a reality. ... nance imaging techniques used in medical diagnostics. Com ...

  18. Superconducting magnets for HERA

    International Nuclear Information System (INIS)

    Wolff, S.

    1987-01-01

    The Hadron-Electron-Ring Accelerator (HERA) presently under construction at DESY, Hamburg, consists of an electron storage ring of 30 GeV and a proton storage ring of 820 GeV. Superconducting magnets are used for the proton ring. There are 416 superconducting bending magnets of 4.698 T central field and 8.824 m magnetic length, 224 superconducting quadrupoles of 91.2 T/m central gradient and many superconducting correction dipoles, quadrupoles and sextupoles. The main dipoles and quadrupoles consist of two-layer coils of 75 mm inner diameter clammed with aluminium (for the dipoles) or stainless steel laminations (for the quadrupoles). The collared coils are surrounded by a laminated cold iron yoke and supported inside a low loss cryostat. The protection system uses cold diodes to bypass the current around a quenching magnet. The magnets are cooled with one phase helium supplied by a 3 block central refrigeration system of 20 kW refrigeration power at 4.3 K. Two helium is returned through the magnets in good thermal contact with the one phase helium in the dipoles for temperature control. This paper describes the magnet system and gives the results obtained for prototype magnets

  19. LEP superconducting cavity

    CERN Multimedia

    1995-01-01

    Engineers work in a clean room on one of the superconducting cavities for the upgrade to the LEP accelerator, known as LEP-2. The use of superconductors allow higher electric fields to be produced so that higher beam energies can be reached.

  20. Gossamer superconductivity, new paradigm?

    Energy Technology Data Exchange (ETDEWEB)

    Won, Hyekyung [Department of Physics, Hallym University, Chuncheon 200-702 (Korea); Haas, Stephan; Parker, David [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Maki, Kazumi [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Max-Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden (Germany); Dora, Balazs [Department of Physics, Budapest University of Technology and Economics, 1521 Budapest (Hungary); Virosztek, Attila [Department of Physics, Budapest University of Technology and Economics, 1521 Budapest (Hungary); Research Institute for Solid State Physics and Optics, P.O. Box 49, 1525 Budapest (Hungary)

    2006-01-01

    We review our recent works on d-wave density wave (dDW) and gossamer superconductivity (i.e. d-wave superconductivity in the presence of dDW) in high-T{sub c} cuprates and CeCoIn{sub 5}. a) We show that both the giant Nernst effect and the angle dependent magnetoresistance (ADMR) in the pseudogap phases of the cuprates and CeCoIn{sub 5} are manifestations of dDW. b) The phase diagram of high-T{sub c} cuprates is understood in terms of mean field theory, which includes two order parameters {delta}{sub 1} and {delta}{sub 2}, where one order paremeter is from dDW and the other from d-wave superconductivity. c) In the optimally to the overdoped region we find the spatially periodic dDW, an analogue of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, becomes more stable. d) In the underdoped region where {delta}{sub 2}/{delta}{sub 1}<<1 the Uemera relation is obtained within the present model. We speculate that the gossamer superconductivity is at the heart of high-T{sub c} cuprate superconductors, the heavy-fermion superconductor CeCoIn{sub 5} and the organic superconductors {kappa}-(ET){sub 2}Cu(NCS){sub 2} and (TMTSF){sub 2}PF{sub 6}. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Superconductivity : Controlling magnetism

    NARCIS (Netherlands)

    Golubov, Alexandre Avraamovitch; Kupriyanov, Mikhail Yu.

    Manipulation of the magnetic state in spin valve structures by superconductivity has now been achieved, opening a new route for the development of ultra-fast cryogenic memories. Spintronics is a rapidly developing field that allows insight into fundamental spin-dependent physical properties and the

  2. High-temperature superconductivity

    International Nuclear Information System (INIS)

    Lynn, J.W.

    1990-01-01

    This book discusses development in oxide materials with high superconducting transition temperature. Systems with Tc well above liquid nitrogen temperature are already a reality and higher Tc's are anticipated. The author discusses how the idea of a room-temperature superconductor appears to be a distinctly possible outcome of materials research

  3. Magnetic levitation and superconductivity

    International Nuclear Information System (INIS)

    Albrecht, C.

