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Sample records for bepc ii superconducting

  1. Heat transfer and thermal fluid calculation of superconducting quadrupole magnet in BEPC II

    International Nuclear Information System (INIS)

    A pair of interaction region superconducting quadrupole (SCQ) magnets in Beijing Electron-Positron Collider Upgrade (BEPC II) are key facilities cooled by liquid helium in the constrained cooling channels. The heat loads to the SCQ magnet and temperature contour of the magnet cryostat are calculated. Based on the calculation, the method to decrease the heat load is presented. The results of thermal fluid modeling for the magnet cryostat are also provided. Two types of cooling schemes, the subcooled liquid helium and the supercritical helium flow, are numerically analyzed. (authors)

  2. Numerical analyses on cooling process of superconducting insertion quadrupole magnets for BEPC II

    International Nuclear Information System (INIS)

    A pair of superconducting insertion quadrupole magnets (SCQ), and a superconducting solenoid magnets (SSM) were used in the Beijing Electron-Positron Collider Upgrade (BEPC II) in order to reduce the length of the beam, and to increase distinguish and identification ability of the particle. A cryogenic plant of 500 W at 4.5 K was to be built for the operation of the superconducting magnets. The paper described the cooling process for the SCQ and SSM magnets. Two kinds of cooling schemes for SCQ magnets, supercritical helium cooling and subcooled liquid helium cooling, were compared by numerical method. Thermal parameters of two kinds of cooling process were provided. Finally, the design of the subcooler, one of key components was presented. (authors)

  3. Study on the performance of the input coupler for the BEPC II superconducting RF cavity

    International Nuclear Information System (INIS)

    The input coupler for the accelerator cavity is one of the most critical parts in the RF accelerating system, its performance directly influences the RF power coupling to cavity, therefore, directly influences the cavity's quality. In the RF system of the BEPC II, an antenna coaxial input coupler based on the design of KEKB superconducting (SC) cavity's coupler will be used. It's first to use this kind of high power coupler under the frequency of 500 MHz in China. Some studies on this RF coupler have been done, which includes the multi-pacting (MP) effect, the transmission performance and the thermal layout simulation. The results show that (1) there are several serious MP points exist in this kind of coupler and some necessary ways must be taken to protect the coupler from destroying; (2) the transmission performance under BEPC II operation frequency can be improved by optimizing the configuration of the coupler; (3) the heat-distributing pattern of the coupler from the simulation provides the important information for the cooling system design. (authors)

  4. The development of OPC client in BEPC II

    International Nuclear Information System (INIS)

    The OPC technology is being widely used today. This paper describes the advantages and relative concepts of the OPC. The main purpose is discussing the design and development of the OPC client in BEPC II. (authors)

  5. Simulation of the electron cloud density in BEPC II

    International Nuclear Information System (INIS)

    Electron Cloud Instability (ECI) may take place in positron storage ring when the machine is operated with multi-bunch positron beam. According to the actual shape of the vacuum chamber in the BEPC II, a program has been developed. With the code, authors can calculate the electron density in the chamber with different length of antechamber and the different secondary electron yield respectively. By the simulation, the possibility to put clearing electrodes in the chamber to reduce the electron density in the central region of the chamber is investigated. The simulation provides meaningful and important results for the BEPC II project and electron cloud instability research

  6. Upgrade of Beam Energy Measurement System at BEPC-II

    CERN Document Server

    Zhang, Jian-Yong; Mo, Xiao-Hu; Guo, Di-Zhou; Wang, Jian-Li; Liu, Bai-Qi; Achasov, M N; Krasnov, A A; Muchnoi, N Yu; Pyata, E E; Mamoshkina, E V; Harris, F A

    2015-01-01

    The beam energy measurement system is of great importance and profit for both BEPC-II accelerator and BES-III detector. The system is based on measuring the energies of Compton back-scattered photons. Many advanced techniques and precise instruments are employed to realize the highly accurate measurement of positron/electron beam energy. During five year's running period, in order to meet the requirement of data taking and improve the capacity of measurement itself, the upgradation of system is continued, which involve the component reformation of laser and optics subsystem, replacement of view-port of the laser to vacuum insertion subsystem, the purchase of electric cooling system for high purity germanium detector, and the improvement of data acquisition and processing subsystem. The upgrading of system guarantees the smooth and efficient measuring of beam energy at BEPC-II and accommodates the accurate offline energy values for further physics analysis at BES-III.

  7. Upgrade of beam energy measurement system at BEPC-II

    Science.gov (United States)

    Zhang, Jian-Yong; Cai, Xiao; Mo, Xiao-Hu; Guo, Di-Zhou; Wang, Jian-Li; Liu, Bai-Qi; Achasov, M. N.; Krasnov, A. A.; Muchnoi, N. Yu.; Pyata, E. E.; Mamoshkina, E. V.; Harris, F. A.

    2016-07-01

    The beam energy measurement system is of great importance for both BEPC-II accelerator and BES-III detector. The system is based on measuring the energies of Compton back-scattered photons. In order to meet the requirements of data taking and improve the measurement accuracy, the system has continued to be upgraded, which involves the updating of laser and optics subsystems, replacement of a view-port of the laser to the vacuum insertion subsystem, the use of an electric cooling system for a high purity germanium detector, and improvement of the data acquisition and processing subsystem. The upgrade system guarantees the smooth and efficient measurement of beam energy at BEPC-II and enables accurate offline energy values for further physics analysis at BES-III. Supported in part by National Natural Science Foundation of China (NSFC)(11375206, 10775142, 10825524, 11125525, 11235011), the Ministry of Science and Technology of China (2015CB856700, 2015CB856705), State key laboratory of particle and detection and electronics; and the CAS Center for Excellence in Particle Physics (CCEPP); the RFBR grant(14-02-00129-a), U.S. Department of Energy (DE-FG02-04ER41291, DE-FG02-05ER41374, DE-FG02-94ER40823, DESC0010118), U.S. National Science Foundation, part of this work related to the design of ZnSe viewports is supported by the Russian Science Foundation (14-50-00080)

  8. Bunch gap signal picking-up in BEPC II

    International Nuclear Information System (INIS)

    A high speed circuit is designed for obtaining the BEPC II bunch fiducial signal based on tunnel diode circuit, monostable multivibrator and ECL logic technology. The bunch train with a gap in storage ring is described. The waveforms of the induced signal of the pickup electrode after long cable transmission decay are analyzed. A monostable multivibrator using tunnel diode is described, with which a positive pulse of 0.3 ns is stretched to a 4 ns ECL signal. The ways to find out gap in standard and non-standard injection mode are presented. The test result shows that the circuit works well in standard and non-standard bunch injection modes and the measured timing jitter of 80.49 ps(RMS) fits for the design. (authors)

  9. The beam energy calibration system for the BEPC-II collider

    CERN Document Server

    Achasov, M N; Mo, Xiaohu; Muchnoi, N Yu; Qin, Qing; Qu, Huamin; Wang, Yifang; Xu, Jinqiang

    2008-01-01

    This document contains a proposal of the BEPC-II collider beam energy calibration system (IHEP, Beijing). The system is based on Compton backscattering of carbon dioxide laser radiation, producing a beam of high energy photons. Their energy spectrum is then accurately measured by HPGe detector. The high-energy spectrum edge will allow to determine the average electron or positron beam energy with relative accuracy about 3x10^-5.

  10. Acceptance tests of the BEPC II RF transmitter and the circulator

    International Nuclear Information System (INIS)

    The high power RF transmitter and the circulator with 500 MHz/250 kW which will be operated in Beijing Electron-Positron Collider Upgrade (BEPC II) project have been installed on site, and adjustments and acceptance test have been finished, which is the first transmitter system of 500 MHz/250 kW in China. In this paper, the test principle and all measurements as well as commissioning result in the acceptance test are introduced in details, and the actual machine technical parameters and performance are presented. An acceptance test conclusion by comparing with the design requirements is given. (authors)

  11. Signal processing system for parallel plate ionization chamber at test beam of BEPC II

    International Nuclear Information System (INIS)

    A signal processing system has been designed in order to read out the electrode signals of 2D parallel plate ionization chamber at test beam facility of BEPC II. The system mainly includes that charge sensitive pre-amplifier, main-amplifier, analog to digital convertor and personal computer. Digital signals were recorded and displayed real time in histograms using data acquirement program based on Linux operating system. This signal processing system can be operated easily and has lower electronic noise and stable performance. (authors)

  12. Non-linear pressure rise with beam current in BEPC II positron ring

    International Nuclear Information System (INIS)

    It was found that the pressure-current curves were linear in electron ring, while non-linear in positron ring, especially in arc sections of positron ring. It might be since that the synchrotron photoelectrons transversely kicked by the positron beam bunches hit the vacuum chamber surface and the hit produces secondary electrons, which cause beam-induced multipacting (BIM) and large outgassing under some conditions. To find these conditions, bunch filling patterns of positron beams were changed to derive the corresponding non-linear pressure-current curves. The result is consistent with that from KEK-B low energy ring, which shows the non-linearity exhibits a threshold behavior. The non-linearity will take place only when the single bunch current and the quantity of the successive bunch in one train are both sufficiently large. With the total current increasing, BEPC II positron beam should take certain bunch filling patterns of smaller single bunch current and larger bunch number to avoid BIM. (authors)

  13. New BEPC interlock system

    International Nuclear Information System (INIS)

    A new interlock system for BEPC (Beijing Electron Positron Collider) has been developed in order to improve the reliability of the personal safety and the subsystem's interlocks. Another role of the system is to update the BEPC TV status screen once every 6 seconds. The hardware for the new interlock system is based on industrial Programmable logic controllers (PLC). By means of the PC-links, the interlock system is composed as a distributed control system. One inexpensive multimedia IBM/486 PC is used as the host computer of the PLCs. The application programs dedicated for the system is written in visual C++ language under Chinese MS-Windows. In case there is a failure in a subsystem, the message is displayed visually, supplemented by a voice message, which causes the operators to pay attention

  14. BEPC new interlock system

    International Nuclear Information System (INIS)

    A new interlock system for BEPC has been developed in order to improve the reliability of the personal safety and the subsystem's interlocks. Another role of the system is to update the BEPC TV status screen once very 6 seconds. The hardware for the new interlock system is based on industrial Programmable logic controllers (PLC). By means of the PC links, the interlock system is composed as a distributed control system. One inexpensive multimedia IBM/486 PC is used as the host computer of the PLCs. The application programs dedicated for the system is written in visual C++ language under Chinese MS-Windows. In case there is a failure in a sub-system, the message is displayed visually, supplemented by a voice message, which causes the operators to pay attention

  15. Superconductivity in energy technology II

    International Nuclear Information System (INIS)

    The conference on ''Superconductivity in energy technology II'' was held on May 10 and 11, 1995 in Munich and was jointly organised by the VDI society for energy technology, the Energietechnische Gesellschaft of VDI, and the Karlsruhe Research Center and Munich Technical University. This VDI report 1187 presents the full-text papers read at the conference, the focus being on the following aspects: (1) state of development of HT superconductors and conventional LT superconductors; (2) HT superconducting permanent magnets and current leads; (3) electrical energy transmission: cables and current limiters; (4) energy storage; (5) electrical machines; (6) electrical network loads; (7) superconductivity in nuclear fusion devices; (8) cryogenic engineering; (9) activities for the promotion of superconductivity. (orig./MM)

  16. Upgrading the BEPC control system

    International Nuclear Information System (INIS)

    The BEPC control system has been put into operation and operated normally since the end of 1987. Three years's experience shows this system can satisfy basically the operation requirements, also exhibits some disadvantages araised from the original centralized system architecture based on the VAX-VCC-CAMAC, such as slow response, bottle neck of VCC, less CPU power for control etc.. This paper describes the method and procedure for upgrading the BEPC control system which will be based on DEC net and DEC-WS, and thus intend to upgrade the control system architecture from the centralized to the distributed and improve the integral system performance. (author)

  17. Application software for new BEPC interlock system

    International Nuclear Information System (INIS)

    New BEPC (Beijing electron Positron collider) interlock system has been built in order to improve the reliability of personnel safety and interlock functions. Moreover, the system updates BEPC operation message once every 6 seconds, which are displayed on TV screens at the major entrances. Since March of 1996, new BEPC interlock system has been operating reliably. The hardware of the system is based on Programmable Logic Controllers (PLC). A multimedia IBM/PC-586 as the host computer of the PLCs, monitors the PLC system via serial port COM2. The PC communicates with the central computer VAX-4500 of BEPC control system and gets operating massage of the accelerator through serial port COM3. The application software on the host computer has been developed. Visual C++ for MS-Windows 3.2 TM is selected as the work bench. It provides nice tools for building programs, such as APP STUDIO, CLASS WIZARD, APP WIZARD and debugger tool. The author describes the design idea and the structure of the application software. Error tolerance is taken into consideration. The author also presents a small database and its data structure for the application

  18. Beijing Electron Positron Collider (BEPC) project

    International Nuclear Information System (INIS)

    BEPC is China's first high energy accelerator project which is being built to serve the dual purposes of carrying out particle physics studies on one hand and conducting synchrotron radiation experiments on the other. This project was formally approved at the end of 1983, and is scheduled to be completed at the end of 1988. Construction is in full swing. A brief account of the design, progress, and management of the project is presented

  19. 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).

  20. J/psi physics at BEPC

    International Nuclear Information System (INIS)

    J/psi physics is discussed which will be of interest at T > 1988, the period of operation of the Beijing Electron Positron Collider. Emphasis is placed on the gluonic states which are best studied in radiative J/psi decay. The difficulties of these studies are discussed and the need for very high statistics is stressed. In particular it is essential to partial-wave-analyze the hadronic final states produced in J/psi → γX. An estimate using fixed target data suggests that 0(108) J/psi decays are needed to do an unambiguous partial wave analysis for hadron masses up to about 2 GeV. This requirement is an excellent match to the BEPC design parameters, which imply production of 0(108) J/psi's per year. With a J/psi production rate an order of magnitude greater than other electron-positron storage rings, BEPC will be a unique world facility for these studies. 58 references

  1. Forced-flow gas cooled current leads for SCQ magnets in BEPC

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-bin; WANG Li; JIA Lin-xiang

    2007-01-01

    Current leads are used to connect the superconducting magnets in cryogenic temperature to the power station in room temperature. It is the main source of heat leak into the cryostat of magnets on static operation.This paperpresents the optimized methods of the leads for BEPC Ⅱ, and the effects of different cross section area on the heat leak, temperature profile as well as the voltage drop of the leads. The multi-tube structure is adopted and improved for the leads. The results of numerical simulation using CFD software package Fluent6.0 for the multi-tube-structure leads are presented, which can be used to improve the design of the leads.

  2. Magnetic pinning interaction of a type-II superconducting cylinder

    International Nuclear Information System (INIS)

    A model of the magnetic pinning interaction (i.e., a system of N-curved flux lines (FLs) and a cylindrical inclusion) has been developed. The field components inside and outside the inclusion have been calculated. The energy of the system and the magnetic pinning force are completely determined from the field distribution inside the superconductor. The properties of the curved FLs near the surface of a type-II superconducting cylinder have been established. The energy of the system as well as the magnetic field and the current density have been calculated. The force on a flux line (FL) element is completely determined by the total current density at the element position. (author)

  3. 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

  4. A test beam upgrade based on the BEPC-LINAC

    International Nuclear Information System (INIS)

    A total of three beam lines, E1, E2 and E3 have based on the LINAC of BEPC. The E1 beam is to be used for intense slow-positron facility. The E2 is a primary positron or electron beam with an energy of 1.3-1.5 GeV. The E3 is a secondary electron or pion test beam with a momentum can be adjustable continuously. The position accuracy of a detected particle is 0.2-0.4 mm with an event rate of 3 - 4 Hz. This beam has been successfully used for some detectors beam test. (author)

  5. Superconductivity

    International Nuclear Information System (INIS)

    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-Tc 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. BNL Direct Wind Superconducting Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Parker, B.; Anerella, M.; Escallier, J.; Ghosh, A.; Jain, A.; Marone, A.; Muratore, A.; Wanderer, P.

    2011-09-12

    BNL developed Direct Wind magnet technology is used to create a variety of complex multi-functional multi-layer superconducting coil structures without the need for creating custom production tooling and fixturing for each new project. Our Direct Wind process naturally integrates prestress into the coil structure so external coil collars and yokes are not needed; the final coil package transverse size can then be very compact. Direct Wind magnets are produced with very good field quality via corrections applied during the course of coil winding. The HERA-II and BEPC-II Interaction Region (IR) magnet, J-PARC corrector and Alpha antihydrogen magnetic trap magnets and our BTeV corrector magnet design are discussed here along with a full length ILC IR prototype magnet presently in production and the coils that were wound for an ATF2 upgrade at KEK. A new IR septum magnet design concept for a 6.2 T combined-function IR magnet for eRHIC, a future RHIC upgrade, is introduced here.

  7. Dynamical states of a system due to localized wake forces in a BEPC storage ring

    CERN Document Server

    Nam, S K; Zhang, C; Kim, E S

    1999-01-01

    We examine the dynamical states of a system in the storage ring of the Beijing electron-positron collider (BEPC) by using an extended model with the combination of a constant wake and a delta wake function. The influences of parameters on the stable equilibrium states and the transitions of the states in the BEPC ring are also investigated by using a new extended model with a constant wake function and a delta wake function.

  8. The cosmic ray test of BEPC II luminosity monitor

    International Nuclear Information System (INIS)

    The counter of γ photons is a detecting system including converter and fused silica Cherenkov radiator to detect emitted γ photons from zero degree single Bremsstrahlung radiation Bhabha so that the luminosity of e+e- collisions can be monitored. Cosmic ray test shows that the responses of the system on Minimum Ionization Particles (MIP) are: the average photoelectron number collected by the photo-cathode of each photomultiplier is 6.9 ± 3.7; time resolution is 0.25 ns; With 30 mV threshold of the discriminators and x5(25) magnification of preamplifiers, detection efficiency of the system for MIP is better than 98% when the high voltage of photomultiplier is 800 V. (authors)

  9. Beam induced vacuum measurement error in BEPC II

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    When the beam in BEPCII storage ring aborts suddenly, the measured pressure of cold cathode gauges and ion pumps will drop suddenly and decrease to the base pressure gradually. This shows that there is a beam induced positive error in the pressure measurement during beam operation. The error is the difference between measured and real pressures. Right after the beam aborts, the error will disappear immediately and the measured pressure will then be equal to real pressure. For one gauge, we can fit a non-linear pressure-time curve with its measured pressure data 20 seconds after a sudden beam abortion. From this negative exponential decay pumping-down curve, real pressure at the time when the beam starts aborting is extrapolated. With the data of several sudden beam abortions we have got the errors of that gauge in different beam currents and found that the error is directly proportional to the beam current, as expected. And a linear data-fitting gives the proportion coefficient of the equation, which we derived to evaluate the real pressure all the time when the beam with varied currents is on.

  10. Superconductivity

    International Nuclear Information System (INIS)

    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

  11. Study of Helium II heat transport phenomena in superconducting rutherford type cables

    OpenAIRE

    Galinhas, Bruno Emanuel Martins

    2015-01-01

    This thesis is a study of how heat is transported in non-steady-state conditions from a superconducting Rutherford cable to a bath of superfluid helium (He II). The same type of superconducting cable is used in the dipole magnets of the Large Hadron Collider (LHC). The dipole magnets of the LHC are immersed in a bath of He II at 1.9 K. At this temperature helium has an extremely high thermal conductivity. During operation, heat needs to be efficiently extracted from the dipole magnets to keep...

  12. 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...

  13. 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

  14. Computational modelling for type-II superconductivity and the investigation of high temperature superconducting electrical machines

    International Nuclear Information System (INIS)

    In recent years, the possibility of incorporating type-ll superconducting materials into engineering power applications such as motors, generators, bearings and levitation systems has attracted much attention. However, in order to fully develop the potential of using these relatively new materials in such applications, suitable computational modelling is required. The aim of the research presented in this thesis was to further the development of electrical machines incorporating high temperature superconductors (HTSs) by formulating and then implementing mathematical models. After identifying and justifying necessary assumptions, two such models are developed: the first deriving from the ideas of fluxon motion leading to a finite difference scheme, and the second deriving from more fundamental macroscopic ideas of induced currents leading to a finite element formulation. In both cases, the critical state model of type-ll superconductivity is employed and, because of its intrinsic non-linear properties, computational numerical solution techniques are utilised. After validating the modelling techniques with simple problems, and comparing to approximate analytical solutions when available, the remainder of the thesis concerns the modelling of HTS electrical machines and in particular, hysteresis, reluctance, trapped-field and linear motors. In each case, by evaluating the magnetic field and current distributions inside the machine, the roles of the superconducting materials are clearly revealed. Once this has been achieved, further studies indicate the most desirable parameters which are expected to optimise the performance. (author)

  15. Superconductivity:

    Science.gov (United States)

    Sacchetti, N.

    In this paper a short historical account of the discovery of superconductivity and of its gradual development is given. The physical interpretation of its various aspects took about forty years (from 1911 to 1957) to reach a successful description of this phenomenon in terms of a microscopic theory At the very end it seemed that more or less everything could be reasonably interpreted even if modifications and refinements of the original theory were necessary. In 1986 the situation changed abruptly when a cautious but revolutionary paper appeared showing that superconductivity was found in certain ceramic oxides at temperatures above those up to then known. A rush of frantic experimental activity started world-wide and in less than one year it was shown that superconductivity is a much more widespread phenomenon than deemed before and can be found at temperatures well above the liquid air boiling point. The complexity and the number of the substances (mainly ceramic oxides) involved call for a sort of modern alchemy if compounds with the best superconducting properties are to be manufactured. We don't use the word alchemy in a deprecatory sense but just to emphasise that till now nobody can say why these compounds are what they are: superconductors.

  16. Computational modelling for type-II superconductivity and the investigation of high temperature superconducting electrical machines

    CERN Document Server

    Barnes, G J

    2000-01-01

    are clearly revealed. Once this has been achieved, further studies indicate the most desirable parameters which are expected to optimise the performance. In recent years, the possibility of incorporating type-ll superconducting materials into engineering power applications such as motors, generators, bearings and levitation systems has attracted much attention. However, in order to fully develop the potential of using these relatively new materials in such applications, suitable computational modelling is required. The aim of the research presented in this thesis was to further the development of electrical machines incorporating high temperature superconductors (HTSs) by formulating and then implementing mathematical models. After identifying and justifying necessary assumptions, two such models are developed: the first deriving from the ideas of fluxon motion leading to a finite difference scheme, and the second deriving from more fundamental macroscopic ideas of induced currents leading to a finite element...

  17. He II cooling for superconductive magnetic energy storage

    International Nuclear Information System (INIS)

    Diurnal energy storage magnet systems place unique requirements on the helium cryogenics for conductor stability. Safety is a key issue because of the need for reliable operation and interfacing with a utility system. Economy is also very important because of the competition the system enjoys with alternative energy storage and generation concepts. The magnet design for energy storage is unique principally because of its physical dimensions, which are several orders of magnitude larger than other magnet systems. Led by these special circumstances, the Wisconsin energy storage magnet system design team has adopted the following set of design decisions: bedrock support; load transfer through fiber reinforced composite struts; aluminum stabilized NbTi composite conductor; and superfluid He II cooling. These factors were selected because of the need for innovative design and the belief that each represents a reasonable extrapolation of available technology. The present paper addresses the superfluid He II cooling decision. In considering He II cooling, three factors are discussed. First, the logic behind the coolant selection is reviewed including comparison with alternative schemes. Next, a discussion of the general concepts of composite conductor stability in He II is presented principally from the viewpoint of heat transfer. Finally, the He II stability criteria are applied to the energy storage magnet system design

  18. Phenomenological approach to the coexistence of planar antiferromagnetism with high Tc type II superconductivity

    International Nuclear Information System (INIS)

    A phenomenological study in d-spatial dimensions is presented for the coexistence of planar antiferromagnetism and type II superconductivity. In this approach critical temperatures in the range 30-100 K arise due to the proposed coupling of magnons and conduction electron-pairs. We discuss some remarkable features of oxide ceramics, including a longer London penetration depth, shorter coherence length, lower Hcl, higher Hc2, large current densities, and large pinning force. (author). 45 refs, 3 figs

  19. Superconductivity

    International Nuclear Information System (INIS)

    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 MgB2 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 Nb3Sn 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 YBa2Cu3O7-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 TUCN and

  20. Control of the Superconducting Magnets current Power Supplies of the TJ-II Gyrotrons

    International Nuclear Information System (INIS)

    The TJ-II ECRH heating system consists of two gyrotrons, which can deliver a maximum power of 300 kW at a frequency of 53.2 GHz. Another 28 GHz gyrotron is going to be used in the Bernstein waves heating system. In order to get the required frequency, the gyrotrons need and homogeneous magnetic field of several tesla, which is generated by a superconducting coil field by a current source. This document describes the current source control as well as the high precision ammeters control. These ammeters measure the current in the superconducting coils. The user interface and the programming of the control system are described. The communication between devices is also explained. (author) 9 Refs

  1. Simulation of the RF Coupler for TRIUMF ISAC-II Superconducting Quarter Wave Resonators

    CERN Document Server

    Zvyagintsev, V

    2004-01-01

    The inductive RF coupler for the TRIUMF ISAC-II 106 MHz superconducting accelerating quarter wave resonators was used as a basis for the simulation model of stationary transmission processes of RF power and thermal fluxes. Electromagnetic simulation of the coupler was done with ANSOFT HFSS code. Transmission line theory was used for electromagnetic wave calculations along the drive line to the Coupler. An analogy between electric and thermal processes allows the thermal calculations to be expressed in terms of electrical circuits. The data obtained from the simulation are compared to measured values on the RF coupler.

  2. Stability and fast heat removal with He-II cooling for pulsed superconductive magnets

    International Nuclear Information System (INIS)

    The use of pressurized superfluid helium between 1.6 K and 1.8 K is being considered for a number of superconducting magnet applications. This type of cooling is particularly interesting in the case of pulsed field magnets where large heat fluxes need to be evacuated in a short time. This paper reviews a few recent experiments on heat transport properties and stability in He-II, which contribute to evaluating its potential use for such an application. Present technology is illustrated by the description of a large test facility recently operated at Saclay

  3. Superconductivity

    International Nuclear Information System (INIS)

    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. 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.

  5. The upgrade of data acquisition system and the offline data analysis of test beam on BEPC

    International Nuclear Information System (INIS)

    Test beam on BEPC-LINAC makes full use of online detectors and offline data analysis software to select the single particle events for different beam tests. This paper introduces the upgrade of data acquisition system and the method of offline data analysis. The offline data analysis system is inclusive of the analysis of TOF, the identification of single particle events, the calculation of hit coordinates and so on. (authors)

  6. Error and jitter effect studies on the SLED for the BEPC Ⅱ-linac

    Institute of Scientific and Technical Information of China (English)

    PEI Shi-Lun; LI Xiao-Ping; XIAO Ou-Zheng

    2012-01-01

    An RF pulse compressor is a device used to convert a long RF pulse to a short one with a much higher peak RF magnitude.SLED can be regarded as the earliest RF pulse compressor to be used in large-scale linear accelerators.It has been widely studied around the world and applied in the BEPC and BEPC Ⅱ linac for many years.During routine operation,error and jitter effects will deteriorate the performance of SLED,either on the output electromagnetic wave amplitude or phase.The error effects mainly include the frequency drift induced by cooling water temperature variation and the frequency/Qo/β unbalances between the two energy storage cavities caused by mechanical fabrication or microwave tuning.The jitter effects refer to the PSK switching phase and time jitters.In this paper,we re-derive the generalized formulae for the conventional SLED used in the BEPC Ⅱ linac,and the error and jitter effects on SLED performance are also investigated.

  7. SRAM single event upset calculation and test using protons in the secondary beam in the BEPC

    Institute of Scientific and Technical Information of China (English)

    Wang Yuanming; Guo Hongxia; Zhang Fengqi; Zhang Keying; Chen Wei; Luo Yinhong; Guo Xiaoqiang

    2011-01-01

    The protons in the secondary beam in the Beijing Electron Positron Collider (BEPC) are first analyzed and a large proportion at the energy of 50 100 MeV supply a source gap of high energy protons.In this study,the proton energy spectrum of the secondary beam was obtained and a model for calculating the proton single event upset (SEU) cross section of a static random access memory (SRAM) cell has been presented in the BEPC secondary beam proton radiation environment.The proton SEU cross section for different characteristic dimensions has been calculated.The test of SRAM SEU cross sections has been designed,and a good linear relation between SEUs in SRAM and the fluence was found,which is evidence that an SEU has taken place in the SRAM.The SEU cross sections were measured in SRAM with different dimensions.The test result shows that the SEU cross section per bit will decrease with the decrease of the characteristic dimensions of the device,while the total SEU cross section still increases upon the increase of device capacity.The test data accords with the calculation results,so the high-energy proton SEU test on the proton beam in the BEPC secondary beam could be conducted.

  8. SRAM single event upset calculation and test using protons in the secondary beam in the BEPC

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yuanming; Guo Hongxia; Zhang Fengqi; Zhang Keying; Chen Wei; Luo Yinhong; Guo Xiaoqiang, E-mail: wangym2007@gmail.com [Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

    2011-09-15

    The protons in the secondary beam in the Beijing Electron Positron Collider (BEPC) are first analyzed and a large proportion at the energy of 50-100 MeV supply a source gap of high energy protons. In this study, the proton energy spectrum of the secondary beam was obtained and a model for calculating the proton single event upset (SEU) cross section of a static random access memory (SRAM) cell has been presented in the BEPC secondary beam proton radiation environment. The proton SEU cross section for different characteristic dimensions has been calculated. The test of SRAM SEU cross sections has been designed, and a good linear relation between SEUs in SRAM and the fluence was found, which is evidence that an SEU has taken place in the SRAM. The SEU cross sections were measured in SRAM with different dimensions. The test result shows that the SEU cross section per bit will decrease with the decrease of the characteristic dimensions of the device, while the total SEU cross section still increases upon the increase of device capacity. The test data accords with the calculation results, so the high-energy proton SEU test on the proton beam in the BEPC secondary beam could be conducted. (semiconductor physics)

  9. SRAM single event upset calculation and test using protons in the secondary beam in the BEPC

    International Nuclear Information System (INIS)

    The protons in the secondary beam in the Beijing Electron Positron Collider (BEPC) are first analyzed and a large proportion at the energy of 50-100 MeV supply a source gap of high energy protons. In this study, the proton energy spectrum of the secondary beam was obtained and a model for calculating the proton single event upset (SEU) cross section of a static random access memory (SRAM) cell has been presented in the BEPC secondary beam proton radiation environment. The proton SEU cross section for different characteristic dimensions has been calculated. The test of SRAM SEU cross sections has been designed, and a good linear relation between SEUs in SRAM and the fluence was found, which is evidence that an SEU has taken place in the SRAM. The SEU cross sections were measured in SRAM with different dimensions. The test result shows that the SEU cross section per bit will decrease with the decrease of the characteristic dimensions of the device, while the total SEU cross section still increases upon the increase of device capacity. The test data accords with the calculation results, so the high-energy proton SEU test on the proton beam in the BEPC secondary beam could be conducted. (semiconductor physics)

  10. Ac susceptibility components of a current-carrying thin type-II superconducting annulus

    International Nuclear Information System (INIS)

    Highlights: • The real and imaginary parts of magnetic susceptibility of a superconducting annulus in a perpendicular field are studied. • The calculations are done in the absence and the presence of a transport radial current. • The comparison shows that by applying a radial current, the imaginary part of susceptibility increases. • The variations of imaginary part with respect to the real part of susceptibility are also studied. • By applying a radial current, the imaginary part decreases when the aspect ratio is increased. - Abstract: By assuming a spatial dependence on the sheet-current density, we have investigated the real (χ′) and imaginary parts (χ″) of the susceptibility of a thin type-II superconducting annulus (with the inner and outer radii a and b, respectively) in the absence and also in the presence of a radial transport current, using the Bean critical state model in which the critical current density is assumed to be independent of the local magnetic field. The results of our calculations on the components of the magnetic susceptibilities in two cases and for the different aspect ratios are compared with each other. The comparison shows that by applying a radial current to the sample, the imaginary part of the susceptibility is increased. We have studied the variations of the χ″ with respect to χ′ for a several aspect ratios. We also found that when a transport radial current is passed through the washer, by increasing the aspect ratio a/b in the parametric plot of χ″ vs. χ′, the imaginary part decreases and the peak of χ″ decreases in magnitude but shifted towards χ″ = 0

  11. Phasing system for the Injector of Beijing Electron Positron Collider (BEPC)

    International Nuclear Information System (INIS)

    The Injector of Beijing Electron Positron Collider is a 1.4 Gev. Electron Linear Accelerator. The sixteen klystrons and their energy doublers are used to provide microwave accelerating power for electron (or positron) beam. In order to make the energy of the accelerated electron beam maximum and the energy spectrum width minimum, every klystron must be phased to make the crests of the RF traveling wave in the accelerator coincide with the electron bunch centers. A phasing system has been designed and built in the BEPC Injector. The system is based on the beam induction technique. The heterodyne technique is used to process signals and to do phase discrimination. The step motor-driven phase shifters (FOX phase shifter) are used to shift the phases of klystrons. A single board microcomputer is used to provide programme control for the system. The system can phase every klystron automatically or manually and can manually shift the phase of any klystron as operator likes. The system can be operated by operator at Central Control Room, Injector Control Room or Local Panel. The system has been installed well in the klystron gallery of BEPC Injector. In order to leave over the possibility improving the system in the future, 17 equal length phase stable cables are used to be reference signal cable and phase sample cables

  12. Heat Transfer Measurements through Thermally Enhanced Insulation Schemes for Nb-Ti Superconducting Magnets operating in He-II

    CERN Document Server

    Granieri, P P

    2011-01-01

    Superconducting magnets submitted to large heat loads, as the low-β quadrupoles for the LHC luminosity upgrade, need the development of new concepts of cable electrical insulation featuring a He-II porous wrapping scheme. This paper reports and discusses recent results of dedicated heat transfer measurements performed on different variants of such schemes, with emphasis on the heat transfer enhancements achievable with respect to the state-of-the-art insulation used for the main LHC magnets.

  13. Dendritic flux avalanches and the accompanied thermal strain in type-II superconducting films: effect of magnetic field ramp rate

    Science.gov (United States)

    Jing, Ze; Yong, Huadong; Zhou, You-He

    2015-07-01

    Dendritic flux avalanches and the accompanying thermal stress and strain in type-II superconducting thin films under transverse magnetic fields are numerically simulated in this paper. The influence of the magnetic field ramp rate, edge defects, and the temperature of the surrounding coolant are considered. Maxwell's equations and the highly nonlinear E-J power-law characteristics of superconductors, coupled with the heat diffusion equation, are adopted to formulate these phenomena. The fast Fourier transform-based iteration scheme is used to track the evolution of the magnetic flux and the temperature in the superconducting film. The finite element method is used to analyze the thermal stress and strain induced in the superconducting film. It is found that the ramp rate has a significant effect on the flux avalanche process. The avalanches nucleate more easily for a film under a large magnetic field ramp rate than for a film under a small one. In addition, the avalanches always initiate from edge defects or areas that experience larger magnetic fields. The superconducting films experience large thermal strain induced by the large temperature gradient during the avalanche process, which may even lead to the failure of the sample.

  14. RF characteristic study on whole accelerating structure for BEPC Ⅱ linac

    International Nuclear Information System (INIS)

    In order to understand and obtain the whole structure RF characteristics of the disk-loaded accelerating tube, the redesigned axis-symmetric coupler was adopted to replace the real 3-D one during the calculation process by ANSYS. Much less computer sources and time were required to simulate the whole structure with only one single PC by taking full advantage of the structure's axis-symmetric characteristic. The accelerating tube for the BEPC Ⅱ linac was used as an example to validate this method. The ANSYS simulated filling time, attenuation factor and bandwidth are 856 ns, 0.56 Np and 3.55 MHz respectively, while the experimental measured ones are 830 ns, 0.57 Np and 4.7 MHz respectively. It can be seen that the ANSYS simulation and experimental measurement are consistent as a whole, and the simulation can provide very valuable reference for the real design and fabrication. (authors)

  15. Itinerant Ferromagnetism and Superconductivity

    OpenAIRE

    Karchev, Naoum

    2004-01-01

    Superconductivity has again become a challenge following the discovery of unconventional superconductivity. Resistance-free currents have been observed in heavy-fermion materials, organic conductors and copper oxides. The discovery of superconductivity in a single crystal of $UGe_2$, $ZrZn_2$ and $URhGe$ revived the interest in the coexistence of superconductivity and ferromagnetism. The experiments indicate that: i)The superconductivity is confined to the ferromagnetic phase. ii)The ferromag...

  16. Noncentrosymmetric superconductivity in a clean crystal of type II superconductor Bi-Pd

    Science.gov (United States)

    Ramakrishnan, Srinivasan; Pratap, Bhanu; Thamizhavel, A.

    2016-02-01

    In this work, we present the bulk superconductivity of a high-quality single crystal of monoclinic BiPd (α-BiPd, space group P21) below 3.8 K by studying its electrical resistivity, magnetic susceptibility, and heat capacity. This is the cleanest noncentrosymmetric superconductor (NCS) that display anisotropy due to spin-orbit scattering and also exhibits unusual superconducting properties due to s and p wave mixing as evidenced by the observation of Andreev bound state and multiple energy gaps via point contact measurements. In addition, Fermi surface studies suggest multiband superconductivity in this compound. Penetration depth studies and NQR investigations support mixing of s and p wave Copper paring in this crystal. Moroever, Muon spin rotation measurements indicate strong field dependence of the Ginzburg- Landau coefficient of this superconductor. Unusual pairing and multiband superconductivity are extremely sensitive to disorder and they can be observed only in cleanest (RRR > 170) single crystals.

  17. Infrared Vortex-State Electrodynamics in Type-II Superconducting Thin Films

    OpenAIRE

    Xi, Xiaoxiang; Park, J.-H.; Graf, D.; Carr, G. L.; Tanner, D. B.

    2013-01-01

    The vortex-state electrodynamics of s-wave superconductors has been studied by infrared spectroscopy. Far-infrared transmission and reflection spectra of superconducting NbTiN and NbN thin films were measured in a magnetic field perpendicular to the film surface, and the optical conductivity was extracted. The data show clear reduction of superconducting signature. We consider the vortex state as a two-component effective medium of normal cores embedded in a BCS superconductor. The spectral f...

  18. Monte Carlo simulation of the BEPC II/BES III backgrounds--touschek effect

    International Nuclear Information System (INIS)

    Motivation of the Touschek backgrounds study is introduced. Also introduced are the theory and modeling methods of the Touschek effect. The Touschek backgrounds of the main detectors of the BES III are studied in detail using the self-reprogrammed general simulation tools. Comparison of the beam lifetime between the simulated and calculated ones shows that the simulations are reasonable and the results are meaningful. Results of the detectors' backgrounds show that the Touschek backgrounds will not affect the normal run of the future BES III and will not damage the main detectors. (authors)

  19. Development of beam position monitor for test beam of BEPC II

    International Nuclear Information System (INIS)

    Three stripline beam position monitors and some feed-throughs were developed to measure the position of beam non-interceptively in test beam facility. After three stripline beam position monitors were produced, calibrations of the monitors were carried out on a workbench, which has high precision and is controlled by a computer. Then two monitor's were installed at the beam line and some experiments were carried out. Four 1 mm thickness stainless steel strips are main modules of the monitor, signals induced in these strips reflect the position of the beam bunch. Calibration coefficient, system characteristic impedance and port transmission coefficient of monitor are introduced in this paper. (authors)

  20. 1 kW S-band RF solid state amplifier for BEPC linac microwave driver system

    International Nuclear Information System (INIS)

    This paper presents the development of a 1 kW S-Band RF Solid State Amplifier (SSA) for the BEPC Linac. 1 kW peak power with a pulse width of 2-10 μs under low voltage operation is achieved by combining eight 160 W high power Solid State Amplifiers using a low-loss (0.3 dB) combiner. Other key performance parameters are: RF phase drift during pulse ≤±1 degree, RF rise time/fall time is 88 ns/40 ns, RF pulse flatness is 0.7%, and RF power stability is 0.1 dB

  1. Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

    Science.gov (United States)

    Geng, J.; Matsuda, K.; Fu, L.; Fagnard, J.-F.; Zhang, H.; Zhang, X.; Shen, B.; Dong, Q.; Baghdadi, M.; Coombs, T. A.

    2016-03-01

    Superconducting flux pumps are the kind of devices which can generate direct current into superconducting circuit using external magnetic field. The key point is how to induce a dc voltage across the superconducting load by ac fields. Giaever (1966 IEEE Spectr. 3 117) pointed out flux motion in superconductors will induce a dc voltage, and demonstrated a rectifier model which depended on breaking superconductivity. van de Klundert et al (1981 Cryogenics 21 195, 267) in their review(s) described various configurations for flux pumps all of which relied on inducing the normal state in at least part of the superconductor. In this letter, following their work, we reveal that a variation in the resistivity of type II superconductors is sufficient to induce a dc voltage in flux pumps and it is not necessary to break superconductivity. This variation in resistivity is due to the fact that flux flow is influenced by current density, field intensity, and field rate of change. We propose a general circuit analogy for travelling wave flux pumps, and provide a mathematical analysis to explain the dc voltage. Several existing superconducting flux pumps which rely on the use of a travelling magnetic wave can be explained using the analysis enclosed. This work can also throw light on the design and optimization of flux pumps.

