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Sample records for superconducting air core

  1. Antiferromagnetic hedgehogs with superconducting cores

    Energy Technology Data Exchange (ETDEWEB)

    Goldbart, P.M.; Sheehy, D.E. [Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    1998-09-01

    Excitations of the antiferromagnetic state that resemble antiferromagnetic hedgehogs at large distances but are predominantly superconducting inside a core region are discussed within the context of Zhang{close_quote}s SO(5)-symmetry-based approach to the physics of high-temperature superconducting materials. Nonsingular, in contrast with their hedgehog cousins in pure antiferromagnetism, these texture excitations are what hedgehogs become when the antiferromagnetic order parameter is permitted to {open_quotes}escape{close_quotes} into superconducting directions. The structure of such excitations is determined in a simple setting, and a number of their experimental implications are examined. {copyright} {ital 1998} {ital The American Physical Society}

  2. Superconducting shielded core reactor with reduced AC losses

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Yung S.; Hull, John R.

    2006-04-04

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

  3. Core Journals of the Rapidly Changing Research Front of "Superconductivity."

    Science.gov (United States)

    Brooks, Terrence A.

    1989-01-01

    Analyzes journals contributing to the literature on superconductivity from 1973 to 1987. Reveals that the literature has tripled in absolute size and has grown in intensity. Identifies core journals and reveals a communication pattern dominated by two journals, "Physical Review Letters" and "Physical Review B." Critiques…

  4. Thermal analysis of HTS air-core transformer used in voltage compensation type active SFCL

    Science.gov (United States)

    Song, M.; Tang, Y.; Li, J.; Zhou, Y.; Chen, L.; Ren, L.

    2010-11-01

    The three-phase voltage compensation type active superconducting fault current limiter (SFCL) is composed of three HTS air-core transformers and a three-phase four-wire Pulse Width Modulation (PWM) converter. The primary winding of the each phase HTS air-core transformer is in series with the main system, and the second winding is connected with the PWM converter. The single-phase conduction-cooled HTS air-core transformer is consisting of four double-pancakes wound by the Bi2223/Ag tape. In this paper, according to the electromagnetic analysis on the single-phase HTS air-core transformer, its AC loss corresponding to different operation modes is calculated. Furthermore, the thermal behaviors are studied by the time-stepping numerical simulations. On the basis of the simulation results, the related problems with the HTS air-core transformer's thermal stability are discussed.

  5. Earth's core and inner-core resonances from analysis of VLBI nutation and superconducting gravimeter data

    Science.gov (United States)

    Rosat, S.; Lambert, S. B.; Gattano, C.; Calvo, M.

    2017-01-01

    Geophysical parameters of the deep Earth's interior can be evaluated through the resonance effects associated with the core and inner-core wobbles on the forced nutations of the Earth's figure axis, as observed by very long baseline interferometry (VLBI), or on the diurnal tidal waves, retrieved from the time-varying surface gravity recorded by superconducting gravimeters (SGs). In this paper, we inverse for the rotational mode parameters from both techniques to retrieve geophysical parameters of the deep Earth. We analyse surface gravity data from 15 SG stations and VLBI delays accumulated over the last 35 yr. We show existing correlations between several basic Earth parameters and then decide to inverse for the rotational modes parameters. We employ a Bayesian inversion based on the Metropolis-Hastings algorithm with a Markov-chain Monte Carlo method. We obtain estimates of the free core nutation resonant period and quality factor that are consistent for both techniques. We also attempt an inversion for the free inner-core nutation (FICN) resonant period from gravity data. The most probable solution gives a period close to the annual prograde term (or S1 tide). However the 95 per cent confidence interval extends the possible values between roughly 28 and 725 d for gravity, and from 362 to 414 d from nutation data, depending on the prior bounds. The precisions of the estimated long-period nutation and respective small diurnal tidal constituents are hence not accurate enough for a correct determination of the FICN complex frequency.

  6. 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

  7. Superconductivity

    CERN Document Server

    Thomas, D B

    1974-01-01

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

  8. Effect of superconducting solenoid model cores on spanwise iron magnet roll control

    Science.gov (United States)

    Britcher, C. P.