    1989-01-01

    The paper explains the impressive advances made in the development of superconducting magnets, in cryogenic engineering, and in the development of drive and vehicle concepts in Japan in the period following termination of West German development work for the electrodynamical system (MLU 001, MLU 002). The potentials engineering due to the development of high-Tc superconductors are discussed. (orig./MM) [de

  4. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, G [Jefferson Lab (United States)

    2014-07-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  5. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  6. Comparison of two superconducting elliptical undulators for generating circularly polarized light

    Directory of Open Access Journals (Sweden)

    C. S. Hwang

    2004-09-01

    Full Text Available The potential use of two planar superconducting elliptical undulators—a vertically wound racetrack coil structure and a staggered array structure—to generate a circularly polarized hard x-ray source was investigated. The magnetic poles and wires of the up and down magnet arrays were rotated in alternating directions on the horizontal plane, an elliptical field is generated to provide circularly polarized light in the electron-storage ring and the energy-recovery linac accelerator. Rapid switching between right- and left-circularly polarized radiations is performed using two undulators with oppositely rotated wires and poles. Given a periodic length of 15 mm and a gap of 5 mm, the magnetic-flux densities in the elliptical undulator are B_{z}=1.2   T (B_{x}=0.6   T and B_{z}=0.35   T (B_{x}=0.15   T in the planar vertically wound racetrack coil and the staggered structure with poles rotated by 35° and 25°, respectively. In maximizing the merit of the flux and the width of the effective field region in the two superconducting elliptical undulators, the trade-off rotation angles of the coils and poles are 20° and 5°, for vertically wound racetrack coil and staggered undulators, respectively.

  7. Determination of the crystallite orientation distribution from direct pole figures

    International Nuclear Information System (INIS)

    Araujo Gomes, P.A.M. de.

    1977-01-01

    A method is described which allows to calculate the crystallite orientation distribution in polycrystalline material, from direct pole figures data of its crystallographic planes (Roe's Method). The programme was applied to (1010), (0002), (1011) and (1120) complete pole figures data for a commercial, thin sheet Zircaloy-4 tubing specimen. A semi-automatic Rigaku-Denki texture goniometer, which scans the reciprocal lattice sphere pointwise outputting the data in a punched tape, was used to obtain the pole figures. This is consistent with the results obtained through direct conclusion from the pole figures. (author)

  8. Thermal poling of multi-wire array optical fiber

    DEFF Research Database (Denmark)

    Huang, Lin; An, Honglin; Hayashi, Juliano G.

    2018-01-01

    We demonstrate in this paper thermal poling of multi-wire array fibers, which extends poling of fibers with two anodes to similar to 50 and similar to 500 wire array anodes. The second harmonic microscopy observations show that second order nonlinearity (SON) layers are developed surrounding all...... the rings of wires in the similar to 50 anode array fiber with poling of 1.8kV, 250 degrees C and 30min duration, and the outer rings of the similar to 500 anode array fiber at lower poling temperature. Our simulations based on a two-dimensional charge dynamics model confirm this can be explained...

  9. POLE mutations in families predisposed to cutaneous melanoma

    DEFF Research Database (Denmark)

    Aoude, Lauren G; Heitzer, Ellen; Johansson, Peter

    2015-01-01

    Germline mutations in the exonuclease domain of POLE have been shown to predispose to colorectal cancers and adenomas. POLE is an enzyme involved in DNA repair and chromosomal DNA replication. In order to assess whether such mutations might also predispose to cutaneous melanoma, we interrogated...... variants in the exonuclease domain of POLE. Although this frequency is not significantly higher than that in unselected Caucasian controls, we observed multiple cancer types in the melanoma families, suggesting that some germline POLE mutations may predispose to a broad spectrum of cancers, including...

  10. Generalized pole inflation: Hilltop, natural, and chaotic inflationary attractors

    Energy Technology Data Exchange (ETDEWEB)

    Terada, Takahiro, E-mail: takahiro.terada@apctp.org [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Asia Pacific Center for Theoretical Physics, Pohang 37673 (Korea, Republic of)

    2016-09-10

    A reformulation of inflationary model analyses appeared recently, in which inflationary observables are determined by the structure of a pole in the inflaton kinetic term rather than the shape of the inflaton potential. We comprehensively study this framework with an arbitrary order of the pole taking into account possible additional poles in the kinetic term or in the potential. Depending on the setup, the canonical potential becomes the form of hilltop or plateau models, variants of natural inflation, power-law inflation, or monomial/polynomial chaotic inflation. We demonstrate attractor behaviors of these models and compute corrections from the additional poles to the inflationary observables.

  11. South Pole Region of the Moon as Seen by Clementine

    Science.gov (United States)

    1994-01-01

    Lunar mosaic of 1500 Clementine images of the south polar region of the moon. The projection is orthographic, centered on the south pole. The Schrodinger Basin (320 km in diameter) is located in the lower right of the mosaic. Amundsen-Ganswindt is the more subdued circular basin between Schrodinger and the pole. The polar regions of the moon are of special interest because of the postulated occurrence of ice in permanently shadowed areas. The south pole is of greater interest because the area that remains in shadow is much larger than that at the north pole.