  2. Two-component superconductivity. II. Copper oxide high-Tc superconductors

    International Nuclear Information System (INIS)

    A systematic relationship between the Cu-O-based high-Tc materials and a two-component theory is developed. The two components are mobile-single-particle states associated with Cu-O planes and localized paired (negative-U) states associated with oxygen vacancies. The focus is on identification of the relevant electronic states in theoretical calculations and experimental observations. The family of Cu-O-based materials is discussed and an understanding is developed of the implications of layering and dimensionality, oxygenation, and doping. The relationship to superconducting properties is developed through the pair-density dependence and single-particle-density dependence of superconductivity. Comparisons with existing experimental data are made, distinctive experimental results are predicted. New directions for finding high-Tc materials are suggested both within the Cu-O-based family and in the more general class of materials which share with the Cu-O-based family the structure of metal-semiconductor layering and can be formed with off-stoichiometric compositions

  3. Configuration-induced vortex motion in type-II superconducting films with periodic magnetic dot arrays

    International Nuclear Information System (INIS)

    Using the molecular dynamic method we investigate numerically the current driven vortex motion in a superconducting film with periodic arrays of both ferromagnetic (FM) and anti-parallel ferromagnetic (AFM) dots. The simulation results show that in the absence of thermal fluctuation the vortex motion is dominated by the configurations of the magnetic dot array. This guided vortex motion is only observed at the onset of the depinning of the interstitial vortices. Two guided vortex motion mechanisms are discussed in this work. For the AFM configuration the vortex motion is mainly originated by the existence of magnetic dots with opposite magnetized moments, while for the FM case it is mainly dependent on the degree of the condensed packing of the magnetic dot lattice constant. (paper)

  4. Calorimetry in superfluid He II to measure losses in superconducting magnets

    International Nuclear Information System (INIS)

    A method using calorimetry to measure magnet losses in pressurized Helium II is described. The isothermal nature of He II is used in measuring the overall heat capacity of the system and the net refrigeration power. During the measurements, the refrigeration power is held fixed, and the system (400 liters) temperature is near 1.92 K. The calorimetric measurement was calibrated against known power inputs between 1 and 20 W. This technique can even measure heat loads higher than the available refrigeration. Results of loss measurement on two dipole magnets are reported

  5. Impurity dependent superconductivity, Berry phase and bulk Fermi surface of the Weyl type-II semi-metal candidate MoTe2

    OpenAIRE

    D. Rhodes; Zhou, Q.; Schönemann, R.; Zhang, Q. R.; Kampert, E.; Shimura, Y.; McCandless, G.T.; Chan, J. Y.; S. Das; Manousakis, E.; M. D. Johannes; Balicas, L.

    2016-01-01

    Orthorhombic MoTe$_2$ and its isostructural compound WTe$_2$ were recently claimed to belong to a new class (type II) of Weyl semi-metals characterized by a linear touching between hole and electron Fermi surfaces in addition to nodal lines. To validate these predictions, we synthesized high quality single-crystals of $\\beta$-MoTe$_2$, finding that its superconducting transition temperature depends on disorder as quantified by the ratio between the room- and low-temperature resistivities. Sim...

  6. Field limit and nano-scale surface topography of superconducting radio-frequency cavity made of extreme type II superconductor

    CERN Document Server

    Kubo, Takayuki

    2014-01-01

    The field limit of superconducting radio-frequency cavity made of type II superconductor with a large Ginzburg-Landau parameter is studied with taking effects of nano-scale surface topography into account. If the surface is ideally flat, the field limit is imposed by the superheating field. On the surface of cavity, however, nano-defects almost continuously distribute and suppress the superheating field everywhere. The field limit is imposed by an effective superheating field given by the product of the superheating field for ideal flat surface and a suppression factor that contains effects of nano-defects. A nano-defect is modeled by a triangular groove with a depth smaller than the penetration depth. An analytical formula for the suppression factor of bulk and multilayer superconductors are derived in the framework of the London theory. As an immediate application, the suppression factor of the dirty Nb processed by the electropolishing is evaluated by using results of surface topographic study. The estimat...

  7. Design And Preliminary Test Of The 1500 MHZ NSLS-II Passive Superconducting RF Cavity

    International Nuclear Information System (INIS)

    NSLS-II is a new ultra-bright 3 GeV 3rd generation synchrotron radiation light source. The performance goals require operation with a beam current of 500mA and a bunch current of at least 0.5mA. Ion clearing gaps are required to suppress ion effects on the beam. The natural bunch length of 3mm is planned to be lengthened by means of a third harmonic cavity in order to increase the Touschek limited lifetime. Earlier work described the design alternatives and the geometry selected for a copper prototype. We subsequently have iterated the design to lower the R/Q of the cavity and to increase the diameter of the beam pipe ferrite HOM dampers to reduce the wakefield heating. A niobium cavity and full cryomodule including LN2 shield, magnetic shield and insulating vacuum vessel have been fabricated and installed. A passive SRF 3rd harmonic cavity consisting of two tightly coupled cells has been designed and fabricated for NSLS-II. Initial cold tests of this cavity are very promising. These tests have verified that the cavity frequency and mode separation between the 0 and π-modes can be set at manufacture. Further, the frequency separation can be maintained over wide tuning ranges necessary for operation. Future work includes HOM damper and motorized tuner development.

  8. Control of the Superconducting Magnets current Power Supplies of the TJ-II Gyrotrons; Control de las Fuentes de Corriente de las Bobinas Superconductoras de los Girotrones del TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Ros, A.; Fernandez, A.; Tolkachev, A.; Catalan, G.

    2006-07-01

    The TJ-II ECRH heating system consists of two gyrotrons, which can deliver a maximum power of 300 kW at a frequency of 53.2 GHz. Another 28 GHz gyrotron is going to be used in the Bernstein waves heating system. In order to get the required frequency, the gyrotrons need and homogeneous magnetic field of several tesla, which is generated by a superconducting coil field by a current source. This document describes the current source control as well as the high precision ammeters control. These ammeters measure the current in the superconducting coils. The user interface and the programming of the control system are described. The communication between devices is also explained. (author) 9 Refs.

  9. Superconductivity applications for infrared and microwave devices II; Proceedings of the Meeting, Orlando, FL, Apr. 4, 5, 1991

    Science.gov (United States)

    Heinen, Vernon O. (Editor); Bhasin, Kul B. (Editor)

    1991-01-01

    Topics discussed include thin-film technology, microwave transmission lines and resonators, microwave devices and circuits, infrared detectors and bolometers, and superconducting junctions. Papers are presented on possible enhancement in bolometric response using free-standing film of YBa2Cu3O(x), aging and surface instability in high-Tc superconductors, epitaxial Tl2Ba2CaCu2O8 thin films on LaAlO3 and their microwave device properties, the performance of stripline resonators using sputtered YBCO films, and a coplanar waveguide microwave filter of YBa2Cu3O7. Attention is also given to the performance characteristics of Y-Ba-Cu-O microwave superconducting detectors, high-Tc bolometer developments for planetary missions, infrared detectors from YBaCuO thin films, high-temperature superconductor junction technology, and submillimeter receiver components using superconducting tunnel junctions.

  10. Studies and optimization of Pohang Light Source-II superconducting radio frequency system at stable top-up operation with beam current of 400 mA

    International Nuclear Information System (INIS)

    After three years of upgrading work, the Pohang Light Source-II (PLS-II) is now successfully operating. The final quantitative goal of PLS-II is a top-up user-service operation with beam current of 400 mA to be completed by the end of 2014. During the beam store test up to 400 mA in the storage ring (SR), it was observed that the vacuum pressure around the radio frequency (RF) window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. Although available beam current is enhanced by setting a higher RF accelerating voltage, it is better to keep the RF accelerating voltage as low as possible in the long time top-up operation. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. In our simulation, an equivalent physical modeling was developed using a finite-difference time-domain code. The simulation revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window, which comes with the rapid increase of window vacuum pressure. The RF accelerating voltage of PLS-II RF system was set to 4.95 MV, which was estimated using the maximum available beam current that works as a function of RF voltage, and the top-up operation test with the beam current of 400 mA was successfully carried out

  11. Interpretation of transmission through type II superconducting thin film on dielectric substrate as observed by laser thermal spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Šindler, Michal; Tesař, Roman; Koláček, Jan; Skrbek, L.

    2012-01-01

    Roč. 483, DEC (2012), s. 127-135. ISSN 0921-4534 R&D Projects: GA ČR(CZ) GAP204/11/0015 Grant ostatní: European Science Foundation(XE) NES, 2007 - 2012 Institutional research plan: CEZ:AV0Z10100521 Keywords : far-infrared transmission * NbN * superconducting film * vortices * terahertz waves Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.718, year: 2012

  12. (Cu,Tl)Ba2Ca3Cu4Ox compositions: II. Heating rate applied to synthesis of superconducting ceramics

    International Nuclear Information System (INIS)

    Superconducting samples with a starting composition Cu0.5TlxBa2Ca3Cu4O12 (x=1-0.35) were prepared in Au tubes from oxides by using different heating rates. The optimum heating rate was 0.11 deg. C min-1 applied between 860 and 880 deg. C. These samples show the highest content of 1234 phase and the lowest of Ba-Cu-O phases as well as the highest critical temperatures. The highest values were Tc=119.2 K and Tc0=115.1 K. All samples show Jc values around 6x105 A cm-2, at 60 K and 0.5 T. In the rest of the samples, heated by using lower or higher heating rates, a high concentration of 1223 and/or 1245 phases is detected. The content of the 1234 phase and of Ba(Ca,Tl)-Cu-O residual liquid phase, in the samples synthesized for the optimum heating rate, depends on the Tl content in the starting mixture. The influence of the oxygen content in the starting mixture on phase composition is not as strong as of Tl, but it has a major role in establishing the superconducting behaviour of the 1234 grains. Some arguments that suggest the dependence of the transport properties of the non-superconducting matrix on oxygen content will be discussed. In our technological arrangement the determined optimum heating rate can be applied to the synthesis of other single-layered superconducting phases, e.g. 1212 phase from a Cu0.25Tl0.75Ba2CaCu2O8.115 starting composition. (author)

  13. Design and performance measurement of the 1 GeV/c multiparticle magnetic spectrometer in the BEPC-linac test beam

    International Nuclear Information System (INIS)

    The 2Q2D magnetic spectrometer operating at the BEPC-Linac test beam site consists of 2 quadrupole magnets, 2 dipoles and 2 position sensitive detectors. The spectrometer has a maximum acceptance of solid angle 5 x 10-4 sr, a momentum range 0.2-1.3 GeV/c. Beam cross section and momentum spectra have been measured on the focal plane. A reference method for momentum measurement based on the TOF difference of proton and electron is introduced. (authors)

  14. Macroscopic Models of Superconductivity

    Science.gov (United States)

    Chapman, S. J.

    Available from UMI in association with The British Library. Requires signed TDF. After giving a description of the basic physical phenomena to be modelled, we begin by formulating a sharp -interface free-boundary model for the destruction of superconductivity by an applied magnetic field, under isothermal and anisothermal conditions, which takes the form of a vectorial Stefan model similar to the classical scalar Stefan model of solid/liquid phase transitions and identical in certain two-dimensional situations. This model is found sometimes to have instabilities similar to those of the classical Stefan model. We then describe the Ginzburg-Landau theory of superconductivity, in which the sharp interface is 'smoothed out' by the introduction of an order parameter, representing the number density of superconducting electrons. By performing a formal asymptotic analysis of this model as various parameters in it tend to zero we find that the leading order solution does indeed satisfy the vectorial Stefan model. However, at the next order we find the emergence of terms analogous to those of 'surface tension' and 'kinetic undercooling' in the scalar Stefan model. Moreover, the 'surface energy' of a normal/superconducting interface is found to take both positive and negative values, defining Type I and Type II superconductors respectively. We discuss the response of superconductors to external influences by considering the nucleation of superconductivity with decreasing magnetic field and with decreasing temperature respectively, and find there to be a pitchfork bifurcation to a superconducting state which is subcritical for Type I superconductors and supercritical for Type II superconductors. We also examine the effects of boundaries on the nucleation field, and describe in more detail the nature of the superconducting solution in Type II superconductors--the so-called 'mixed state'. Finally, we present some open questions concerning both the modelling and analysis of

  15. Superconducting transistor

    Science.gov (United States)

    Gray, Kenneth E.

    1979-01-01

    A superconducting transistor is formed by disposing three thin films of superconducting material in a planar parallel arrangement and insulating the films from each other by layers of insulating oxides to form two tunnel junctions. One junction is biased above twice the superconducting energy gap and the other is biased at less than twice the superconducting energy gap. Injection of quasiparticles into the center film by one junction provides a current gain in the second junction.

  16. Superconducting technology

    International Nuclear Information System (INIS)

    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 Nb3Sn, resulting in the creation of various application fields based on the superconducting technologies. High-Tc 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)

  17. Interface superconductivity

    International Nuclear Information System (INIS)

    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 Tc in a monolayer of FeSe deposited on SrTiO3 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 LaAlO3 and SrTiO3. 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 SrTiO3 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 Tc in a monolayer of FeSe deposited on SrTiO3

  18. Production of Seamless Superconducting Radio Frequency Cavities from Ultra-fine Grained Niobium, Phase II Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Roy Crooks, Ph.D., P.E.

    2009-10-31

    The positron and electron linacs of the International Linear Collider (ILC) will require over 14,000, nine-cell, one meter length, superconducting radio frequency (SRF) cavities [ILC Reference Design Report, 2007]. Manufacturing on this scale will benefit from more efficient fabrication methods. The current methods of fabricating SRF cavities involve deep drawing of the halves of each of the elliptical cells and joining them by high-vacuum, electron beam welding, with at least 19 circumferential welds per cavity. The welding is costly and has undesirable effects on the cavity surfaces, including grain-scale surface roughening at the weld seams. Hydroforming of seamless tubes avoids welding, but hydroforming of coarse-grained seamless tubes results in strain-induced surface roughening. Surface roughness limits accelerating fields, because asperities prematurely exceed the critical magnetic field and become normal conducting. This project explored the technical and economic feasibility of an improved processing method for seamless tubes for hydroforming. Severe deformation of bulk material was first used to produce a fine structure, followed by extrusion and flow-forming methods of tube making. Extrusion of the randomly oriented, fine-grained bulk material proceeded under largely steady-state conditions, and resulted in a uniform structure, which was found to be finer and more crystallographically random than standard (high purity) RRR niobium sheet metal. A 165 mm diameter billet of RRR grade niobium was processed into five, 150 mm I.D. tubes, each over 1.8 m in length, to meet the dimensions used by the DESY ILC hydroforming machine. Mechanical properties met specifications. Costs of prototype tube production were approximately twice the price of RRR niobium sheet, and are expected to be comparable with economies of scale. Hydroforming and superconducting testing will be pursued in subsequent collaborations with DESY and Fermilab. SRF Cavities are used to construct

  19. Superconductivity basics and applications to magnets

    CERN Document Server

    Sharma, R G

    2015-01-01

    This book presents the basics and applications of superconducting magnets. It explains the phenomenon of superconductivity, theories of superconductivity, type II superconductors and high-temperature cuprate superconductors. The main focus of the book is on the application to superconducting magnets to accelerators and fusion reactors and other applications of superconducting magnets. The thermal and electromagnetic stability criteria of the conductors and the present status of the fabrication techniques for future magnet applications are addressed. The book is based on the long experience of the author in studying superconducting materials, building magnets and numerous lectures delivered to scholars. A researcher and graduate student will enjoy reading the book to learn various aspects of magnet applications of superconductivity. The book provides the knowledge in the field of applied superconductivity in a comprehensive way.

  20. Thermal analysis of the forced cooled conductor for the TF superconducting coils in the TIBER II ETR Design

    International Nuclear Information System (INIS)

    The baseline design for TIBER II is to provide steady-state nuclear burn capabilities. The design is constrained to be cost effective and must therefore be sized as small as possible. This constraint limits the nuclear shielding in TIBER and dictates a nuclear heat load of up to 4.5 kW per coil for the toroidal field coils. The cooling scenario and thermal analysis for this design are presented

  1. Superconducting cavities

    International Nuclear Information System (INIS)

    The basic properties of superconducting cavities for electron accelerators are discussed with special emphasis on the following topics: technical motivation for the use of superconducting cavities; surface impedance; the critical field of superconductors; anomalous losses; materials other than niobium; technological achievements for accelerating cavities. (author)

  2. 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}.

  3. Progress in high-temperature superconducting transistors and other devices II; Proceedings of the Meeting, San Jose, CA, Sept. 12, 13, 1991

    Science.gov (United States)

    Singh, Rajendra; Nisenoff, Martin; Pavuna, Davor

    The present conference on high-temperature superconducting transistors and related devices encompasses applications of superconducting thin films, the deposition, patterning, and characterization of thin films, superconducting digital technology, two- and three-terminal devices, and superconducting devices and programs. Specific issues addressed include the application of HTSC films in hybrid optoelectronic devices, the growth and control of epitaxial Ba2YCu3O(7-delta) thin films, atomic layer epitaxy of YBaCuO for optoelectronic applications, single-flux quantum logic, and all-YBaCu3O(7-x) edge-geometry weak links. Also addressed are inverted cylindrical magnetron sputtering for HTSC thin film growth, HTSC films for novel optronic devices, large-area ion-beam-sputtered YBA2Cu3O(7-delta) films for novel device structures, and the High-temperature Superconductivity Space Experiment.

  4. Progress in high-temperature superconducting transistors and other devices II; Proceedings of the Meeting, San Jose, CA, Sept. 12, 13, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Singh, R.; Nisenoff, M.; Pavuna, D. (Clemson University, SC (United States) U.S. Navy, Naval Research Laboratory, Washington, DC (United States) Lausanne, Ecole Polytechnique Federale, (Switzerland))

    1992-01-01

    The present conference on high-temperature superconducting transistors and related devices encompasses applications of superconducting thin films, the deposition, patterning, and characterization of thin films, superconducting digital technology, two- and three-terminal devices, and superconducting devices and programs. Specific issues addressed include the application of HTSC films in hybrid optoelectronic devices, the growth and control of epitaxial Ba2YCu3O(7-delta) thin films, atomic layer epitaxy of YBaCuO for optoelectronic applications, single-flux quantum logic, and all-YBaCu3O(7-x) edge-geometry weak links. Also addressed are inverted cylindrical magnetron sputtering for HTSC thin film growth, HTSC films for novel optronic devices, large-area ion-beam-sputtered YBA2Cu3O(7-delta) films for novel device structures, and the High-temperature Superconductivity Space Experiment.

  5. Progress in high-temperature superconducting transistors and other devices II; Proceedings of the Meeting, San Jose, CA, Sept. 12, 13, 1991

    International Nuclear Information System (INIS)

    The present conference on high-temperature superconducting transistors and related devices encompasses applications of superconducting thin films, the deposition, patterning, and characterization of thin films, superconducting digital technology, two- and three-terminal devices, and superconducting devices and programs. Specific issues addressed include the application of HTSC films in hybrid optoelectronic devices, the growth and control of epitaxial Ba2YCu3O(7-delta) thin films, atomic layer epitaxy of YBaCuO for optoelectronic applications, single-flux quantum logic, and all-YBaCu3O(7-x) edge-geometry weak links. Also addressed are inverted cylindrical magnetron sputtering for HTSC thin film growth, HTSC films for novel optronic devices, large-area ion-beam-sputtered YBA2Cu3O(7-delta) films for novel device structures, and the High-temperature Superconductivity Space Experiment

  6. Effects of Boundary Curvature on Surface Superconductivity

    Science.gov (United States)

    Correggi, Michele; Rougerie, Nicolas

    2016-04-01

    We investigate, within 2D Ginzburg-Landau theory, the ground state of a type-II superconducting cylinder in a parallel magnetic field varying between the second and third critical values. In this regime, superconductivity is restricted to a thin shell along the boundary of the sample and is to leading order constant in the direction tangential to the boundary. We exhibit a correction to this effect, showing that the curvature of the sample affects the distribution of superconductivity.

  7. Color Superconductivity in a Dense Quark Matter

    OpenAIRE

    Ren, Hai-cang

    2003-01-01

    The color superconductivity of a dense quark matter is reviewed with emphasis on the long range nature of the pairing force and the multiplicity of the order parameter. The former gives rise to a non BCS behavior of the superconducting energy scale and the latter modifies the critical value of the Ginzburg-Landau parameter that separates the superconductivity of type I and that of type II.

  8. Superconducting device

    International Nuclear Information System (INIS)

    The present invention provides a superconducting device to be used in a thermonuclear device and capable of unifying a current distribution in a parallel superconducting main line without consumption of liquid helium caused by Joule loss. That is, the device has a paired coils comprising a coil comprising one of plurality of superconducting wires and another coil comprising the other of plurality of superconducting wires and having a reverse winding or negative mutual inductance relative to the coil. A circuit comprising a portion of a main line is disposed to the one coil of the paired coils, and a circuit comprising the remainder of the main line is connected to the other coil each in series. The circuit has a parallel constitution. Such a constitution can provide an effect of unifying the current distribution in the main line without consumption of liquid helium due to Joule loss. (I.S.)

  9. Superconducting linac

    International Nuclear Information System (INIS)

    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

  10. Superconducting magnets

    International Nuclear Information System (INIS)

    This report provides a self-consistent description of a magnetic field in the aperture of a superconducting magnet and details how this field can be calculated in a magnet with cos θ current distribution in the coils. A description of an apparatus that can be used to measure the field uniformity in the aperture has been given. Finally, a detailed description of the magnet being developed for use in the Superconducting Super Collider is given. When this machine is built, it will be by far the largest application of superconductivity to date and promises to make possible the experimental discoveries needed to understand the basic laws of nature governing the world in which we live

  11. Brucella ovis PA mutants for outer membrane proteins Omp10, Omp19, SP41, and BepC are not altered in their virulence and outer membrane properties.

    Science.gov (United States)

    Sidhu-Muñoz, Rebeca S; Sancho, Pilar; Vizcaíno, Nieves

    2016-04-15

    Mutants in several genes have been obtained on the genetic background of virulent rough (lacking O-polysaccharide) Brucella ovis PA. The target genes encode outer membrane proteins previously associated with the virulence of smooth (bearing O-polysaccharide chains in the lipopolysaccharide) Brucella strains. Multiple attempts to delete omp16, coding for a homologue to peptidoglycan-associated lipoproteins, were unsuccessful, which suggests that Omp16 is probably essential for in vitro survival of B. ovis PA. Single deletion of omp10 or omp19 - that encode two other outer membrane lipoproteins - was achieved, but the simultaneous removal of both genes failed, suggesting an essential complementary function between both proteins. Two other deletion mutants, defective in the Tol-C-homologue BepC or in the SP41 adhesin, were also obtained. Surprisingly when compared to previous results obtained with smooth Brucella, none of the B. ovis mutants showed attenuation in the virulence, either in the mouse model or in cellular models of professional and non-professional phagocytes. Additionally, and in contrast to the observations reported with smooth Brucella strains, several properties related to the outer membrane remained almost unaltered. These results evidence new distinctive traits between naturally rough B. ovis and smooth brucellae. PMID:27016758

  12. PREFACE: Superconducting materials Superconducting materials

    Science.gov (United States)

    Charfi Kaddour, Samia; Singleton, John; Haddad, Sonia

    2011-11-01

    The discovery of superconductivity in 1911 was a great milestone in condensed matter physics. This discovery has resulted in an enormous amount of research activity. Collaboration among chemists and physicists, as well as experimentalists and theoreticians has given rise to very rich physics with significant potential applications ranging from electric power transmission to quantum information. Several superconducting materials have been synthesized. Crucial progress was made in 1987 with the discovery of high temperature superconductivity in copper-based compounds (cuprates) which have revealed new fascinating properties. Innovative theoretical tools have been developed to understand the striking features of cuprates which have remained for three decades the 'blue-eyed boy' for researchers in superconductor physics. The history of superconducting materials has been notably marked by the discovery of other compounds, particularly organic superconductors which despite their low critical temperature continue to attract great interest regarding their exotic properties. Last but not least, the recent observation of superconductivity in iron-based materials (pnictides) has renewed hope in reaching room temperature superconductivity. However, despite intense worldwide studies, several features related to this phenomenon remain unveiled. One of the fundamental key questions is the mechanism by which superconductivity takes place. Superconductors continue to hide their 'secret garden'. The new trends in the physics of superconductivity have been one of the two basic topics of the International Conference on Conducting Materials (ICoCoM2010) held in Sousse,Tunisia on 3-7 November 2010 and organized by the Tunisian Physical Society. The conference was a nice opportunity to bring together participants from multidisciplinary domains in the physics of superconductivity. This special section contains papers submitted by participants who gave an oral contribution at ICoCoM2010

  13. A distributed network PCs/Linux system and its application in study of charm physics in BES/BES-II experiments

    International Nuclear Information System (INIS)

    The authors report the configuration of a small PC-PARM and/or a distributed network clustered Linux PCs system and its application in study of the BES/BES-II charm physics. With the system the authors did a full Monte Carlo study of ψ(3770) D physics which will be carried out in the BES-II experiment. Using the J/ψ data collected with the BES-II at BEPC, the authors studied the stability and reliability of the system, as well as the possibility and capability of the system in the data off-line processing

  14. Superconductive detectors

    International Nuclear Information System (INIS)

    Various attempts to use superconductors in the field of radiation detection are reviewed with particular emphasis on the stimulating perspectives offered by superconducting tunnel devices. Applications in the context of energy spectroscopy as well as in the fast discrimination are discussed in the light of recent results. In this framework the central role of nonequilibrium state of superconductors is analyzed in some detail. (orig.)

  15. Superconducting magnets

    International Nuclear Information System (INIS)

    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-Tc superconductor at low temperature

  16. Superconducting materials

    International Nuclear Information System (INIS)

    This report discusses the following topics: Fermi liquid nesting in high temperature superconductors; optical properties of high temperature superconductors; Hall effect in superconducting La2-xSrxCuO4; source of high transition temperatures; and prospects for new superconductors

  17. A new apparatus for measuring the critical currents of hard type-II superconductive wires and tapes in high fields as a function of temperature throughout their superconducting phase

    International Nuclear Information System (INIS)

    The paper describes an update of an earlier apparatus which measures the critical current of superconducting wires and tapes as a function of magnetic field and temperature. The critical element is a compact probe of 25 mm diameter which can be inserted into the bore of one of several high-field magnets. A description is given of the design and critical features of the probe which incorporates high-resolution thermometry and accurate temperature control in the demanding environment of high sample currents and large magnetic fields. Data obtained on a sample of multifilamentary V3Ga wire are presented as an illustration of the probe's capabilities. (author)

  18. SUPERCONDUCTING PHOTOINJECTOR

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI,I.; BURRILL, A.; CALAGA, R.; CHANG, X.; GROVER, R.; GUPTA, R.; HAHN, H.; HAMMONS, L.; KAYRAN, D.; KEWISCH, J.; LAMBIASE, R.; LITVINENKO, V.; MCINTYRE, G.; NAIK, D.; PATE, D.; PHILLIPS, D.; POZDEYEV, E.; RAO, T.; SMEDLEY, J.; THAN, R.; TODD, R.; WEISS, D.; WU, Q.; ZALTSMAN, A.; ET AL.

    2007-08-26

    One of the frontiers in FEL science is that of high power. In order to reach power in the megawatt range, one requires a current of the order of one ampere with a reasonably good emittance. The superconducting laser-photocathode RF gun with a high quantum efficiency photocathode is the most natural candidate to provide this performance. The development of a 1/2 cell superconducting photoinjector designed to operate at up to a current of 0.5 amperes and beam energy of 2 MeV and its photocathode system are the subjects covered in this paper. The main issues are the photocathode and its insertion mechanism, the power coupling and High Order Mode damping. This technology is being developed at BNL for DOE nuclear physics applications such as electron cooling at high energy and electron ion colliders..

  19. 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.

  20. Around the laboratories: Rutherford: Successful tests on bubble chamber target technique; Stanford (SLAC): New storage rings proposal; Berkeley: The HAPPE project to examine cosmic rays with superconducting magnets; The 60th birthday of Professor N.N. Bogolyubov; Argonne: Performance of the automatic film measuring system POLLY II

    CERN Multimedia

    1969-01-01

    Around the laboratories: Rutherford: Successful tests on bubble chamber target technique; Stanford (SLAC): New storage rings proposal; Berkeley: The HAPPE project to examine cosmic rays with superconducting magnets; The 60th birthday of Professor N.N. Bogolyubov; Argonne: Performance of the automatic film measuring system POLLY II

  1. Superconducting accelerator technology

    International Nuclear Information System (INIS)

    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

  2. Space applications of superconductivity

    Science.gov (United States)

    Sullivan, D. B.; Vorreiter, J. W.

    1979-01-01

    Some potential applications of superconductivity in space are summarized, e.g., the use of high field magnets for cosmic ray analysis or energy storage and generation, space applications of digital superconducting devices, such as the Josephson switch and, in the future, a superconducting computer. Other superconducting instrumentation which could be used in space includes: low frequency superconducting sensors, microwave and infrared detectors, instruments for gravitational studies, and high-Q cavities for use as stabilizing elements in clocks and oscillators.

  3. 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

  4. High-temperature superconductivity

    International Nuclear Information System (INIS)

    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

  5. Superconductive communication transmission

    International Nuclear Information System (INIS)

    Recent developments in superconducting techniques have made possible the application of superconductivity in communication cables. Extensive studies have been made, and several experimental coaxial lines and superconductive communication cables have been produced and tested. The attenuation and transmission capacities of superconductive coaxial lines are greatly improved compared with existing cables. Furthermore, the cost of superconductive communication cables is far less than that of existing cables. (author)

  6. Comparative study of type-II superconducting properties in polycrystalline NdFeAsO 0.88F 0.12 prepared by different methods

    Science.gov (United States)

    Ding, Y.; Sun, Y.; Wang, X. D.; Wang, H. C.; Shi, Z. X.; Ren, Z. A.; Yang, J.; Lu, W.

    2010-12-01

    Polycrystalline NdFeAsO 0.88F 0.12 superconductors prepared by high pressure (HP) and ambient pressure (AP) methods were comparatively studied by magnetization and transport measurements. Upper critical field Hc2, irreversibility field Hirr and the anisotropy parameter Γ were estimated from resistance transition curves. The broadening of transition width was observed, and was ascribed to both Hc2 anisotropy and superconductivity inhomogeneity of samples. Magnetic hysteresis loops (MHLs) in low fields were measured to detect the trace of weak-link behavior. The reclosed hysteresis loops in low fields indicate that there are weak links in both samples. Magnetization critical current density Jcm were derived from MHLs. Sample HP shows higher Jcm than sample AP. Direct transport I- V measurements show that the transport critical current density Jct are very low but persist up to 9 T, suggesting intrinsic strong-link existing in both samples.

  7. A disorder parameter for dual superconductivity in gauge theories

    OpenAIRE

    Di Giacomo, A.; Paffuti, G.

    1997-01-01

    A detailed discussion is given of the disorder parameter for dual superconductivity of lattice gauge theories, introduced in a previous paper, and of its relation to other approaches. New lattice data are reported. Among other results, we find that the dual superconductivity of compact U(1) is type II.

  8. Superconductivity for mirror fusion

    International Nuclear Information System (INIS)

    Mirror experiments have led the way in applying superconductivity to fusion research because of unique requirements for high and steady magnetic fields. The first significant applications were Baseball II at LLL and IMP at ORNL, which used multifilamentary niobium--titanium and niobium--tin tape, respectively. Now the USSR at Kurchatov is building a smaller baseball coil with a 6.5 mm square multifilamentary niobium--titanium superconductor similar to the Baseball II conductor. However, the largest advance in fusion magnets will be used in the Mirror Fusion Test Facility (MFTF) now under construction at LLL. Improvements in the technology of the previous LLL experiment, Baseball II, have been made using new conductor joining techniques, a ventilated wrap-around copper stabilizer, and stronger structural welding methods. The MFTF coil winding is proceeding on a separate former to allow parallel construction of the main structure. Not only does this shorten the project schedule to equal that of other conventional constructions, but a second vacuum barrier is created between the magnet helium and the plasma environment for reliable operation

  9. WORKSHOPS: Radiofrequency superconductivity

    International Nuclear Information System (INIS)

    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

  10. Room Temperature Superconductivity

    OpenAIRE

    Luiz, Adir Moyses

    2011-01-01

    This is the first book on the subject of room-temperature superconductivity. The main purpose of the book is twofold. First, to show that, under suitable conditions, superconductivity can occur above room temperature. Secondly, to present general guidelines on how to synthesize a room temperature superconductor. The book begins with an introduction into the physics of the superconducting state and superconducting materials. The mechanisms of conventional, half-conventional and unconventional ...

  11. Engineering Superconducting Phase Qubits

    OpenAIRE

    Blatter, G.; Geshkenbein, V. B.; Ioffe, L.

    1999-01-01

    The superconducting phase qubit combines Josephson junctions into superconducting loops and defines one of the promising solid state device implementations for quantum computing. While conventional designs are based on magnetically frustrated superconducting loops, here we discuss the advantages offered by $\\pi$-junctions in obtaining naturally degenerate two-level systems. Starting from a basic five-junction loop, we show how to construct degenerate two-level junctions and superconducting ph...

  12. Superconducting Power Generation

    CERN Document Server

    Rabinowitz, M

    2000-01-01

    The superconducting ac generator has the greatest potential for large-scale commercial application of superconductivity that can benefit the public. Electric power is a vital ingredient of modern society, and generation may be considered to be the vital ingredient of a power system. This articles gives background, and an insight into the physics and engineering of superconducting power generation.

  13. Basic principle of superconductivity

    OpenAIRE

    De Cao, Tian

    2007-01-01

    The basic principle of superconductivity is suggested in this paper. There have been two vital wrong suggestions on the basic principle, one is the relation between superconductivity and the Bose-Einstein condensation (BEC), and another is the relation between superconductivity and pseudogap.

  14. I. Low frequency noise in metal films at the superconducting transition. II. Resistance of superconductor - normal metal- superconductor sandwiches and the quasiparticle relaxation time

    International Nuclear Information System (INIS)

    Measurements of the noise power spectra of tin and lead films at the superconducting transition in the frequency range of 0.1 Hz to 5k Hz are reported. Two types of samples were made. Type A were evaporated directly onto glass substrate, while Type B were evaporated onto glass or sapphire substrate with a 50A aluminum underlay. The results were consistent with a thermal diffusion model which attributes the noise to the intrinsic temperature fluctuation in the metal film driven with a random energy flux source. In both types of metal films, the noise power was found to be proportional to (V-bar)2 β2/Ω, where V-bar was the mean voltage across the sample, β was the temperature coefficient of resistance and Ω was the volume of the sample. Correlation of noises in two regions of the metal film a distance d apart was detected at frequencies less than or = D/πd2. A possible explanation of the noises using quantitative boundary conditions and implications of this work for device applications are discussed. Theoretical and experimental investigation are reported on the resistance of superconductor-normal metal-superconductor sandwiches near T/sub c/. The increase in SNS resistance is attributed to the penetration of normal electric current in the superconductor. It is proved from first principles that an electric field can exist inside the superconductor when quasiparticles are not equally populated on the two branches of the excitation spectrum, and such is the case in a current biased SNS junction. The electric field inside S decays according to a diffusion law. The diffusion length is determined by the quasiparticle ''branch-crossing'' relaxation time. The branch-crossing relaxation times were measured. Impurity-doping of tin was found to decrease this relaxation time

  15. I. Low frequency noise in metal films at the superconducting transition. II. Resistance of superconductor - normal metal- superconductor sandwiches and the quasiparticle relaxation time

    Energy Technology Data Exchange (ETDEWEB)

    Hsiang, T.Y.

    1977-07-01

    Measurements of the noise power spectra of tin and lead films at the superconducting transition in the frequency range of 0.1 Hz to 5k Hz are reported. Two types of samples were made. Type A were evaporated directly onto glass substrate, while Type B were evaporated onto glass or sapphire substrate with a 50A aluminum underlay. The results were consistent with a thermal diffusion model which attributes the noise to the intrinsic temperature fluctuation in the metal film driven with a random energy flux source. In both types of metal films, the noise power was found to be proportional to (V-bar)/sup 2/ ..beta../sup 2//..cap omega.., where V-bar was the mean voltage across the sample, ..beta.. was the temperature coefficient of resistance and ..cap omega.. was the volume of the sample. Correlation of noises in two regions of the metal film a distance d apart was detected at frequencies less than or = D/..pi..d/sup 2/. A possible explanation of the noises using quantitative boundary conditions and implications of this work for device applications are discussed. Theoretical and experimental investigation are reported on the resistance of superconductor-normal metal-superconductor sandwiches near T/sub c/. The increase in SNS resistance is attributed to the penetration of normal electric current in the superconductor. It is proved from first principles that an electric field can exist inside the superconductor when quasiparticles are not equally populated on the two branches of the excitation spectrum, and such is the case in a current biased SNS junction. The electric field inside S decays according to a diffusion law. The diffusion length is determined by the quasiparticle ''branch-crossing'' relaxation time. The branch-crossing relaxation times were measured. Impurity-doping of tin was found to decrease this relaxation time.

  16. Superconducting microfabricated ion traps

    CERN Document Server

    Wang, Shannon X; Labaziewicz, Jaroslaw; Dauler, Eric; Berggren, Karl; Chuang, Isaac L

    2010-01-01

    We fabricate superconducting ion traps with niobium and niobium nitride and trap single 88Sr ions at cryogenic temperatures. The superconducting transition is verified and characterized by measuring the resistance and critical current using a 4-wire measurement on the trap structure, and observing change in the rf reflection. The lowest observed heating rate is 2.1(3) quanta/sec at 800 kHz at 6 K and shows no significant change across the superconducting transition, suggesting that anomalous heating is primarily caused by noise sources on the surface. This demonstration of superconducting ion traps opens up possibilities for integrating trapped ions and molecular ions with superconducting devices.

  17. Biggest superconducting solenoid magnet in China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ At 8:00am, Sept. 19, the magnetic field of supercon ducting nagnet at the BESⅢ, an upgrade of Beijing Spectrometer, reached 1.0T. The current intensity reached 3,368A, and the energy stored by the solenoid reached 10MJ. Tests showed that the designed requirements had been fully met, which constitutes an important milestone for the BEPC Upgrade now underway at the CAS Institute of High Energy Physic (IHEP).

  18. Superconductivity in aromatic hydrocarbons

    International Nuclear Information System (INIS)

    Highlights: • Aromatic superconductor is one of core research subjects in superconductivity. Superconductivity is observed in certain metal-doped aromatic hydrocarbons. Some serious problems to be solved exist for future advancement of the research. This article shows the present status of aromatic superconductors. - Abstract: ‘Aromatic hydrocarbon’ implies an organic molecule that satisfies the (4n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (Kxpicene, five benzene rings). Its superconducting transition temperatures (Tc’s) were 7 and 18 K. Recently, we found a new superconducting Kxpicene phase with a Tc as high as 14 K, so we now know that Kxpicene possesses multiple superconducting phases. Besides Kxpicene, we discovered new superconductors such as Rbxpicene and Caxpicene. A most serious problem is that the shielding fraction is ⩽15% for Kxpicene and Rbxpicene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of Tc that is clearly observed in some phases of aromatic hydrocarbon superconductors

  19. Superconducting solenoids for nuclear physics at Orsay

    International Nuclear Information System (INIS)

    Two systems using large superconducting solenoids are described. The first, SOLENO, is composed of two magnets (3T, 600 KJ each) and will replace a standard triplet of magnetic lenses; for the moment only the first magnet has gone into operation. The second system, a 5T solenoid, CRYEBIS II, is built in duplicate and will be used on heavy ion sources: one for our laboratory and the other one for the Research Institute of Physics/STOCKHOLM (Sweden). This system employs a superconducting switch to short-circuit the current on the magnet

  20. Principles of Superconductivity

    OpenAIRE

    Mourachkine, A.

    2004-01-01

    The purpose of this chapter is to discuss the main principles of superconductivity as a phenomenon, valid for every superconductor independently of its characteristic properties and material. The underlying mechanisms of superconductivity can be different for various materials, but certain principles must be satisfied. The chapter introduces four principles of superconductivity. (The chapter is slightly nodified from the original one in order to be self-contained.)

  1. Heavy Fermion Superconductivity

    OpenAIRE

    Heffner, Robert H.; Norman, Michael R.

    1995-01-01

    A brief review is given on the current state of experimental and theoretical work in the field of heavy fermion superconductivity. Particular emphasis is placed on those experiments which demonstrate the presence of an unconventional order parameter, as well as the intricate interplay of magnetism and superconductivity in these metals. On the theoretical front, current phenomenological models of the superconductivity are reviewed along with potential pairing mechanisms.

  2. 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.