    1985-01-01

    Compared with conventional ferromagnetic fuselage cores, superconducting solenoid cores appear to offer significant reductions in the projected cost of a large wind tunnel magnetic suspension and balance system. The provision of sufficient magnetic roll torque capability has been a long-standing problem with all magnetic suspension and balance systems; and the spanwise iron magnet scheme appears to be the most powerful system available. This scheme utilizes iron cores which are installed in the wings of the model. It was anticipated that the magnetization of these cores, and hence the roll torque generated, would be affected by the powerful external magnetic field of the superconducting solenoid. A preliminary study has been made of the effect of the superconducting solenoid fuselage model core concept on the spanwise iron magnet roll torque generation schemes. Computed data for one representative configuration indicate that reductions in available roll torque occur over a range of applied magnetic field levels. These results indicate that a 30-percent increase in roll electromagnet capacity over that previously determined will be required for a representative 8-foot wind tunnel magnetic suspension and balance system design.

  9. Superconductivity

    Science.gov (United States)

    1989-07-01

    SUPERCONDUCTIVITY HIGH-POWER APPLICATIONS Electric power generation/transmission Energy storage Acoustic projectors Weapon launchers Catapult Ship propulsion • • • Stabilized...temperature superconductive shields could be substantially enhanced by use of high-Tc materials. 27 28 NRAC SUPERCONDUCTIVITY SHIP PROPULSION APPLICATIONS...motor shown in the photograph. As a next step in the evolution of electric-drive ship propulsion technology, DTRC has proposed to scale up the design

  10. Analytical Model of Thermo-electrical Behaviour in Superconducting Resistive Core Cables

    CERN Document Server

    Calvi, M; Breschi, M; Coccoli, M; Granieri, P; Iriart, G; Lecci, F; Siemko, A

    2006-01-01

    High field superconducting Nb3Sn accelerators magnets above 14 T, for future High Energy Physics applications, call for improvements in the design of the protection system against resistive transitions. The longitudinal quench propagation velocity (vq) is one of the parameters defining the requirements of the protection. Up to now vq has been always considered as a physical parameter defined by the operating conditions (the bath temperature, cooling conditions, the magnetic field and the over all current density) and the type of superconductor and stabilizer used. It is possible to enhance the quench propagation velocity by segregating a percent of the stabilizer into the core, although keeping the total amount constant and tuning the contact resistance between the superconducting strands and the core. Analytical model and computer simulations are presented to explain the phenomenon. The consequences with respect to minimum quench energy are evidenced and the strategy to optimize the cable designed is discuss...

  11. 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...

  12. Suppression of superconductivity in thin Nb nanowires fabricated in the vortex cores of superfluid helium

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Eugene B., E-mail: Gordon.eb@gmail.com [Institute of Problems of Chemical Physics RAS, Semenov Avenue 1, 142432 Chernogolovka, Moscow Region (Russian Federation); Bezryadin, Alexey V. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61874 (United States); Karabulin, Alexander V. [Institute of Problems of Chemical Physics RAS, Semenov Avenue 1, 142432 Chernogolovka, Moscow Region (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe Highway 31, 115409 Moscow (Russian Federation); Matyushenko, Vladimir I. [The Branch of Talrose Institute for Energy Problems of Chemical Physics RAS, Semenov Avenue 1/10, 142432 Chernogolovka, Moscow Region (Russian Federation); Khodos, Igor I. [Institute of Microelectronics Technology and High Purity Materials RAS, Institutskaya Street 6, 142432 Chernogolovka, Moscow Region (Russian Federation)

    2015-09-15

    Highlights: • Laser ablation in superfluid helium allows producing thin nanowires of any metal. • Nb nanowires, about 4 nm in diameter, form in the cores of superfluid vortices. • Our oxide-free Nb nanowires exhibit a quantum superconductor-to-insulator transition. • The insulating behavior in Nb wires is explained in terms of quantum phase slips. • Such nanowires can be used in superconducting phase-slip qubits and transistors. - Abstract: Nanowires of niobium, platinum and indium–lead In{sub 88}Pb{sub 12} alloy with diameters of 4.2, 3.6 and 8 nm, respectively, were grown in quantized vortices of superfluid helium, and the dependences of their resistance on temperature have been studied. Through a detailed comparison of these dependences we present evidence that superconducting niobium wires allow a high rate of quantum phase slip. This phase slippage leads to a phase transition to an insulating state at T → 0.

  13. Tokamak Fusion Core Experiment: design studies based on superconducting and hybrid toroidal field coils. Design overview

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, C.A. (ed.)