  12. Measurement and control of quasiparticle dynamics in a superconducting qubit.

    Science.gov (United States)

    Wang, C; Gao, Y Y; Pop, I M; Vool, U; Axline, C; Brecht, T; Heeres, R W; Frunzio, L; Devoret, M H; Catelani, G; Glazman, L I; Schoelkopf, R J

    2014-12-18

    Superconducting circuits have attracted growing interest in recent years as a promising candidate for fault-tolerant quantum information processing. Extensive efforts have always been taken to completely shield these circuits from external magnetic fields to protect the integrity of the superconductivity. Here we show vortices can improve the performance of superconducting qubits by reducing the lifetimes of detrimental single-electron-like excitations known as quasiparticles. Using a contactless injection technique with unprecedented dynamic range, we quantitatively distinguish between recombination and trapping mechanisms in controlling the dynamics of residual quasiparticle, and show quantized changes in quasiparticle trapping rate because of individual vortices. These results highlight the prominent role of quasiparticle trapping in future development of superconducting qubits, and provide a powerful characterization tool along the way.

  13. Fabrication of Superconducting Traction Transformer for Railway Rolling Stock

    International Nuclear Information System (INIS)

    Kamijo, H; Hata, H; Fujimoto, H; Inoue, A; Nagashima, K; Ikeda, K; Yamada, H; Sanuki, Y; Tomioka, A; Uwamori, K; Yoshida, S; Iwakuma, M; Funaki, K

    2006-01-01

    We designed a floor type single-phase 4 MVA superconducting traction transformer for Shinkansen rolling stock. In this study, we fabricated a prototype superconducting traction transformer based on this design. This transformer of the core-type design has a primary winding, four secondary windings and a tertiary winding. The windings are wound by Bi2223 superconducting tapes and cooled by subcooled liquid nitrogen. The core is kept at room temperature. The cryostat is made of GFRP with two holes to pass core legs through. The outer dimensions are about 1.2m x 0.7m x 1.9m excluding the compressor. Its weight is 1.71t excluding that of refrigerator and compressor. The transformer was tested according to Japanese Industrial Standards (JIS)-E5007. We confirmed that the performance of transformer has been achieved almost exactly as planned. The rated capacity is equivalent to 3.5MVA in the superconducting state

  14. Nematicity, magnetism and superconductivity in FeSe.

    Science.gov (United States)

    Böhmer, Anna E; Kreisel, Andreas

    2018-01-17

    Iron-based superconductors are well known for their complex interplay between structure, magnetism and superconductivity. FeSe offers a particularly fascinating example. This material has been intensely discussed because of its extended nematic phase, whose relationship with magnetism is not obvious. Superconductivity in FeSe is highly tunable, with the superconducting transition temperature, T c , ranging from 8 K in bulk single crystals at ambient pressure to almost 40 K under pressure or in intercalated systems, and to even higher temperatures in thin films. In this topical review, we present an overview of nematicity, magnetism and superconductivity, and discuss the interplay of these phases in FeSe. We focus on bulk FeSe and the effects of physical pressure and chemical substitutions as tuning parameters. The experimental results are discussed in the context of the well-studied iron-pnictide superconductors and interpretations from theoretical approaches are presented.

  15. Electronic structure and superconductivity of FeSe-related superconductors.

    Science.gov (United States)

    Liu, Xu; Zhao, Lin; He, Shaolong; He, Junfeng; Liu, Defa; Mou, Daixiang; Shen, Bing; Hu, Yong; Huang, Jianwei; Zhou, X J

    2015-05-13

    FeSe superconductors and their related systems have attracted much attention in the study of iron-based superconductors owing to their simple crystal structure and peculiar electronic and physical properties. The bulk FeSe superconductor has a superconducting transition temperature (Tc) of ~8 K and it can be dramatically enhanced to 37 K at high pressure. On the other hand, its cousin system, FeTe, possesses a unique antiferromagnetic ground state but is non-superconducting. Substitution of Se with Te in the FeSe superconductor results in an enhancement of Tc up to 14.5 K and superconductivity can persist over a large composition range in the Fe(Se,Te) system. Intercalation of the FeSe superconductor leads to the discovery of the AxFe2-ySe2 (A = K, Cs and Tl) system that exhibits a Tc higher than 30 K and a unique electronic structure of the superconducting phase. A recent report of possible high temperature superconductivity in single-layer FeSe/SrTiO3 films with a Tc above 65 K has generated much excitement in the community. This pioneering work opens a door for interface superconductivity to explore for high Tc superconductors. The distinct electronic structure and superconducting gap, layer-dependent behavior and insulator-superconductor transition of the FeSe/SrTiO3 films provide critical information in understanding the superconductivity mechanism of iron-based superconductors. In this paper, we present a brief review of the investigation of the electronic structure and superconductivity of the FeSe superconductor and related systems, with a particular focus on the FeSe films.