  3. A STUDY OF THE ENERGY DEPENDENCE OF RADIATION DAMAGE IN SUPERCONDUCTING COILS FOR A NEXT GENERATION MU2E AT PIP - II

    Energy Technology Data Exchange (ETDEWEB)

    Pronskikh, V. [Fermilab; Glenzinski, D. [Fermilab; Knoepfel, K. [Fermilab; Mokhov, N. [Fermilab; Tschirhart, Tschirhart [Fermilab

    2016-04-01

    The Mu2e experiment at Fermilab is being designed to study the coherent neutrino-less conversion of a negative muon into an electron in the field of a nucleus. This process has an extremely low probability in the Standard Model, and its observation would provide unambiguous evidence for beyond the standard model physics. The Mu2e design aims to reach a single-event-sensitivity of about 2.5 x $10^{-17}$ and will probe effective new physics mass scales in the $10^{3}-10^{4}$ TeV range, well beyond the reach of the LHC. This work will examine the maximum beam power that can be tolerated for beam energies in the 0.5-8 GeV range. This has implications for how the sensitivity might be further improved with a second generation experiment using an upgraded proton beam from the PIP-II project, which will be capable of providing MW beams to Fermilab experiments later in the next decade.

  4. Fundamentals of Superconducting Nanoelectronics

    CERN Document Server

    Sidorenko, Anatolie

    2011-01-01

    This book demonstrates how the new phenomena in superconductivity on the nanometer scale (FFLO state, triplet superconductivity, Crossed Andreev Reflection, synchronized generation etc.) serve as the basis for the invention and development of novel nanoelectronic devices and systems. It demonstrates how rather complex ideas and theoretical models, like odd-pairing, non-uniform superconducting state, pi-shift etc., adequately describe the processes in real superconducting nanostructues and novel devices based on them. The book is useful for a broad audience of readers, researchers, engineers, P

  5. Superconductivity and its application

    International Nuclear Information System (INIS)

    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

  6. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

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

    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...... 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...

  7. Superconductivity in Nb2InC

    International Nuclear Information System (INIS)

    In this work the Nb2InC phase is investigated by X-ray diffraction, heat capacity, magnetic and resistivity measurements. Polycrystalline samples with Nb2InC nominal compositions were prepared by solid state reaction. X-ray powder patterns suggest that all peaks can be indexed with the hexagonal phase of Cr2AlC prototype. The electrical resistance as a function of temperature for Nb2InC shows superconducting behavior below 7.5 K. The M(H) data show typical type-II superconductivity with HC1 ∼ 90 Oe at 1.8 K. The specific heat data are consistent with bulk superconductivity. The Sommerfeld constant is estimated as γ ∼ 12.6 mJ mol-1 K-1.

  8. Superconductivity in carrier-doped silicon carbide

    Directory of Open Access Journals (Sweden)

    Takahiro Muranaka, Yoshitake Kikuchi, Taku Yoshizawa, Naoki Shirakawa and Jun Akimitsu

    2008-01-01

    Full Text Available We report growth and characterization of heavily boron-doped 3C-SiC and 6H-SiC and Al-doped 3C-SiC. Both 3C-SiC:B and 6H-SiC:B reveal type-I superconductivity with a critical temperature Tc=1.5 K. On the other hand, Al-doped 3C-SiC (3C-SiC:Al shows type-II superconductivity with Tc=1.4 K. Both SiC:Al and SiC:B exhibit zero resistivity and diamagnetic susceptibility below Tc with effective hole-carrier concentration n higher than 1020 cm−3. We interpret the different superconducting behavior in carrier-doped p-type semiconductors SiC:Al, SiC:B, Si:B and C:B in terms of the different ionization energies of their acceptors.

  9. 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...

  10. High temperature superconductivity

    International Nuclear Information System (INIS)

    This book contains the proceedings of a conference on high temperature superconductivity. The papers presented include: Microstructural considerations in polycrystalline YBa2Cu3O7 and The role of the metallic orbital and of crest and trough superconduction in high temperature superconductors

  11. High temperature superconductivity

    International Nuclear Information System (INIS)

    This book covers the proceedings of the 3rd National Meeting on High Temperature Superconductivity Topics includes: Crystal growth of superconductors; thermodynamic stability of superconducting materials; spectroscopy of High Tc Superconductors; synchrotron radiation investigation of superconductors; density state determination; measurements of current density; preparation and characterization of superconductors

  12. Non-Abelian Superconductivity

    OpenAIRE

    Cho, Y. M.

    2001-01-01

    We establish a non-Abelian superconductivity and a non-Abelian Meissner effect by constructing an effective field theory of superconductivity in which a genuine SU(2) gauge symmetry governs the dynamics. We show that the magnetic flux is quantized in the unit of $4\\pi/g$, not $2\\pi/g$, in the non-Abelian superconductor.

  13. Large superconducting magnets

    CERN Document Server

    Pérot, J

    1981-01-01

    Discusses the use of large superconducting magnets in the areas of particle physics, thermonuclear fusion, and magnetohydrodynamics. In addition to considering the physics of the superconducting state, the article considers machines such as BEBC (Big European Bubble Chamber) at CERN, the LINAC at SLAC and possible Tokamak applications. The future application of superconductors to high speed trains is discussed. (0 refs).

  14. Superconducting RF cavities

    CERN Document Server

    Bernard, Philippe

    1999-01-01

    It was 20 years ago when the research and development programme for LEP superconducting cavities was initiated. It lasted about 10 years. Today, my aim is not to tell you in great detail about the many innovations made thanks to our research, but I would like to point out some milestones in the development of superconducting cavities where Emilio's influence was particularly important.

  15. Superconducting cavities for LEP

    CERN Multimedia

    1983-01-01

    Above: a 350 MHz superconducting accelerating cavity in niobium of the type envisaged for accelerating electrons and positrons in later phases of LEP. Below: a small 1 GHz cavity used for investigating the surface problems of superconducting niobium. Albert Insomby stays on the right. See Annual Report 1983 p. 51.

  16. Fast granular superconducting bolometer

    International Nuclear Information System (INIS)

    A granular superconducting thin film bolometer made by anodizing a thin film of such materials as niobium nitride to form a thin granular film separated by and covered with the anodized oxide. The bolometer is cooled to its superconducting state and electrically connected to a biasing and detecting network. Its temporal response is better than 1 ns

  17. Superconducting photonic crystals

    OpenAIRE

    Berman, Oleg L.; Lozovik, Yurii E.; Eiderman, Sergey L.; Coalson, Rob D.

    2006-01-01

    The band structure of a novel type of photonic crystal with superconducting constituent elements is calculated numerically via a plane wave expansion. The density of states and the dependence of the width of the photonic gap on the filling factor is analyzed for a two-dimensional photonic crystal consisting of an infinite array of parallel superconducting cylinders.

  18. Superconducting Graphene Nanoelectronic Devices

    Science.gov (United States)

    Wang, Joel; Zaffalon, Michele; Jarillo-Herrero, Pablo

    2010-03-01

    Graphene, a single atom-thick sheet of graphite discovered in recent years, has attracted tremendous attention due to its exotic electronic properties. At low energy, its gapless linear band structure results in transport properties described by the Dirac equation, making it an ideal system for the study of exotic quantum phenomena and other new physics. Graphene may also exhibit many novel transport characteristics in the superconducting regime. New phenomena, such as pseudo-diffusive dynamics of ballistic electrons, the relativistic Josephson effect, and specular Andreev reflection are predicted by theoretical models combining relativistic quantum mechanics and superconductivity. We study these phenomena experimentally with superconductor-graphene-superconductor junctions. The supercurrent in graphene is induced by the superconducting contacts through proximity effect. Various superconducting materials are considered for different explorations. Preliminary tests indicate clean electrical contact with graphene and superconducting properties as expected.

  19. Superconductivity in aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Kubozono, Yoshihiro, E-mail: kubozono@cc.okayama-u.ac.jp [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Japan Science and Technology Agency, ACT-C, Kawaguchi 332-0012 (Japan); Goto, Hidenori; Jabuchi, Taihei [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Yokoya, Takayoshi [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Kambe, Takashi [Department of Physics, Okayama University, Okayama 700-8530 (Japan); Sakai, Yusuke; Izumi, Masanari; Zheng, Lu; Hamao, Shino; Nguyen, Huyen L.T. [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Sakata, Masafumi; Kagayama, Tomoko; Shimizu, Katsuya [Center of Science and Technology under Extreme Conditions, Osaka University, Osaka 560-8531 (Japan)

    2015-07-15

    Highlights: • Aromatic superconductor is one of core research subjects in superconductivity. Superconductivity is observed in certain metal-doped aromatic hydrocarbons. Some serious problems to be solved exist for future advancement of the research. This article shows the present status of aromatic superconductors. - Abstract: ‘Aromatic hydrocarbon’ implies an organic molecule that satisfies the (4n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (K{sub x}picene, five benzene rings). Its superconducting transition temperatures (T{sub c}’s) were 7 and 18 K. Recently, we found a new superconducting K{sub x}picene phase with a T{sub c} as high as 14 K, so we now know that K{sub x}picene possesses multiple superconducting phases. Besides K{sub x}picene, we discovered new superconductors such as Rb{sub x}picene and Ca{sub x}picene. A most serious problem is that the shielding fraction is ⩽15% for K{sub x}picene and Rb{sub x}picene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of T{sub c} that is clearly

  20. Development of superconducting electromagnets

    International Nuclear Information System (INIS)

    The contribution of superconduction techniques to high energy physics has increased recently, and the experiment on high energy physics is no more possible if superconduction techniques are neglected. The development of superconducting magnets for a proton ring in the phase 2 of TRISTAN project of KEK, the superconducting proton synchrotron in Fermi National Accelerator Laboratory already in operation, the superconducting supercollider of 20TeV x 20TeV proton-proton in USA, and the JSC project of 30TeV x 30TeV proton-antiproton collision type accelerator are the examples. For the superconducting electromagnets of the SSC project, the full scale mass production lines will be completed. The intensity of their magnetic field is from 3T to 8T. As to the electromagnets for the JSC project, the intensity of magnetic field as high as 9T is required. The material of wires, two-layer shell type structure, cold iron and cold bore type, self correction coil and so on are discussed. The problems of electromagnetic force acting on coils and stored electromagnetic energy at the time of quenching are described. The present status and the project of superconducting electromagnet development in KEK are explained. (Kako, I.)

  1. The superconducting spin valve and triplet superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Garifullin, I.A., E-mail: ilgiz_garifullin@yahoo.com [Zavoisky Physical-Technical Institute, Kazan Scientific Center of Russian Academy of Sciences, 420029 Kazan (Russian Federation); Leksin, P.V.; Garif' yanov, N.N.; Kamashev, A.A. [Zavoisky Physical-Technical Institute, Kazan Scientific Center of Russian Academy of Sciences, 420029 Kazan (Russian Federation); Fominov, Ya.V. [L. D. Landau Institute for Theoretical Physics RAS, 119334 Moscow (Russian Federation); Moscow Institute of Physics and Technology, 141700 Dolgoprudny (Russian Federation); Schumann, J.; Krupskaya, Y.; Kataev, V.; Schmidt, O.G. [Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden (Germany); Büchner, B. [Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden (Germany)

    2015-01-01

    A review of our recent results on the spin valve effect is presented. We have used a theoretically proposed spin switch design F1/F2/S comprising a ferromagnetic bilayer (F1/F2) as a ferromagnetic component, and an ordinary superconductor (S) as the second interface component. Based on it we have prepared and studied in detail a set of multilayers CoO{sub x}/Fe1/Cu/Fe2/S (S=In or Pb). In these heterostructures we have realized for the first time a full spin switch effect for the superconducting current, have observed its sign-changing oscillating behavior as a function of the Fe2-layer thickness and finally have obtained direct evidence for the long-range triplet superconductivity arising due to noncollinearity of the magnetizations of the Fe1 and Fe2 layers. - Highlights: • We studied a spin switch design F1/F2/S. • We prepared a set of multilayers CoOx/Fe1/Cu/Fe2/S (S=In or Pb). • The full spin switch effect for the superconducting current was realized. • We observed its oscillating behavior as a function of the Fe2-layer thickness. • We obtained direct evidence for the long-range triplet superconductivity.

  2. High temperature superconductivity

    International Nuclear Information System (INIS)

    New superconducting oxides and physical basis of the high-temperature superconductivity developed from 1979 till 1986 are reviewed. The analysis is based upon the concept of exchange amplification of electron-phonon interaction put forward by the author in 1964. Using the high-temperature superconductivity theory an approach to increasing the critical temperature of high-temperature superconductors (HTSC) is proposed along with the means for synthesis of HTSC with higher critical fields. The feasibility of HTSC implementation in the modern physical experiment technology is also considered, e.g. for detecting the magnetic monopoles. 35 refs.; 2 figs

  3. Superconductivity in doped insulators

    International Nuclear Information System (INIS)

    It is shown 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. 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. (orig.)

  4. Superconducting accelerator magnets

    International Nuclear Information System (INIS)

    In the near future, a large number of high quality superconducting dipole and quadrupole magnets will be required for construction of the next generation multi-TeV high energy hadron accelerator-colliders. To establish the construction technology of such accelerator- colliders, extensive and world-wide R and D programs are now carrying out at several laboratories. In this paper the important issues in superconducting accelerator magnets such as cables, design, fabrication, testing and cryogenic system are discussed together with some details on coil cross- sectional current configurations, quality control of materials, quench protections, radiation heating and etc. The key technology in superconducting accelerator magnets is summarized

  5. Tunneling in superconducting structures

    Science.gov (United States)

    Shukrinov, Yu. M.

    2010-12-01

    Here we review our results on the breakpoint features in the coupled system of IJJ obtained in the framework of the capacitively coupled Josephson junction model with diffusion current. A correspondence between the features in the current voltage characteristics (CVC) and the character of the charge oscillations in superconducting layers is demonstrated. Investigation of the correlations of superconducting currents in neighboring Josephson junctions and the charge correlations in neighboring superconducting layers reproduces the features in the CVC and gives a powerful method for the analysis of the CVC of coupled Josephson junctions. A new method for determination of the dissipation parameter is suggested.

  6. Superconducting materials and magnets

    International Nuclear Information System (INIS)

    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

  7. Superconductivity in the thirties

    International Nuclear Information System (INIS)

    The author discusses the theoretical advances made in understanding superconductivity by the introduction of new quantum mechanics. He concludes with a few comments on the present theory, BCS theory. (G.T.H.)

  8. 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...

  9. Superconductivity of magnesium diboride

    International Nuclear Information System (INIS)

    Highlights: • Over the past 14 years MgB2 has gone from a startling discovery to a promising, applied superconductor. • In this article we present a brief overview of the synthesis and the basic superconducting properties of this remarkable compound. • In particular, the effects of pressure, substitutions and neutron irradiation on superconducting properties are discussed. - Abstract: Over the past 14 years MgB2 has gone from a startling discovery to a promising, applied superconductor. In this article we present a brief overview of the synthesis and the basic superconducting properties of this remarkable compound. In particular, the effect of pressure, substitutions and neutron irradiation on superconducting properties are discussed

  10. Superconductivity: materials and applications

    International Nuclear Information System (INIS)

    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.)

  11. Photoemission, Correlation and Superconductivity:

    Science.gov (United States)

    Abrecht, M.; Ariosa, D.; Cloëtta, D.; Pavuna, D.; Perfetti, L.; Grioni, M.; Margaritondo, G.

    We review some of the problems still affecting photoemission as a probe of high-temperature superconductivity, as well as important recent results concerning their solution. We show, in particular, some of the first important results on thin epitaxial films grown by laser ablation, which break the monopoly of cleaved BCSCO in this type of experiments. Such results, obtained on thin LSCO, may have general implications on the theory of high-temperature superconductivity.

  12. Introduction to Color Superconductivity

    OpenAIRE

    Nardulli, G.

    2006-01-01

    At high nuclear density and small temperature, due to the asymptotic freedom property of Quantum ChromoDynamics and to the existence of an attractive channel in the color interaction, diquark condensates might be formed. Since these condensates break the color gauge symmetry, this phenomenon has the name of color superconductivity. In the last few years this has become a very active field of research. While a direct experimental test is still missing, color superconductivity might have implic...

  13. Relativistic Theory of Superconductivity

    OpenAIRE

    Capelle, K.; Marques, M. A. L.; Gross, E. K. U.

    2001-01-01

    The relativistic generalization of the theory of superconductivity is reviewed with respect to its conceptual basis and first applications. The construction of relativistically covariant order parameters for superconductors is outlined and the generalization of the Dirac equation for the superconducting state is presented. A weakly relativistic expansion of this equation leads to the Pauli equation for superconductors, which describes the lowest-order relativistic corrections to the conventio...

  14. Superconducting crab cavity

    International Nuclear Information System (INIS)

    Complete overlapping of the electron and positron bunches at colliding point can be attained by using the strong time-depending electromagnetic RF field in the superconducting crab cavity. Commissioning of the crab cavities started in February 2007 at KEKB. Effective head-on collision of electron and positron has been achieved successfully. After introduction of crab crossing and crab cavity, the structure and the fabrication of the KEKB superconducting crab cavity are discussed. (author)

  15. High temperature interfacial superconductivity

    Science.gov (United States)

    Bozovic, Ivan; Logvenov, Gennady; Gozar, Adrian Mihai

    2012-06-19

    High-temperature superconductivity confined to nanometer-scale interfaces has been a long standing goal because of potential applications in electronic devices. The spontaneous formation of a superconducting interface in bilayers consisting of an insulator (La.sub.2CuO.sub.4) and a metal (La.sub.1-xSr.sub.xCuO.sub.4), neither of which is superconducting per se, is described. Depending upon the layering sequence of the bilayers, T.sub.c may be either .about.15 K or .about.30 K. This highly robust phenomenon is confined to within 2-3 nm around the interface. After exposing the bilayer to ozone, T.sub.c exceeds 50 K and this enhanced superconductivity is also shown to originate from a 1 to 2 unit cell thick interfacial layer. The results demonstrate that engineering artificial heterostructures provides a novel, unconventional way to fabricate stable, quasi two-dimensional high T.sub.c phases and to significantly enhance superconducting properties in other superconductors. The superconducting interface may be implemented, for example, in SIS tunnel junctions or a SuFET.

  16. 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.

  17. Electron pairing without superconductivity

    Science.gov (United States)

    Levy, Jeremy

    Strontium titanate (SrTiO3) is the first and best known superconducting semiconductor. It exhibits an extremely low carrier density threshold for superconductivity, and possesses a phase diagram similar to that of high-temperature superconductors--two factors that suggest an unconventional pairing mechanism. Despite sustained interest for 50 years, direct experimental insight into the nature of electron pairing in SrTiO3 has remained elusive. Here we perform transport experiments with nanowire-based single-electron transistors at the interface between SrTiO3 and a thin layer of lanthanum aluminate, LaAlO3. Electrostatic gating reveals a series of two-electron conductance resonances--paired electron states--that bifurcate above a critical pairing field Bp of about 1-4 tesla, an order of magnitude larger than the superconducting critical magnetic field. For magnetic fields below Bp, these resonances are insensitive to the applied magnetic field; for fields in excess of Bp, the resonances exhibit a linear Zeeman-like energy splitting. Electron pairing is stable at temperatures as high as 900 millikelvin, well above the superconducting transition temperature (about 300 millikelvin). These experiments demonstrate the existence of a robust electronic phase in which electrons pair without forming a superconducting state. Key experimental signatures are captured by a model involving an attractive Hubbard interaction that describes real-space electron pairing as a precursor to superconductivity. Support from AFOSR, ONR, ARO, NSF, DOE and NSSEFF is gratefully acknowledged.

  18. Superconductivity and the Periodic Table

    International Nuclear Information System (INIS)

    In view of the inability of the present theory of superconductivity to make reliable predictions for the magnitude of Tsub(c) it seems useful to search for empirical relationships between the composition of the compound and the Tsub(c) value. Table I gives a list of the available Tsub(c) data for transition metals (TM) having from 3 to 9 outer electrons and Tsub(c) data for non-transition elements (NTE) of groups IIB, IIIB and IVB, including data for amorphous (Am) structures and structures (marked by triangles) obtained at high pressures. The analogous metals have therefore the same structure. In Tables II to IV the Tsub(c) data are presented for analogous compounds of NTE from IB - VIB group. Conclusions are presented. (author)

  19. Gapless superconductivity and string theory

    Directory of Open Access Journals (Sweden)

    Sergei Khlebnikov

    2014-10-01

    Full Text Available Coexistence of superconducting and normal components in nanowires at currents below the critical (a “mixed” state would have important consequences for the nature and range of potential applications of these systems. For clean samples, it represents a genuine interaction effect, not seen in the mean-field theory. Here we consider properties of such a state in the gravity dual of a strongly coupled superconductor constructed from D3 and D5 branes. We find numerically uniform gapless solutions containing both components but argue that they are unstable against phase separation, as their free energies are not convex. We speculate on the possible nature of the resulting non-uniform sate (“emulsion” and draw analogies between that state and the familiar mixed state of a type II superconductor in a magnetic field.

  20. Gapless superconductivity and string theory

    International Nuclear Information System (INIS)

    Coexistence of superconducting and normal components in nanowires at currents below the critical (a “mixed” state) would have important consequences for the nature and range of potential applications of these systems. For clean samples, it represents a genuine interaction effect, not seen in the mean-field theory. Here we consider properties of such a state in the gravity dual of a strongly coupled superconductor constructed from D3 and D5 branes. We find numerically uniform gapless solutions containing both components but argue that they are unstable against phase separation, as their free energies are not convex. We speculate on the possible nature of the resulting non-uniform sate (“emulsion”) and draw analogies between that state and the familiar mixed state of a type II superconductor in a magnetic field

  1. Exploring the Fragile Antiferromagnetic Superconducting Phase in CeCoIn5

    DEFF Research Database (Denmark)

    Blackburn, E.; Das, P.; Eskildsen, M.R.;

    2010-01-01

    CeCoIn5 is a heavy fermion type-II superconductor showing clear signs of Pauli-limited superconductivity. A variety of measurements give evidence for a transition at high magnetic fields inside the superconducting state, when the field is applied either parallel to or perpendicular to the c axis...

  2. The magnetism of superconductivity

    International Nuclear Information System (INIS)

    Plutonium has been added to the list of superconductors and may shed new light on the mechanism responsible for high-temperature superconductivity. There is something magnetic about superconductivity. Those who work in the field may have started out in a rather casual way, thinking 'I will just do this one measurement and then go back to what I was doing before'. But superconductivity holds such a strong fascination that it can soon become a lifelong obsession. One attraction might be the appearance of quantum interference on a macroscopic level, but the mechanism of superconductivity itself also appeals to something quite deep within us. A crystalline metal is composed of a lattice of positively charged ions. These are left behind when their valence electrons 'melt' to produce the electron liquid that is responsible for the current-carrying ability of the metal. Electrons in a metal repel each other violently due to their like-charges, but according to the highly successful Bardeen-Cooper-Schrieffer (BCS) theory of 1958, a superconductor can overcome this repulsion by the action of a third party. Pairs of electrons attract each other via fluctuating concentrations of positive charge that they induce on the ionic lattice. Nature also likes superconductors, because we are finding them in increasingly unlikely places. Now John Sarrao and collaborators at the Los Alamos National Laboratory, the University of Florida and the Institute for Transuranium Elements in Karlsruhe, Germany, have announced the discovery of superconductivity in PuCoGa5 or plutonium cobalt gallium-5 (J L Sarrao et al. 2002 Nature 420,297). The superconductivity survives up to the astonishingly high temperature of 18 K. In the February issue of Physics World, Stephen Julian describes the superconducting nature of plutonium in more detail. (U.K.)

  3. Superconducting nanostructured materials

    International Nuclear Information System (INIS)

    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

  4. Superconductivity for hydrogen economy

    International Nuclear Information System (INIS)

    The emerging hydrogen economy is expected to deal with a large amount of liquid hydrogen produced from the renewable energy resources. The main advantage of liquid hydrogen in comparison with other forms of its storage and transportation is in allowing wide use of superconductivity, which would optimise energy efficiency of the economy. The basic element of the infrastructure for hydrogen economy is a network of superconducting pipelines carrying simultaneously liquid hydrogen and loss-free electricity. The most likely material for such infrastructure is MgB2, the only superconductor efficiently working at boiling temperature of liquid hydrogen and not showing strong critical current reduction on grain boundaries. The cheap techniques for the preparation of MgB2 are hot isostatic pressing, resistive sintering and paint coating. These and other advanced techniques are able to provide MgB2 with suitable for the infrastructure structural and superconducting properties. The preparation of a large-area superconducting joint between two pieces of MgB2 as a technique enabling this infrastructure is reported. A potential of synergy between liquid hydrogen and superconductivity is revealed in a range of possible new energy applications.

  5. Superconductivity and macroscopic quantum phenomena

    International Nuclear Information System (INIS)

    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.)

  6. From constant to non-degenerately vanishing magnetic fields in superconductivity

    OpenAIRE

    Helffer, Bernard; Kachmar, Ayman

    2015-01-01

    We explore the relationship between two reference functions arising in the analysis of the Ginzburg-Landau functional. The first function describes the distribution of superconductivity in a type II superconductor subjected to a constant magnetic field. The second function describes the distribution of superconductivity in a type II superconductor submitted to a variable magnetic field that vanishes non-degenerately along a smooth curve.

  7. Superconducting HERA magnets

    International Nuclear Information System (INIS)

    The 820 GeV HERA proton storage ring, presently under construction at DESY, will be equipped with about 650 superconducting main magnets (dipoles and quadrupoles) and approximately the same number of superconducting correction elements (dipoles, quadrupoles and sextupoles). These magnets will form a continuous cold string through the 6.3 km long HERA tunnel interrupted only by warm sections around the interaction regions. The magnet system is cooled with one phase helium supplied by a 3 block central refrigeration system of 20 kW refrigeration power at 4.3 K. Two phase helium is returned through the magnets for temperature control. Prototypes of all types of superconducting magnets have been built and tested at liquid helium temperatures. The tested magnets have good field quality and good quench behaviour, which proves that these magnets are well suited for HERA

  8. Large Superconducting Magnet Systems

    CERN Document Server

    Védrine, P

    2014-01-01

    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.

  9. Superconducting accelerator magnet design

    International Nuclear Information System (INIS)

    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.)

  10. Superconductivity at Any Temperature

    CERN Document Server

    Anber, Mohamed M; Sabancilar, Eray; Shaposhnikov, Mikhail

    2016-01-01

    We construct a 2+1 dimensional model that sustains superconductivity at all temperatures. This is achieved by introducing a Chern Simons mixing term between two Abelian gauge fields A and Z. The superfluid is described by a complex scalar charged under Z, whereas a sufficiently strong magnetic field of A forces the superconducting condensate to form at all temperatures. In fact, at finite temperature, the theory exhibits Berezinsky-Kosterlitz-Thouless phase transition due to proliferation of topological vortices admitted by our construction. However, the critical temperature is proportional to the magnetic field of A, and thus, the phase transition can be postponed to high temperatures by increasing the strength of the magnetic field. This model can be a step towards realizing the long sought room temperature superconductivity.

  11. Superconducting super collider

    International Nuclear Information System (INIS)

    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

  12. 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.

  13. Nonlinear terahertz superconducting plasmonics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jingbo; Liang, Lanju; Jin, Biaobing, E-mail: bbjin@nju.edu.cn, E-mail: tonouchi@ile.osaka-u.ac.jp, E-mail: phwu@nju.edu.cn; Kang, Lin; Xu, Weiwei; Chen, Jian; Wu, Peiheng, E-mail: bbjin@nju.edu.cn, E-mail: tonouchi@ile.osaka-u.ac.jp, E-mail: phwu@nju.edu.cn [Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Zhang, Caihong; Kawayama, Iwao; Murakami, Hironaru; Tonouchi, Masayoshi, E-mail: bbjin@nju.edu.cn, E-mail: tonouchi@ile.osaka-u.ac.jp, E-mail: phwu@nju.edu.cn [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Wang, Huabing [Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2014-10-20

    Nonlinear terahertz (THz) transmission through subwavelength hole array in superconducting niobium nitride (NbN) film is experimentally investigated using intense THz pulses. The good agreement between the measurement and numerical simulations indicates that the field strength dependent transmission mainly arises from the nonlinear properties of the superconducting film. Under weak THz pulses, the transmission peak can be tuned over a frequency range of 145 GHz which is attributed to the high kinetic inductance of 50 nm-thick NbN film. Utilizing the THz pump-THz probe spectroscopy, we study the dynamic process of transmission spectra and demonstrate that the transition time of such superconducting plasmonic device is within 5 ps.

  14. Applied Superconductivity Conference 2014

    CERN Document Server

    2015-01-01

    Energy Efficiency is a worldwide imperative driven by an increasing awareness of the need to conserve valuable natural resources. Superconductivity, the technology which revolutionized non-invasive medical imaging through MRI starting in the 1980’s, is one of the most promising enablers of energy efficiency in the 21st century. From energy efficient supercomputers to power generation, transmission, and storage, the spectrum of applications of superconductivity is broad in its reach and potential. As ASC comes to Charlotte, site of the hall of fame of NASCAR, our theme, “Race to Energy Efficiency,” is intended to inspire the world experts in superconductivity who will converge to Charlotte to present their latest results, exchange information, network, and plan and project the future breakthroughs.

  15. Enhancing superconducting critical current by randomness

    Science.gov (United States)

    Wang, Y. L.; Thoutam, L. R.; Xiao, Z. L.; Shen, B.; Pearson, J. E.; Divan, R.; Ocola, L. E.; Crabtree, G. W.; Kwok, W. K.

    2016-01-01

    The key ingredient of high critical currents in a type-II superconductor is defect sites that pin vortices. Contrary to earlier understanding on nanopatterned artificial pinning, here we show unequivocally the advantages of a random pinscape over an ordered array in a wide magnetic field range. We reveal that the better performance of a random pinscape is due to the variation of its local density of pinning sites (LDOPS), which mitigates the motion of vortices. This is confirmed by achieving even higher enhancement of the critical current through a conformally mapped random pinscape, where the distribution of the LDOPS is further enlarged. The demonstrated key role of LDOPS in enhancing superconducting critical currents gets at the heart of random versus commensurate pinning. Our findings highlight the importance of random pinscapes in enhancing the superconducting critical currents of applied superconductors.

  16. Phonon spectroscopy with superconducting tunnel junctions

    International Nuclear Information System (INIS)

    Superconducting tunnel junctions can be used as generators and detectors of monochromatic phonons of frequency larger than 80 GHz, as was first devised by Eisenmenger and Dayem (1967) and Kinder (1972a, 1973). In this report, we intend to give a general outline of this type of spectroscopy and to present the results obtained so far. The basic physics underlying phonon generation and detection are described in chapter I, a wider approach being given in the references therein. In chapter II, the different types of junctions are considered with respect to their use. Chapter III deals with the evaporation technique for the superconducting junctions. The last part of this report is devoted to the results that we have obtained on γ-irradiated LiF, pure Si and Phosphorous implanted Si. In these chapters, the limitations of the spectrometer are brought out and suggestions for further work are given

  17. Superconductive analogue of spin glasses

    International Nuclear Information System (INIS)

    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

  18. Possibility of color magnetic superconductivity

    OpenAIRE

    Tatsumi, Toshitaka; Maruyama, Tomoyuki; Nakano, Eiji

    2003-01-01

    Two aspects of quark matter at high density are addressed: one is color superconductivity and the other is ferromagnetism. We are mainly concerned with the latter and its relation to color superconductivity, which we call "color magnetic superconductivity". The relation of ferromagnetism and chiral symmetry restoration is also discussed.

  19. High Pressure Effects on Superconductivity

    OpenAIRE

    Lorenz, B.; Chu, C. W.

    2004-01-01

    The review is devoted to a discussion of the effects of high pressure imposed on superconducting materials. Low-temperature superconductors, high-temperature superconducting cuprates, and some unconventional superconducting compounds are investigated. Experimental as well as theoretical results regarding the pressure effects on Tc and other interesting properties are summarized.

  20. Hybrid Superconducting Neutron Detectors

    OpenAIRE

    Merlo, V.; Salvato, M.; Cirillo, M.; Lucci, M.; Ottaviani, I.; Scherillo, A.; Celentano, G.; Pietropaolo, A.

    2014-01-01

    A new neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction 10B+n $\\rightarrow$ $\\alpha$+ 7Li , with $\\alpha$ and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection...

  1. Superconducting current generators

    International Nuclear Information System (INIS)

    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)

  2. 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.

  3. Fingerprints of Mott Superconductivity

    Institute of Scientific and Technical Information of China (English)

    王强华

    2003-01-01

    We improve a previous theory of doped Mott insulators with duality between pairing and magnetism by a further duality transform. As the result we obtained a quantum Ginzburg-Landau theory describing the Cooper pair condensate and the dual of spin condensate. We address the superconductivity by doping a Mott insulator,which we call the Mott superconductivity. Some fingerprints of such novelty in cuprates are the scaling between neutron resonance energy and superfluid density, and the induced quantized spin moment by vortices or Zn impurity (together with circulating charge super-current to be checked by experiments).

  4. Today's markets for superconductivity

    International Nuclear Information System (INIS)

    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

  5. Superconducting magnets for HERA

    International Nuclear Information System (INIS)

    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

  6. Superconductive magnetic energy storage

    International Nuclear Information System (INIS)

    Technical and economic aspects of large scale superconductive magnetic energy storage are discussed. This paper is a review of a program which has been under way at the University of Wisconsin since 1970. Early work between 1970 and 1976 was primarily involved in providing economic and technical feasibility of the concept. The present program deals with component development and detailed design ultimately leading to construction of a large superconducting magnet capable of storing 1000 to 10,000 MWh. The magnet is a single-layered segmented solenoid approx. 100 m radius. Energy containment is achieved economically by burying the magnet underground in bedrock tunnels. Magnetic loads are transmitted from the conductor to bedrock through glass fiber reinforced composite struts. The conductor consists of a composite of aluminium and NbTi and is designed for full cryogenic stability in 1.8 K superfluid helium. The dewar-conductor assembly will be rippled in a 1 m radius of curvature to reduce the hoop stress tension. A Graetz bridge is required to convert the d.c. superconducting current into a.c. current in the three-phase power system. Economic analysis indicates that superconductive magnetic energy storage is competitive with alternative large scale storage schemes for units greater than 1000 MWh size. (U.K.)

  7. 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.

  8. Superconductivity committee planning report

    Energy Technology Data Exchange (ETDEWEB)

    1988-11-01

    The recent discovery of superconductors that operate at relatively high temperatures has generated a large amount of research which promises to have applications in almost all branches of high technology, notably those in which high electric current densities are used. After a background description of the properties of superconductors, the market for superconductor technology is described from the Canadian perspective. Worldwide markets are growing rapidly and are estimated to total $920 million by 1990, considering only conventional low-temperature superconductors. Applications for superconductivity include the use of thin films and microelectronics, low loss signal transmission, tunnel injections, and sensitive magnetic detectors. Superconducting magnets find application in magnetic separation, magnetic levitation and propulsion, and for energy storage and transmission by power utilities. Research in superconductivity in British Columbia, reviewed in this report, has been under way at 3 universities and 4 or 5 compaines, where a small group of qualified researchers and some high-technology laboratories are focusing on thin-film and electonic applications. The potential market for superconductivity is felt to warrant more effort in British Columbia, and a number of recommendations are made for coordinating and promoting research, funding joint university-industry projects for innovative applications, and facilitating technology transfer.

  9. Superconducting doped topological materials

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Satoshi, E-mail: sasaki@sanken.osaka-u.ac.jp [Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Mizushima, Takeshi, E-mail: mizushima@mp.es.osaka-u.ac.jp [Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Department of Physics, Okayama University, Okayama 700-8530 (Japan)

    2015-07-15

    Highlights: • Studies on both normal- and SC-state properties of doped topological materials. • Odd-parity pairing systems with the time-reversal-invariance. • Robust superconductivity in the presence of nonmagnetic impurity scattering. • We propose experiments to identify the existence of Majorana fermions in these SCs. - Abstract: Recently, the search for Majorana fermions (MFs) has become one of the most important and exciting issues in condensed matter physics since such an exotic quasiparticle is expected to potentially give rise to unprecedented quantum phenomena whose functional properties will be used to develop future quantum technology. Theoretically, the MFs may reside in various types of topological superconductor materials that is characterized by the topologically protected gapless surface state which are essentially an Andreev bound state. Superconducting doped topological insulators and topological crystalline insulators are promising candidates to harbor the MFs. In this review, we discuss recent progress and understanding on the research of MFs based on time-reversal-invariant superconducting topological materials to deepen our understanding and have a better outlook on both the search for and realization of MFs in these systems. We also discuss some advantages of these bulk systems to realize MFs including remarkable superconducting robustness against nonmagnetic impurities.

  10. ISR Superconducting Quadrupoles

    CERN Multimedia

    1980-01-01

    This picture shows four of the eight Quadrupoles manufacured by industry after assembly in their cryostat at CERN.They were then installed at intersection I8 of the ISR, where together with the other four they formed the Superconducting High-Luminosity ( Low-beta )Insertion. See also photo 7702690X and its abstract.

  11. Applications of Superconductivity

    Science.gov (United States)

    Goodkind, John M.

    1971-01-01

    Presents a general review of current practical applications of the properties of superconducters. The devices are classified into groups according to the property that is of primary importance. The article is inteded as a first introduction for students and professionals. (Author/DS)

  12. AC/RF Superconductivity

    OpenAIRE

    Ciovati, G.

    2015-01-01

    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.

  13. Nonequilibrium superconducting detectors

    International Nuclear Information System (INIS)

    Nonequilibrium superconducting detectors exploit the early stages of the energy down cascade which occur after the absorption of radiation. They operate on a short temporal scale ranging from few microseconds down to tens of picoseconds. In such a way they provide fast counting capability, high time discrimination and also, for some devices, energy sensitivity. Nonequilibrium superconducting detectors are developed for their use both in basic science and in practical applications for detection of single photons or single ionized macromolecules. In this paper we consider two devices: distributed readout imaging detectors (DROIDs) based on superconducting tunnel junctions (STJs), which are typically used for high-speed energy spectroscopy applications, and hot-electron superconductive detectors (HESDs), which are typically used as fast counters and time discriminators. Implementation of the DROID geometry to use a single superconductor is discussed. Progress in the fabrication technology of NbN nanostructured HESDs is presented. The two detectors share the high sensitivity that makes them able to efficiently detect even single photons down to infrared energy

  14. Superconducting quantum point contacts

    Science.gov (United States)

    Bretheau, L.; Girit, Ç.; Tosi, L.; Goffman, M.; Joyez, P.; Pothier, H.; Esteve, D.; Urbina, C.

    2012-01-01

    We review our experiments on the electronic transport properties of atomic contacts between metallic electrodes, in particular superconducting ones. Despite ignorance of the exact atomic configuration, these ultimate quantum point contacts can be manipulated and well characterized in-situ. They allow performing fundamental tests of the scattering theory of quantum transport. In particular, we discuss the case of the Josephson effect.

  15. Superconducting Quantum Point Contacts

    OpenAIRE

    Bretheau, L.; Girit, Ç.; Tosi, L.; Goffman, M.; Joyez, P.; Pothier, H.; Esteve, D.; Urbina, C.

    2012-01-01

    We review our experiments on the electronic transport properties of atomic contacts between metallic electrodes, in particular superconducting ones. Despite ignorance of the exact atomic configuration, these ultimate quantum point contacts can be manipulated and well characterized in-situ. They allow performing fundamental tests of the scattering theory of quantum transport. In particular, we discuss the case of the Josephson effect.

  16. Coupled superconducting flux qubits

    NARCIS (Netherlands)

    Plantenberg, J.H.

    2007-01-01

    This thesis presents results of theoretical and experimental work on superconducting persistent-current quantum bits. These qubits offer an attractive route towards scalable solid-state quantum computing. The focus of this work is on the gradiometer flux qubit which has a special geometric design, t

  17. 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.

  18. 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.

  19. 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.

  20. Forecasting of superconducting compounds

    International Nuclear Information System (INIS)

    In forecasting new superconducting intermetallic compounds of the A15 and Mo3Se 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

  1. Hybrid superconducting neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Merlo, V.; Lucci, M.; Ottaviani, I. [Dipartimento di Fisica, Università Tor Vergata, Via della Ricerca Scientifica, I-00133 Roma (Italy); Salvato, M.; Cirillo, M. [Dipartimento di Fisica, Università Tor Vergata, Via della Ricerca Scientifica, I-00133 Roma (Italy); CNR SPIN Salerno, Università di Salerno, Via Giovanni Paolo II, n.132, 84084 Fisciano (Italy); Scherillo, A. [Science and Technology Facility Council, ISIS Facility Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Celentano, G. [ENEA Frascati Research Centre, Via. E. Fermi 45, 00044 Frascati (Italy); Pietropaolo, A., E-mail: antonino.pietropaolo@enea.it [ENEA Frascati Research Centre, Via. E. Fermi 45, 00044 Frascati (Italy); Mediterranean Institute of Fundamental Physics, Via Appia Nuova 31, 00040 Marino, Roma (Italy)

    2015-03-16

    A neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction, {sup 10}B + n → α + {sup 7}Li, with α and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current I{sub c}, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed.

  2. Hybrid superconducting neutron detectors

    International Nuclear Information System (INIS)

    A neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction, 10B + n → α + 7Li, with α and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current Ic, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed

  3. Superconducting Super Collider project

    International Nuclear Information System (INIS)

    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

  4. Superconducting magnetic separation

    International Nuclear Information System (INIS)

    The initially high hopes of a speedy replacement of conventional magnetic separators by superconducting ones have not been realised. The reasons for this are complex, ranging from the conservative nature of the mineral processing industry to insufficient cryogenic reliability and poor magnet design. The major systems delivered to industry will be described and some possible future developments will be outlined

  5. Levitation Kits Demonstrate Superconductivity.

    Science.gov (United States)

    Worthy, Ward

    1987-01-01

    Describes the "Project 1-2-3" levitation kit used to demonstrate superconductivity. Summarizes the materials included in the kit. Discusses the effect demonstrated and gives details on how to obtain kits. Gives an overview of the documentation that is included. (CW)

  6. Superconducting magnets 1992

    International Nuclear Information System (INIS)

    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-Tc at Low Temperature; Cable and Cabling-Machine Development; and Analytical Magnet Design

  7. Hybrid superconducting neutron detectors

    Science.gov (United States)

    Merlo, V.; Salvato, M.; Cirillo, M.; Lucci, M.; Ottaviani, I.; Scherillo, A.; Celentano, G.; Pietropaolo, A.

    2015-03-01

    A neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction, 10B + n → α + 7Li, with α and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current Ic, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed.

  8. Niobium superconducting cavity

    CERN Multimedia

    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.

  9. First prototype Copper-Niobium RF Superconducting Cavity

    CERN Multimedia

    1983-01-01

    This is the first RF superconducting cavity made of copper with a very thin layer of pure niobium deposited on the inner wall by sputtering. This new developpment lead to a considerable increase of performance and stability of superconducting cavities and to non-negligible economy. The work was carried out in the ISR workshop. This technique was adopted for the LEP II accelerating cavities. At the centre is Cristoforo Benvenuti, inventor of this important technology, with his assistants, Nadia Circelli and Max Hauer, carrying the sputtering electrode. See also 8209255, 8312339.

  10. Superconducting Accelerator Magnets

    CERN Document Server

    Mess, K H; Wolff, S

    1996-01-01

    The main topic of the book are the superconducting dipole and quadrupole magnets needed in high-energy accelerators and storage rings for protons, antiprotons or heavy ions. The basic principles of low-temperature superconductivity are outlined with special emphasis on the effects which are relevant for accelerator magnets. Properties and fabrication methods of practical superconductors are described. Analytical methods for field calculation and multipole expansion are presented for coils without and with iron yoke. The effect of yoke saturation and geometric distortions on field quality is studied. Persistent magnetization currents in the superconductor and eddy currents the copper part of the cable are analyzed in detail and their influence on field quality and magnet performance is investigated. Superconductor stability, quench origins and propagation and magnet protection are addressed. Some important concepts of accelerator physics are introduced which are needed to appreciate the demanding requirements ...

  11. High temperature interface superconductivity

    Science.gov (United States)

    Gozar, A.; Bozovic, I.

    2016-02-01

    High-Tc 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-Tc 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.

  12. Statistical mechanics of superconductivity

    CERN Document Server

    Kita, Takafumi

    2015-01-01

    This book provides a theoretical, step-by-step comprehensive explanation of superconductivity for undergraduate and graduate students who have completed elementary courses on thermodynamics and quantum mechanics. To this end, it adopts the unique approach of starting with the statistical mechanics of quantum ideal gases and successively adding and clarifying elements and techniques indispensible for understanding it. They include the spin-statistics theorem, second quantization, density matrices, the Bloch–De Dominicis theorem, the variational principle in statistical mechanics, attractive interaction, and bound states. Ample examples of their usage are also provided in terms of topics from advanced statistical mechanics such as two-particle correlations of quantum ideal gases, derivation of the Hartree–Fock equations, and Landau’s Fermi-liquid theory, among others. With these preliminaries, the fundamental mean-field equations of superconductivity are derived with maximum mathematical clarity based on ...

  13. Superconducting nanostructured magnesium diboride

    International Nuclear Information System (INIS)

    Like conventional superconductors, MgB2 is a phonon-mediated superconductor with a relatively long coherence length. Its properties make the prospects for fabricating reproducible uniform Josephson junctions, the fundamental element of superconducting circuits, much more favorable for MgB2 than for high-temperature superconductors. Here, we report bulk superconductivity in nanophase MgB2, using a two-step technique of mechanically activated self-propagated high-temperature synthesis (MASHS). The conditions of synthesis and some properties of the product (structure, susceptibility, resistivity) were studied. It was shown that a single-phase product was obtained after 2 hours of intense mechanical treatment of reagents (Mg and B powders), and MASHS induced at 30 A.cm-2. (authors)

  14. Superconductivity an introduction

    CERN Document Server

    Kleiner, Reinhold

    2016-01-01

    The third edition of this proven text has been developed further in both scope and scale to reflect the potential for superconductivity in power engineering to increase efficiency in electricity transmission or engines. The landmark reference remains a comprehensive introduction to the field, covering every aspect from fundamentals to applications, and presenting the latest developments in organic superconductors, superconducting interfaces, quantum coherence, and applications in medicine and industry. Due to its precise language and numerous explanatory illustrations, it is suitable as an introductory textbook, with the level rising smoothly from chapter to chapter, such that readers can build on their newly acquired knowledge. The authors cover basic properties of superconductors and discuss stability and different material groups with reference to the latest and most promising applications, devoting the last third of the book to applications in power engineering, medicine, and low temperature physics. An e...

  15. Time ripe for superconductivity?

    Directory of Open Access Journals (Sweden)

    George Marsh

    2002-04-01

    But there is a crucial deadline and failure to meet it could send superconductivity back to the commercial shadows (at least outside the medical and scientific niches where it is a key enabler in analytical instruments, magnetic resonance imaging, and particle accelerators for another 30 years. Later this decade, the vintage infrastructure of dense copper conductors that supports power distribution in developed countries, in particular in the US, will become due for renewal. (Recent power problems in California were largely those of distribution infrastructure. At the same time, boosting capacity to serve the needs of increasingly affluent populations will pose a challenge. Superconductivity could provide the answer — if the technology matures in time and cost targets are met.

  16. Dual superconductivity and vacuum properties in Yang--Mills theories

    CERN Document Server

    D'Alessandro, A; Tagliacozzo, L

    2006-01-01

    We address, within the dual superconductivity model for color confinement, the question whether the Yang-Mills vacuum behaves as a superconductor of type I or type II. In order to do that we compare, for the theory with gauge group SU(2), the determination of the field penetration depth $\\lambda$ with that of the superconductor correlation length $\\xi$. The latter is obtained by measuring the temporal correlator of a disorder parameter developed by the Pisa group to detect dual superconductivity. The comparison places the vacuum close to the border between type I and type II and marginally on the type II side. We also check our results against the study of directly measurable effects such as the interaction between two parallel flux tubes, obtaining consistent indications for a weak repulsive behaviour. Future strategies to improve our investigation are discussed.

  17. Dual superconductivity and vacuum properties in Yang Mills theories

    Science.gov (United States)

    D'Alessandro, A.; D'Elia, M.; Tagliacozzo, L.

    2007-07-01

    We address, within the dual superconductivity model for color confinement, the question whether the Yang-Mills vacuum behaves as a superconductor of type I or type II. In order to do that we compare, for the theory with gauge group SU(2), the determination of the field penetration depth λ with that of the superconductor correlation length ξ. The latter is obtained by measuring the temporal correlator of a disorder parameter developed by the Pisa group to detect dual superconductivity. The comparison places the vacuum close to the border between type I and type II and marginally on the type II side. We also check our results against the study of directly measurable effects such as the interaction between two parallel flux tubes, obtaining consistent indications for a weak repulsive behaviour. Future strategies to improve our investigation are discussed.

  18. Plasma model of superconducting crystals

    Science.gov (United States)

    Netesova, Nadezhda P.

    2016-04-01

    Within inharmonious plasma oscillation model the superconducting crystal AB is considered consisting of two subsystems 2AB=A2+B2. In high-temperature superconductors spontaneous division into two phases: superconducting and isolating was revealed. Phase separation was caused by plasma instability. It is obtained the transition superconducting phase temperature dependence Tc = F (q12, q1, q2, V12, V1, V2) on the isotopic substitution physical parameters: q - initial and component interaction parameters, V - volume in initial and component crystal lattices. The isotopic transition superconducting phase temperature displacement ΔTc is associated with the change of the initial and component interaction and crystal lattice parameters. From the plasma mechanism of superconductivity follows superconducting crystals exist at room temperature.

  19. Vector superconductivity in cosmic strings

    International Nuclear Information System (INIS)

    We argue that in most realistic cases, the usual Witten-type bosonic superconductivity of the cosmic string is automatically (independent of the existence of superconducting currents) accompanied by the condensation of charged gauge vector bosons in the core giving rise to a new vector type superconductivity. The value of the charged vector condensate is related with the charged scalar expectation value, and vanishes only if the latter goes to zero. The mechanism for the proposed vector superconductivity, differing fundamentally from those in the literature, is delineated using the simplest realistic example of the two Higgs doublet standard model interacting with the extra cosmic string. It is shown that for a wide range of parameters, for which the string becomes scalarly superconducting, W boson condensates (the sources of vector superconductivity) are necessarily excited. (author). 14 refs

  20. Electrodynamics of superconducting pnictide superlattices

    International Nuclear Information System (INIS)

    It was recently shown that superlattices where layers of the 8% Co-doped BaFe2As2 superconducting pnictide are intercalated with non superconducting ultrathin layers of either SrTiO3 or of oxygen-rich BaFe2As2, can be used to control flux pinning, thereby increasing critical fields and currents, without significantly affecting the critical temperature of the pristine superconducting material. However, little is known about the electron properties of these systems. Here, we investigate the electrodynamics of these superconducting pnictide superlattices in the normal and superconducting state by using infrared reflectivity, from THz to visible range. We find that multigap structure of these superlattices is preserved, whereas some significant changes are observed in their electronic structure with respect to those of the original pnictide. Our results suggest that possible attempts to further increase the flux pinning may lead to a breakdown of the pnictide superconducting properties.

  1. Superconductivity in power engineering

    International Nuclear Information System (INIS)

    The advantages of low power loss, high magnetic fields and compactness of size of superconducting magnets have generated world-wide interest in using them for MHD generators, Tokamak fusion reactors, energy storage systems etc. With a view to assess the feasibility of using the technology in power engineering in India, the status of the efforts in the country is reviewed and the areas of R and D required are indicated. 13 figures, 15 refs. (author)

  2. Advanced superconducting materials

    International Nuclear Information System (INIS)

    The superconducting properties of various materials are reviewed in view of their use in high field magnets. The critical current densities above 12 T of conductors based on NbN or PbMo6S8 are compared to those of the most advanced practical conductors based on alloyed by Nb3Sn. Different aspects of the mechanical reinforcement of high field conductors, rendered necessary by the strong Lorentz forces (e.g. in fusion magnets), are discussed. (orig.)

  3. Superconducting cascade electron refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Camarasa-Gómez, M.; Giazotto, F. [NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127 Pisa (Italy); Di Marco, A.; Hekking, F. W. J. [LPMMC, CNRS and Université Joseph Fourier, 38042 Grenoble (France); Winkelmann, C. B.; Courtois, H. [Univ. Grenoble Alpes, Institut Néel, 38042 Grenoble (France); CNRS, Institut Néel, 38042 Grenoble (France)

    2014-05-12

    The design and operation of an electronic cooler based on a combination of superconducting tunnel junctions is described. The cascade extraction of hot-quasiparticles, which stems from the energy gaps of two different superconductors, allows for a normal metal to be cooled down to about 100 mK starting from a bath temperature of 0.5 K. We discuss the practical implementation, potential performance, and limitations of such a device.

  4. Unconventional superconductivity near inhomogeneities

    International Nuclear Information System (INIS)

    After the presentation of a quasi-classical theory the specific heat of Sr2RuO4 is considered. Then tunneling spectroscopy on cuprate superconductors is discussed. Thereafter the subharmonic gap structure in d-wave superconductors is considered. Finally the application of the S-matrix in superconductivity is discussed with spin mixing, CrO2 as example, and an interface model. (HSI)

  5. Superconducting terahertz metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-tong [Los Alamos National Laboratory; Singh, Ranjan [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory; Azad, Abul K [Los Alamos National Laboratory; Trugman, Stuart A [Los Alamos National Laboratory; Jia, Quanxi [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory

    2010-01-01

    During the past ten years subwavelength metallic structures have enabled metamaterials exhibiting exotic physical properties that are not possible or difficult to realize using naturally occurring materials, This bottom-up metamaterial approach is particularly attractive in the terahertz (THz) frequency range, where the THz gap is inherently associated with the lack of materials with appropriate reponse. In fact THz metamaterial devices have accomplished unprecedented performance towards practical applications. In these devices, the key is to incorporate natural materials, e,g, semiconductors, as the metamaterial substrates or integration parts of metamaterial structures. The active or dynamic tunability of metamaterials is through the application of external stimuli such as temperature, photoexcitation, or electric field. to modify the capacitive gaps in split-ring resonators (SRRs), It becomes clear that we would not be able to do much on the metallic SRRs, i.e. the metal conductivity and therefore the inductance largely remain constant not affected by external stimuli. Recently, there has been increasing interest in superconducting metamaterials towards loss reduction. Significant Joule losses have often prevented resonant metal metamaterials from achieving proposed applications. particularly in the optical frequency range. At low temperatures, superconducting materials possess superior conductivity than metals at frequencies up to THz. and therefore it is expected that superconducting melamaterials will have a lower loss than metal metamatetials, More interestingly, superconductors exhibit tunable complex conductivity over a wide range of values through change of temperature and application of photoexcitation, electrical currents and magnetic fields. Therefore, we would expect correspondingly tunable metamaterials. which originate from the superconducting materials composing the metamaterial, in contrast to tuning the metamaterial embedded environment.

  6. Supercurrent in superconducting graphene

    Science.gov (United States)

    Kopnin, N. B.; Sonin, E. B.

    2010-07-01

    The problem of supercurrent in superconducting graphene is revisited and the supercurrent is calculated within the mean-field model employing the two-component wave functions on a honeycomb lattice with pairing between different valleys in the Brillouin zone. We show that the supercurrent within the linear approximation in the order-parameter-phase gradient is always finite even if the doping level is exactly zero.

  7. Supercurrent in superconducting graphene

    OpenAIRE

    Kopnin, N. B.; Sonin, E. B.

    2010-01-01

    The problem of supercurrent in superconducting graphene is revisited and the supercurrent is calculated within the mean-field model employing the two-component wave functions on a honeycomb lattice with pairing between different valleys in the Brillouin zone. We show that the supercurrent within the linear approximation in the order-parameter-phase gradient is always finite even if the doping level is exactly zero.

  8. RF superconducting cavities

    CERN Document Server

    Kojima, Y

    1980-01-01

    The history and present activity in research on RF superconducting cavities in various countries are reviewed. The program of the July 1980 Karlsruhe workshop is reproduced and research activity in this field at Stanford HEPL and SLAC, Cornell, Oregon, Brookhaven, KEK (Japan), Weismann (Israel), Genoa, CERN and Karlsruhe (KfK) listed. The theoretical basis of surface resistance and intracavity magnetic field, multipacing and non-resonant electron loading are outlined. (20 refs).

  9. Unconventional superconductivity near inhomogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Poenicke, A.F.

    2008-01-25

    After the presentation of a quasi-classical theory the specific heat of Sr{sub 2}RuO{sub 4} is considered. Then tunneling spectroscopy on cuprate superconductors is discussed. Thereafter the subharmonic gap structure in d-wave superconductors is considered. Finally the application of the S-matrix in superconductivity is discussed with spin mixing, CrO{sub 2} as example, and an interface model. (HSI)

  10. Time ripe for superconductivity?

    OpenAIRE

    George Marsh

    2002-01-01

    Commercial applications of superconducting materials have been slow to take off and the early promise of magnetically-levitated trains, compact electric motors of stunning power, and super-efficient power transmission has, in the main, not been met. Recent emergence of power distribution applications in the US and Europe, however, suggests that this could change. At last, it seems, this singular phenomenon, in which electrical resistance becomes vanishingly small in certain materials at extre...

  11. US Navy superconductivity program

    Science.gov (United States)

    Gubser, Donald U.

    1991-01-01

    Both the new high temperature superconductors (HTS) and the low temperature superconductors (LTS) are important components of the Navy's total plan to integrate superconductivity into field operational systems. Fundamental research is an important component of the total Navy program and focuses on the HTS materials. Power applications (ship propulsion) use LTS materials while space applications (millimeter wave electronics) use HTS materials. The Space Experiment to be conducted at NRL will involve space flight testing of HTS devices built by industry and will demonstrate the ability to engineer and space qualify these devices for systems use. Another important component of the Navy's effort is the development of Superconducting Quantum Interference Device (SQUID) magnetometers. This program will use LTS materials initially, but plans to implement HTS materials as soon as possible. Hybrid HTS/LTS systems are probable in many applications. A review of the status of the Navy's HTS materials research is given as well as an update on the Navy's development efforts in superconductivity.

  12. Navy superconductivity efforts

    Science.gov (United States)

    Gubser, D. U.

    1990-01-01

    Both the new high temperature superconductors (HTS) and the low temperature superconductors (LTS) are important components of Navy's total plan to integrate superconductivity into field operational systems. Fundamental research is an important component of the total Navy program and focuses on the HTS materials. Power applications (ship propulsion, etc.) use LTS materials while space applications (MMW electronics, etc.) use HTS materials. The Space Experiment being conducted at NRL will involve space flight testing of HTS devices built by industry and will demonstrate the ability to engineer and space qualify these devices for systems use. Another important component of the Navy's effort is the development of Superconducting Quantum Interference Device (SQUID) magnetometers. This program will use LTS materials initially, but plans to implement HTS materials as soon as possible. Hybrid HTS/LTS systems are probable in many applications. A review of the status of the Navy's HTS materials research is given as well as an update on the Navy's development efforts in superconductivity, with particular emphasis on the related SDIO sponsored program on HTS applications.

  13. Advanced superconducting optical detectors

    International Nuclear Information System (INIS)

    We have investigated advanced superconducting optical and infrared detectors for their integration with superconductive active circuits. The detectors are based on ultra-thin NbN striplines. NbN is the material of choice for single photon optical and infrared detectors, as already demonstrated in the literature. The detectors so far proposed are based on conceptually simple, although difficult to realize, sub-micrometric meander type structures. Most applications of such detectors require some treatment of the signal generated, either as pulse shaping or signal amplification, to fully exploit the detection capabilities, such as sub-ns response time and proportional response. We have developed a room temperature process that, while preserving reasonable superconducting properties of NbN, allows a simple integration of the detectors in Nb-based circuits. Moreover we have developed a passivation technique, by using a protective AlN layer on top of the NbN one. The developed technology allows complex detector configurations, such as integrated RSFQ circuits or SQUID readout, to be relatively easily realized. The response of our NbN strip to photon irradiation will be presented

  14. The origin of superconductivity

    International Nuclear Information System (INIS)

    We have shown in the other article of ours, published in the same issue as this one and entitled “Superconductivity in a Fermi liquid: The role of electron-phonon interaction,” that the quasiparticle interaction is just the particle interaction with an opposite sign. In other words, the interaction between two quasielectrons in k- or momentum-space is attractive while the interaction between two electrons in real space is repulsive. Since the quasiparticles are responsible for all properties of a Fermi liquid, then investigations of behaviors of quasipartilces will be sufficient for one to understand the relevant properties of the system consisting of those quasiparticles (particles), Moreover, as shown in our earlier work [1,2], pairing of two quasiparticles in a spin singlet state due to the Coulomb interaction is well-reasoned without needing any boson like retarded mediation between them, and a quartet structure among paired four quasiparticles will be further formed, leading to the doubly lower biding energy than that from a single Cooper’s pair. Under a certain condition a superconducting phase transition, corresponding to the resonance of a many-electron system with repulsion in the spin singlet state, may occur naturally. This showcases the physical picture of our earlier assertion [3] that superconductivity takes place naturally due to the Coulombic repulsive interaction

  15. Superconducting traveling wave accelerators

    International Nuclear Information System (INIS)

    This note considers the applicability of superconductivity to traveling wave accelerators. Unlike CW operation of a superconducting standing wave or circulating wave accelerator section, which requires improvement factors (superconductor conductivity divided by copper conductivity) of about 106 in order to be of practical use, a SUperconducting TRaveling wave Accelerator, SUTRA, operating in the pulsed mode requires improvement factors as low as about 103, which are attainable with niobium or lead at 4.2K, the temperature of liquid helium at atmospheric pressure. Changing from a copper traveling wave accelerator to SUTRA achieves the following. (1) For a given gradient SUTRA reduces the peak and average power requirements typically by a factor of 2. (2) SUTRA reduces the peak power still further because it enables us to increase the filling time and thus trade pulse width for gradient. (3) SUTRA makes possible a reasonably long section at higher frequencies. (4) SUTRA makes possible recirculation without additional rf average power. 8 references, 6 figures, 1 table

  16. Hybrid Superconducting Neutron Detectors

    CERN Document Server

    Merlo, V; Cirillo, M; Lucci, M; Ottaviani, I; Scherillo, A; Celentano, G; Pietropaolo, A

    2014-01-01

    A new neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction 10B+n $\\rightarrow$ $\\alpha$+ 7Li , with $\\alpha$ and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current Ic, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the supercond...

  17. The Lorentz force and superconductivity

    OpenAIRE

    Hirsch, J. E.

    2003-01-01

    To change the velocity of an electron requires that a Lorentz force acts on it, through an electric or a magnetic field. We point out that within the conventional understanding of superconductivity electrons appear to change their velocity in the absence of Lorentz forces. This indicates a fundamental problem with the conventional theory of superconductivity. A hypothesis is proposed to resolve this difficulty. This hypothesis is consistent with the theory of hole superconductivity.

  18. Friction Domination with Superconducting Strings

    OpenAIRE

    Dimopoulos, Konstantinos; Davis, Anne-Christine

    1997-01-01

    We investigate the evolution of a superconducting string network with arbitrary, constant string current in the friction dominated regime. In the absence of an external magnetic field the network always reaches a scaling solution. However, for string current stronger than a critical value, it is different than the usual, horizon-scaling of the non-superconducting string case. In this case the friction domination era never ends. Whilst the superconducting string network can be much denser than...

  19. Relativistic Model for two-band Superconductivity

    OpenAIRE

    Ohsaku, Tadafumi

    2003-01-01

    To understand the superconductivity in MgB2, several two-band models of superconductivity were proposed. In this paper, by using the relativistic fermion model, we clearize the effect of the lower band in the superconductivity.

  20. Superconductivity in graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert P. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Weller, Thomas E.; Howard, Christopher A. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Dean, Mark P.M. [Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Rahnejat, Kaveh C. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Saxena, Siddharth S. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Ellerby, Mark, E-mail: mark.ellerby@ucl.ac.uk [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom)

    2015-07-15

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC{sub 6} and YbC{sub 6} in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  1. Superconductivity in graphite intercalation compounds

    International Nuclear Information System (INIS)

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC6 and YbC6 in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition

  2. Unconventional superconductivity in honeycomb lattice

    OpenAIRE

    P. Sahebsara; R Mohammadi

    2013-01-01

      ‎ The possibility of symmetrical s-wave superconductivity in the honeycomb lattice is studied within a strongly correlated regime, using the Hubbard model. The superconducting order parameter is defined by introducing the Green function, which is obtained by calculating the density of the electrons ‎ . In this study showed that the superconducting order parameter appears in doping interval between 0 and 0.5, and x=0.25 is the optimum doping for the s-wave superconductivity in honeycomb latt...

  3. Unconventional superconductivity in honeycomb lattice

    Directory of Open Access Journals (Sweden)

    P Sahebsara

    2013-03-01

    Full Text Available   ‎ The possibility of symmetrical s-wave superconductivity in the honeycomb lattice is studied within a strongly correlated regime, using the Hubbard model. The superconducting order parameter is defined by introducing the Green function, which is obtained by calculating the density of the electrons ‎ . In this study showed that the superconducting order parameter appears in doping interval between 0 and 0.5, and x=0.25 is the optimum doping for the s-wave superconductivity in honeycomb lattice.

  4. Korea's developmental program for superconductivity

    Science.gov (United States)

    Hong, Gye-Won; Won, Dong-Yeon; Kuk, Il-Hyun; Park, Jong-Chul

    1995-01-01

    Superconductivity research in Korea was firstly carried out in the late 70's by a research group in Seoul National University (SNU), who fabricated a small scale superconducting magnetic energy storage system under the financial support from Korea Electric Power Company (KEPCO). But a few researchers were involved in superconductivity research until the oxide high Tc superconductor was discovered by Bednorz and Mueller. After the discovery of YBaCuO superconductor operating above the boiling point of liquid nitrogen (77 K)(exp 2), Korean Ministry of Science and Technology (MOST) sponsored a special fund for the high Tc superconductivity research to universities and national research institutes by recognizing its importance. Scientists engaged in this project organized 'High Temperature Superconductivity Research Association (HITSRA)' for effective conducting of research. Its major functions are to coordinate research activities on high Tc superconductivity and organize the workshop for active exchange of information. During last seven years the major superconductivity research has been carried out through the coordination of HITSRA. The major parts of the Korea's superconductivity research program were related to high temperature superconductor and only a few groups were carrying out research on conventional superconductor technology, and Korea Atomic Energy Research Institute (KAERI) and Korea Electrotechnology Research Institute (KERI) have led this research. In this talk, the current status and future plans of superconductivity research in Korea will be reviewed based on the results presented in interim meeting of HITSRA, April 1-2, 1994. Taejeon, as well as the research activity of KAERI.

  5. Superconducting tape characterization under flexion

    Science.gov (United States)

    Álvarez, A.; Suárez, P.; Cáceres, D.; Pérez, B.; Cordero, E.; Castaño, A.

    2002-08-01

    Electrotechnical applications of high temperature superconducting materials are limited by the difficulty of constructing classical windings with ceramic materials. While Bi-2223 tape may be a solution, it cannot be bent to radii less than a certain value since its superconducting capacity disappears. We describe an automated measurement system of the characteristics of this tape under flexion. It consists of a device that coils the tape over cylinders with different radii. At the same time, the parameters of its superconducting behaviour (e.g. resistance) are taken and processed. This system was developed at the “Benito Mahedero Laboratory of Superconducting Electrical Applications” in the University of Extremadura.

  6. The development of superconducting equipment

    CERN Document Server

    Ueda, T; Hiue, H

    2003-01-01

    Fuji Electric has been developing various types of superconducting equipment for over a quarter of a century. This paper describes the development results achieved for superconducting equipment and especially focuses on large-capacity current leads and superconducting transmission systems, the development of which is being promoted for application to the field of nuclear fusion. High temperature superconductor (HTS) is becoming the mainstream in the field of superconductivity, and the HTS floating coil and conduction-cooled HTS transformed are also introduced as recent developments for devices that utilize this technology. (author)

  7. Contactless superconducting synchronous electrical machine

    International Nuclear Information System (INIS)

    A contactless superconducting synchronous electrical machine comprises a rotor affixed to a rotatable shaft and provided with a superconducting field winding, the superconducting field winding being positioned within a cryostat; an annular stator located in concentrical relation with the rotor; and an exciter for the superconducting field winding provided with an inductor and a superconducting armature winding, the superconducting armature winding being positioned within the cryostat, affixed to the shaft and electrically connected to the superconducting field winding. The superconducting armature winding is implemented in the form of a cylindrical sheating affixed to a cylindrical surface of an annular former which is rigidly fixed to the shaft in concentrical relation therewith. The inductor comprises an immovable annular core with a multiphase winding, positioned in concentrical relation with the armature winding, and also comprises at least one magnetizing superconducting annular coil affixed to the shaft in axial relation to the former, in the vicinity of an end face thereof, and positioned within the cryostat. That portion of the vacuum shell of the cryostat which is within the gap between the annular core and the armature winding is made of dielectric material

  8. The BaBar superconducting coil: design, construction and test

    International Nuclear Information System (INIS)

    The BABAR Detector, located in the PEP-II B-Factory at the Stanford Linear Accelerator Center, includes a large 1.5 Tesla superconducting solenoid, 2.8 m bore and length 3.7 m. The two layer solenoid is wound with an aluminum stabilized conductor which is graded axially to produce a +/- 3% field uniformity in the tracking region. This paper summarizes the 3 year design, fabrication and testing program of the superconducting solenoid. The work was carried out by an international collaboration between INFN, LLNL and SLAC. The coil was constructed by Ansaldo Energia. Critical current measurements of the superconducting strand, cable and conductor, cool-down, operation with the thermo-siphon cooling, fast and slow discharges, and magnetic forces are discussed in detail

  9. Self-similarity in applied superconductivity

    International Nuclear Information System (INIS)

    Self-similarity is a descriptive term applying to a family of curves. It means that the family is invariant to a one-parameter group of affine (stretching) transformations. The property of self-similarity has been exploited in a wide variety of problems in applied superconductivity, namely, (i) transient distribution of the current among the filaments of a superconductor during charge-up, (ii) steady distribution of current among the filaments of a superconductor near the current leads, (iii) transient heat transfer in superfluid helium, (iv) transient diffusion in cylindrical geometry (important in studying the growth rate of the reacted layer in A15 materials), (v) thermal expulsion of helium from quenching cable-in-conduit conductors, (vi) eddy current heating of irregular plates by slow, ramped fields, and (vii) the specific heat of type-II superconductors. Most, but not all, of the applications involve differential equations, both ordinary and partial. The novel methods explained in this report should prove of great value in other fields, just as they already have done in applied superconductivity. (author)

  10. Optimization of superconducting tiling pattern for superconducting bearings

    Science.gov (United States)

    Hull, John R.

    1996-01-01

    An apparatus and method for reducing magnetic field inhomogeneities which produce rotational loss mechanisms in high temperature superconducting magnetic bearings. Magnetic field inhomogeneities are reduced by dividing high temperature superconducting structures into smaller structures, and arranging the smaller structures into tiers which stagger the magnetic field maximum locations of the smaller structures.

  11. Interplay between superconductivity and magnetism in iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chubukov, Andrey V [University of Wisconsin

    2015-06-10

    This proposal is for theoretical work on strongly correlated electron systems, which are at the center of experimental and theoretical activities in condensed-matter physics. The interest to this field is driven fascinating variety of observed effects, universality of underlying theoretical ideas, and practical applications. I propose to do research on Iron-based superconductors (FeSCs), which currently attract high attention in the physics community. My goal is to understand superconductivity and magnetism in these materials at various dopings, the interplay between the two, and the physics in the phase in which magnetism and superconductivity co-exist. A related goal is to understand the origin of the observed pseudogap-like behavior in the normal state. My research explores the idea that superconductivity is of electronic origin and is caused by the exchange of spin-fluctuations, enhanced due to close proximity to antiferromagnetism. The multi-orbital/multi-band nature of FeSCs opens routes for qualitatively new superconducting states, particularly the ones which break time-reversal symmetry. By all accounts, the coupling in pnictdes is below the threshold for Mott physics and I intend to analyze these systems within the itinerant approach. My plan is to do research in two stages. I first plan to address several problems within weak-coupling approach. Among them: (i) what sets stripe magnetic order at small doping, (ii) is there a preemptive instability into a spin-nematic state, and how stripe order affects fermions; (iii) is there a co-existence between magnetism and superconductivity and what are the system properties in the co-existence state; (iv) how superconductivity emerges despite strong Coulomb repulsion and can the gap be s-wave but with nodes along electron FSs, (v) are there complex superconducting states, like s+id, which break time reversal symmetry. My second goal is to go beyond weak coupling and derive spin-mediated, dynamic interaction between

  12. Eigenvalue problems in surface superconductivity

    International Nuclear Information System (INIS)

    The aim of the meeting is to discuss several classes of Schroedinger equations appearing within the Ginzburg-Landau theory of superconductivity. The related problems are discussed from several perspectives including semiclassical analysis, PDE in non-smooth domains, geometric spectral theory and operator theory, which should provide a new insight into various phenomena appearing in superconducting systems.

  13. Superconducting bearings for flywheel applications

    OpenAIRE

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings in flywheels.

  14. Metallic Xenon. Conductivity or Superconductivity?

    OpenAIRE

    Bogomolov, V. N.

    1999-01-01

    It is demonstrated that the point of view that metallization of xenon as a result of a band - gap closure has some discrepancies with experimental result. A superconductivity transition as an alternative possibility is examined. At such supposition critical temperature of superconductivity transition T is about 5000 K. A mechanism of inert gas condensation by virtual excitations of molecular type is discussed.

  15. The Danish Superconducting Cable Project

    DEFF Research Database (Denmark)

    Tønnesen, Ole

    1997-01-01

    The design and construction of a superconducting cable is described. The cable has a room temperature dielectric design with the cryostat placed inside the electrical insulation.BSCCO 2223 superconducting tapes wound in helix form around a former are used as the cable conductor. Results from...

  16. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  17. Cooperating on superconductivity

    International Nuclear Information System (INIS)

    This paper reports that in the late 1980s, there were fears that the United States would fall behind in the development and commercialization of high-temperature superconductivity. So on March 15, 1988, a committee was formed by the president's Council of Advisors on Science and Technology to advise the executive branch on how to improve the country's competitive position in the field. Ralph E Gomory, then chief scientist at IBM Corp., was named to the chair of the committee, which within a year produced several recommendations. An immediate consequence was the formation of the Consortium for Superconducting Electronics (CSE) by IBM, AT and T, the Massachusetts Institute of Technology (MIT), and the Lincoln Laboratory, which is run for the Federal government by MIT. The organization has now been in existence for approximately two years---long enough not only to have formulated goals and methods but to have achievements to report as well. The Gomory committee had judged that it would take a decade or more to bring high-temperature superconductivity to market, and only broadly based consortia would have the resources and stability to persevere to a successful conclusion. So in a key recommendation, the committee had urged that precompetitive R and D in the technology be conducted by a number of consortia linking universities, government laboratories, and industrial laboratories. The committee's report was released in January 1989, and the four future members of the CSE began negotiations in the same month. By October 1989, negotiations were complete and a proposal had been sent to the Defense Advanced Research Projects Agency (Darpa), Arlington, Va., for funding of the university and government laboratory parts of the consortium. Research began as soon as the participation agreement binding the members to the CSE had been signed

  18. A superconducting magnetic gear

    Science.gov (United States)

    Campbell, A. M.

    2016-05-01

    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.

  19. 100 years of superconductivity

    CERN Multimedia

    Globe Info

    2011-01-01

    Public lecture by Philippe Lebrun, who works at CERN on applications of superconductivity and cryogenics for particle accelerators. He was head of CERN’s Accelerator Technology Department during the LHC construction period. Centre culturel Jean Monnet, route de Gex Tuesday 11 October from 8.30 p.m. to 10.00 p.m. » Suitable for all – Admission free - Lecture in French » Number of places limited For further information: +33 (0)4 50 42 29 37

  20. Superconducting wiggler for ADONE

    International Nuclear Information System (INIS)

    A superconducting wiggler magnet has been successfully tested at ANSALDO COMPONENTI works. The design field of 6 Tesla has been reached after limited training. The field of 6.025 ± 0.003 Tesla has been measured by means of a flip coil connected to an integrating magnetometer. Field profile measurements were made at 5.0, 5.75 and 6.025 Tesla, during which time, the magnet showed high stability. The overall cryogenic losses have been measured and they are consistent with the computed ones

  1. Superconducting ac cable

    International Nuclear Information System (INIS)

    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.)

  2. Superconductivity in nanowires

    CERN Document Server

    Bezryadin, Alexey

    2012-01-01

    The importance and actuality of nanotechnology is unabated and will be for years to come. A main challenge is to understand the various properties of certain nanostructures, and how to generate structures with specific properties for use in actual applications in Electrical Engineering and Medicine.One of the most important structures are nanowires, in particular superconducting ones. They are highly promising for future electronics, transporting current without resistance and at scales of a few nanometers. To fabricate wires to certain defined standards however, is a major challenge, and so i

  3. High gradient superconducting quadrupoles

    International Nuclear Information System (INIS)

    Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

  4. Induced superconductivity in graphene

    Science.gov (United States)

    Heersche, Hubert B.; Jarillo-Herrero, Pablo; Oostinga, Jeroen B.; Vandersypen, Lieven M. K.; Morpurgo, Alberto F.

    2007-07-01

    Graphene layers, prepared by mechanical exfoliation, were contacted by superconducting electrodes consisting of a titanium-aluminium bilayer. Quantum hall measurements in the normal state confirmed the single layer nature of the graphene samples. Proximity induced supercurrents were observed in all samples, below 1 K. Using a backgate, the Fermi energy could be swept from valence to conduction band via the Charge neutrality point, demonstrating supercurrents carried by holes and electrons, respectively. Interestingly, a finite supercurrent was also observed at the charge neutrality (or Dirac) point, where the density of carrier states vanishes. Our results demonstrate phase coherence in graphene.

  5. Introduction to superconductivity

    CERN Document Server

    Rose-Innes, AC

    1978-01-01

    Introduction to Superconductivity differs from the first edition chiefly in Chapter 11, which has been almost completely rewritten to give a more physically-based picture of the effects arising from the long-range coherence of the electron-waves in superconductors and the operation of quantum interference devices. In this revised second edition, some further modifications have been made to the text and an extra chapter dealing with """"high-temperature"""" superconductors has been added. A vast amount of research has been carried out on these since their discovery in 1986 but the results, both

  6. Pseudogap of Color Superconductivity

    CERN Document Server

    Kitazawa, M; Kunihiro, T; Nemoto, Y; Kitazawa, Masakiyo; Koide, Tomoi; Kunihiro, Teiji; Nemoto, Yukio

    2004-01-01

    We show that the pseudogap of the quark density of states is formed in hot quark matter as a precursory phenomenon of the color superconductivity on the basis of a low-energy effective theory. We clarify that the soft mode of the di-quark pair field gives rise to a peculiar behavior of the quark dispersion relation and a short life-time of the quasiparticles near the Fermi surface, both of which make a depression of the density of states of quarks. Our result suggests that the appearance of the pseudogap is a universal phenomenon of strong coupling superconductors, irrespective of the dimensionality.

  7. Three-terminal superconducting devices

    International Nuclear Information System (INIS)

    The transistor has a number of properties that make it so useful. The authors discuss these and the additional properties a transistor would need to have for high performance applications at temperatures where superconductivity could contribute advantages to system-level performance. These properties then serve as criteria by which to evaluate three-terminal devices that have been proposed for applications at superconducting temperatures. FETs can retain their transistor properties at low temperatures, but their power consumption is too large for high-speed, high-density cryogenic applications. They discuss in detail why demonstrated superconducting devices with three terminals -Josephson effect based devices, injection controlled weak links, and stacked tunnel junction devices such as the superconducting transistor proposed by K. Gray and the quiteron -- each fail to have true transistor-like properties. They conclude that the potentially very rewarding search for a transistor compatible with superconductivity in high performance applications must be in new directions

  8. Japan. Superconductivity for Smart Grids

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, K.

    2012-11-15

    Currently, many smart grid projects are running or planned worldwide. These aim at controlling the electricity supply more efficiently and more stably in a new power network system. In Japan, especially superconductivity technology development projects are carried out to contribute to the future smart grid. Japanese cable makers such as Sumitomo Electric and Furukawa Electric are leading in the production of high-temperature superconducting (HTS) power cables. The world's largest electric current and highest voltage superconductivity proving tests have been started this year. Big cities such as Tokyo will be expected to introduce the HTS power cables to reduce transport losses and to meet the increased electricity demand in the near future. Superconducting devices, HTS power cables, Superconducting Magnetic Energy Storage (SMES) and flywheels are the focus of new developments in cooperations between companies, universities and research institutes, funded by the Japanese research and development funding organization New Energy and Industrial Technology Development Organization (NEDO)

  9. Pulsed Superconductivity Acceleration

    CERN Document Server

    Liepe, M

    2000-01-01

    The design of the proposed linear collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities, operated in pulsed mode. Within the framework of an international collaboration the TESLA Test Facility (TTF) has been set up at DESY, providing the infrastructure for cavity R&D towards higher gradients. More than 60 nine-cell cavities were tested, accelerating gradients as high as 30 MV/m were measured. In the second production of TTF-cavities the average gradient was measured to be 24.7 MV/m. Two modules, each containing eight resonators, are presently used in the TTF-linac. These cavities are operated in pulsed mode: 0.8 ms constant gradient with up to 10 Hz repetitions rate. We will focus on two aspects: Firstly, the cavity fabrication and treatment is discussed, allowing to reach high gradients. Latest results of single cell cavities will be shown, going beyond 40 MV/m. Secondly, the pulsed mode operation of superconducting cavities is reviewed. This includes Lorentz force detuning, mechanic...

  10. Overview of Superconducting Photoinjectors

    CERN Document Server

    Arnold, A

    2009-01-01

    The success of most of the proposed ERL based electron accelerator projects for future storage ring replacements (SRR) and high power IR-FELs is contingent upon the development of an appropriate source. Electron beams with an unprecedented combination of high brightness, low emittance (0.1 µm rad) and high average current (hundreds of mA) are required to meet the FEL specification [1]. An elegant way to create such an unique beam is to combine the high beam quality of a normal conducting RF photo injector with the superconducting technology to get a superconducting RF photo injector (SRF gun). SRF gun R&D programs based on different approaches are under investigation at a growing number of institutes and companies (AES, Beijing University, BESSY, BNL, DESY, FZD, JLab, Niowave, NPS, Wisconsin University). Lot of progress could be achieved during the last years and first long term operation was demonstrated at the FZD [2]. In the near future, this effort will lead to SRF guns, which are indispensab...