  16. Flexible ureterorenoscopy for lower pole stones: influence of the collecting system's anatomy.

    Science.gov (United States)

    Jessen, Jan Peter; Honeck, Patrick; Knoll, Thomas; Wendt-Nordahl, Gunnar

    2014-02-01

    The impact of renal anatomy on the success rate of flexible ureterorenoscopy (fURS) for lower pole stones is less clear than it is on shock wave lithotripsy, for which it is a recognized influence factor. We analyzed safety and efficiency of fURS using modern endoscopes for lower pole stones dependent on the collecting system's configuration. We retrospectively evaluated a consecutive sample of 111 fURS for lower pole stones at our tertiary care center between January 2010 and September 2012 from our prospectively kept database. All procedures were performed with modern flexible ureterorenoscopes, nitinol baskets, holmium laser lithotripsy, and ureteral access sheaths whenever needed. The infundibular length (IL) and width (IW) and infundibulopelvic angle (IPA) were measured and the data were stratified for stone-free status and complications classified by the Clavien-Dindo scale. Univariate and multifactorial statistical analyses were performed. Correlation of operation time (OR-time) with anatomical parameters was conducted. Ninety-eight (88.3%) of the 111 patients were stone free after a single fURS. On multifactorial analysis, the stone size and IL had significant influence on the stone-free rate (SFR) (panatomy. fURS is a safe and efficient treatment option for lower pole kidney stones. A long infundibulum and a very acute IPA (anatomy.

  17. Pole inflation in Jordan frame supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Saikawa, Ken' ichi [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Yamaguchi, Masahide [Tokyo Institute of Technology, Ookayama (Japan). Dept. of Physics; Yamashita, Yasuho [Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics; Yoshida, Daisuke [Montreal Univ., QC (Canada). Dept. of Physics

    2017-09-15

    We investigate inflation models in Jordan frame supergravity, in which an inflaton non-minimally couples to the scalar curvature. By imposing the condition that an inflaton would have the canonical kinetic term in the Jordan frame, we construct inflation models with asymptotically flat potential through pole inflation technique and discuss their relation to the models based on Einstein frame supergravity. We also show that the model proposed by Ferrara et al. has special position and the relation between the Kaehler potential and the frame function is uniquely determined by requiring that scalars take the canonical kinetic terms in the Jordan frame and that a frame function consists only of a holomorphic term (and its anti-holomorphic counterpart) for symmetry breaking terms. Our case corresponds to relaxing the latter condition.

  18. Performance of new generation pole light

    International Nuclear Information System (INIS)

    Foo, K C; Karunanithi, S; Thio, G

    2013-01-01

    This paper describes the design and implementation of a standalone photovoltaic power supply which caters for garden lighting scheme. New Generation Pole Light (NGPL) consists of three parts which are light dependent resistor (LDR) and pyroelectric infrared (PIR) sensors, microcontroller and light emitting diode (LED) and finally, solar charging system. During the night, LED is switched on with two operating modes which are ultra-bright lighting for a predetermine period (when human presence is detected) and dim lighting. Meanwhile, LED is switched off at day time and solar charging system will recover the capacity of discharged battery. NGPL provides portable, sustainable, environmental friendly and requires minimal maintenance for outdoor lighting scheme for both urban and rural areas.

  19. Retratos da metrópole parisiense

    OpenAIRE

    Saint-Julien, Thérèse; Goix, Renaud Le

    2009-01-01

    « La métropole parisienne, centralité, inégalité, proximité » propõe uma leitura e uma interpretação das tendências do território da Île de France (a região que inclui Paris e sete outros départements), ou seja, uma grande metrópole mundial de cerca de 11,3 milhões de habitantes em 2004, ligada às redes da globalização e da metropolização. O livro esboça os traços principais de suas estruturas territoriais emergentes, sublinha os desafios, o alcance dos mesmos e as contradições. Sem pretensão...

  20. Retratos da metrópole parisiense

    Directory of Open Access Journals (Sweden)

    Thérèse Saint-Julien

    2009-07-01

    Full Text Available « La métropole parisienne, centralité, inégalité, proximité » propõe uma leitura e uma interpretação das tendências do território da Île de France (a região que inclui Paris e sete outros départements, ou seja, uma grande metrópole mundial de cerca de 11,3 milhões de habitantes em 2004, ligada às redes da globalização e da metropolização. O livro esboça os traços principais de suas estruturas territoriais emergentes, sublinha os desafios, o alcance dos mesmos e as contradições. Sem pretensão...