  11. Overview on superconducting photoinjectors

    CERN Document Server

    Arnold, A

    2011-01-01

    The success of most of the proposed energy recovery linac (ERL) based electron accelerator projects for future storage ring replacements (SRR) and high power IR–free-electron lasers (FELs) largely depends on the development of an appropriate source. For example, to meet the FEL specifications [J.W. Lewellen, Proc. SPIE Int. Soc. Opt. Eng. 5534, 22 (2004)] electron beams with an unprecedented combination of high brightness, low emittance (0.1 µmrad), and high average current (hundreds of mA) are required. An elegant way to create a beam of such quality is to combine the high beam quality of a normal conducting rf photoinjector with the superconducting technology, i.e., to build a superconducting rf photoinjector (SRF gun). SRF gun R&D programs based on different approaches have been launched at a growing number of institutes and companies (AES, Beijing University, BESSY, BNL, DESY, FZD, TJNAF, Niowave, NPS, Wisconsin University). Substantial progress was achieved in recent years and the first long term ...

  12. Superconducting magnetic energy storage

    International Nuclear Information System (INIS)

    Superconducting inductors provide a compact and efficient means of storing electrical energy without an intermediate conversion process. Energy storage inductors are under development for diurnal load leveling and transmission line stabilization in electric utility systems and for driving magnetic confinement and plasma heating coils in fusion energy systems. Fluctuating electric power demands force the electric utility industry to have more installed generating capacity than the average load requires. Energy storage can increase the utilization of base-load fossil and nuclear power plants for electric utilities. Superconducting magnetic energy storage (SMES) systems, which will store and deliver electrical energy for load leveling, peak shaving, and the stabilization of electric utility networks are being developed. In the fusion area, inductive energy transfer and storage is also being developed by LASL. Both 1-ms fast-discharge theta-pinch and 1-to-2-s slow tokamak energy transfer systems have been demonstrated. The major components and the method of operation of an SMES unit are described, and potential applications of different size SMES systems in electric power grids are presented. Results are given for a 1-GWh reference design load-leveling unit, for a 30-MJ coil proposed stabilization unit, and for tests with a small-scale, 100-kJ magnetic energy storage system. The results of the fusion energy storage and transfer tests are also presented. The common technology base for the systems is discussed

  13. High temperature superconductivity

    International Nuclear Information System (INIS)

    More than 20 years have passed since Bednorz and Mueller discovered high-temperature superconductivity (HTS) below 35 K in the La-Ba-Cu-O system. Before that discovery theories based on a phonon-mediated pairing mechanism for electrons predicted maximum transition temperatures (Tc) for superconductors of the order of 30 K. Available low-temperature superconductors (LTS) used for high-current applications like magnets, motors, generators or transformers were NbTi (Tc∝9 K) and A15 compounds like Nb3Sn (Tc∝18K) and Nb3Al (Tc∝19 K), though cooling with expensive liquid helium was necessary. Since the discovery of high-temperature superconductivity in La-Ba-Cu-O many other cuprates with perovskite-type structure and even higher critical temperatures have been found. The highest transition temperatures up to 134 K at ambient pressure were reported for the Hg-Ba-Ca-Cu-O system. Under pressures up to 30 GPa the critical temperature of this material increased to 164 K, the highest confirmed value reported up to now. (orig.)

  14. Superconducting composites materials

    International Nuclear Information System (INIS)

    The new superconductor materials with a high critical current own a large importance as well in the electronic components or in the electrotechnical devices fields. The deposit of such materials with the thick films technology is to be more and more developed in the years to come. Therefore, we tried to realize such thick films screen printed on alumina, and composed mainly of the YBa2Cu3O7-δ material. We first realized a composite material glass/YBa2Cu3O7-δ, by analogy with the classical screen-printed inks where the glass ensures the bonding with the substrate. We thus realized different materials by using some different classes of glass. These materials owned a superconducting transition close to the one of the pure YBa2Cu3O7-δ material. We made a slurry with the most significant composite materials and binders, and screen-printed them on an alumina substrate preliminary or not coated with a diffusion barrier layer. After firing, we studied the thick films adhesion, the alumina/glass/composite material interfaces, and their superconducting properties. 8 refs.; 14 figs.; 9 tabs

  15. Miniaturized superconducting microwave filters

    International Nuclear Information System (INIS)

    In this paper we present methods for the miniaturization of superconducting filters. We consider two designs of seventh-order bandpass Chebyshev filters based on lumped elements and a novel quasi-lumped element resonator. In both designs the area of the filters, with a central frequency of 2-5 GHz, is less than 1.2 mm2. Such small filters can be readily integrated on a single board for multi-channel microwave control of superconducting qubits. The filters have been experimentally tested and the results are compared with simulations. The miniaturization resulted in parasitic coupling between resonators and within each resonator that affected primarily the stopband and increased the bandwidth. The severity of the error depends on the design in particular, and was less sensitive when a groundplane was used under the inductances of the resonators. The best performance was reached for the quasi-lumped filter with central frequency of 4.45 GHz, quality factor of 40 and 50 dB stopband

  16. Meissner effect in superconducting microtraps

    Energy Technology Data Exchange (ETDEWEB)

    Cano, Daniel

    2009-04-30

    This thesis investigates the impact of the Meissner effect on magnetic microtraps for ultracold atoms near superconducting microstructures. This task has been accomplished both theoretically and experimentally. The Meissner effect distorts the magnetic fields near superconducting surfaces, thus altering the parameters of magnetic microtraps. Both computer simulations and experimental measurements demonstrate that the Meissner effect shortens the distance between the magnetic microtrap and the superconducting surface, reduces the magnetic-field gradients and dramatically lowers the trap depth. A novel numerical method for calculating magnetic fields in atom chips with superconducting microstructures has been developed. This numerical method overcomes the geometrical limitations of other calculation techniques and can solve superconducting microstructures of arbitrary geometry. The numerical method has been used to calculate the parameters of magnetic microtraps in computer-simulated chips containing thin-film wires. Simulations were carried out for both the superconducting and the normal-conducting state, and the differences between the two cases were analyzed. Computer simulations have been contrasted with experimental measurements. The experimental apparatus generates a magnetic microtrap for ultracold Rubidium atoms near a superconducting Niobium wire of circular cross section. The design and construction of the apparatus has met the challenge of integrating the techniques for producing atomic quantum gases with the techniques for cooling solid bodies to cryogenic temperatures. By monitoring the position of the atom cloud, one can observe how the Meissner effect influences the magnetic microtrap. (orig.)

  17. Meissner effect in superconducting microtraps

    International Nuclear Information System (INIS)

    This thesis investigates the impact of the Meissner effect on magnetic microtraps for ultracold atoms near superconducting microstructures. This task has been accomplished both theoretically and experimentally. The Meissner effect distorts the magnetic fields near superconducting surfaces, thus altering the parameters of magnetic microtraps. Both computer simulations and experimental measurements demonstrate that the Meissner effect shortens the distance between the magnetic microtrap and the superconducting surface, reduces the magnetic-field gradients and dramatically lowers the trap depth. A novel numerical method for calculating magnetic fields in atom chips with superconducting microstructures has been developed. This numerical method overcomes the geometrical limitations of other calculation techniques and can solve superconducting microstructures of arbitrary geometry. The numerical method has been used to calculate the parameters of magnetic microtraps in computer-simulated chips containing thin-film wires. Simulations were carried out for both the superconducting and the normal-conducting state, and the differences between the two cases were analyzed. Computer simulations have been contrasted with experimental measurements. The experimental apparatus generates a magnetic microtrap for ultracold Rubidium atoms near a superconducting Niobium wire of circular cross section. The design and construction of the apparatus has met the challenge of integrating the techniques for producing atomic quantum gases with the techniques for cooling solid bodies to cryogenic temperatures. By monitoring the position of the atom cloud, one can observe how the Meissner effect influences the magnetic microtrap. (orig.)

  18. 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.

  19. Competition between singlet and triplet superconductivity

    OpenAIRE

    De Cao, Tian; Wang, Tie Bang

    2009-01-01

    The competition between singlet and triplet superconductivity is examined in consideration of correlations on an extended Hubbard model. It is shown that the triplet superconductivity may not be included in the common Hubbard model since the strong correlation favors the singlet superconductivity, and thus the triplet superconductivity should be induced by the electron-phonon interaction and the ferromagnetic exchange interaction. We also present a superconducting qualification with which mag...

  20. Domain wall description of superconductivity

    International Nuclear Information System (INIS)

    In the present work we shall address the issue of electrical conductivity in superconductors in the perspective of superconducting domain wall solutions in the realm of field theory. We take our set up made out of a dynamical complex scalar field coupled to gauge field to be responsible for superconductivity and an extra scalar real field that plays the role of superconducting domain walls. The temperature of the system is interpreted through the fact that the soliton following accelerating orbits is a Rindler observer experiencing a thermal bath

  1. Electrodynamics of superconducting pnictide superlattices

    OpenAIRE

    Perucchi, A.; Capitani, F.; Di Pietro, P.; Lupi, S.; Lee, S.; Kang, J. H.; J. Jiang; Weiss, J. D.; Hellstrom, E. E.; Eom, C. B.; Dore, P.

    2014-01-01

    It has been recently reported (S. Lee et al., Nature Materials 12, 392, 2013) that superlattices where layers of the 8% Co-doped BaFe2As2 superconducting pnictide are intercalated with non superconducting ultrathin layers of either SrTiO3 or of oxygen-rich BaFe2As2, can be used to control flux pinning, thereby increasing critical fields and currents, without significantly affecting the critical temperature of the pristine superconducting material. However, little is known about the electron p...

  2. Superconducting super collider magnet cryostat

    International Nuclear Information System (INIS)

    The proposed Superconducting Super Collider high energy physics research facility will entail one of the major cryogenic system undertakings of the next decade. The two 30 Km diameter accelerator rings contain an integrated system of ≅ 10,000 superconducting devices that must have low capital cost and operate reliably and efficiently over the lifetime of the machine. The design for the ≅ 8000 superconducting dipole magnet cryostats has been developed and evaluated by both component and systems tests. The details of the design are presented along with summaries of the experimental evaluations of the suspension system, insulation, transient phenomena, systems' performance, etc

  3. Nozzle for superconducting fiber production

    Science.gov (United States)

    Righi, Jamal

    1992-11-17

    A nozzle apparatus for producing flexible fibers of superconducting material receives melted material from a crucible for containing a charge of the superconducting material. The material is melted in the crucible and falls in a stream through a bottom hole in the crucible. The stream falls through a protecting collar which maintains the stream at high temperatures. The stream is then supplied through the downwardly directed nozzle where it is subjected to a high velocity air flow which breaks the melted superconducting material into ligaments which solidify into the flexible fibers. The fibers are collected by blowing them against a porous cloth.

  4. Spinon Superconductivity and Superconductivities Mediated by Spin-Waves and Phonons in Cuprates

    OpenAIRE

    Mourachkine, A.

    1998-01-01

    The disclosure of spinon superconductivity and superconductivity mediated by spin-waves in hole-doped Bi2212 cuprate raises the question about the origin of the superconductivity in other cuprates and specially in an electron-doped NCCO cuprate.

  5. Superconducting dark energy

    CERN Document Server

    Liang, Shi-Dong

    2015-01-01

    Based on the analogy with superconductor physics we consider a scalar-vector-tensor gravitational model, in which the dark energy action is described by a gauge invariant electromagnetic type functional. By assuming that the ground state of the dark energy is in a form of a condensate with the U(1) symmetry spontaneously broken, the gauge invariant electromagnetic dark energy can be described in terms of the combination of a vector and of a scalar field (corresponding to the Goldstone boson), respectively. The gravitational field equations are obtained by also assuming the possibility of a non-minimal coupling between the cosmological mass current and the superconducting dark energy. The cosmological implications of the dark energy model are investigated for a Friedmann-Robertson-Walker homogeneous and isotropic geometry for two particular choices of the electromagnetic type potential, corresponding to a pure electric type field, and to a pure magnetic field, respectively. The time evolution of the scale fact...

  6. Superconducting energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Giese, R.F.

    1993-10-01

    This report describes the status of energy storage involving superconductors and assesses what impact the recently discovered ceramic superconductors may have on the design of these devices. Our description is intended for R&D managers in government, electric utilities, firms, and national laboratories who wish an overview of what has been done and what remains to be done. It is assumed that the reader is acquainted with superconductivity, but not an expert on the topics discussed here. Indeed, it is the author`s aim to enable the reader to better understand the experts who may ask for the reader`s attention, support, or funding. This report may also inform scientists and engineers who, though expert in related areas, wish to have an introduction to our topic.

  7. Superconducting cavity development

    International Nuclear Information System (INIS)

    Design and development work of the superconducting cavities for the Neutron Science Project is being continued since 1995. In the cavity design work, RF and structural analyses were carried out in order to determine the cavity shape and to obtain the RF and structural parameters. In the cavity development work, preparation of the test facility, fabrication and tests of the two single-cell prototype cavities of β=0.5 were performed. Good performance of the cavity was demonstrated in the test; obtained surface peak electric field of 44 MV/m is much higher than the design value of 16 MV/m. Resonant frequency shifts due to the vacuum load and the Lorentz force were also measured in the test. (author)

  8. Applied superconductivity. Vol. 1

    International Nuclear Information System (INIS)

    Since the discovery of of high-temperature superconducting (HTS) cuprates, R and D efforts were considerably accelerated. Besides the YBaCuO, Bi- and Tl-based high-temperature superconductors it is now known from recent experiments that Hg-Ba-Ca-Cu-1223 oxides become superconducting at 132 K and under pressure of 150 kbar, Tc of this 1223-high-temperature superconductor can be raised to 153 K. The technology for the processing of metallic low-temperature superconductors (LTS) on the basis of Nb-Ti and Nb3Sn is largely developed. These materials are widely used for magnetic resonance imaging and NMR spectroscopy. However a new challenge appears, namely complex system design, which requires creativity of scientists and engineers (e.g. magnets for fusion and accelerators). This holds a/o also for complex systems in LTS thin-film technology, where on the basis of Nb/Al-oxide/Nb junctions, sensors for bio-and geomagnetic measurements as well as nondestructive testing of materials or standards, e.g. voltage standards, were developed. In the area of digital LTS electronics, based on niobium technology, shift registers and onchip logic circuits were produced and operated up to clock frequencies of 20 GHz, simple RSFQ (rapid single flux quantum) devices even up to 100 GHz. The processing of long HTS wires and tapes is much more difficult. For Bi-2223 HTS, short-sample current carrying capabilities of about 80.000 A/cm2 at 77 K in zero magnetic field have been obtained. Wires up to 300 m long were manufactured, however with smaller critical currents. Furthermore we were learning the technology to produce bulk monolithic Y-Ba-Cu-O HTS by melt texturing. These materials are considered to be used in magnetic bearings or as permanent magnets, where at 65 K a field of 4 T could be reached (at the surface). (orig.)

  9. Digital superconductive electronics: where does it fit?

    International Nuclear Information System (INIS)

    Superconductivity has been pursuing the world of digital electronics ever since 1956. During all this time its supporters have emphasized the 'obvious' advantages of 'low power' and 'unmatched device speed'. However, still no digital electronics product is in a system; silicon-based digital devices overwhelm all others in the applications world. This is true today, in spite of even faster superconductive devices and circuits as well as greatly reduced power. The major issues that must be faced and resolved in order to insert this immature technology into the market place are the following: (i) What is the problem for which we are the enabling solution? (ii) Is it important enough to warrant the 'inconvenience' of cryogenics? (iii) Can we make the cryogenics 'transparent' to the user? (iv) Can we interface to the ubiquitous room-temperature electronics? (v) At what size (chip count, MCM count) are we attractive? In spite of the customer reluctance, there are some very important niches which this technology can fit provided that we take lessons from those which support the silicon 'master'. Magnetics (data storage), GaAs (optical communications) and optics (communications, storage) are all examples. These questions of system applications, examples of small- or large-scale uses and the problems to be solved will be discussed together with competing technology alternatives. (author)

  10. Superconducting graphite intercalation compounds with calcium

    Science.gov (United States)

    Emery, N.; Hérold, C.; Marêché, J.-F.; Lagrange, P.; Bellouard, C.; Lamura, G.; Di Gennaro, E.; Andreone, A.

    2008-04-01

    In the graphite-lithium-calcium system, four well-defined intercalation compounds were synthesised. Two of them, CaC 6 and Li 3Ca 2C 6, exhibit superconducting properties at 11.5 K and 11.15 K, respectively, the highest critical temperatures among those of graphite intercalation compounds. The samples are synthesised using a liquid-solid method allowing the preparation of pure bulk samples, auspicious for crystallographic and magnetic measurements. The crystal structure of CaC 6 was entirely specified; this compound crystallises in the R-3 m space group. The two-dimensional unit cell of Li 3Ca 2C 6 is hexagonal and commensurate with that of graphite and the intercalated sheets, very rich in metal, are seven-layered. The magnetic properties of these phases were studied with an applied field parallel and perpendicular to the graphene sheets. In both cases the magnetic phase diagram indicates that these compounds are type II superconducting materials slightly anisotropic in spite of their lamellar structure. In the case of CaC 6, in-plane magnetic penetration depth measurements show a clear exponential behaviour at low temperatures, consistent with an s-wave symmetry of the gap function, well fitted by the standard BCS theory in the dirty limit.

  11. Superconducting heterostructures: from antipinning to pinning potentials

    International Nuclear Information System (INIS)

    We study vortex lattice dynamics in a heterostructure that combines two type-II superconductors: a niobium film and a dense triangular array of submicrometric vanadium (V) pillars. Magnetic ac susceptibility measurements reveal a sudden increase in ac penetration, related to an increase in vortex mobility above a magnetic field, H∗(T), that decreases linearly with temperature. Additionally, temperature independent matching effects that occur when the number of vortices in the sample is an integer of the number of V pillars, strongly reduce vortex mobility, and were observed for the first and second matching fields, H1 and H2. The angular dependence of H1, H2 and H∗(T) shows that matching is determined by the normal applied field component, while H∗(T) is independent of the applied field orientation. This important result identifies H∗(T) with the critical field boundary for the normal to superconducting transition of V pillars. Below H∗(T), superconducting V pillars repel vortices, and the array becomes an ‘antipinning’ landscape that is more effective in reducing vortex mobility than the ‘pinning’ landscape of the normal V sites above H∗(T). Matching effects are observed both below and above H∗(T), implying the presence of ordered vortex configurations for ‘antipinning’ or ‘pinning’ arrays. (paper)

  12. Optically activated high Tc superconducting microbolometer

    International Nuclear Information System (INIS)

    A laser beam, precisely focused on the patterned superconducting structure, was used to nucleate a resistive area that is sensitive to external thermal effects. The electron beam lithography and wet chemical etching were applied as pattern transfer processes in epitaxial Y-Ba-Cu-O films. Two different sensor designs were tested: (i) 3 millimeters long and 40 micrometers wide stripe and (ii) 1.25 millimeters long, and 50 micron wide meander -like structure. It is shown experimentally that scanning the laser beam along the stripe leads to physical displacement of the sensitive area and, therefore may be used as a basis for imaging over a broad spectral range. For example, patterning the superconducting film into a meander structure is equivalent to a two-dimensional detector array. In additional to the simplicity of the detector fabrication sequence (one step mask transfer), a clear advantage of this approach is the simplicity of the read-out process: an image is formed by registering the signal with only two electrical terminals. The proposed approach can be extended for imaging over a wide spectral range

  13. Mixed-mu superconducting bearings

    Science.gov (United States)

    Hull, John R.; Mulcahy, Thomas M.

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  14. Advanced Superconducting Test Accelerator (ASTA)

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Superconducting Test Accelerator (ASTA) facility will be based on upgrades to the existing NML pulsed SRF facility. ASTA is envisioned to contain 3 to...

  15. Superconductivity in all its states

    CERN Multimedia

    Globe Info

    2011-01-01

    Temporary exhibition at the Saint-Genis-Pouilly Tourist Office. For the 100th anniversary of its discovery, take a plunge into the amazing world of superconductivity. Some materials, when cooled down to extreme temperatures, acquire a remarkable property -  they become superconducting. Superconductivity is a rare example of a quantum effect that can be witnessed on the macroscopic scale and is today at the heart of much research. In laboratories, researchers try to gain a better understanding of its origins, study new superconducting materials, explore the phenomenon at the nanometric scale and pursue their indefatigable search for new applications. Monday to Friday: 09:00 a.m. to 12:00 and 2:30 p.m. to 6:30 p.m. Saturday: 10:00 a.m. to 12:00 noon » Open to all – Admission free For further information: +33 (0)4 50 42 29 37

  16. Superconductivity in Layered Organic Metals

    Directory of Open Access Journals (Sweden)

    Jochen Wosnitza

    2012-04-01

    Full Text Available In this short review, I will give an overview on the current understanding of the superconductivity in quasi-two-dimensional organic metals. Thereby, I will focus on charge-transfer salts based on bis(ethylenedithiotetrathiafulvalene (BEDT-TTF or ET for short. In these materials, strong electronic correlations are clearly evident, resulting in unique phase diagrams. The layered crystallographic structure leads to highly anisotropic electronic as well as superconducting properties. The corresponding very high orbital critical field for in-plane magnetic-field alignment allows for the occurrence of the Fulde–Ferrell– Larkin–Ovchinnikov state as evidenced by thermodynamic measurements. The experimental picture on the nature of the superconducting state is still controversial with evidence both for unconventional as well as for BCS-like superconductivity.

  17. Superconducting Aero Propulsion Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Superconducting electric propulsion systems will yield improvements in total ownership costs due to the simplicity of electric drive when compared with gas turbine...

  18. High temperature superconductivity from Russia

    CERN Document Server

    Larkin, AI

    1989-01-01

    This volume covers up-to-date ideas associated with the studies of high Tc superconductivity. Diverse theoretical points of view on the nature of this phenomenon are presented in the book. Experimental works discuss the results obtained in the studies of Bi and Tl superconductivity compounds as well as the thorough investigation of the different properties of 123 (YBaCu) compounds. Several articles are devoted to SQUIDs functioning at nitrogen temperatures and their application in research work.

  19. Exciton-polariton mediated superconductivity

    OpenAIRE

    Laussy, Fabrice P.; Kavokin, Alexey V; Shelykh, Ivan A

    2010-01-01

    We revisit the exciton mechanism of superconductivity in the framework of microcavity physics, replacing virtual excitons as a binding agent of Cooper pairs by excitations of an exciton-polariton Bose-Einstein condensate. We consider a model microcavity where a quantum well with a two-dimensional electron gas is sandwiched between two undoped quantum wells, where a polariton condensate is formed. We show that the critical temperature for superconductivity dramatically increases with the conde...

  20. Superconductivity in domains with corners

    DEFF Research Database (Denmark)

    Bonnaillie-Noel, Virginie; Fournais, Søren

    2007-01-01

    We study the two-dimensional Ginzburg-Landau functional in a domain with corners for exterior magnetic field strengths near the critical field where the transition from the superconducting to the normal state occurs. We discuss and clarify the definition of this field and obtain a complete...... asymptotic expansion for it in the large $\\kappa$ regime. Furthermore, we discuss nucleation of superconductivity at the boundary....

  1. The superconducting bending magnets 'CESAR'

    CERN Document Server

    Pérot, J

    1978-01-01

    In 1975, CERN decided to build two high precision superconducting dipoles for a beam line in the SPS north experimental area. The aim was to determine whether superconducting magnets of the required accuracy and reliability can be built and what their economies and performances in operation will be. Collaboration between CERN and CAE /SACLAY was established in order to make use of the knowledge and experience already acquired in the two laboratories. (0 refs).

  2. Superconducting versus normal conducting cavities

    OpenAIRE

    Podlech, Holger

    2013-01-01

    One of the most important issues of high-power hadron linacs is the choice of technology with respect to superconducting or room-temperature operation. The favour for a specific technology depends on several parameters such as the beam energy, beam current, beam power and duty factor. This contribution gives an overview of the comparison between superconducting and normal conducting cavities. This includes basic radiofrequency (RF) parameters, design criteria, limitations, required RF and plu...

  3. Conceptual design report: superconducting booster

    International Nuclear Information System (INIS)

    The Superconducting Booster project includes the construction of a new high-voltage injector and buncher for the existing tandem, a magnetic transport system, an rf linac with superconducting resonators, and a rebuncher-debuncher. The booster will fit in existing space so that a new building is not required. The layout of the accelerator is given in Fig. I-1. The University of Washington is contributing approximately $1 M to this project

  4. Electrodynamics of superconducting pnictide superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Perucchi, A.; Pietro, P. Di [INSTM Udr Trieste-ST and Elettra - Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Trieste (Italy); Capitani, F. [Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 2, I-00185 Rome (Italy); Lupi, S. [CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza, P.le Aldo Moro 2, I-00185 Roma (Italy); Lee, S.; Kang, J. H.; Eom, C. B. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Jiang, J.; Weiss, J. D.; Hellstrom, E. E. [Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, 2031 East Paul Dirac Drive, Tallahassee, Florida 32310 (United States); Dore, P. [CNR-SPIN and Dipartimento di Fisica, Università di Roma Sapienza, P.le Aldo Moro 2, I-00185 Roma (Italy)

    2014-06-02

    It was recently shown that superlattices where layers of the 8% Co-doped BaFe{sub 2}As{sub 2} superconducting pnictide are intercalated with non superconducting ultrathin layers of either SrTiO{sub 3} or of oxygen-rich BaFe{sub 2}As{sub 2}, can be used to control flux pinning, thereby increasing critical fields and currents, without significantly affecting the critical temperature of the pristine superconducting material. However, little is known about the electron properties of these systems. Here, we investigate the electrodynamics of these superconducting pnictide superlattices in the normal and superconducting state by using infrared reflectivity, from THz to visible range. We find that multigap structure of these superlattices is preserved, whereas some significant changes are observed in their electronic structure with respect to those of the original pnictide. Our results suggest that possible attempts to further increase the flux pinning may lead to a breakdown of the pnictide superconducting properties.

  5. Radiation effects on superconducting materials

    International Nuclear Information System (INIS)

    Superconducting magnets will be used in plasma confinement of future fusion reactors. They will be subjected to neutron irradiation at low temperatures, so information is required on the effects of irradiation at low temperatures upon superconducting properties (critical current density, superconducting transition temperature, etc.) of the superconducting materials, electrical resistivity of the stabilizing materials such as Cu, multifilamentary composite materials of the magnets, and mechanical and electrical properties of the electrical insulating materials. A review is made of the existing data of radiation effects on the superconducting magnets. The superconducting transition temperature of the elements, alloys and compounds decreases with neutron irradiation, more in the compounds than in the alloys. The critical current density J sub(c) of the alloys decreases with fast neutron irradiation at low temperatures. In Nb3Sn, J sub(c) increases by low temperature fast neutron irradiation below the fluence of about 1018n/cm2, and the degradation of J sub(c) appears at over 1018n/cm2. Fast neutron irradiation causes resitivity increase of Cu and Al. Radiation damage in the materials may have large influence on stability characteristics of the composite wires. Extensive studies are necessary to clarify the problems, especially the irradiation effect at low temperatures. (auth.)

  6. Three phase superconducting armature: Windings and cryostat

    International Nuclear Information System (INIS)

    The existence of superconducting wires with reduced losses under AC magnetic fields allows to design AC Machines using superconducting coils for both field and armature windings. A superconduction armature needs new materials and new concepts for the windings and the cryostat: Glass fiber reinforced epoxy structure; Non impregnated superconducting windings; Low losses horizontal cryostat. The paper presents a cryostat designed to receive a three phase superconducting winding as to form, with a superconducting field winding rotor, a 20 kVa synchronous machine. Construction and preliminary test on the cryostat and the windings are reported

  7. Superconductivity and the environment: a Roadmap

    Science.gov (United States)

    Nishijima, Shigehiro; Eckroad, Steven; Marian, Adela; Choi, Kyeongdal; Kim, Woo Seok; Terai, Motoaki; Deng, Zigang; Zheng, Jun; Wang, Jiasu; Umemoto, Katsuya; Du, Jia; Febvre, Pascal; Keenan, Shane; Mukhanov, Oleg; Cooley, Lance D.; Foley, Cathy P.; Hassenzahl, William V.; Izumi, Mitsuru

    2013-11-01

    severe impacts such as the explosion in 1969 in the waters of Kent in the UK that caused a reading of 4.5 on the Richter scale for earthquake monitors. Another example was a land-based detonation of a 500 kg World War II bomb in Germany killing three people in 2010. There is countless UXO from recent conflicts worldwide. Detection and accurate location with 100% reliability is required to return land to safe civilian use. Keenan provides details of a prototype magnetic gradiometer developed for this purpose. Reducing power needs for high-end IT. Supercomputers are so large that they are close to requiring their own small power plant to support the energy needed to run the computer. For example, in 2011 Facebook data centers and operations used 532 million kW hours of energy. Mukhanov explores the potential of reducing the power dissipation for future supercomputers from more than 500 MW for Exascale systems to 0.2 MW by using superconducting-ferromagnetic Josephson junctions for magnetic memory and programmable logic. Clearly superconductivity is an ultimate energy-saving technology, and its practical implementation will contribute to the reduction of CO2 emissions, improved water purification, reduction of waste and timely preparedness for natural disasters or significant events. This Roadmap shows how the application of superconducting technologies will have a significant impact when they are adopted.

  8. Superconducting bearings in flywheels

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, T.A.; Campbell, A.M.; Ganney, I.; Lo, W. [Cambridge Univ. (United Kingdom). Interdisciplinary Research Centre in Superconductivity (IRC); Twardowski, T. [International Energy Systems, Chester High Road, Neston, South Wirral (United Kingdom); Dawson, B. [British Nuclear Fuels, Capenhurst, South Wirral (United Kingdom)

    1998-05-01

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette(TM). The Pirouette(TM) system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will provide up to 50 kW). IES (a British Nuclear Fuels subsidiary) the owners of the Pirouette(TM) machine have supplied Cambridge with a flywheel. This flywheel weighs >40 kg and is being levitated using an Evershed-type arrangement in which the superconductor is being used to stabilize the interaction between two magnets. To date we have demonstrated stable levitation in static and low speed tests in a rig designed for low speeds of rotation in air. A second rig which is currently under construction at BNFL will run in vacuum at speeds of up to 50 (orig.) 5 refs.

  9. Superconducting bearings in flywheels

    International Nuclear Information System (INIS)

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette(TM). The Pirouette(TM) system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will provide up to 50 kW). IES (a British Nuclear Fuels subsidiary) the owners of the Pirouette(TM) machine have supplied Cambridge with a flywheel. This flywheel weighs >40 kg and is being levitated using an Evershed-type arrangement in which the superconductor is being used to stabilize the interaction between two magnets. To date we have demonstrated stable levitation in static and low speed tests in a rig designed for low speeds of rotation in air. A second rig which is currently under construction at BNFL will run in vacuum at speeds of up to 50 (orig.)

  10. Energy applications of superconductivity

    International Nuclear Information System (INIS)

    The excitement over the new superconductors repeats the enthusiasm following the initial discovery in 1911 as well as that following the discovery of more practical metallic materials in the early 1960s. Higher temperature and the rapid progression from 35 K to 95 K and then to 125 K in a period of less than two years increased the normal enthusiasm to what could be described whimsically as hyperbole. Such excessive optimism led to some backlash and various expressions of pessimism in the media as the difficulty of the technical challenge of development was recognized. Now nearly five years after the initial discoveries and with fairly steady progress in both the science and the technology, the hype has been reduced and a more rational atmosphere prevails. This paper reports that high-temperature superconductivity generally promises an evolutionary rather than a revolutionary impact on energy applications. In other words, it could improve efficiency and reliability, but not make large power plants or petroleum obsolete

  11. Superconductivity in doped fullerenes

    International Nuclear Information System (INIS)

    While there is not complete agreement on the microscopic mechanism of superconductivity in alkali-metal-doped C sup 0, further research may well lead to the production of analogous materials that lose resistance at even higher temperatures. Carbon 60 is a fascinating and arrestingly beautiful molecule. With 12 pentagonal and 20 hexagonal faces symmetrically arrayed in a soccer-ball-like structure that belongs to the icosahedral point group, I sub h, its high symmetry alone invites special attention. The publication in september 1990 of a simple technique for manufacturing and concentrating macroscopic amounts of this new form of carbon announced to the scientific community that enabling technology had arrived. Macroscopic amounts of C sub 6 sub 0 (and the higher fullerenes, such as C sub 7 sub 0 and C sub 8 sub 4) can now be made with an apparatus as simple as an arc furnace powered with an arc welding supply. Accordingly, chemists, physicists and materials scientists have joined forces in an explosion of effort to explore the properties of this unusual molecular building block. (author). 23 refs., 6 figs

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

    OpenAIRE

    Maheshwari, P. K.; Rajveer Jha; Bhasker Gahtori; Awana, V. P. S.

    2015-01-01

    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 ...

  13. Interplay Between Ferromagnetism and Superconductivity

    Science.gov (United States)

    Linder, Jacob; Sudbø, Asle

    This chapter presents results on transport properties of hybrid structures where the interplay between ferromagnetism and superconductivity plays a central role. In particular, the appearance of so-called odd-frequency pairing in such structures is investigated in detail. The basic physics of superconductivity in such structures is presented, and the quasiclassical theory of Greens functions with appropriate boundary conditions is given. Results for superconductor∣ferromagnet bilayers as well as magnetic Josephson junctions and spin valves are presented. Further phenomena that are studied include transport in the presence of inhomogenous magnetic textures, spin-Josephon effect, and crossed Andreev reflection. We also investigate the possibility of intrinsic coexistence of ferromagnetism and superconductivity, as reported in a series of uranium-based heavy-fermion compounds. The nature of such a coexistence and the resulting superconducting order parameter is discussed along with relevant experimental results. We present a thermodynamic treatment for a model of a ferromagnetic supercondcutor and moreover suggest ways to experimentally determine the pairing symmetry of the superconducting gap, in particular by means of conductance spectroscopy.

  14. Liquid phase sintered superconducting cermet

    International Nuclear Information System (INIS)

    This patent describes a method of making a superconducting cermet having superconducting properties with improved bulk density, low porosity and in situ stabilization. It comprises: forming a structure of a superconducting ceramic material having the formula RM2Cu3O(6.5+x)wherein R is one or more rare earth elements capable of reacting to form a superconducting ceramic, M is one or more alkaline earth metal elements selected from barium and strontium capable of reacting to form a superconducting ceramic, x is greater than 0 and less than 0.5; and a precious metal compound in solid form selected from the class consisting of oxides, sulfides and halides of silver; and liquid phase sintering the mixture at a temperature wherein the precious metal of the precious metal compound is molten and below the melting point of the ceramic material. The liquid phase sintering is carried out for a time less than 36 hours but sufficient to improve the bulk density of the cermet

  15. Working on an LHC superconducting cavity

    CERN Multimedia

    Laurent Guiraud

    2000-01-01

    The delicate superconducting equipment for CERN’s LHC collider has to be assembled in ultra-clean conditions to safeguard performance. Here we see the power supply being installed on one of the superconducting cavities.

  16. Superconductivity research in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Jirsa, Miloš

    -, č. 1 (2007), s. 1-6. ISSN N Institutional research plan: CEZ:AV0Z10100520 Keywords : superconductivity * research to superconductivity * financial support of the research Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. High-Tc superconducting electric motors

    International Nuclear Information System (INIS)

    In this paper, the advantages and limitations of using superconductors in motors are discussed. A synchronous motor with a high temperature superconducting field winding for pump and fan drive applications is described and some of its unique design features are identified. A 10,000 horsepower superconducting motor design is presented. The critical field and current density requirements for high temperature superconducting wire in motors is discussed. Finally, recent progress in superconducting wire performance is presented

  18. Materials and mechanisms of hole superconductivity

    OpenAIRE

    Hirsch, J. E.

    2011-01-01

    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 $T_c$ cuprates both hole-doped and electron-doped, $MgB_2$, iron pnictides, doped semiconductors, and elements under high pressure.

  19. WORKSHOP: Radiofrequency superconductivity

    International Nuclear Information System (INIS)

    Full text: With superconducting radiofrequency playing a major role in the push for new machines to break fresh physics frontiers, it has become a tradition for experts and newcomers in this field from all over the world to meet every second year to hear progress reports from laboratories and to discuss common problems and possible solutions. The sixth such workshop was held from 4-8 October under the chairmanship of Ron Sundelin at the Continuous Electron Beam Accelerator Facility (CEBAF) under construction in Newport News, Virginia. With 170 participants from 14 countries including Eastern Europe and China, it reflected the growing interest in the field - looking back to 1984, when CERN was the host laboratory, the second workshop had less than 100 participants. The CEBAF meeting began with laboratory status reports, covering both high beam energy ('high beta') applications with 'spherical' cavities (as with CERN's LEP200), all using niobium as superconductor and working between 352 MHz and 3 GHz, and lower energy (low beta') applications with geometrically more complicated shapes such as quarter or half wave, split ring or spoke resonators, some using electrodeposited lead as superconductor and working around 100 MHz. During these talks it became clear that more and more laboratories have focused on routine problems, such as reliable series production and testing, running cavities with ancillaries in the machines, or building complete prototypes for projects to be approved by critical funding authorities. This contrasts with the heady days just a few years ago when - at least in the high beta community - the main objective was to explore new ideas. State-of-the-art summaries showed how at 1.3 and 3 GHz 25-30 MV/m have been reached by several laboratories using different preparation methods. Newer developments for common problems included r.f. windows, couplers, controls, and especially field emission, public enemy number one for

  20. Superconductivity in Spain. Midas program

    International Nuclear Information System (INIS)

    The different activities in the field of applied superconductivity carried out in Spain under the auspices of the MIDAS program are reported. Applications using both low- and high-temperature superconductors are considered. In the low temperature superconductors case, the design and construction of a 1 mega joule SMES (Superconducting Magnetic Energy Storage) unit, as well as the fabrication of voltage and resistance standards, are reviewed. Developments involving the design and fabrication of an inductive current fault limited and mono- and multi-filamentary wires and tapes using high-temperature superconductors are discussed. Finally, the prospects for the application of superconductivity technology to electric power systems for the electric utilities is considered. (author)

  1. Superconductivity in Spain. Midas program

    Energy Technology Data Exchange (ETDEWEB)

    Yndurain, F. [Red Electrica de Espana, Alcobendas (Spain). Midas Program

    1996-12-31

    The different activities in the field of applied superconductivity carried out in Spain under the auspices of the MIDAS program are reported. Applications using both low- and high-temperature superconductors are considered. In the low temperature superconductors case, the design and construction of a 1 mega joule SMES (Superconducting Magnetic Energy Storage) unit, as well as the fabrication of voltage and resistance standards, are reviewed. Developments involving the design and fabrication of an inductive current fault limited and mono- and multi-filamentary wires and tapes using high-temperature superconductors are discussed. Finally, the prospects for the application of superconductivity technology to electric power systems for the electric utilities is considered. (author).

  2. Transport Measurements on Superconducting Nanowires

    Science.gov (United States)

    Kurtz, J. S.; Tian, M.; Garcia, R.; Mallouk, T. E.; Mayer, T. S.; Liu, Y.; Chan, M. H. W.

    2003-03-01

    High quality, single-crystal nanowires of various elemental metals and superconductors have been fabricated by electro-deposition into porous alumina and polycarbonate membranes. We report here recent magneto-transport measurements at low temperatures on such superconducting Sn nanowires with diameters smaller than the bulk coherence length and penetration depth. These wires allow an investigation of one-dimensional superconductivity in the regime of very low disorder. Transport properties were measured for wires of various diameters in a dilution refrigerator under magnetic fields up to 9 Tesla. Superconducting transitions were observed, and deviations from bulk, 3D behavior such as low-temperature resistive tails and high critical fields will be presented and discussed. This work is supported by NSF MRSEC Grants DMR 0080019 and DMR 0213623.

  3. Sensing with Superconducting Point Contacts

    Directory of Open Access Journals (Sweden)

    Argo Nurbawono

    2012-05-01

    Full Text Available Superconducting point contacts have been used for measuring magnetic polarizations, identifying magnetic impurities, electronic structures, and even the vibrational modes of small molecules. Due to intrinsically small energy scale in the subgap structures of the supercurrent determined by the size of the superconducting energy gap, superconductors provide ultrahigh sensitivities for high resolution spectroscopies. The so-called Andreev reflection process between normal metal and superconductor carries complex and rich information which can be utilized as powerful sensor when fully exploited. In this review, we would discuss recent experimental and theoretical developments in the supercurrent transport through superconducting point contacts and their relevance to sensing applications, and we would highlight their current issues and potentials. A true utilization of the method based on Andreev reflection analysis opens up possibilities for a new class of ultrasensitive sensors.

  4. Superconductivity in Anderson lattice model

    International Nuclear Information System (INIS)

    We study the superconducting instabilities generated by the inclusion in the Anderson lattice model of a density-density attractive potential between correlated electrons on nearest-neighbouring sites. Using a description of the normal phase based on a perturbative expansion around the atomic limit, we treat the attractive potential in the broken symmetry Hartree-Fock scheme and analyze which of the possible symmetries of the superconducting order parameter leads to the highest possible transition temperature in the case of a two-dimensional square lattice. For values of the on-site f-repulsion large compared to the hopping amplitude, a suppression of any possible superconducting phase occurs, regardless of the of the symmetry of the order parameter. (author)

  5. Superhard and superconductive polymorphs of diamond-like BC3

    International Nuclear Information System (INIS)

    We have explored the crystal structures of synthesized diamond-like BC3 (d-BC3) with particle swarm optimization (PSO) algorithm combined with first-principles structural optimizations. Three intriguing metallic low-energy structures are uncovered: (i) orthorhombic Pmma-a consisting of a sandwich-like 'B-layer' between C layers, (ii) orthorhombic Pmma-b with novel B-B bondings, and (iii) tetragonal P-4m2. The simulated Raman modes of Pmma-b phase are in agreement with experiments. Further hardness and electron-phonon calculations revealed that all the three candidate d-BC3 phases are superhard (>40 GPa) and superconductive materials with the superconducting critical temperature reaching at 16.6-23.4 K for Pmma-a phase.

  6. Scaling of Superconducting Switches for Extraction of Magnetic Energy

    CERN Document Server

    Ballarino, A

    2010-01-01

    In certain cases it is necessary to extract the energy from a superconducting magnet when it quenches, in order to limit the heat generated by the event and thus prevent irreversible damage. This is usually achieved by opening a contact breaker across a resistor in the circuit feeding the magnet. For the heavy currents used to excite large magnets such switches incorporate sophisticated devices to limit arcing during the operation; besides being quite large and expensive, such switches have a limited lifetime. It is therefore interesting to consider the use of superconducting switches to perform this function, the advantage being that such switches would (i) not require maintenance and (ii) would be housed within the cryogenic environment of the magnet, and thus avoid permanent diversion of the current in and out of that environment to the mechanical switch (which operates at room temperature). However, practical switches for such an application are made up of superconductor in a metal matrix, and it is conve...

  7. Control and data acquisition systems for high field superconducting wigglers

    CERN Document Server

    Batrakov, A; Karpov, G; Kozak, V; Kuzin, M; Kuper, E; Mamkin, V; Mezentsev, N A; Repkov, V V; Selivanov, A; Shkaruba, V A

    2001-01-01

    This paper describes the control and DAQ system of superconducting wigglers with magnetic field range up to 10.3 T. The first version of the system controls a 7 T superconducting wiggler prepared for installation at Bessy-II (Germany). The second one controls a 10 T wiggler which is under testing now at the SPring-8 site (Japan). Both systems are based on VME apparatus. The set of specialized VME modules is elaborated to arrange wiggler power supply control, full time wiggler monitoring, and magnetic field high accuracy measurement and field stabilization. The software for the control of the wigglers is written in C language for VxWorks operation system for a Motorola-162 VME controller. The task initialization, stops and acquisition of the data can be done from the nearest personal computer (FTP host for VME), or from the remote system as well.

  8. 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.

  9. Superconductivity in Single-Crystal YIn3

    OpenAIRE

    Johnson, S D; Young, J. R.; Zieve, R. J.; Cooley, J. C.

    2011-01-01

    We measure the superconducting transition of YIn$_3$ by resistivity, susceptibility, and specific heat. Despite using high-quality single-crystal samples, the transitions detected by the three techniques are shifted from each other in temperature, suggesting a region of filamentary superconductivity. We discuss the possible implications for filamentary superconductivity in unconventional superconductors.

  10. Surface superconductivity in multilayered rhombohedral graphene: Supercurrent

    Science.gov (United States)

    Kopnin, N. B.

    2011-09-01

    The supercurrent for the surface superconductivity of a flat-band multilayered rhombohedral graphene is calculated. Despite the absence of dispersion of the excitation spectrum, the supercurrent is finite. The critical current is proportional to the zero-temperature superconducting gap, i.e., to the superconducting critical temperature and to the size of the flat band in the momentum space.

  11. Surface superconductivity in multilayered rhombohedral graphene: Supercurrent

    OpenAIRE

    Kopnin, N. B.

    2011-01-01

    The supercurrent for the surface superconductivity of a flat-band multilayered rhombohedral graphene is calculated. Despite the absence of dispersion of the excitation spectrum, the supercurrent is finite. The critical current is proportional to the zero-temperature superconducting gap, i.e., to the superconducting critical temperature and to the size of the flat band in the momentum space.

  12. Superconductivity in Spain: ``MIDAS`` program

    Energy Technology Data Exchange (ETDEWEB)

    Yndurain, F.

    1995-12-31

    The different activities in the field of applied superconductivity carried out in Spain under the auspices of the ``MIDAS`` program are reported. Applications using both low and high temperature superconductors are considered. In the low temperature superconductors case, the design and construction of a 1 MJ SMES unit as well as the fabrication of voltage and resistance standards is reviewed. Developments involving the design and fabrication of an inductive current fault limiter and mono and multi filamentary wires and tapes using high superconductors are discussed. Finally, the prospects of the applications of the superconductivity technology to electric power systems for the electric utilities is considered. (author). 7 refs., 5 figs.

  13. Power applications for superconducting cables

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Hansen, Steen; Jørgensen, Preben; Lomholt, Karin; Mikkelsen, Søren D.; Okholm, Jan; Salvin, Sven; Østergaard, Jacob

    2000-01-01

    High temperature superconducting (HTS) cables for use in electric ac power systems are under development around the world today. There are two main constructions under development: the room temperature dielectric design and the cryogenic dielectric design. However, theoretical studies have shown...... that the insertion of these cables in the network is not without problems. The network stability requirements may impose severe constraints on the actual obtainable length of superconducting cables. Load flow considerations show that it may be difficult to use these high current cables to their full...

  14. Cooling device of superconducting coils

    International Nuclear Information System (INIS)

    This device is rotating around an horizontal axis. The superconducting coils are contained in a cryogenic enclosure feeded in liquid helium forced circulation. They are related to an electric generator by electric mains each of them comprising a gas exchanger, and an exchanger-evaporator set between the cryogenic device and those exchangers. The exchanger-evaporator is aimed at dissipating the heat arriving by conductors connected to the superconducting coils. According to the invention, the invention includes an annular canalization with horizontal axis in which the connection conductors bathe in liquid helium

  15. Aspects of superconducting power transformers

    International Nuclear Information System (INIS)

    High-temperature superconductivity opens up novel possibilities in power transformer design, and the applications of such novel transformers promise interesting advantages in terms of economics and ecology. The time horizon predictable for applicability of the novel equipment essentially depends on materials development progress, because R+D activities have not yet achieved the low-loss AC conductor required for this technology. Nonetheless and notwithstanding, it seems appropriate to consider already at this stage the technical problems involved and the features of the new systems with HT superconducting power transformers. (orig./MM)

  16. The Mechanism of High-Tc Superconductivity: "Nonlinear" Superconductivity

    OpenAIRE

    Mourachkine, A.

    2001-01-01

    The main purpose of the paper is to present an overview of the current situation in the development of understanding of the mechanism of high-Tc superconductivity which arises due to moderately strong, nonlinear electron-phonon interactions and due to magnetic (spin) fluctuations.

  17. Development of Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Mijatovic, Nenad; Abrahamsen, Asger Bech

    2012-01-01

    In this paper the commercial activities in the field of superconducting machines, particularly superconducting wind turbine generators, are reviewed and presented. Superconducting generators have the potential to provide a compact and light weight drive train at high torques and slow rotational...... (HTS); and one is a fully superconducting generator based on MgB2. It is concluded that there is large commercial interest in superconducting machines, with an increasing patenting activity. Such generators are however not without their challenges. The superconductors have to be cooled down to...

  18. Hierarchic Models of Turbulence, Superfluidity and Superconductivity

    CERN Document Server

    Kaivarainen, A

    2000-01-01

    New models of Turbulence, Superfluidity and Superconductivity, based on new Hierarchic theory, general for liquids and solids (physics/0102086), have been proposed. CONTENTS: 1 Turbulence. General description; 2 Mesoscopic mechanism of turbulence; 3 Superfluidity. General description; 4 Mesoscopic scenario of fluidity; 5 Superfluidity as a hierarchic self-organization process; 6 Superfluidity in 3He; 7 Superconductivity: General properties of metals and semiconductors; Plasma oscillations; Cyclotron resonance; Electroconductivity; 8. Microscopic theory of superconductivity (BCS); 9. Mesoscopic scenario of superconductivity: Interpretation of experimental data in the framework of mesoscopic model of superconductivity.

  19. Demonstration of superconducting micromachined cavities

    International Nuclear Information System (INIS)

    Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics. Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions, and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million, despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing

  20. Collaring of Po Superconducting Dipole

    CERN Document Server

    1983-01-01

    The picture shows the placing of a stack of stainless steel collars around the superconducting coils.Pre-assembled collar stacks were placed under and on top of the coils,the collars interleaving as comb teeth. During the following collaring operation of compression under a press the collars were locked together by means of side wedges. See also photos 8211532X, 7903168

  1. Modern technologies in rf superconductivity

    International Nuclear Information System (INIS)

    The development and application of superconducting rf cavities in particle accelerators is a fine example of advanced technology and of close cooperation with industry. This contribution examines the theoretical and present-day practical limitations of sc cavities and describes some advanced technologies needed for their large scale applications. (orig.)

  2. Superconducting cavity model for LEP

    CERN Multimedia

    1979-01-01

    A superconducting cavity model is being prepared for testing in a vertical cryostat.At the top of the assembly jig is H.Preis while A.Scharding adjusts some diagnostic equipment to the cavity. See also photo 7912501X.

  3. ISR Superconducting High luminosity Insertion

    CERN Multimedia

    1981-01-01

    The picture shows two of the eight superconducting quadrupoles of the low-beta insertion at intersection I8.The increase of luminosity produced by this insertion was above a factor 7. At right one can also see the Open- Axial- Field Magnet. The person is Stephan Pichler. See also 7702690X, 8102123, 8010397, 8008332.

  4. Superconducting magnets and cryogenics: proceedings

    International Nuclear Information System (INIS)

    Separate abstracts were prepared for 70 papers in these workshop proceeedings. Topics covered include: superconducting accelerator magnet research and development; superconductor development; electrical measurements; magnet design and construction methods; field correction methods; power schemes and quench protection; cryogenic systems; and magnet measurements

  5. A unified theory of superconductivity

    CERN Document Server

    Huang, Xiuqing

    2008-01-01

    In this work, we argue that the phonon-mediated BCS theory may be incorrect. Two kinds of glues, pairing (pseudogap) glue and superconducting glue, are suggested based on a real space Coulomb confinement effect. The scenarios provide a unified explanation of the pairing symmetry, pseudogap and superconducting states, spin--charge stripe order, magic doping fractions and vortex structures in conventional and unconventional (the high-Tc cuprates, MgB2 and the newly-discovered Fe-based family) superconductors. The theory agrees with the existence of a pseudogap in high-temperature superconductors, while no pseudogap feature could be observed in MgB2, iron-based and most of the conventional superconductors. Our results indicate that the superconducting phase can coexist with a triangular vortex lattice in pure MgB2 single crystal with a charge carrier density n=1.49*10^22/cm3. For iron-based superconductors, the relationship between the superconducting vortex phases and the optimal doping levels are analytically ...

  6. Superconductivity and the periodic table

    International Nuclear Information System (INIS)

    Compiled data on superconducting transition temperature Tc for pure metals (including amorphous and high-pressure phases) from the first, second, and third long periods of the Periodic Table and for their analogous compounds show that a significant regularity exists in the relative values of Tc

  7. Fireballs from Superconducting Cosmic Strings

    CERN Document Server

    Gruzinov, Andrei

    2016-01-01

    Thermalized fireballs should be created by cusp events on superconducting cosmic strings. This simple notion allows to reliably estimate particle emission from the cusps in a given background magnetic field. With plausible assumptions about intergalactic magnetic fields, the cusp events can produce observable fluxes of high-energy photons and neutrinos with unique signatures.

  8. Superconductivity of small metal grains

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Renrong; CHEN; Zhiqian; ZHU; Shunquan

    2005-01-01

    The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

  9. Discovering superconductivity an investigative approach

    CERN Document Server

    Ireson, Gren

    2012-01-01

    The highly-illustrated text will serve as excellent introduction for students, with and without a physics background, to superconductivity. With a strong practical, experimental emphasis, it will provide readers with an overview of the topic preparing them for more advanced texts used in more advanced undergraduate and post-graduate courses.

  10. Nonlinear diffusion and superconducting hysteresis

    Energy Technology Data Exchange (ETDEWEB)

    Mayergoyz, I.D. [Univ. of Maryland, College Park, MD (United States)

    1996-12-31

    Nonlinear diffusion of electromagnetic fields in superconductors with ideal and gradual resistive transitions is studied. Analytical results obtained for linear and nonlinear polarizations of electromagnetic fields are reported. These results lead to various extensions of the critical state model for superconducting hysteresis.

  11. Demonstration of superconducting micromachined cavities

    Energy Technology Data Exchange (ETDEWEB)

    Brecht, T., E-mail: teresa.brecht@yale.edu; Reagor, M.; Chu, Y.; Pfaff, W.; Wang, C.; Frunzio, L.; Devoret, M. H.; Schoelkopf, R. J. [Department of Applied Physics, Yale University, New Haven, Connecticut 06511 (United States)

    2015-11-09

    Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics. Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions, and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million, despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing.

  12. Superconductivity in the Kondo lattice

    International Nuclear Information System (INIS)

    Superconductivity in the Kondo lattice was theoretically studied in connection with superconductivity in CeCu2Si2 and UBe13. To achieve superconductivity in these systems, coherence between Ce ions or U ions is of crucial importance. To take account of the coherence, the periodic Anderson model with a small dispersion of the f band was used. With the use of a single-site approximation for the self-energy of the f electron, the heavy fermion state near the Fermi level was derived. This state is a highly correlated state, and the Coulomb repulsive interaction is strongly reduced. The f electrons are found to be responsible for superconductivity. Both the specific heat in the normal state C/sub N/(T) and the specific-heat jump ΔC at T/sub c/ are very large, and the ratio ΔC/C/sub N/(T/sub c/) has the BCS value in the weak-coupling approximation. The thermodynamic critical field is very high

  13. Vacuum Technology for Superconducting Devices

    OpenAIRE

    Chiggiato, P.

    2015-01-01

    The basic notions of vacuum technology for superconducting applications are presented, with an emphasis on mass and heat transport in free molecular regimes. The working principles and practical details of turbomolecular pumps and cryopumps are introduced. The specific case of the Large Hadron Collider's cryogenic vacuum system is briefly reviewed.

  14. Demonstration of superconducting micromachined cavities

    Science.gov (United States)

    Brecht, T.; Reagor, M.; Chu, Y.; Pfaff, W.; Wang, C.; Frunzio, L.; Devoret, M. H.; Schoelkopf, R. J.

    2015-11-01

    Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics. Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions, and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million, despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing.

  15. Study on superconducting accelerating cavities

    International Nuclear Information System (INIS)

    A test cavity of cylindrical shape has been designed and constructed to study superconducting accelerating cavities for TRISTAN e+e- Ring. Higher order modes have been calculated by using SUPERFISH program and an analytical method, and measured. The measured resonant frequencies well agree with the calculated results. (author)

  16. Florida State University superconducting linac

    International Nuclear Information System (INIS)

    As early as the fall of 1977 it was decided that the future research needs of their nuclear structure laboratory required an increase in energy capability to at least 8 MeV per nucleon for the lighter ions, and that these needs could be met by the installation of a 17 MV tandem Van de Graaff accelerator. The chief problem with this proposal was the high cost. It became apparent that a far less expensive option was to construct a linear accelerator to boost the energy from their existing 9 MV tandem. The options open to them among linac boosters were well represented by the room temperature linac at Heidelberg and the superconducting Stony Brook and Argonne systems. By the Spring of 1979 it had been decided that both capital cost and electric power requirements favored a superconducting system. As regards the two superconducting resonator technologies - the Argonne niobium-copper or the Caltech-Stony Brook lead plated copper - the Argonne resonators, though more expensive to construct, had the advantages of more boost per resonator, greater durability of the superconducting surface and less stringent beam bunching requirements. In 1980 pilot funding from the State of Florida enabled the construction of a building addition to house the linac and a new target area, and the setting up of a small, three resonator, test booster. Major funding by the NSF for the laboratory upgrade started in 1984. With these funds they purchased their present helium liquefaction and transfer system and constructed three large cryostats, each housing four Argonne beta = 0.105 resonators and two superconducting solenoids. The last large cryostat was completed and installed on-line early this year and the linac was dedicated on March 20. Nuclear physics experiments using the whole linac began in early June. 4 references, 6 figures, 1 table

  17. Inelastic magnetic scattering of polarized neutrons by a superconducting ring

    International Nuclear Information System (INIS)

    The inelastic scattering of cold neutrons by a ring leads to quantum jumps of a superconducting current which correspond to a decrease in the fluxoid quantum number by one or several units while the change in the ring energy is transferred to the kinetic energy of the scattered neutron. The scattering cross sections of transversely polarized neutrons have been calculated for a thin type-II superconductor ring, the thickness of which is smaller than the field penetration depth but larger than the electron mean free path.

  18. The Beijing electron-positron collider and its second phase construction

    International Nuclear Information System (INIS)

    As a powerful tool for research on the micro-world, colliders have played an essential role in the exciting discovery of particle physics in the past 30 years, and continue to serve as the dominant machines for high energy physics research. Aiming at τ and charm physics, the Beijing Electron-Positron Collider (BEPC) has become a leading machine in the world in its energy region. Many important results in high energy physics and synchrotron radiation research have been obtained with the BEPC. To maintain China's leading positron in τ and charm physics, Chinese scientists proposed the BEPC II project as the second phase construction, and this was approved by the Chinese government at the end of 2003. As with the BEPC, BEPC II will serve two purposes, i.e. research on high energy physics and synchrotron radiation. The luminosity of BEPC II will be two orders of magnitude higher than the present BEPC, and its synchrotron radiation operation will also be significantly improved. The performance of BEPC and progress in the construction of BEPC II as well as their prospects are reviewed. (author)

  19. Superconducting characteristics of 4-Å carbon nanotube-zeolite composite

    KAUST Repository

    Lortz, Rolf W.

    2009-04-15

    We have fabricated nanocomposites consisting of 4-A carbon nanotubes embedded in the 0.7-nm pores of aluminophosphate- five (AFI) zeolite that display a superconducting specific heat transition at 15 K. MicroRaman spectra of the samples show strong and spatially uniform radial breathing mode (RBM) signals at 510 cm-1 and 550 cm-1, characteristic of the (4,2) and (5,0) nanotubes, respectively. The specific heat transition is suppressed at >2T, with a temperature dependence characteristic of finite-size effects. Comparison with theory shows the behavior to be consistent with that of a type II BCS superconductor, characterized by a coherence length of 14 ± 2 nm and a magnetic penetration length of 1.5 ± 0.7 μm. Four probe and differential resistance measurements have also indicated a superconducting transition initiating at 15 K, but the magnetoresistance data indicate the superconducting network to be inhomogeneous, with a component being susceptible to magnetic fields below 3 T and other parts capable of withstanding a magnetic field of 5Tor beyond.

  20. Superconductivity and magnetic properties of spin-ladder compounds

    International Nuclear Information System (INIS)

    A review is given of the structural, magnetic and transport studies on two-leg spin-ladder (M2Cu2O3)m(CuO2)n systems (where M are divalent or/and trivalent cations). The crystals belonging to these systems consist of two interpenetrated subsystems. The first subsystem [M2Cu2O3] is composed of (Cu2O3) two-leg ladder planes and M ions coordinated to them. The second subsystem consists of CuO2 1D-chains. In these materials, the superconductivity was discovered for m/n = 1/1, 5/7, 7/10. The intrinsic and extrinsic superconducting properties of spin-ladder systems are presented and discussed in detail. The important role played by the hole transfer from CuO2 planes to the spin-ladder planes is stressed. It is shown that the superconductivity in this new family of high-temperature superconductors should be described as an extreme type II limit. (orig.)

  1. Magnetic confinement of neutral atoms based on patterned vortex distributions in superconducting disks and rings

    CERN Document Server

    Zhang, B; Chan, K S; Beian, M; Lim, M J; Dumke, R; 10.1103/PhysRevA.85.013404

    2012-01-01

    We propose and analyze neutral atom traps generated by vortices imprinted by magnetic field pulse sequences in type-II superconducting disks and rings. We compute the supercurrent distribution and magnetic field resulting from the vortices in the superconductor. Different patterns of vortices can be written by versatile loading field sequences. We discuss in detail procedures to generate quadrupole traps, self-sufficient traps and ring traps based on superconducting disks and rings. The ease of creating these traps and the low current noise in supercurrent carrying structures makes our approach attractive for designing atom chip interferometers and probes.

  2. Superconducting energy gap and pairing interaction in high T/sub c/ oxides

    International Nuclear Information System (INIS)

    The authors propose two characteristic features in high T/sub c/ oxides, La-Sr-Cu-O and Y-Ba-Cu-O: (i) the apparent discrepancy of the superconducting energy gap between far-infrared and quasi-particle tunneling measurements can be an indication of anisotropic Cooper pairing with spin singlet; (ii) the Coulomb interaction induces spin wave mode with the wave number of the Brillouin zone boundary and the energy close to 2Δ0, Δ0 being the maximum value of the superconducting energy gap. This mode may be observed by neutron inelastic scattering and tunneling experiments

  3. Chain of Majorana states from superconducting Dirac fermions at a magnetic domain wall

    International Nuclear Information System (INIS)

    We study theoretically a strongly type-II s-wave superconducting state of two-dimensional Dirac fermions in proximity to a ferromagnet having in-plane magnetization. It is shown that a magnetic domain wall can host a chain of equally spaced vortices in the superconducting order parameter, each of which binds a Majorana-fermion state. The overlap integral of neighboring Majorana states is sensitive to the position of the chemical potential of the Dirac fermions. Thermal transport and scanning tunneling microscopy experiments to probe the Majorana fermions are discussed.

  4. Design of the superconducting magnet system for the SuperKEKB interaction region

    International Nuclear Information System (INIS)

    The design of the superconducting magnet system for the SuperKEKB interaction region has been developed. The magnet system consists of 8 main quadrupoles, 40 correctors and 4 compensation solenoids. Focusing beams in the interaction region is designed to be performed by the quadrupole doublets on the beam lines. The compensation solenoids integrally cancel the Belle-II solenoid field. As part of the R and D of the main quadrupoles, the QC1E prototype magnet was constructed and cold tested at 4K. The magnet showed the good superconducting characteristics. (author)

  5. Superconducting magnet technology for accelerators

    International Nuclear Information System (INIS)

    A review article on superconducting magnets for accelerators should first answer the question, why superconductivity. The answer revolves around two pivotal facts: (1) fields in the range of 2 T to 10 T can be achieved; and (2) the operating cost can be less than conventional magnets. The relative importance of these two factors depends on the accelerator. In the case where an upgrade of an accelerator at an existing facility is planned, the ability to obtain fields higher than conventional magnets leads directly to an increase in machine energy for the given tunnel. In the case of a new facility, both factors must be balanced for the most economical machine. Ways to achieve this are discussed

  6. Technical tasks in superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Kenji [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    1997-11-01

    The feature of superconducting rf cavities is an extremely small surface resistance on the wall. It brings a large energy saving in the operation, even those are cooled with liquid helium. That also makes possible to operate themselves in a higher field gradient comparing to normal conducting cavities, and brings to make accelerators compact. These merits are very important for the future accelerator engineering which is planed at JAERI for the neutron material science and nuclear waste transmutation. This machine is a high intensity proton linac and uses sc cavities in the medium and high {beta} sections. In this paper, starting R and D of proton superconducting cavities, several important technical points which come from the small surface resistance of sc cavities, are present to succeed it and also differences between the medium and high - {beta} structures are discussed. (author)

  7. Color superconductivity and quark stars

    International Nuclear Information System (INIS)

    The search for new phases of strange quark matter inside neutron stars has recently received a lot of attention since it has been shown that the attractive nature of the one gluon exchange interaction in QCD may produce a superconducting phase in quark matter. We study an extended version of the Chromodielectric model with a BCS quark pairing implemented, and analyze the superconducting color flavor locked phase. We show that the inclusion in the free energy density of a negative term of the diquark condensate ensures the stability of quark matter. We explore the implications of our results in the structure of compact quark stars and explicitly show that CFL stars can be absolutely stable and more compact than strange stars

  8. Color superconductivity and quark stars

    Energy Technology Data Exchange (ETDEWEB)

    Malheiro, M. [Instituto Tecnologico de Aeronautica, CTA, 12-228-900, Sao Jose dos Campos (Brazil); Instituto de Fisica, Universidade Federal Fluminense, 24-210-320, Niteroi (Brazil); Linares, L.P. [Instituto de Fisica, Universidade Federal Fluminense, 24-210-320, Niteroi (Brazil); Fiolhais, M. [Departamento de Fisica, Centro de Fisica Computacional, Universidade de Coimbra, P-3004-516 Coimbra (Portugal); Taurines, A. [Department of Physics, University of Wales Swansea, Singleton Park, Swansea, SA2 8PP (United Kingdom)

    2007-06-15

    The search for new phases of strange quark matter inside neutron stars has recently received a lot of attention since it has been shown that the attractive nature of the one gluon exchange interaction in QCD may produce a superconducting phase in quark matter. We study an extended version of the Chromodielectric model with a BCS quark pairing implemented, and analyze the superconducting color flavor locked phase. We show that the inclusion in the free energy density of a negative term of the diquark condensate ensures the stability of quark matter. We explore the implications of our results in the structure of compact quark stars and explicitly show that CFL stars can be absolutely stable and more compact than strange stars.

  9. Siting the superconducting super collider

    International Nuclear Information System (INIS)

    At the request of the Department of Energy, the National Academy of Sciences and the National Academy of Engineering established the Super Collider Site Evaluation Committee to evaluate the suitability of proposed sites for the Superconducting Super Collider. Thirty-six proposals were examined by the committee. Using the set of criteria announced by DOE in its Invitation for Site Proposals, the committee identified eight sites that merited inclusion on a ''best qualified list.'' The list represents the best collective judgment of 21 individuals, carefully chosen for their expertise and impartiality, after a detailed assessment of the proposals using 19 technical subcriteria and DOE's life cycle cost estimates. The sites, in alphabetical order, are: Arizona/Maricopa; Colorado; Illinois; Michigan/Stockbridge; New York/Rochester; North Carolina; Tennessee; and Texas/Dallas-Fort Worth. The evaluation of these sites and the Superconducting Super Collider are discussed in this book

  10. Graphene Superconducting Quantum Interference Device

    Science.gov (United States)

    Girit, Çaǧlar; Bouchiat, Vincent; Naaman, Ofer; Zhang, Yuanbo; Crommie, Michael; Zettl, Alex; Siddiqi, Irfan

    2010-03-01

    Graphene can support Cooper pair transport when contacted with two superconducting electrodes, resulting in the well-known Josephson effect. By depositing aluminum/palladium electrodes in the geometry of a loop onto a single graphene sheet, we fabricate a two junction dc superconducting quantum interference device (SQUID). Not only an the supercurrent in this device be increased by moving the electrostatic gate away from the Dirac point, but it can also be modulated periodically by an applied magnetic field---a potentially powerful probe of electronic transport in graphene. We analyze the magnetic field modulation of the critical current with the asymmetric/inductive SQUID model of Fulton and Dynes and discuss the variation of the fitting parameters with gate voltage.

  11. Superconductivity in the Tungsten Bronzes

    Science.gov (United States)

    Wu, Phillip; Ishii, Satoshi; Tanabe, Kenji; Munakata, Ko; Hammond, Robert H.; Tokiwa, Kazuyasu; Geballe, Theodore H.; Beasley, Malcolm R.

    2015-03-01

    Via pulsed laser deposition and post-annealing, high quality K-doped WO3-y films with reproducible transport properties are obtained. A home built two-coil mutual inductance setup is used to probe the behavior of the films in the superconducting and normal state. The inverse penetration depths and dissipation peaks are measured as a function of temperature and field. Separately, via thin film deposition techniques, we report for the first time stable crystalline hexagonal WO3 on substrates. In order to tune the physical properties of the undoped material, we utilized an ionic liquid gating technique. We observe an insulator-to-metal transition, showing the ionic liquid gate to be a viable technique to alter the electrical transport properties of this material. By comparing the alkali and ionic liquid gated WO3, we conclude with some remarks regarding how superconductivity arises in this system.

  12. Surface superconductivity in thin cylindrical Bi nanowire.

    Science.gov (United States)

    Tian, Mingliang; Wang, Jian; Ning, Wei; Mallouk, Thomas E; Chan, Moses H W

    2015-03-11

    The physical origin and the nature of superconductivity in nanostructured Bi remains puzzling. Here, we report transport measurements of individual cylindrical single-crystal Bi nanowires, 20 and 32 nm in diameter. In contrast to nonsuperconducting Bi nanoribbons with two flat surfaces, cylindrical Bi nanowires show superconductivity below 1.3 K. However, their superconducting critical magnetic fields decrease with their diameter, which is the opposite of the expected behavior for thin superconducting wires. Quasiperiodic oscillations of magnetoresistance were observed in perpendicular fields but were not seen in the parallel orientation. These results can be understood by a model of surface superconductivity with an enhanced surface-to-bulk volume in small diameter wires, where the superconductivity originates from the strained surface states of the nanowires due to the surface curvature-induced stress. PMID:25658139

  13. Superconductivity in metal-coated graphene

    Energy Technology Data Exchange (ETDEWEB)

    Calandra, Matteo; Mauri, Francesco [IMPMC, Universite Paris 6, CNRS, 4 Place Jussieu, 75005 Paris (France); Profeta, Gianni [SPIN-CNR - Dipartimento di Fisica Universita degli Studi di L' Aquila, 67100 L' Aquila (Italy)

    2012-12-15

    In this work we explore, by first-principles density functional theory (DFT) calculations, the possibility of inducing electron-phonon mediated superconductivity in a graphene sheet by doping its surface with alkaline metal adatoms. We demonstrate that, contrary to what could be naively believed, simple exfoliation to one layer of superconducting graphite intercalated compounds (GICs) does not necessarily lead to superconducting graphene, as it is the case in CaC{sub 6}. On the contrary, it is meaningful to look for superconductivity in monolayers obtained by exfoliating non-superconducting GICs. In particular, we demonstrate that Li coating and double-coating of graphene leads to superconductivity in graphene with T{sub c} that could be as large as 18 K. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Plasmonic Scaling of Superconducting Metamaterials

    OpenAIRE

    Kurter, C.; Abrahams, J.; Shvets, G.; Anlage, Steven M.

    2013-01-01

    Superconducting metamaterials are utilized to study the approach to the plasmonic limit simply by tuning temperature to modify the superfluid density, and thus the superfluid plasma frequency. We examine the persistence of artificial magnetism in a metamaterial made with superconductors in the plasmonic limit, and compare to the electromagnetic behavior of normal metals as a function of frequency as the plasma frequency is approached from below. Spiral-shaped Nb thin film meta-atoms of scaled...

  15. RF Characterization of Superconducting Samples

    CERN Document Server

    Junginger, T; Welsch, C

    2009-01-01

    At CERN a compact Quadrupole Resonator has been re-commissioned for the RF characterization of superconducting materials at 400 MHz. In addition the resonator can also be excited at multiple integers of this frequency. Besides Rs it enables determination of the maximum RF magnetic field, the thermal conductivity and the penetration depth of the attached samples, at different temperatures. The features of the resonator will be compared with those of similar RF devices and first results will be presented.

  16. Photon-detecting superconducting resonators

    OpenAIRE

    Barends, R.

    2009-01-01

    One of the greatest challenges in astronomy is observing star and planetary formation, redshifted distant galaxies and molecular spectral ‘fingerprints’ in the far-infrared spectrum of light, using highly sensitive and large cameras. In this thesis we investigate superconducting resonators for photon detection. In superconductors the electrons are paired. The incoming light then breaks these pairs into unpaired electrons, so-called quasiparticles, influencing the superconductor’s inductance. ...

  17. Stimulated Superconductivity at Strong Coupling

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Ning; Dong, Xi; Silverstein, Eva; Torroba, Gonzalo; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC

    2011-08-12

    Stimulating a system with time dependent sources can enhance instabilities, thus increasing the critical temperature at which the system transitions to interesting low-temperature phases such as superconductivity or superfluidity. After reviewing this phenomenon in non-equilibrium BCS theory (and its marginal fermi liquid generalization) we analyze the effect in holographic superconductors. We exhibit a simple regime in which the transition temperature increases parametrically as we increase the frequency of the time-dependent source.

  18. Proximity fingerprint of s+- superconductivity

    OpenAIRE

    Koshelev, A. E.; Stanev, V.

    2011-01-01

    We suggest a straightforward and unambiguous test to identify possible opposite signs of superconducting order parameter in different bands proposed for iron-based superconductors (s+- state). We consider proximity effect in a weakly coupled sandwich composed of a s+- superconductor and thin layer of s-wave superconductor. In such system the s-wave order parameter is coupled differently with different s+- gaps and it typically aligns with one of these gaps. This forces the other s+- gap to be...

  19. The hunt for anyon superconductivity

    International Nuclear Information System (INIS)

    Various models of high-temperature superconductivity, including in particular the models with particles obeying fractional statistics (anyons), imply spontaneously broken time-reversal symmetry. Experiments which might show manifestations of this broken symmetry include muon spin relaxation, and optical experiments looking for an antisymmetric contribution to the dielectric tensor. The current experimental situation is very confusing, however, as results from different groups are seemingly contradictory. (orig.)

  20. Superconducting electron and hole lenses

    Science.gov (United States)

    Cheraghchi, H.; Esmailzadeh, H.; Moghaddam, A. G.

    2016-06-01

    We show how a superconducting region (S), sandwiched between two normal leads (N), in the presence of barriers, can act as a lens for propagating electron and hole waves by virtue of the so-called crossed Andreev reflection (CAR). The CAR process, which is equivalent to Cooper pair splitting into two N electrodes, provides a unique possibility of constructing entangled electrons in solid state systems. When electrons are locally injected from an N lead, due to the CAR and normal reflection of quasiparticles by the insulating barriers at the interfaces, sequences of electron and hole focuses are established inside another N electrode. This behavior originates from the change of momentum during electron-hole conversion beside the successive normal reflections of electrons and holes due to the barriers. The focusing phenomena studied here are fundamentally different from the electron focusing in other systems, such as graphene p-n junctions. In particular, due to the electron-hole symmetry of the superconducting state, the focusing of electrons and holes is robust against thermal excitations. Furthermore, the effects of the superconducting layer width, the injection point position, and barrier strength are investigated on the focusing behavior of the junction. Very intriguingly, it is shown that by varying the barrier strength, one can separately control the density of electrons or holes at the focuses.

  1. Nanoscale high-temperature superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, P.; Wei, J.Y.T.; Ananth, V.; Morales, P.; Skocpol, W

    2004-08-01

    We discuss the exciting prospects of studying high-temperature superconductivity in the nanometer scale from the perspective of experiments, theory and simulation. In addition to enabling studies of novel quantum phases in an unexplored regime of system dimensions and parameters, nanoscale high-temperature superconducting structures will allow exploration of fundamental mechanisms with unprecedented insight. The prospects include, spin-charge separation, detection of electron fractionalization via novel excitations such as vison, stripe states and their dynamics, preformed cooper pairs or bose-condensation in the underdoped regime, and other quantum-ordered states. Towards this initiative, we present the successful development of a novel nanofabrication technique for the epitaxial growth of nanoscale cuprates. Combining the techniques of e-beam lithography and nanomachining, we have been able to fabricate the first generation of high-temperature superconducting nanoscale devices, including Y-junctions, four-probe wires and rings. Their initial transport characterization and scanning tunneling microscopy reveal the integrity of the crystal structure, grown on nanometer scale lateral dimensions. Here, we present atomic force micrographs and electrical characterization of a few nanoscale YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) samples.

  2. Pauli-Limited Superconductivity in Small Grains

    OpenAIRE

    Bonsager, M. C.; MacDonald, A. H.

    1998-01-01

    We report on an exploration of the mean-field phase diagram for Pauli-limited superconductivity in small metallic grains. Emphasis is placed on the crossover from the ultra-small grain limit where superconductivity disappears to the bulk thin-film limit as the single-particle level spacing in the grain decreases. We find that the maximum Zeeman coupling strength compatible with superconductivity increases with decreasing grain size, in spite of a monotonically decreasing condensation energy p...

  3. Ten questions and answers about superconductivity

    OpenAIRE

    De Cao, Tian

    2010-01-01

    This work answers the basic questions of superconductivity in a question-and-answer format. We extend a basic hypothesis to various superconductors. This hypothesis is that superconductivity requires that the pairing gap locates around the Fermi level. On the basis of this hypothesis our calculations give the so-called three factor theory with which some key problems of the high temperature superconductivity are explained.

  4. Strong Correlations and High Temperature Superconductivity

    OpenAIRE

    Kotliar, Gabriel

    2014-01-01

    The BCS theory of superconductivity of phonon mediated pairing is one of the most remarkable intellectual achievements of the twentieth century. It was so successful that by the early 70’s superconductivity was considered by many a completely understood subject, with the maximum achievable critical temperatures believed to have been reached in the A15 compounds. The field of superconductivity research then took a dramatic turn. Completely new classes of materials such as organics, heavy fermi...

  5. Superconductivity in the palladium-hydrogen system

    Science.gov (United States)

    Papaconstantopoulos, D. A.; Klein, B. M.

    1975-01-01

    Band theory and phonon measurements are used to calculate the electron-phonon coupling constant wavelength for Pd and PdD. The results indicate that superconductivity is absent in Pd metal because of the large value of the Coulomb pseudopotential, and that superconductivity occurs in PdD primarily because of coupling with the optic phonons. These results are consistent with superconducting transition-temperature measurements for these systems.

  6. Mechanical Design of Superconducting Accelerator Magnets

    OpenAIRE

    Toral, Fernando

    2015-01-01

    This paper is about the mechanical design of superconducting accelerator magnets. First, we give a brief review of the basic concepts and terms. In the following sections, we describe the particularities of the mechanical design of different types of superconducting accelerator magnets: solenoids, cos-theta, superferric, and toroids. Special attention is given to the pre-stress principle, which aims to avoid the appearance of tensile stresses in the superconducting coils. A case study on a co...

  7. Development of superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Mijatovic, Nenad; Abrahamsen, Asger Bech

    2013-01-01

    In this paper, the commercial activities in the field of superconducting machines, particularly superconducting wind turbine generators, are reviewed and presented. Superconducting generators have the potential to provide a compact and light weight drive train at high torques and slow rotational...... production volumes prohibit a large scale impact on the wind sector. The low temperature superconductors are readily available, but will need more sophisticated cooling. Eventually the Cost of Energy from superconducting wind turbines, with particular emphasis on reliability, will determine if they become...

  8. Accelerators and superconductivity: A marriage of convenience

    International Nuclear Information System (INIS)

    This lecture deals with the relationship between accelerator technology in high-energy-physics laboratories and the development of superconductors. It concentrates on synchrotron magnets, showing how their special requirements have brought about significant advances in the technology, particularly the development of filamentary superconducting composites. Such developments have made large superconducting accelerators an actuality: the Tevatron in routine operation, the Hadron Electron Ring Accelerator (HERA) under construction, and the Superconducting Super Collider (SSC) and Large Hadron Collider (LHC) at the conceptual design stage. Other applications of superconductivity have also been facilitated - for example medical imaging and small accelerators for industrial and medical use. (orig.)

  9. Interfacing superconducting qubits and single optical photons

    CERN Document Server

    Das, Sumanta; Sørensen, Anders S

    2016-01-01

    We propose an efficient light-matter interface at optical frequencies between a superconducting qubit and a single photon. The desired interface is based on a hybrid architecture composed of an organic molecule embedded inside an optical waveguide and electrically coupled to a superconducting qubit far from the optical axis. We show that high fidelity, photon-mediated, entanglement between distant superconducting qubits can be achieved with incident pulses at the single photon level. Such low light level is highly sought for to overcome the decoherence of the superconducting qubit caused by absorption of optical photons.

  10. Superconducting fault current limiter for railway transport

    International Nuclear Information System (INIS)

    A resistive switching superconducting fault current limiter (SFCL) for DC networks with voltage of 3.5 kV and nominal current of 2 kA is developed. The SFCL consists of two series-connected units: block of superconducting modules and high-speed vacuum breaker with total disconnection time not more than 8 ms. The results of laboratory tests of superconducting SFCL modules in current limiting mode are presented. The recovery time of superconductivity is experimentally determined. The possibility of application of SFCL on traction substations of Russian Railways is considered

  11. Superconducting fault current limiter for railway transport

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, L. M., E-mail: LMFisher@niitfa.ru; Alferov, D. F.; Akhmetgareev, M. R.; Budovskii, A. I.; Evsin, D. V.; Voloshin, I. F.; Kalinov, A. V. [National Technical Physics and Automation Research Institute (Russian Federation)

    2015-12-15

    A resistive switching superconducting fault current limiter (SFCL) for DC networks with voltage of 3.5 kV and nominal current of 2 kA is developed. The SFCL consists of two series-connected units: block of superconducting modules and high-speed vacuum breaker with total disconnection time not more than 8 ms. The results of laboratory tests of superconducting SFCL modules in current limiting mode are presented. The recovery time of superconductivity is experimentally determined. The possibility of application of SFCL on traction substations of Russian Railways is considered.

  12. Foreword: Focus on Superconductivity in Semiconductors

    Directory of Open Access Journals (Sweden)

    Yoshihiko Takano

    2008-01-01

    Full Text Available Since the discovery of superconductivity in diamond, much attention has been given to the issue of superconductivity in semiconductors. Because diamond has a large band gap of 5.5 eV, it is called a wide-gap semiconductor. Upon heavy boron doping over 3×1020 cm−3, diamond becomes metallic and demonstrates superconductivity at temperatures below 11.4 K. This discovery implies that a semiconductor can become a superconductor upon carrier doping. Recently, superconductivity was also discovered in boron-doped silicon and SiC semiconductors. The number of superconducting semiconductors has increased. In 2008 an Fe-based superconductor was discovered in a research project on carrier doping in a LaCuSeO wide-gap semiconductor. This discovery enhanced research activities in the field of superconductivity, where many scientists place particular importance on superconductivity in semiconductors.This focus issue features a variety of topics on superconductivity in semiconductors selected from the 2nd International Workshop on Superconductivity in Diamond and Related Materials (IWSDRM2008, which was held at the National Institute for Materials Science (NIMS, Tsukuba, Japan in July 2008. The 1st workshop was held in 2005 and was published as a special issue in Science and Technology of Advanced Materials (STAM in 2006 (Takano 2006 Sci. Technol. Adv. Mater. 7 S1.The selection of papers describe many important experimental and theoretical studies on superconductivity in semiconductors. Topics on boron-doped diamond include isotope effects (Ekimov et al and the detailed structure of boron sites, and the relation between superconductivity and disorder induced by boron doping. Regarding other semiconductors, the superconducting properties of silicon and SiC (Kriener et al, Muranaka et al and Yanase et al are discussed, and In2O3 (Makise et al is presented as a new superconducting semiconductor. Iron-based superconductors are presented as a new series of high

  13. Enhancing superconducting critical current by randomness.

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y. L.; Thoutam, L. R.; Xiao, Z. L.; Shen, B.; Pearson, J.; Divan, R.; Ocola, L. E.; Crabtree, G. W.; Kwok, W. K.

    2016-01-11

    The key ingredient of high critical currents in a type-II superconductor is defect sites that pin vortices. Here, we demonstrate that a random pinscape, an overlooked pinning system in nanopatterned superconductors, can lead to a substantially larger critical current enhancement at high magnetic fields than an ordered array of vortex pin sites. We reveal that the better performance of a random pinscape is due to the variation of the local density of its pinning sites, which mitigates the motion of vortices. This is confirmed by achieving even higher enhancement of the critical current through a conformally mapped random pinscape, where the distribution of the local density of pinning sites is further enlarged. Our findings highlight the potential of random pinscapes in enhancing the superconducting critical currents of applied superconductors in which random pin sites of nanoscale defects emerging in the materials synthesis process or through ex-situ irradiation are the only practical choice for large-scale production. Our results may also stimulate research on effects of a random pinscape in other complementary systems such as colloidal crystals, Bose-Einstein condensates, and Luttinger liquids.

  14. Progress in the Development of Superconducting RF

    Science.gov (United States)

    Martinello, Martina

    2016-03-01

    The R &D of superconducting radiofrequency (SRF) cavities is focused on lowering the power dissipation, i.e. increasing the Q factor, during their operation in accelerators. Nitrogen doping is the innovative high Q SRF technology currently implemented in the LCLS-II cavity production. Of crucial importance is the understanding on how high Q factors can be maintained from the cavity vertical test to the cryomodule operation. One of the major issue of SRF cavity operation is the remnant magnetic field which will always be present during the cool down through the critical temperature, jeopardizing the cavity performance. Research is ongoing both to reduce the remnant field levels and to avoid magnetic field trapping during the SC transition. In addition, fundamental studies allowed us to define the best nitrogen doping treatment needed to lower the sensitivity to trapped flux. Recent developments on the preparation of Nb3Sn coatings for SRF cavities will be also presented. This alternative technology has been demonstrated to allow high Q operation even at 4.2 K. In addition, the maximum field limit of Nb3Sn is predicted to be twice that of niobium, potentially providing a significant decrease in the required length of an accelerator to reach a given energy.

  15. Chiral p -wave superconductivity in Sb(111) thin films close to Van Hove singularities

    Science.gov (United States)

    Huang, Jin-Qin; Hsu, Chuang-Han; Lin, Hsin; Yao, Dao-Xin; Tsai, Wei-Feng

    2016-04-01

    We theoretically investigate the development of unconventional superconductivity in the Sb(111) thin film when its Fermi level is tuned to near type-II Van Hove singularities (VHS), which locate at non-time-reversal invariant momenta. Via patch renormalization group analysis, we show that the leading instability is a chiral p +i p -wave superconducting order. The origin of such pairing relies on the hexagonal structure of the VHS and strong spin-orbit coupling, resulting in the anisotropy of the electron-electron scattering to provide an attractive channel. Our study hence suggests that superconducting Sb thin films originated from VHS physics may host Majorana zero modes in the magnetic vortices and provides another application perspective to such material.

  16. Microtraps for neutral atoms using superconducting structures in the critical state

    International Nuclear Information System (INIS)

    Recently demonstrated superconducting atom chips provide a platform for trapping atoms and coupling them to solid-state quantum systems. Controlling these devices requires a full understanding of the supercurrent distribution in the trapping structures. For type-II superconductors, this distribution is hysteretic in the critical state due to the partial penetration of the magnetic field in the thin superconducting film through pinned vortices. We report here an experimental observation of this memory effect. Our results are in good agreement with the predictions of the Bean model of the critical state without adjustable parameters. The memory effect allows to write and store permanent currents in micron-sized superconducting structures and paves the way toward engineered trapping potentials.

  17. The Emergence of Superconducting Systems in Anti-de Sitter Space

    CERN Document Server

    Wu, W M; Forrester, D M; Kusmartsev, F V

    2016-01-01

    In this article, we investigate the mathematical relationship between a (3+1) dimensional gravity model inside Anti-de Sitter space $\\rm AdS_4$, and a (2+1) dimensional superconducting system on the asymptotically flat boundary of $\\rm AdS_4$ (in the absence of gravity). We consider a simple case of the Type II superconducting model (in terms of Ginzburg-Landau theory) with an external perpendicular magnetic field ${\\bf H}$. An interaction potential $V(r,\\psi) = \\alpha(T)|\\psi|^2/r^2+\\chi|\\psi|^2/L^2+\\beta|\\psi|^4/(2 r^k )$ is introduced within the Lagrangian system. This provides more flexibility within the model, when the superconducting system is close to the transition temperature $T_c$. Overall, our result demonstrates that the two Ginzburg-Landau differential equations can be directly deduced from Einstein's theory of general relativity.

  18. Superconductivity in a layered cobalt oxyhydrate Na0.31CoO2·1.3H2O

    International Nuclear Information System (INIS)

    We report the electrical, magnetic and thermal measurements on a layered cobalt oxyhydrate Na0.31CoO2·1.3H2O. Bulk superconductivity at 4.3 K has been confirmed; however, the measured superconducting fraction is relatively low probably due to the sample's intrinsic two-dimensional characteristic. The compound exhibits weak-coupled and extreme type-II superconductivity with an average energy gap Δa(0) and a Ginzburg-Landau parameter κ of ∼0.50 meV and 140, respectively. The temperature dependence of the normalized electronic specific heat in the superconducting state gives a clue to the superconducting gap structure. (letter to the editor)

  19. Stability of Majorana vortex bound states on the surface of superconducting topological insulators

    Science.gov (United States)

    Zhang, Junyi; Cano, Jennifer; Neupert, Titus

    Fu and Kane showed that superconductivity induced on the surface of a 3D topological insulator results in isolated Majorana bound states that appear in the cores of vortices. Many efforts to realize this idea are based on proximity-induced superconducting order in a heterostructure. Recently, superconductivity has been observed in PbTaSe2, which has the band topology of a topological insulator with Dirac cone surface states. Hence, it nourishes the vision of realizing the Fu and Kane proposal in a stoichiometric material without the need for doping or fabricating heterostructures. Motivated by this possibility, we give a comprehensive analysis of stability and localization properties of the vortex Majorana modes in such a topological superconducting material. In particular, we address the experimentally relevant questions regarding (i) the energy separation between the vortex bound and excited states, (ii) the dependence of the hybridization between Majorana modes from opposite surfaces on the thickness of a thin-film sample, (iii) the influence of the bulk superconducting pockets on the Majorana states.

  20. Stoichiometry and thickness dependence of superconducting properties of niobium nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Beebe, Melissa R., E-mail: mrbeebe@email.wm.edu; Beringer, Douglas B.; Burton, Matthew C.; Yang, Kaida; Lukaszew, R. Alejandra [Department of Physics, The College of William & Mary, Small Hall, 300 Ukrop Way, Williamsburg, Virginia 23185 (United States)

    2016-03-15

    The current technology used in linear particle accelerators is based on superconducting radio frequency (SRF) cavities fabricated from bulk niobium (Nb), which have smaller surface resistance and therefore dissipate less energy than traditional nonsuperconducting copper cavities. Using bulk Nb for the cavities has several advantages, which are discussed elsewhere; however, such SRF cavities have a material-dependent accelerating gradient limit. In order to overcome this fundamental limit, a multilayered coating has been proposed using layers of insulating and superconducting material applied to the interior surface of the cavity. The key to this multilayered model is to use superconducting thin films to exploit the potential field enhancement when these films are thinner than their London penetration depth. Such field enhancement has been demonstrated in MgB{sub 2} thin films; here, the authors consider films of another type-II superconductor, niobium nitride (NbN). The authors present their work correlating stoichiometry and superconducting properties in NbN thin films and discuss the thickness dependence of their superconducting properties, which is important for their potential use in the proposed multilayer structure. While there are some previous studies on the relationship between stoichiometry and critical temperature T{sub C}, the authors are the first to report on the correlation between stoichiometry and the lower critical field H{sub C1}.

  1. Stoichiometry and thickness dependence of superconducting properties of niobium nitride thin films

    International Nuclear Information System (INIS)

    The current technology used in linear particle accelerators is based on superconducting radio frequency (SRF) cavities fabricated from bulk niobium (Nb), which have smaller surface resistance and therefore dissipate less energy than traditional nonsuperconducting copper cavities. Using bulk Nb for the cavities has several advantages, which are discussed elsewhere; however, such SRF cavities have a material-dependent accelerating gradient limit. In order to overcome this fundamental limit, a multilayered coating has been proposed using layers of insulating and superconducting material applied to the interior surface of the cavity. The key to this multilayered model is to use superconducting thin films to exploit the potential field enhancement when these films are thinner than their London penetration depth. Such field enhancement has been demonstrated in MgB2 thin films; here, the authors consider films of another type-II superconductor, niobium nitride (NbN). The authors present their work correlating stoichiometry and superconducting properties in NbN thin films and discuss the thickness dependence of their superconducting properties, which is important for their potential use in the proposed multilayer structure. While there are some previous studies on the relationship between stoichiometry and critical temperature TC, the authors are the first to report on the correlation between stoichiometry and the lower critical field HC1

  2. Stress and magnetostriction in an infinite hollow superconducting cylinder with a filling in its central hole

    International Nuclear Information System (INIS)

    Highlights: ► An analytical solution is showed to evaluate the stress of a superconductor cylinder. ► The stress concentration near the hole is certainly suppressed by a filling method. ► The penetration field parameter has a significant influence on stress of the cylinder. ► A maximum magnetostriction of the cylinder is achieved during a cycled field. -- Abstract: In this paper, the stress and magnetostriction induced by flux pinning in an infinite hollow cylinder of type-II superconductor with a non-superconductive filling in its central hole are analytically investigated. Based on the exponent model of critical state of superconductor, the magnetic and current distributions in the hollow cylinder superconductor are obtained firstly. The stress and magnetostriction of the composite superconductive cylinder are then formulated and the magnetoelastic behaviors are characterized analytically. The results show that the hoop stress concentration near the central hole is dominant due to the tension Lorentz force and it is certainly suppressed by filling a non-superconductive material in the hole. Without change of the magnetization characteristic of the superconductor, the filling material provides effective way to remedy the stress state at the verge of the hollow in the superconductive cylinder by adjusting its Young modulus. The magnetostriction of the composite cylinder under the cycled magnetic field is further presented. Effect of the applied maximum field, complete penetration field parameter and filling material parameter on the profile of the cycled magnetostriction for the composite superconducting cylinder is discussed in detail

  3. Superconducting RF activities at Cornell University

    International Nuclear Information System (INIS)

    This paper outlines the RF superconductivity research and development work that has taken place at Cornell Laboratory of Nuclear Studies over the past years. The work that has been performed since the last RF superconductivity workshop is emphasized together with a discussion of the direction of future efforts. Past work is summarized first, focusing on research and development activities in the area of RF superconductivity. Superconducting TeV linear collider is then discussed focusing on the application of superconducting RF to a future TeV linear collider. Linear collider structure development is then described centering on the development of a simpler (thereby cheaper) structure for a TeV linear collider. B-factory with superconducting RF is outlined focusing on the formulation of a conceptual design for a B-factory. B-factory structure development is discussed in relation to the advancement in the capability of SC cavities to carry beam currents of several amperes necessary for a high luminosity storage ring. High gradients are discussed as the key to the realization of a high energy superconducting linac or a superconducting RF B-factory. (N.K.)

  4. Recent developments in high temperature superconductivity. Proceedings

    International Nuclear Information System (INIS)

    The following topics were dealt with: high-temperature superconductivity: synthesis, structural features, doping and pressure effects, electronic transitions, recent magnetic studies, electron-doped superconductors, spin fluctuations and d wave pairing, properties of layers and multilayers, transport properties, vortices in superconductors, coexistence of magnetism and superconductivity. All 22 papers are separately analyzed for the database

  5. Josephson plasma resonance in superconducting multilayers

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig

    1999-01-01

    We derive an analytical solution for the josephson plasma resonance of superconducting multilayers. This analytical solution is derived mainly for low T-c systems with magnetic coupling between the superconducting layers, but many features of our results are more general, and thus an application to...... the recently derived plasma resonance phenomena for high T-c superconductors of the BSCCO type is discussed....

  6. Cryogenic structural materials for superconducting magnets

    International Nuclear Information System (INIS)

    This paper reviews research in the United States and Japan on structural materials for high-field superconducting magnets. Superconducting magnets are used for magnetic fusion energy devices and for accelerators that are used in particle-physics research. The cryogenic structural materials that we review are used for magnet cases and support structures. We expect increased materials requirements in the future

  7. Superconductivity of Magnesium Diboride: Theoretical Aspects

    OpenAIRE

    Dahm, T.

    2004-01-01

    In this work we review our present understanding of superconductivity in Magnesium Diboride from the theoretical perspective as it evolves from band structure calculations. Particular emphasis is placed on two gap superconductivity. Some of its peculiar consequences are discussed, in particular upper critical field anisotropy and microwave conductivity.

  8. Spontaneous fluxoid formation in superconducting loops

    DEFF Research Database (Denmark)

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

    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 a...

  9. Superconductivity and Quantum Spin Disorder in Cuprates

    OpenAIRE

    Havilio, Moshe; Auerbach, Assa

    1999-01-01

    A fundamental connection between superconductivity and quantum spin fluctuations in underdoped cuprates, is revealed. A variational calculation shows that {\\em Cooper pair hopping} strongly reduces the local magnetization $m_0$. This effect pertains to recent neutron scattering and muon spin rotation measurements in which $m_0$ varies weakly with hole doping in the poorly conducting regime, but drops precipitously above the onset of superconductivity.

  10. Color Superconducting Quark Matter in Neutron Stars

    OpenAIRE

    Heiselberg, H.

    1999-01-01

    Color superconductivity in quark matter is studied for electrically charge neutral neutron star matter in $\\beta$-equilibrium. Both bulk quark matter and mixed phases of quark and nuclear matter are treated. The electron chemical potential and strange quark mass affect the various quark chemical potentials and therefore also the color superconductivity due to dicolor pairing or color-flavor locking.

  11. Josephson plasma resonance in superconducting multilayers

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig

    We derive an analytical solution for the josephson plasma resonance of superconducting multilayers. This analytical solution is derived mainly for low T-c systems with magnetic coupling between the superconducting layers, but many features of our results are more general, and thus an application to...

  12. 17th International Conference on RF Superconductivity

    CERN Document Server

    2015-01-01

    RF superconductivity is the key technology of accelerators for particle physics, nuclear physics and light sources. SRF 2015 covered the latest advances in the science, technology, and applications of superconducting RF. There was also an industrial exhibit during the conference with the key vendors in the community available to discuss their capabilities and products.

  13. Development of superconducting ship propulsion system

    International Nuclear Information System (INIS)

    When we plan displacement-type monohull high speed vessels, it is difficult to get the hull form with the wave-making resistance minimum, because the stern shape is restricted by arrangement of propulsive machines and shafts. A small-sized and light-weight propulsive machines will reduce the limit to full form design. Superconducting technology will have capability of realizing the small-sized and light-weight propulsion motor. The superconducting electric propulsion system which is composed of superconducting propulsion motors and generators, seems to be an ideal propulsion system for future vehicles. We have constructed a 480 kW superconducting DC homopolar laboratory test motor for developing this propulsion system. The characteristic of this motor is that it has a superconducting field winding and a segmented armature drum. The superconducting field winding which operates in the persistent current mode, is cooled by a condensation heat exchanger and helium refigerating system built into the cryostat of the superconducting field winding. The operating parameters of this motor agreed well with the design parameters. Using the design concepts of this motor, we have conceptually designed a 150,000-200,000 PS superconducting electric propulsive system for a displacement-type monohull high speed ship. (author)

  14. Design study of a superconducting SOR facility

    International Nuclear Information System (INIS)

    This paper describes the design study on a synchrotron orbital radiation (SOR) facility composed of a superconducting linac and storage rings. The rings using superconducting magnets and a superconducting cavity can store electron beams of 1 GeV with beam current of 200 mA. Design features are as follows: (1) Superconducting magnets and a superconducting cavity are employed to save both operating power and space. (2) High vacuum in the beam chamber is expected shortly after the start of initial operation, because electrons are accelerated by the superconducting linac and injected at full energy of 1 GeV. (3) Each storage ring has three super periods in the lattice, and three long drift spaces for electron beam injection, cavity installation and optional insertion devices, respectively. (4) A superconducting TW linac as the injector can save electric power and increase electric field gradient. (5) The accelerating guides of the superconducting traveling wave linac are indirectly cooled with LHe flows in order to make maintenance and cryostat construction easier. (6) An optional acceleration and storage system of positrons can be installed

  15. Vortex formation in small size superconducting specimens

    International Nuclear Information System (INIS)

    An expression is derived for the critical magnetic field of a cylinder or cylindrical cavity within a superconducting matrix. Possible states of the superconducting cylinder with a radius R approx. equal to xi(T), when the number of vortexes in it is not high, are investigated. (orig./GG)

  16. On kinetic energy stabilized superconductivity in cuprates

    OpenAIRE

    Singh, D. J.

    2006-01-01

    The possibility of kinetic energy driven superconductivity in cuprates as was recently found in the $tJ$ model is discussed. We argue that the violation of the virial theorem implied by this result is serious and means that the description of superconductivity within the $tJ$ model is pathological.

  17. Superconductivity Enhancements in Small Metallic Grains

    Science.gov (United States)

    Zheng, Renrong; Chen, Zhi Qian; Zhu, Shun Quan

    The reasons for superconductivity enhancement in small metallic grains including hundreds of thousand electrons are investigated by solving the generalized gap equation based on BCS mean field theory. The analysis suggests that the superconductivity enhancement in small metallic grains are the results caused by the pairing correlation and the level statistics in the Gaussian orthogonal ensemble (GOE) and the Gaussian unitary ensemble (GUE).

  18. Glass-Derived Superconductive Ceramic

    Science.gov (United States)

    Bansal, Narottam P.; Farrell, D. E.

    1992-01-01

    Critical superconducting-transition temperature of 107.2 K observed in specimen made by annealing glass of composition Bi1.5Pb0.5Sr2Ca2Cu3Ox for 243 h at 840 degrees C. PbO found to lower melting temperature and viscosity of glass, possibly by acting as fluxing agent. Suggested partial substitution of lead into bismuth oxide planes of crystalline phase having Tc of 110 K stabilizes this phase and facilitates formation of it.

  19. Support structure for superconducting magnet

    International Nuclear Information System (INIS)

    Multilayered cylinder systems are used to support superconductive coils. These supports are made of GFRP, G/CFRP thin-walled circular cylinders. Compression tests of single cylinder, multilayered cylinder nontightened, tightened; bending tests and torsional tests were conducted. G/CFRP's interhybrid structure using carbon fiber cloth, increases torsional strength, which in turn increases spring constant and fracture load in a bending test of multilayered cylinders tightened. This system can withstand a much greater compression load than an all-GFRP system. (author)

  20. Large superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Magnusson, Niklas; Jensen, Bogi Bech;

    2012-01-01

    To realize large (>10 MW) direct-driven off-shore wind turbines, a number of steps are needed to reduce weight and cost compared to on-shore technologies. One of the major challenges is to provide drive trains which can comply with the large torque as the turbine rotor diameter is scaled up and the...... thereby having a smaller size and weight [1, 2]. A 5 MW superconducting wind turbine generator forms the basics for the feasibility considerations, particularly for the YBCO and MgB2 superconductors entering the commercial market. Initial results indicate that a 5 MW generator with an active weight of 34...

  1. The superconducting OGMS separator optimization

    Energy Technology Data Exchange (ETDEWEB)

    Janowski, T.; Kozak, S. (Institute of Electrotechnics, Warszawa (Poland))

    1993-11-01

    The constructional parameters of the electromagnet influence the efficiency of the OGMS (Open Gradient Magnetic Separation) process. An analysis of the relationships between the superconducting magnet dimensions and the efficiency of the separator for the paramagnetic ([chi]=5e[sup [minus]3]) and ferromagnetic (iron) particles with the diameters 20[mu]m and 100[mu]m for different medium velocities is presented In this paper. The mathematical model of particle's trajectory passing through the separator has been used for numerical calculations.

  2. Three-flavor color superconductivity

    OpenAIRE

    Malekzadeh, Hossein

    2008-01-01

    I investigate some of the inert phases in three-flavor, spin-zero color-superconducting quark matter: the CFL phase (the analogue of the B phase in superfluid 3He), the A and A* phases, and the 2SC and sSC phases. I compute the pressure of these phases with and without the neutrality condition. Without the neutrality condition, after the CFL phase the sSC phase is the dominant phase. However, including the neutrality condition, the CFL phase is again the energetically favored phase except for...

  3. Fermionic models with superconducting circuits

    Energy Technology Data Exchange (ETDEWEB)

    Las Heras, Urtzi; Garcia-Alvarez, Laura; Mezzacapo, Antonio; Lamata, Lucas [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); Solano, Enrique [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)

    2015-12-01

    We propose a method for the efficient quantum simulation of fermionic systems with superconducting circuits. It consists in the suitable use of Jordan-Wigner mapping, Trotter decomposition, and multiqubit gates, be with the use of a quantum bus or direct capacitive couplings. We apply our method to the paradigmatic cases of 1D and 2D Fermi-Hubbard models, involving couplings with nearest and next-nearest neighbours. Furthermore, we propose an optimal architecture for this model and discuss the benchmarking of the simulations in realistic circuit quantum electrodynamics setups. (orig.)

  4. STRIPES AND SUPERCONDUCTIVITY IN CUPRATE SUPERCONDUCTORS

    Energy Technology Data Exchange (ETDEWEB)

    TRANQUADA, J.M.

    2005-08-22

    One type of order that has been observed to compete with superconductivity in cuprates involves alternating charge and antiferromagnetic stripes. Recent neutron scattering studies indicate that the magnetic excitation spectrum of a stripe-ordered sample is very similar to that observed in superconducting samples. In fact, it now appears that there may be a universal magnetic spectrum for the cuprates. One likely implication of this universal spectrum is that stripes of a dynamic form are present in the superconducting samples. On cooling through the superconducting transition temperature, a gap opens in the magnetic spectrum, and the weight lost at low energy piles up above the gap; the transition temperature is correlated with the size of the spin gap. Depending on the magnitude of the spin gap with respect to the magnetic spectrum, the enhanced magnetic scattering at low temperature can be either commensurate or incommensurate. Connections between stripe correlations and superconductivity are discussed.

  5. Exotic Superconductivity in Correlated Electron Systems

    International Nuclear Information System (INIS)

    Over the past decades, the search for high-Tc superconductivity (SC) and its novel superconducting mechanisms is one of the most challenging tasks of condensed matter physicists and material scientists, wherein the most striking achievement is the discovery of high-c and unconventional superconductivity in strongly correlated 3d-electron systems, such as cuprates and iron pnictides/chalcogenides. Those exotic superconductors display the behaviors beyond the scope of the BCS theory (in the SC states) and the Landau-Fermi liquid theory (in the normal states). In general, such exotic superconductivity can be seen as correlated electron systems, where there are strong interplays among charge, spin, orbital, and lattice degrees of freedom. Thus, we focus on the exotic superconductivity in materials with correlated electrons in the present special issue

  6. Low-velocity superconducting accelerating structures

    International Nuclear Information System (INIS)

    The present paper reviews the status of RF superconductivity as applied to low-velocity accelerating properties. Heavy-ion accelerators must accelerate efficiently particles which travel at a velocity much smaller than that of light particles, whose velocity changes along accelerator, and also different particles which have different velocity profiles. Heavy-ion superconducting accelerators operate at frequencies which are lower than high-energy superconducting accelerators. The present paper first discusses the basic features of heavy-ion superconducting structures and linacs. Design choices are then addressed focusing on structure geometry, materials, frequency, phase control, and focusing. The report also gives an outline of the status of superconducting booster projects currently under way at the Argonne National Laboratory, SUNY Stony Brook, Weizmann Institute, University of Washington, Florida State, Saclay, Kansas State, Daresbury, Japanese Atomic Energy Research Institute, Legnaro, Bombay, Sao Paulo, ANU (Canberra), and Munich. Recent developments and future prospects are also described. (N.K.) 68 refs

  7. Superconductivity in compensated and uncompensated semiconductors

    Directory of Open Access Journals (Sweden)

    Youichi Yanase and Naoyuki Yorozu

    2008-01-01

    Full Text Available We investigate the localization and superconductivity in heavily doped semiconductors. The crossover from the superconductivity in the host band to that in the impurity band is described on the basis of the disordered three-dimensional attractive Hubbard model for binary alloys. The microscopic inhomogeneity and the thermal superconducting fluctuation are taken into account using the self-consistent 1-loop order theory. The superconductor-insulator transition accompanies the crossover from the host band to the impurity band. We point out an enhancement of the critical temperature Tc around the crossover. Further localization of electron wave functions leads to the localization of Cooper pairs and induces the pseudogap. We find that both the doping compensation by additional donors and the carrier increase by additional acceptors suppress the superconductivity. A theoretical interpretation is proposed for the superconductivity in the boron-doped diamond, SiC, and Si.

  8. Toroidal sensor of superconducting quantum magnetometer

    International Nuclear Information System (INIS)

    The sensor has a high sensitivity achieved by the 100-times higher suppression of external electromagnetic disturbances as compared with sensors used so far. This is given by the design of the sensor which consists of a superconducting induction loop, electrically closed by a superconducting weak junction and made of one single piece of superconducting material in which there is an O-shaped cavity. In the space defined by this cavity there are two coaxial openings for the insertion of the superconducting junction. The parts of the cavity are interconnected with a planar slot. Also inserted in the cavity are two coils - a field coil and a signal coil. The superconducting weak junction is either of a bridge or point type. The sensor may be used in all areas where the measurement of very small variables may be converted to the measurement of magnetic field. (J.B.) 5 figs

  9. Method for producing substrates for superconducting layers

    DEFF Research Database (Denmark)

    2013-01-01

    There is provided a method for producing a substrate (600) suitable for supporting an elongated superconducting element, wherein, e.g., a deformation process is utilized in order to form disruptive strips in a layered solid element, and where etching is used to form undercut volumes (330, 332......) between an upper layer (316) and a lower layer (303) of the layered solid element. Such relatively simple steps enable providing a substrate which may be turned into a superconducting structure, such as a superconducting tape, having reduced AC losses, since the undercut volumes (330, 332) may be useful...... for separating layers of material. In a further embodiment, there is placed a superconducting layer on top of the upper layer (316) and/or lower layer (303), so as to provide a superconducting structure with reduced AC losses....

  10. Recent Progress in the Superconductivity Research Field

    Science.gov (United States)

    Ichinose, Ataru

    Major developments in the research field of superconductivity have been achieved in 2008. Since the discovery of high-Tc superconductors, their practical application has been studied by many researchers. Coated conductors consisting of an YBa2Cu3Oy superconducting layer deposited on metal tapes buffered oxide layers were developed in the NEDO project between FY2003 and FY2007. These technologies for coated conductors are expected to be applicable to electrical power equipment. A new NEDO project that started in FY2008 is focusing on the development of superconducting electric power equipment such as power cables, superconducting magnetic energy storage devices (SMES) and transformers. Furthermore, a new family of high-Tc superconductors, Fe-As-O-based superconductors, has been discovered. The highest reported critical temperature, Tc, has rapidly increased owing to the considerable effort of many researchers. A new social environment based on superconductivity technology might indeed be realized in the near future.

  11. SUPERCONDUCTING MAGNET NEEDS FOR THE ILC.

    Energy Technology Data Exchange (ETDEWEB)

    PARKER,B.; TOMPKINS, J.C.; KASHIKHIN, VI.; PALMER, M.A.; CLARKE, J.A.

    2007-06-25

    The ILC Reference Design Report was completed early in February 2007. The Magnet Systems Group was formed to translate magnetic field requirements into magnet designs and cost estimates for the Reference Design. As presently configured, the lLC will have more than 13,000 magnetic elements of which more than 2300 will be based on superconducting technology. This paper will describe the major superconducting magnet needs for the ILC as presently determined by the Area Systems Groups, responsible for beam line design, working with the Magnet Systems Group. The superconducting magnet components include Main Linac quadrupoles, Positron Source undulators, Damping Ring wigglers, a complex array of Final Focus superconducting elements in the Beam Delivery System, and large superconducting solenoids in the e{sup +} and e{sup -} Sources, and the Ring to Main Linac lines.

  12. Focus on superconducting properties of iron chalcogenides

    Science.gov (United States)

    Takano, Yoshihiko

    2012-10-01

    Since the discovery of iron-based superconductors, much attention has been given to the exploration of new superconducting compounds. Numerous superconducting iron compounds have been found and categorized into five groups: LnFeAsO (Ln = lanthanide), BaFe2As2, KFeAs, FeSe and FeAs with perovskite blocking layers. Among them, FeSe has the simplest crystal structure. Since the crystal structure is composed of only superconducting Fe layers, the FeSe family must be the best material to investigate the mechanism of iron-based superconductivity. FeSe shows very strong pressure effects. The superconducting transition temperature (Tc) of FeSe is approximately 8 K at ambient pressure. However Tc dramatically increases up to 37 K under applied pressure of 4-6 GPa. This is the third highest Tc value among binary superconductors, surpassed only by CsC60 under pressure (Tc = 38 K) and MgB2 (Tc = 39 K). On the other hand, despite FeTe having a crystal structure analogous to that of FeSe, FeTe shows antiferromagnetic properties without superconductivity. Doping of small ions, either Se or S, however, can induce superconductivity in FeTe1-xSex or FeTe1-xSx . The superconductivity is very weak for small x values, and annealing under certain conditions is required to obtain strong superconductivity, for instance annealing in oxygen or alcoholic beverages such as red wine. The following selection of papers describe many important experimental and theoretical studies on iron chalcogenide superconductors including preparation of single crystals, bulk samples and thin films; NMR measurements; photoemission spectroscopy; high-pressure studies; annealing effects and research on new BiS2-based superconductors. I hope this focus issue will help researchers understand the frontiers of iron chalcogenide superconductors and assist in the discovery of new phenomena related to iron-based superconductivity.

  13. A prototype superconducting gravity gradiometer

    International Nuclear Information System (INIS)

    We report the successful laboratory test of a single-axis gradiometer designed to measure a diagonal component of the earth's gravitational gradient tensor. It consists of a pair of accelerometers mounted with their sensitive axes vertical and in line. The difference in displacement of the accelerometers is proportional to the component of the tensor gradient and is sensed via the modulated inductance of a superconducting coil coupled by a superconducting transformer into an RF biased SHE SQUID with energy sensitivity 4 x 10-29 J/Hz. Rejection of in-line common mode accelerations is achieved by trimming the natural resonant frequency of each accelerometer: the restoring force acting on an accelerometer test mass is partly magnetic and can be trimmed by adjusting the persistent currents in a pair of force coils. A common mode rejection ratio exceeding 95 dB has been achieved in the presence of linear accelerations about 10-3 ms-2, and a laboratory generated gradient of 30 Eo rms has been detected with a signal to noise ratio of about 100. The dependence of this signal on the distance between source and detector has the expected Newtonian form. Under quiet conditions the background noise level of the instrument is at present 3 Eo/√Hz. (1 Eo = 10-9 s-2.) This is close to the practical limit achievable for such a single axis configuration: a three axis instrument for geophysical application is under development

  14. ATLAS superconducting toroids and solenoid

    CERN Document Server

    ten Kate, H H J

    2005-01-01

    The ATLAS particle detector in the Large Hadron Collider at CERN features a hybrid system of four superconducting magnets: a Central Solenoid surrounded by 2 End-cap Toroids and a Barrel Toroid. The magnet system dimensions are 20 m in diameter and 26 m in length. With its 1.55 GJ stored energy in air, it actually is the largest superconducting magnet in the world. The construction of the magnets has started in 1998 and will end in 2006 with the completion of the installation underground. Currently, in October 2004, practically all magnet parts are manufactured and delivered to CERN for final integration. The first two out of 8 full size 25*5 m/sup 2/ size coils for the Barrel Toroid have been completed and tested while the other 6 are near to completion as well. The production of the so- called End-Cap Toroids is progressing well. The Central Solenoid is complete and ready for installation. The installation underground of the entire system including its services has commenced. In the paper the main features ...

  15. Superconducting superconvulsion. Shock US decision

    International Nuclear Information System (INIS)

    After a baffling succession of seesaw decisions which saw the mood swing from the depths of pessimism to supreme optimism and back, on 21 October a US House of Representatives Committee proposed $640 million for the 'orderly termination' of the Superconducting Supercollider (SSC) project in Ellis County, Texas. By next July, the US Secretary of Energy is requested to produce a plan to 'maximize the value of the investment in the project and minimizing the loss to the US, including recommendations as to the feasibility of utilizing SSC assets in whole or in part in pursuit of an international high energy physics endeavour.' The SSC was to have been the biggest of them all - two 87-kilometre rings of superconducting magnets to collide proton beams at a total energy of 40 TeV (40,000 GeV) and search for the mechanisms underlying the behaviour of the quark constituents deep inside the colliding particles. It was from the start an ambitious project. It was meant to be. Conceived in the early 1980s amid all the Reagan euphoria of 'junk' bonds and heavy government borrowing, the SSC idea was in some ways a scientific parallel for the audacious technology of the Strategic Defense Initiative - 'Star Wars'

  16. 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...

  17. Design studies of superconducting generators

    International Nuclear Information System (INIS)

    A study of superconducting, central-station turbine-generators of 300 and 1200 MVA rating is reported. A unique construction concept is used for the superconducting field winding. The goal of this construction is to ensure that the winding can be energized to the current and flux density predicted by the superconductor short-sample data, without the ''training'' instabilities frequently encountered in large coils. The remainder of the rotor components includes an aluminum radiation shield and a compound, steel-aluminum electromagnetic shield, designed to withstand short circuit electromagnetic forces. The study was focused on generator model configurations which were proportioned to have a low transient reactance, approximately 0.2 per unit. The critical clearing times calculated were comparable to conventional units, the low reactance offsetting an inherently lower rotor inertia. These configurations are estimated to have about half the size and weight, and about half the losses of conventional units of the same rating. Transient characteristics are described, including the effect of the rotor shielding configuration on rotor damping. 8 refs

  18. High Temperature Superconducting Underground Cable

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, Roger, A.

    2010-02-28

    The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the world’s first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.

  19. Thermodynamic considerations in superconducting oxides

    International Nuclear Information System (INIS)

    The basic science that underlies processing can be divided into two main areas---thermodynamics and kinetics---which can be further subdivided into phase stability, solid solubility, reaction, and diffusion. This paper focuses on thermodynamics considerations because they impact all methods of materials fabrication. Using Y-Ba-Cu-O as a model system, it demonstrates how advances in materials processing have gone hand-in-hand with increased understanding of the high-temperature chemistry. In particular, the authors show how phase diagrams have provided a framework for understanding, predicting, and controlling the microstructure of YBa2Cu3O6+x in its many desired forms, such as single crystals for basic research, and thin films, tapes, and composites for applications. The authors also discuss briefly some of the thermodynamic issues that have arisen in other families of superconducting oxides. These other systems have not been studied as extensively as the Y-Ba-Cu-O system, but what has been learned demonstrates the pervasive nature of thermodynamic issues in the fabrication of superconducting oxides and the need for further studies

  20. Three-flavor color superconductivity

    International Nuclear Information System (INIS)

    I investigate some of the inert phases in three-flavor, spin-zero color-superconducting quark matter: the CFL phase (the analogue of the B phase in superfluid 3He), the A and A* phases, and the 2SC and sSC phases. I compute the pressure of these phases with and without the neutrality condition. Without the neutrality condition, after the CFL phase the sSC phase is the dominant phase. However, including the neutrality condition, the CFL phase is again the energetically favored phase except for a small region of intermediate densities where the 2SC/A* phase is favored. It is shown that the 2SC phase is identical to the A* phase up to a color rotation. In addition, I calculate the self-energies and the spectral densities of longitudinal and transverse gluons at zero temperature in color-superconducting quark matter in the CFL phase. I find a collective excitation, a plasmon, at energies smaller than two times the gap parameter and momenta smaller than about eight times the gap. The dispersion relation of this mode exhibits a minimum at some nonzero value of momentum, indicating a van Hove singularity. (orig.)

  1. High Temperature Superconducting Underground Cable

    International Nuclear Information System (INIS)

    The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the worlds first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.

  2. Surface superconductivity and order parameter suppression in UPt$_3$

    OpenAIRE

    Agterberg, D. F.; Walker, M. B.

    1995-01-01

    We show that a recent measurement of surface superconductivity in UPt$_3$ (Keller {\\it et. al.}, Phys. Rev. Lett. {\\bf 73}, 2364 (1994)) can be understood if the superconducting pair wavefunction is suppressed anisotropically at a vacuum to superconductor interface. Further measurements of surface superconductivity can distinguish between the various phenomenological models of superconducting UPt$_3$.

  3. Superconducting wire and cable for the superconducting supercollider

    International Nuclear Information System (INIS)

    In the last few years the development of improved fine filamentary NbTi wires has been spurred on by the potential need for material to be used in the dipole and quadrupole magnets for the Superconducting SuperCollider (SSC). The result has been a substantial increase in the current carrying capacity of commercially available materials and a significant reduction in filament diameter. The manner in which these improvements have been achieved is outlined and the problems encountered discussed. The relative importance of factors such as homogeneity of the NbTi raw materials, heat treatment and cold work cycles, reaction between the matrix and the filaments, filament spacing and uniformity of the filament arrav. on the critical current density obtainable, are discussed. 20 refs., 6 figs., 3 tabs

  4. Status of superconducting magnets for the Superconducting Super Collider

    International Nuclear Information System (INIS)

    The arc sections of the High Energy Booster and the two Collider Rings will need more than 10,000, very large, superconducting dipole and quadrupole magnets. Development work on these magnets was carried out at US/DOE laboratories in a program that began in the mid 1980's. In 1991-1992, the technology was transferred to industry and twenty, full-length, Collider dipoles were successfully fabricated and tested. This program, along with HERA and Tevatron experience, has provided industry a data base to use in formulating detailed designs for the prototypes of the accelerator magnets, with an eye to reducing cost and enhancing producibility. Several model magnets from this latest phase of the industrial program have already been tested. The excessive ramp-rate sensitivity of the magnets is understood and solutions are under investigation

  5. Charge order, superconducting correlations, and positive muons

    Energy Technology Data Exchange (ETDEWEB)

    Sonier, J.E., E-mail: jsonier@sfu.ca

    2015-02-15

    The recent discoveries of short-range charge-density wave order in the normal state of several hole-doped cuprate superconductors constitute a significant addition to the known intrinsic properties of these materials. Besides likely being associated with the normal-state pseudogap, the charge-density wave order presumably influences the build-up of known superconducting correlations as the temperature is lowered toward the superconducting state. As a pure magnetic probe, muon spin rotation (μ SR) is not directly sensitive to charge order, but may sense its presence via the effect it has on the magnetic dipolar coupling of the muon with the host nuclei at zero or low magnetic field. At higher field where μ SR is completely blind to the effects of charge order, experiments have revealed a universal inhomogeneous normal-state response extending to temperatures well above T{sub c}. The measured inhomogeneous line broadening has been attributed to regions of superconducting correlations that exhibit varying degrees of fluctuation diamagnetism. Here, the compatibility of these results with other measurements showing charge order correlations or superconducting fluctuations above T{sub c} is discussed. - Highlights: • Superconducting fluctuations in high-T cuprates probed by positive muons are discussed. • Superconducting fluctuations are detected at higher temperatures than by other methods. • The muon experiments indicate that the superconducting fluctuations are inhomogeneous. • The compatibility with short-range charge order in the normal state is considered.

  6. Superconductivity in Ca-doped graphene laminates.

    Science.gov (United States)

    Chapman, J; Su, Y; Howard, C A; Kundys, D; Grigorenko, A N; Guinea, F; Geim, A K; Grigorieva, I V; Nair, R R

    2016-01-01

    Despite graphene's long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc's strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp. PMID:26979564

  7. Superconductivity in Ca-doped graphene laminates

    Science.gov (United States)

    Chapman, J.; Su, Y.; Howard, C. A.; Kundys, D.; Grigorenko, A. N.; Guinea, F.; Geim, A. K.; Grigorieva, I. V.; Nair, R. R.

    2016-01-01

    Despite graphene’s long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc’s strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp. PMID:26979564

  8. Superconductivity in non-centrosymmetric materials

    Energy Technology Data Exchange (ETDEWEB)

    Kneidinger, F.; Bauer, E. [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, A-1040 Wien (Austria); Zeiringer, I.; Rogl, P. [Institute of Physical Chemistry, University of Vienna, Währingerstr. 42, A-1090 Wien (Austria); Blaas-Schenner, C.; Reith, D.; Podloucky, R. [Institute of Physical Chemistry, University of Vienna and Center for Computational Materials Science, Sensengasse 8, A-1090 Wien (Austria)

    2015-07-15

    Highlights: • Superconductivity in absence of inversion symmetry of the crystal structure is characterised by a removal of the spin degeneracy of electrons which allows for spin-triplet pairing in the superconducting condensate, although a theorem of P.W. Anderson requires a centre of inversion in the crystal structure as an essential symmetry element for spin-triplet pairing. • We show that unconventional superconductivity in such materials occurs only in those systems which exhibit strong correlations among electrons. If correlations are absent, simple s-wave superconductivity is observed in general. • Here we present various members of this family of superconductors and discuss the ground state properties with respect to a number of microscopic and macroscopic experiments as well as in the context of ab initio electronic and phononic structure calculations. - Abstract: Superconductivity in absence of inversion symmetry of the crystal structure is basically controlled by a Rashba-like antisymmetric spin orbit coupling which splits the Fermi surface and removes the spin degeneracy of electrons. The Fermi surface splitting can originate a mixing of spin-singlet and spin-triplet states in the superconducting condensate. The presence of spin-triplet states is expected to be responsible for various uncommon features of the superconducting ground state. Experimentally, distinct deviations from the expectations of the BCS theory are found, in general, only in those systems where beside the missing of inversion symmetry strong correlations among electrons are present. Materials of this group are primarily based on Ce, Yb or U. For the much larger group of materials without substantial electronic correlations, BCS-like superconductivity was observed in the overwhelming number of known examples. Hence, unconventional superconductivity requires, in general, the mutual presence of electronic correlations and non-centrosymmetric crystal structures.

  9. Superconductivity Engineering and Its Application for Fusion 3.Superconducting Technology as a Gateway to Future Technology

    Science.gov (United States)

    Asano, Katsuhiko

    Hopes for achieving a new source of energy through nuclear fusion rest on the development of superconducting technology that is needed to make future equipments more energy efficient as well as increase their performance. Superconducting technology has made progress in a wide variety of fields, such as energy, life science, electronics, industrial use and environmental improvement. It enables the actualization of equipment that was unachievable with conventional technology, and will sustain future “IT-Based Quality Life Style”, “Sustainable Environmental” and “Advanced Healthcare” society. Besides coil technology with high magnetic field performance, superconducting electoronics or device technology, such as SQUID and SFQ-circuit, high temperature superconducting material and advanced cryogenics technology might be great significance in the history of nuclear fusion which requires so many wide, high and ultra technology. Superconducting technology seems to be the catalyst for a changing future society with nuclear fusion. As society changes, so will superconducting technology.

  10. The integration of cryogenic cooling systems with superconducting electronic systems

    International Nuclear Information System (INIS)

    The need for cryogenic cooling has been critical issue that has kept superconducting electronic devices from reaching the market place. Even though the performance of the superconducting circuit is superior to silicon electronics, the requirement for cryogenic cooling has put the superconducting devices at a disadvantage. This report will talk about the various methods for refrigerating superconducting devices. Cryocooler types will be compared for vibration, efficiency, and cost. Some solutions to specific problems of integrating cryocoolers to superconducting devices are presented.

  11. Spectra of plasmons in superconducting cuprates

    International Nuclear Information System (INIS)

    Plasmons may provide a promising mechanism for superconductivity providing that certain restrictive conditions on the electronic structure are satisfied. However, these favorable situations were presumed to be quit rare until recently, when the exciting discoveries of high temperature superconducting oxides rejuvenated interest in novel mechanisms of superconductivity. An attempt is made to focus on other physical measurements, in addition to the determination of T/sub c/, which may have a bearing on the theoretical proposals. Thus emphasis is placed on the structure which may be observable in the infrared spectroscopy, electron tunneling and neutron scattering whose origin may be traced to an electronic mechanism such as the presence of acoustic plasmons

  12. Thermodynamic Green functions in theory of superconductivity

    Directory of Open Access Journals (Sweden)

    N.M.Plakida

    2006-01-01

    Full Text Available A general theory of superconductivity is formulated within the thermodynamic Green function method for various types of pairing mediated by phonons, spin fluctuations, and strong Coulomb correlations in the Hubbard and t-J models. A rigorous Dyson equation for matrix Green functions is derived in terms of a self-energy as a many-particle Green function. By applying the noncrossing approximation for the self-energy, a closed self-consistent system of equations is obtained, similar to the conventional Eliashberg equations. A brief discussion of superconductivity mediated by kinematic interaction with an estimation of a superconducting transition temperature in the Hubbard model is given.

  13. Method for Producing Substrates for Superconducting Layers

    DEFF Research Database (Denmark)

    2015-01-01

    There is provided a method for producing a substrate suitable for supporting an elongated superconducting element, wherein one or more elongated strips of masking material are placed on a solid element (202) so as to form one or more exposed elongated areas being delimited on one or two sides by...... portion of filling material and the solid element. The method may further comprise placing buffer material (640) and or superconducting material (642, 644, 646)) on the substrate, so as to provide a superconducting structure (601) with reduced AC losses....

  14. Proximity Action theory of superconductive nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Skvortsov, M A; Larkin, A I; Feigel' man, M V [L D Landau Institute for Theoretical Physics, Russian Academy of Sciences, ul. Kosygina 2, 117940 Moscow (Russian Federation)

    2001-10-01

    We review a novel approach to the superconductive proximity effect in disordered normal-superconducting (N-S) structures. The method is based on the multicharge Keldysh action and is suitable for the treatment of interaction and fluctuation effects. As an application of the formalism, we study the subgap conductance and noise in two-dimensional N-S systems in the presence of the electron-electron interaction in the Cooper channel. It is shown that singular nature of the interaction correction at large scales leads to a nonmonotonuos temperature, voltage and magnetic field dependence of the Andreev conductance. (4. mesoscopic superconductivity)

  15. Multicomponent superconductivity based on multiband superconductors

    International Nuclear Information System (INIS)

    Multicomponent superconductivity is realized in multiband superconductors when an interband pairing interaction is considerably weaker than the intraband interactions. There is a new quantum phase that originates from the interband phase difference in this superconducting condensate. Firstly, we discuss the applicability of this physical viewpoint for known multiband superconductors. Secondly, topics related to the interband phase difference are treated. Finally, we mention that the Bardeen–Cooper–Schrieffer formalism and the Ginzburg–Landau formalism may not be fully guaranteed when we introduce a fluctuation in the interband phase difference mode. We also address plausible new superconducting electronics using the interband phase difference. (review)

  16. The cold wars a history of superconductivity

    CERN Document Server

    Matricon, Jean

    1994-01-01

    Among the most peculiar of matter¡¦s behaviors is superconductivity„oelectric current without resistance. Since the 1986 discovery that superconductivity is possible at temperatures well above absolute zero, research into practical applications has flourished. The Cold Wars tells the history of superconductivity, providing perspective on the development of the field and its relationship with the rest of physics. Superconductivity offers an excellent example of the evolution of physics in the twentieth century: the science itself, its foundations, and its social context. The authors also introduce the reader to the fascinating scientific personalities, including 2003 Nobel Prize winners Alexei Alexeievich Abrikosov and Vitali Ginzburg, and political struggles behind this research.

  17. Cooperative phenomena in superconducting atom-chips

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Sebastian; Kubala, Bjoern; Ankerhold, Joachim [Institut fuer Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany)

    2013-07-01

    We theoretically investigate the physics of hybrid quantum systems, where a cloud of cold atoms is coupled to superconducting microstructures, so called superconducting atom-chips. Coherent enhancement, due to the large number of atoms in the cloud, opens a path to the study of strong coupling effects, like superradiance/Dicke-physics in a decohering environment. A structured environment can be designed by embedding a Cooper pair box within the cavity. Moreover, in such a system the transfer of quantum information between the atomic cloud and the superconducting solid state system can be studied.

  18. Cooperative phenomena in superconducting atom-chips

    International Nuclear Information System (INIS)

    We theoretically investigate the physics of hybrid quantum systems, where a cloud of cold atoms is coupled to superconducting microstructures, so called superconducting atom-chips. Coherent enhancement, due to the large number of atoms in the cloud, opens a path to the study of strong coupling effects, like superradiance/Dicke-physics in a decohering environment. A structured environment can be designed by embedding a Cooper pair box within the cavity. Moreover, in such a system the transfer of quantum information between the atomic cloud and the superconducting solid state system can be studied.

  19. Superconductivity and unusual magnetic behavior in amorphous carbon

    Science.gov (United States)

    Felner, Israel

    2014-03-01

    Traces of superconductivity (SC) at elevated temperatures (up to 65 K) were observed by magnetic measurements in three different inhomogeneous sulfur doped amorphous carbon (a-C) systems: (a) in commercial and (b) synthesized powders and (c) in a-C thin films. (a) Studies performed on a commercial (a-C) powder, which contains 0.21% sulfur, revealed traces of non-percolated superconducting phases below T c = 65 K. The SC volume fraction is enhanced by the sulfur doping. (b) The a-C powder obtained by pyrolytic decomposition of sucrose did not show any sign of SC above 5 K. This powder was mixed with sulfur and synthesized at 400 °C (a-CS). The inhomogeneous products obtained show traces of SC phases at T c = 17 and 42 K. (c) Non-superconducting composite a-C-W thin films were grown by electron-beam induced deposition. SC emerged at T c = 34.4 K only after heat treatment with sulfur. Other parts of the pyrolytic a-CS powder show unusual magnetic features. (i) Pronounced irreversible peaks around 55-75 K appear in the first zero-field-cooled (ZFC) sweep only. Their origin is not known. (ii) Unexpectedly, these peaks are totally suppressed in the second ZFC runs measured a few minutes later. (iii) Around the peak position the field-cooled (FC) curves cross the ZFC plots (ZFC > FC). These peculiar magnetic observations are also ascribed to an a-CS powder prepared from the commercial a-C powder and are connected to each other. All SC and magnetic phenomena observed are intrinsic properties of the sulfur doped a-C materials. It is proposed that the a-CS systems behave similarly to well-known high T c curates and/or pnictides in which SC emerges from magnetic states.

  20. Superconductivity and unusual magnetic behavior in amorphous carbon

    International Nuclear Information System (INIS)

    Traces of superconductivity (SC) at elevated temperatures (up to 65 K) were observed by magnetic measurements in three different inhomogeneous sulfur doped amorphous carbon (a-C) systems: (a) in commercial and (b) synthesized powders and (c) in a-C thin films. (a) Studies performed on a commercial (a-C) powder, which contains 0.21% sulfur, revealed traces of non-percolated superconducting phases below T c = 65 K. The SC volume fraction is enhanced by the sulfur doping. (b) The a-C powder obtained by pyrolytic decomposition of sucrose did not show any sign of SC above 5 K. This powder was mixed with sulfur and synthesized at 400 °C (a-CS). The inhomogeneous products obtained show traces of SC phases at T c = 17 and 42 K. (c) Non-superconducting composite a-C-W thin films were grown by electron-beam induced deposition. SC emerged at T c = 34.4 K only after heat treatment with sulfur. Other parts of the pyrolytic a-CS powder show unusual magnetic features. (i) Pronounced irreversible peaks around 55–75 K appear in the first zero-field-cooled (ZFC) sweep only. Their origin is not known. (ii) Unexpectedly, these peaks are totally suppressed in the second ZFC runs measured a few minutes later. (iii) Around the peak position the field-cooled (FC) curves cross the ZFC plots (ZFC > FC). These peculiar magnetic observations are also ascribed to an a-CS powder prepared from the commercial a-C powder and are connected to each other. All SC and magnetic phenomena observed are intrinsic properties of the sulfur doped a-C materials. It is proposed that the a-CS systems behave similarly to well-known high T c curates and/or pnictides in which SC emerges from magnetic states. (papers)

  1. Superconducting magnets and cryogenics for the steady state superconducting tokamak SST-1

    International Nuclear Information System (INIS)

    SST-1 is a steady state superconducting tokamak for studying the physics of the plasma processes in tokamak under steady state conditions and to learn technologies related to the steady state operation of the tokamak. SST-1 will have superconducting magnets made from NbTi based conductors operating at 4.5 K temperature. The design of the superconducting magnets and the cryogenic system of SST-1 tokamak are described. (author)

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

    International Nuclear Information System (INIS)

    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.

  3. Field errors in superconducting magnets

    International Nuclear Information System (INIS)

    The mission of this workshop is a discussion of the techniques for tracking particles through arbitrary accelerator field configurations to look for dynamical effects that are suggested by various theoretical models but are not amenable to detailed analysis. A major motivation for this type of study is that many of our accelerator projects are based on the use of superconducting magnets which have field imperfections that are larger and of a more complex nature than those of conventional magnets. Questions such as resonances, uncorrectable closed orbit effects, coupling between planes, and diffusion mechanisms all assume new importance. Since, simultaneously, we are trying to do sophisticated beam manipulations such as stacking, high current accelerator, long life storage, and low loss extraction, we clearly need efficient and accurate tracking programs to proceed with confidence

  4. 12 Tesla superconducting multifilamentary magnet

    International Nuclear Information System (INIS)

    The construction and performance of a 12 Tesla 127 mm bore superconducting magnet is presented. The system consists of an 8 Tesla outer two stage NbTi coil with a bore I.D. of 204 mm, a winding O.D. of 326mm, and a length of 391mm which is connected in series with a 246mm long insert coil constructed of multifilamentary Nb/sub 3/Sn. The insert coil was reacted after wind. The system has a stored energy of 782 kJ and operates at 4.2 K with a transport current of 144 Amps which may be achieved within 30 minutes. The magnet may be operated in powered or quasi-persistent mode

  5. Feeding helium to superconducting magnets

    CERN Multimedia

    1979-01-01

    The photo shows two of the 3 superconducting magnets (two MBS dipoles (CESAR) of 150 mm bore and 4.5 T, and one quadrupole (CASTOR) of 90 mm bore and 54 T/m) which were installed in the hall EHN1 (Annual Report 1978 p. 134) and ran until 1985. They formed a section of the beam H6 travelling from target T4 (down the bottom of the photo) towards the NA30 setup followed by the NA11 setup. The two big transversal pipelines are the quench lines of the two magnets (on the right, one quadrupole and one dipole, the other dipole lays down the photo and is not visible). The Jura side of the hall is on the right.

  6. An experimental superconducting helical undulator

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, S.; Taylor, C. [Lawrence Berkeley Lab., CA (United States)

    1995-12-31

    Improvements in the technology of superconducting magnets for high energy physics and recent advancements in SC materials with the artificial pinning centers (APC){sup 2}, have made a bifilar helical SC device an attractive candidate for a single-pass free electron laser (FEL){sup 3}. Initial studies have suggested that a 6.5 mm inner diameter helical device, with a 27 mm period, can generate a central field of 2-2.5 Tesla. Additional studies have also suggested that with a stored energy of 300 J/m, such a device can be made self-protecting in the event of a quench. However, since the most critical area associated with high current density SC magnets is connected with quenching and training, a short experimental device will have to be built and tested. In this paper we discuss technical issues relevant to the construction of such a device, including a conceptual design, fields, and forces.

  7. Color superconductivity in quark matter

    International Nuclear Information System (INIS)

    We have studied color superconductivity (CSC) in high density quark matter with two flavors on the basis of a model hamiltonian with Debye-screened gluon propagator. We found that the most attractive quark interaction of this hamiltonian is in the JP = 0+ - 0- channel with color anti-symmetric and flavor anti-symmetric representation. We also found that there is an attraction in the JP = 1+ - 1- channel although the strength is somewhat weaker. Depending on the strength of αs, the magnitude of the gap can be as large as 50-100 MeV. Even at extremely high baryon density ρB ∼ 20ρ0, the gap still exists with the size of 10-20 MeV. Open problems related to the physics of CSC are also discussed. (author)

  8. An experimental superconducting helical undulator

    International Nuclear Information System (INIS)

    Improvements in the technology of superconducting magnets for high energy physics and recent advancements in SC materials with the artificial pinning centers (APC)2, have made a bifilar helical SC device an attractive candidate for a single-pass free electron laser (FEL)3. Initial studies have suggested that a 6.5 mm inner diameter helical device, with a 27 mm period, can generate a central field of 2-2.5 Tesla. Additional studies have also suggested that with a stored energy of 300 J/m, such a device can be made self-protecting in the event of a quench. However, since the most critical area associated with high current density SC magnets is connected with quenching and training, a short experimental device will have to be built and tested. In this paper we discuss technical issues relevant to the construction of such a device, including a conceptual design, fields, and forces

  9. Advanced Manufacturing of Superconducting Magnets

    Science.gov (United States)

    Senti, Mark W.

    1996-01-01

    The development of specialized materials, processes, and robotics technology allows for the rapid prototype and manufacture of superconducting and normal magnets which can be used for magnetic suspension applications. Presented are highlights of the Direct Conductor Placement System (DCPS) which enables automatic design and assembly of 3-dimensional coils and conductor patterns using LTS and HTS conductors. The system enables engineers to place conductors in complex patterns with greater efficiency and accuracy, and without the need for hard tooling. It may also allow researchers to create new types of coils and patterns which were never practical before the development of DCPS. The DCPS includes a custom designed eight-axis robot, patented end effector, CoilCAD(trademark) design software, RoboWire(trademark) control software, and automatic inspection.

  10. Superconducting RF activities at SACLAY

    International Nuclear Information System (INIS)

    In 1986, it was decided at Saclay to build a facility to study and test Niobium superconducting 1.5 GHz electron accelerating structures. Since then, several laboratories have been set up to master all the parts of the process: computer and copper modeling, R.F. surface preparation, cryogenic testing, helium handling, and R.F. testing at both room and liquid helium temperatures. All of these facilities are now in operation and numerous tests have been carried out on single-cell cavities with and without HOM couplers. In addition, first tests have been performed on a five-cell cavity, and superfluid thermometry has been developed on a rotating system. This paper gives the main results for these topics. 2 refs., 6 figs., 1 tab

  11. Superconductivity in Fe-chalcogenides

    International Nuclear Information System (INIS)

    FeSe, which has the simplest crystal structure among the Fe based superconductors, and related chalcogenide superconductors are ideal candidates for investigating the detailed mechanism of the iron-based superconductors. Here, we summarize recent studies on the Fe-chalcogenides, with the goal to address some unresolved questions such as what is the influence of chemical stoichiometry on the phase diagram, what is the exact parent phase of FeSe system, and why can Tcs be so dramatically enhanced in FeSe based superconductors? Recent developments in novel synthesis to prepare chalcogenide crystals, nano-materials and thin films allow the community to begin to address these issues. Then we review physical properties of the Fe chalcogenides, specifically focusing on optical properties, scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy (ARPES) results. These measurements along with recent theories provide a framework for better understanding the origin of superconductivity in FeSe and Fe-chalcogenides

  12. Superconducting magnet system for RHIC

    International Nuclear Information System (INIS)

    The proposed Relativistic Heavy Ion Collider (RHIC) will operate at ion energies of 7 to 100+ GeV/Amu for ions as heavy as Au197. This paper discusses the superconducting magnet system for this machine. It will consist of 372 dipoles typically 9.7 meters long with an operating field of 3.4 Tesla, 492 quadrupoles with typical length 1.4 meters, gradient 76 T/m, and approximately 1000 sextupole and corrector magnets. A detailed design has been developed for the dipoles which will have a clear bore of 76 mm; less detailed designs are presented for the other components. A proof-of-concept magnet has been constructed and successfully tested. 3 refs., 5 figs

  13. Theory of superconductivity in oxides

    Science.gov (United States)

    Anderson, Philip W.

    1991-11-01

    During the period of this grant the theory of superconductivity in high Technetium cuprates matured into a reasonable, consistent, complete theory which has the capability, often realized, of confronting all of the puzzling experimental properties of the materials. During the period of the grant occurred the Cargese NATO Summer School (June 1990) attended by several of us who were being funded by the grant, and at that school I summarized progress up to that time. B. Doucot who had been one of our group was the local organizer. Perhaps the best summary of the situation at that time was given in my Chapter 2 setting out what I called the Central Dogmas of the theory, which is enclosed. At that meeting was formulated the justification of the Luttinger liquid hypothesis via a finite Fermi surface phase shift which led to several papers, especially the PRL and 'response' on the subject showing how the Fermi liquid theory breaks down.

  14. Composite superconducting transition edge bolometer

    International Nuclear Information System (INIS)

    A composite far-infrared bolometer has been constructed that uses an aluminum film at the superconducting transition temperature of 1.3 K as the temperature-sensitive element. The film is evaporated on one edge of a 4 x 4-mm sapphire substrate, which is coated on the reverse side with an absorbing film of bismuth. The best bolometer has an electrical NEP of (1.7 +- 0.1) x 10-15 W Hz-1/2 at 2 Hz, and a specific detectivity D* of (1.1 +- 0.1) x 1014 cm W-1 Hz1/2. This measured electrical NEP is within a factor 2 of the fundamental thermal noise limit

  15. Superconducting dc fault current limiter

    International Nuclear Information System (INIS)

    Within the framework of the electric power market liberalization, DC networks have many interests compared to alternative ones, but their protections need to use new systems. Superconducting fault current limiters enable by an overstepping of the critical current to limit the fault current to a preset value, lower than the theoretical short-circuit current. For these applications, coated conductors offer excellent opportunities. We worked on the implementation of these materials and built a test bench. We carried out limiting experiments to estimate the quench homogeneity at various short-circuit parameters. An important point is the temperature measurement by deposited sensors on the ribbon, results are in good correlation with the theoretical models. Improved quench behaviours for temperatures close to the critical temperature have been confirmed. Our results enable to better understand the limitation mechanisms of coated conductors. (author)

  16. Pairing theory of striped superconductivity

    International Nuclear Information System (INIS)

    Striped high-Tc superconductors such as La7/8Ba1/8CuO4 show a fascinating competition between spin and charge order on the one hand and superconductivity on the other. A theory for these systems therefore has to capture both the spin correlations in an antiferromagnet and the pair-correlation of a superconductor. For this purpose we have developed an effective Hartree-Fock theory by merging electron pairing with finite center-of-mass momentum and antiferromagnetism. We show that this theory reproduces the key experimental features such as the formation of the antiferromagnetic stripe patterns at 7/8 band filling or the quasi one-dimensional electronic structure observed by photoemission spectroscopy.

  17. Review of superconducting booster linacs

    International Nuclear Information System (INIS)

    Several superconducting boosters have been built and more are planned or under construction. These all use a number of independently phased resonators to permit acceleration of a wide variety of ion masses. For heavy ions, vhf frequencies are involved, and operation of the superconductors at 4.3 K, the normal boiling point of He, is practical. (Because fundamental losses in superconductors depend on frequency, some electron accelerators using much higher frequencies require colder resonators.) For boosters the resonator technology has evolved toward the use of quarter wave resonators with straight loading arms. The superconducting material is either niobium or lead. The latter is deposited as a film on copper, while the former may be sheet metal, may be bonded to copper, or may be (in principle) applied as a film on copper. The trade-offs involved and the successes of the various techniques are discussed. The rf must be controlled accurately both with regard to amplitude and phase. Because of the high unloaded Q of the resonators, additional loading is provided at some temperature well above that of the superconductor, in order to increase the bandwidth to a manageable point. Most boosters provide active control of phase by shifting the driving phase, although at least one system uses a frequency switching technique. Cross talk between independent resonator control systems must be avoided. The cryogenic systems have evolved toward a system based on a large helium refrigerator using turbine expansion and providing gas cooling to heat shields. Conservative design provides excess capacity beyond the expected requirements of the accelerator. Cryogenic distribution must be done carefully to avoid losses, and the system should be designed with capacity to match that of anticipated upgrades of the refrigerator. Most boosters use an approximately periodic focusing system with radial phase advance near 90deg per unit cell. (orig./HSI)

  18. Magnetic shielding of an inhomogeneous magnetic field source by a bulk superconducting tube

    International Nuclear Information System (INIS)

    Bulk type-II irreversible superconductors can act as excellent passive magnetic shields, with a strong attenuation of low frequency magnetic fields. Up to now, the performances of superconducting magnetic shields have mainly been studied in a homogenous magnetic field, considering only immunity problems, i.e. when the field is applied outside the tube and the inner field should ideally be zero. In this paper, we aim to investigate experimentally and numerically the magnetic response of a high-Tc bulk superconducting hollow cylinder at 77 K in an emission problem, i.e. when subjected to the non-uniform magnetic field generated by a source coil placed inside the tube. A bespoke 3D mapping system coupled with a three-axis Hall probe is used to measure the magnetic flux density distribution outside the superconducting magnetic shield. A finite element model is developed to understand how the magnetic field penetrates into the superconductor and how the induced superconducting shielding currents flow inside the shield in the case where the emitting coil is placed coaxially inside the tube. The finite element modelling is found to be in excellent agreement with the experimental data. Results show that a concentration of the magnetic flux lines occurs between the emitting coil and the superconducting screen. This effect is observed both with the modelling and the experiment. In the case of a long tube, we show that the main features of the field penetration in the superconducting walls can be reproduced with a simple analytical 1D model. This model is used to estimate the maximum flux density of the emitting coil that can be shielded by the superconductor. (paper)

  19. NSLS-II RF Cryogenic System

    Energy Technology Data Exchange (ETDEWEB)

    Rose, J.; Dilgen, T.; Gash, B.; Gosman, J.; Mortazavi, P.; Papu, J.; Ravindranath, V.; Sikora, R.; Sitnikov, A.; Wilhelm, H.; Jia, Y.; Monroe, C.

    2015-05-03

    The National Synchrotron Light Source II is a 3 GeV X-ray user facility commissioned in 2014. A new helium refrigerator system has been installed and commissioned to support the superconducting RF cavities in the storage ring. Special care was taken to provide very stable helium and LN2 pressures and flow rates to minimize microphonics and thermal effects at the cavities. Details of the system design along with commissioning and early operations data will be presented.

  20. In/extrinsic granularity in superconducting boron-doped diamond

    International Nuclear Information System (INIS)

    When charge carriers are introduced in diamond, e.g. by chemical doping with Boron (B), the C1-xBx diamond:B can exhibit an insulator-to-metal transition (pMott∼2x1020cm-3). Under even heavier boron doping (nB∼1021cm-3), diamond becomes superconducting. Using microwave plasma-assisted chemical vapor deposition (MPCVD) we have prepared diamond:B thin films with critical offset temperatures TC below 3 K. We have investigated the transport properties of these diamond:B thin films, which show pronounced granular effects. It turns out, that this granularity is both intrinsic as well as extrinsic. The extrinsic granularity is the effect of the growth method which needs to start from a seeding of the substrate with detonation nanodiamond, which acts as nucleation centers for further MPCVD growth of the film. In using SPM/STM techniques, we also observed intrinsic granularity, meaning that within physical grains, we observe also a strong intragrain modulation of the order parameter. As a consequence of these granularities, the transport properties show evidence of (i) strong superconducting fluctuations and (ii) Cooper pair tunneling and/or quasiparticle tunneling. The latter effects explain the observed negative magnetoresistance.

  1. Theory of superconductivity of gravitation and the dark matter enigma

    CERN Document Server

    Santiago-Germán, Wenceslao

    2011-01-01

    In this article, the question of the nature of cold dark matter is approached from a new angle. By invoking the Cauchy problem of relativity it is shown how, under very precise astrophysical conditions, the Einstein general theory of relativity is formally equivalent to the Ginzburg-Landau theory of superconductivity. This fact lead us to suspect that the superconductivity of gravitation ought to be a real physical process occurring in the outskirts of galaxies. It is found that quantum mechanically gravity can achieve a type-II superconductor state characterised by the Gizburg-Landau parameter $\\kappa=1.5$, and it is suggested that a probability flux of Cooper pairs (quantum gravitational geons charged with vacuum energy) are directly responsible for the flatness exhibited by the rotation curves in spiral galaxies, as well as the exotic behaviour observed in galactic cluster collisions. If this hypothesis proves correct, the whole phenomenon of dark matter may count, after all, as another triumph for Einstei...

  2. Magnetic and superconducting order in some random pseudobinary compounds

    International Nuclear Information System (INIS)

    This thesis presents the results of a study on the magnetic and superconducting ordering phenomena in some random pseudobinary compounds. In the investigations ternary systems are utilised in which two of the elements form a binary intermetallic compound, e.g. PdH, GdCu and YCo2. A third element is then randomly substituted into one of the sublattices without changing the basic intermetallic compound structure. In chapter II a study is presented on the Kondo effect and spin-glass freezing of the magnetic impurities Cr, Mn, and Fe in superconducting palladium hydride. Chapter III contains a study on crystal structure transformations and magnetic ordering phenomena in GdCusub(1-x)Gasub(x) and related pseudobinary compounds. In Chapter IV experiments on the magnetic properties and the electrical resistivity of the transition metal Laves phase compounds Y(Cosub(1-x)Fesub(x))2, Y(Irsub(1-x)Fesub(x))2 and Hf(Cosub(1-x)Fesub(x))2 are described. (Auth.)

  3. Superconducting (radiation hardened) magnets for mirror fusion devices

    International Nuclear Information System (INIS)

    Superconducting magnets for mirror fusion have evolved considerably since the Baseball II magnet in 1970. Recently, the Mirror Fusion Test Facility (MFTF-B) yin-yang has been tested to a full field of 7.7 T with radial dimensions representative of a full scale reactor. Now the emphasis has turned to the manufacture of very high field solenoids (choke coils) that are placed between the tandem mirror central cell and the yin-yang anchor-plug set. For MFTF-B the choke coil field reaches 12 T, while in future devices like the MFTF-Upgrade, Fusion Power Demonstration and Mirror Advanced Reactor Study (MARS) reactor the fields are doubled. Besides developing high fields, the magnets must be radiation hardened. Otherwise, thick neutron shields increase the magnet size to an unacceptable weight and cost. Neutron fluences in superconducting magnets must be increased by an order of magnitude or more. Insulators must withstand 1010 to 1011 rads, while magnet stability must be retained after the copper has been exposed to fluence above 1019 neutrons/cm2

  4. Generalized superconducting flows -- Plasma confinement, organization

    Energy Technology Data Exchange (ETDEWEB)

    Mahajan, S.M.

    1997-01-01

    Complete expulsion of magnetic vorticity is used to characterize the superconducting flow. It is shown that a simple, intuitive, but speculative generalization can serve as a paradigm for a variety of organized flows.

  5. Cooling arrangement for a superconducting coil

    International Nuclear Information System (INIS)

    A superconducting device is disclosed, such as a superconducting rotor for a generator or motor. A vacuum enclosure has an interior wall surrounding a cavity containing a vacuum. A superconductive coil is placed in the cavity. A generally-annularly-arranged, thermally-conductive sheet has an inward-facing surface contacting generally the entire outward-facing surface of the superconductive coil. A generally-annularly-arranged coolant tube contains a cryogenic fluid and contacts a generally-circumferential portion of the outward-facing surface of the sheet. A generally-annularly-arranged, thermally-insulative coil overwrap generally circumferentially surrounds the sheet. The coolant tube and the inward-facing surface of the coil overwrap together contact generally the entire outward-facing surface of the sheet. 3 figs

  6. What's hot in superconductivity at NRL

    International Nuclear Information System (INIS)

    The author reviews the latest results on the preparation and properties of the high superconducting transition temperature materials including some recent results on the Bi-Sr-Ca-Cu-O materials. Bulk, single crystal, and thin films are discussed

  7. Simulation of an HTS Synchronous Superconducting Generator

    DEFF Research Database (Denmark)

    Rodriguez Zermeno, Victor Manuel; Abrahamsen, Asger Bech; Mijatovic, Nenad;

    2012-01-01

    In this work we present a simulation of a synchronous generator with superconducting rotor windings. As many other,electrical rotating machines, superconducting generators are exposed to ripple fields that could be produced from a wide variety of sources: short circuit, load change, mechanical...... torque fluctuations, etc. Unlike regular conductors, superconductors, experience high losses when exposed to AC fields. Thus, calculation of such losses is relevant for machine design to avoid quenches and increase performance. Superconducting coated conductors are well known to exhibit nonlinear...... electric load is used to drive the finite element model of a synchronous generator where the current distribution in the rotor windings is assumed uniform. Then, a second finite element model for the superconducting material is linked to calculate the actual current distribution in the windings of the...

  8. Superconducting technology program Sandia 1996 annual report

    International Nuclear Information System (INIS)

    Sandia's Superconductivity Technology Program is a thallium-based high-temperature superconductor (HTS) research and development program consisting of efforts in powder synthesis and process development, open-system thick film conductor development, wire and tape fabrication, and HTS motor design. The objective of this work is to develop high-temperature superconducting conductors (wire and tape) capable of meeting requirements for high-power electrical devices of interest to industry. The research efforts currently underway are: (1) Process development and characterization of thallium-based high-temperature superconducting closed system wire and tape, (2) Investigation of the synthesis and processing of thallium-based thick films using two-zone processing, and (3) Cryogenic design of a 30K superconducting motor. This report outlines the research that has been performed during FY96 in each of these areas

  9. On superconductivity and superfluidity a scientific autobiography

    CERN Document Server

    Ginzburg, Vitaly L

    2009-01-01

    This book presents the Nobel Laureate Vitaly Ginzburg's views on the development in the field of superconductivity. It contains a selection of Ginzburg's key writings, including his amended version of the Nobel lecture in Physics 2003. Also included are an expanded autobiography, which was written for the Nobel Committee, an article entitled "A Scientific Autobiography: An Attempt," a fundamental article co-written with L.D. Landau entitled "To the theory of superconductivity," an expanded review article "Superconductivity and superfluidity (what was done and what was not done)," and some newly written short articles about superconductivity and related subjects. So, in toto, presented here are the personal contributions of Ginzburg, that resulted in the Nobel Prize, in the context of his scientific biography.

  10. Superconducting insertion devices with switchable period length

    International Nuclear Information System (INIS)

    Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they offer the possibility to enhance the tuning range and functionality significantly by period length switching. Period length switching can be realized by employing two or more individually powerable subsets of superconducting coils and reverse the current in a part of the winding. So far, the first demonstration mock-up coil allowing period length tripling was fabricated and tested successfully (A. Grau et al., accepted for publication in IEEE Transactions on Applied Superconductivity). Here, we report on the feasibility of a superconducting switch implemented as proposed by A. Madur et al., Proc. of the 10th International Conference on Synchrotron Radiation Instrumentation 2009, Melbourne, Australia.

  11. Superconducting insertion devices with switchable period length

    Energy Technology Data Exchange (ETDEWEB)

    Holubek, Tomas; Baumbach, Tilo; Casalbuoni, Sara; Gerstl, Stefan; Grau, Andreas; Hagelstein, Michael; Saez de Jauregui, David [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Boffo, Cristian; Walter, Wolfgang [Babcock Noell GmbH, Wuerzburg (Germany)

    2011-07-01

    Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they offer the possibility to enhance the tuning range and functionality significantly by period length switching. Period length switching can be realized by employing two or more individually powerable subsets of superconducting coils and reverse the current in a part of the winding. So far, the first demonstration mock-up coil allowing period length tripling was fabricated and tested successfully (A. Grau et al., accepted for publication in IEEE Transactions on Applied Superconductivity). Here, we report on the feasibility of a superconducting switch implemented as proposed by A. Madur et al., Proc. of the 10th International Conference on Synchrotron Radiation Instrumentation 2009, Melbourne, Australia.

  12. On superconductivity and superfluidity. A scientific autobiography

    International Nuclear Information System (INIS)

    This book presents the Nobel Laureate Vitaly Ginzburg's views on the development in the field of superconductivity. It contains a selection of Ginzburg's key writings, including his amended version of the Nobel lecture in Physics 2003. Also included are an expanded autobiography, which was written for the Nobel Committee, an article entitled ''A Scientific Autobiography: An Attempt,'' a fundamental article co-written with L.D. Landau entitled ''To the theory of superconductivity,'' an expanded review article ''Superconductivity and superfluidity (what was done and what was not done),'' and some newly written short articles about superconductivity and related subjects. So, in toto, presented here are the personal contributions of Ginzburg, that resulted in the Nobel Prize, in the context of his scientific biography. (orig.)

  13. Emergent phenomena: Light-induced superconductivity

    Science.gov (United States)

    Demsar, Jure

    2016-03-01

    Intense light pulses irradiating a sample of K3C60 result in dramatic changes of its high-frequency (terahertz) conductivity. Could these be signatures of fleeting superconductivity at 100 K and beyond?

  14. Insulation systems for superconducting transmission cables

    DEFF Research Database (Denmark)

    Tønnesen, Ole

    This paper describes shortly the status of superconducting transmission lines and assesses what impact the recently discovered BSCCO superconductors may have on the design of the cables.Two basically different insulation systems are discussed:1) The room temperature dielectric design, where the...... electrical insulation is placed outside both the superconducting tube and the cryostat. The superconducting tube is cooled by liquid nitrogen which is pumped through the hollow part of the tube.2) The cryogenic dielectric design, where the electrical insulation is placed inside the cryostat and thus is kept...... at temperature near 77 K.The optimal design is determined by a loss evaluation in relation to the power transfer capacity of the cable. Development work in progress on the design and construction of superconducting cables in Denmark is described as an example....

  15. Operational experience with superconducting synchrotron magnets

    International Nuclear Information System (INIS)

    The operational experience with the Fermilab Tevatron is presented, with emphasis on reliability and failure modes. Comprisons are made between the operating efficiencies for the superconducting machine and for he conventional Main Ring

  16. Superconductivity in alkali-doped C60

    International Nuclear Information System (INIS)

    Highlight: • Superconductivity in alkali-doped C60 (A3C60) is well described by an s-wave state produced by phonon mediated pairing. • Moderate coupling of electrons to high-frequency shape-changing intra-molecular vibrational modes produces transition temperatures up to 33 K in single-phase material. • The good understanding of pairing in A3C60 offers a paradigm for the development of new superconducting materials. - Abstract: Superconductivity in alkali-doped C60 (A3C60, A = an alkali atom) is well described by an s-wave state produced by phonon mediated pairing. Moderate coupling of electrons to high-frequency shape-changing intra-molecular vibrational modes produces transition temperatures (Tc) up to 33 K in single-phase material. The good understanding of pairing in A3C60 offers a paradigm for the development of new superconducting materials

  17. The first LHC superconducting magnet is unloaded

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    The first superconducting magnet is moved into position using a transfer table. This must be performed with great precision so that the LHC ring is correctly aligned, allowing the beams to travel along the correct paths.

  18. Superconducting inductive displacement detection of a microcantilever

    Energy Technology Data Exchange (ETDEWEB)

    Vinante, A., E-mail: anvinante@fbk.eu [Istituto di Fotonica e Nanotecnologie, CNR - Fondazione Bruno Kessler, I-38123 Povo, Trento (Italy)

    2014-07-21

    We demonstrate a superconducting inductive technique to measure the displacement of a micromechanical resonator. In our scheme, a type I superconducting microsphere is attached to the free end of a microcantilever and approached to the loop of a dc Superconducting Quantum Interference Device (SQUID) microsusceptometer. A local magnetic field as low as 100 μT, generated by a field coil concentric to the SQUID, enables detection of the cantilever thermomechanical noise at 4.2 K. The magnetomechanical coupling and the magnetic spring are in good agreement with image method calculations assuming pure Meissner effect. These measurements are relevant to recent proposals of quantum magnetomechanics experiments based on levitating superconducting microparticles.

  19. Structural aspects of superconducting fusion magnets

    International Nuclear Information System (INIS)

    Some methods for studying various static, dynamic, elastic-plastic, and fracture mechanics problems of superconducting magnets are described. Sample solutions are given for the UWMAK-I magnet. Finite element calculations were used

  20. Didactic demonstrations of superfluidity and superconductivity phenomena

    International Nuclear Information System (INIS)

    In order to demonstrate to students phenomena of superfluidity and superconductivity a special helium cryostat has been constructed. The demonstrated effects, construction of the cryostat and the method of demonstration are described. (author)