    1984-10-01

    This document is a design overview that describes the scoping studies and preconceptual design effort performed in FY 1983 on the Tokamak Fusion Core Experiment (TFCX) class of device. These studies focussed on devices with all-superconducting toroidal field (TF) coils and on devices with superconducting TF coils supplemented with copper TF coil inserts located in the bore of the TF coils in the shield region. Each class of device is designed to satisfy the mission of ignition and long pulse equilibrium burn. Typical design parameters are: major radius = 3.75 m, minor radius = 1.0 m, field on axis = 4.5 T, plasma current = 7.0 MA. These designs relay on lower hybrid (LHRH) current rampup and heating to ignition using ion cyclotron range of frequency (ICRF). A pumped limiter has been assumed for impurity control. The present document is a design overview; a more detailed design description is contained in a companion document.

  14. Superconductivity

    CERN Document Server

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

    2014-01-01

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

  15. Design considerations for an air core magnetic actuator

    Science.gov (United States)

    Groom, Nelson J.

    1992-01-01

    Equations for the force produced by an air core electromagnet on a permanent magnet core as a function of the coil height, coil inner and outer radii, and core displacement are developed. The magnetization vector of the permanent magnet core is assumed to be aligned with the central axis of the electromagnet and the forces which are produced lie along the same axis. Variations in force due to changes in electromagnet parameters and core displacement are investigated and parameter plots which should be useful for coil design are presented.

  16. On the magnetic field evolution time-scale in superconducting neutron star cores

    Science.gov (United States)

    Passamonti, Andrea; Akgün, Taner; Pons, José A.; Miralles, Juan A.

    2017-08-01

    We revisit the various approximations employed to study the long-term evolution of the magnetic field in neutron star cores and discuss their limitations and possible improvements. A recent controversy on the correct form of the induction equation and the relevant evolution time-scale in superconducting neutron star cores is addressed and clarified. We show that this ambiguity in the estimation of time-scales arises as a consequence of nominally large terms that appear in the induction equation, but which are, in fact, mostly irrotational. This subtlety leads to a discrepancy by many orders of magnitude when velocity fields are absent or ignored. Even when internal velocity fields are accounted for, only the solenoidal part of the electric field contributes to the induction equation, which can be substantially smaller than the irrotational part. We also argue that stationary velocity fields must be incorporated in the slow evolution of the magnetic field as the next level of approximation.

  17. Pure odd-frequency superconductivity at the cores of proximity vortices

    Science.gov (United States)

    Alidoust, Mohammad; Zyuzin, Alexander; Halterman, Klaus

    2017-01-01

    After more than a decade, direct observation of the odd frequency triplet pairing state in superconducting hybrid structures remains elusive. We propose an experimentally feasible setup that can unambiguously reveal the zero energy peak due to proximity-induced equal spin superconducting triplet correlations. We theoretically investigate a two-dimensional Josephson junction in the diffusive regime. The nanostructure consists of a normal metal sandwiched between two ferromagnetic layers with spiral magnetization patterns. By applying an external magnetic field perpendicular to the junction plane, vortices nucleate in the normal metal. The calculated energy and spatially resolved density of states, along with the pair potential, reveal that remarkably, only triplet Cooper pairs survive in the vortex cores. These isolated odd frequency triplet correlations result in well defined zero energy peaks in the local density of states that can be identified through tunneling spectroscopy experiments. Moreover, the diffusive regime considered here rules out the possibility of Andreev bound states in the vortex core as contributors to the zero energy peaks.

  18. High-voltage air-core pulse transformers

    Energy Technology Data Exchange (ETDEWEB)

    Rohwein, G. J.

    1981-01-01

    General types of air core pulse transformers designed for high voltage pulse generation and energy transfer applications are discussed with special emphasis on pulse charging systems which operate up to the multi-megavolt range. The design, operation, dielectric materials, and performance are described. It is concluded that high voltage air core pulse transformers are best suited to applications outside the normal ranges of conventional magnetic core transformers. In general these include charge transfer at high power levels and fast pulse generation with comparatively low energy. When properly designed and constructed, they are capable of delivering high energy transfer efficiency and have demonstrated superior high voltage endurance. The principal disadvantage of high voltage air core transformers is that they are not generally available from commercial sources. Consequently, the potential user must become thoroughly familiar with all aspects of design, fabrication and system application before he can produce a high performance transformer system. (LCL)

  19. Hybrid design method for air-core solenoid with axial homogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Li; Lee, Sang Jin [Uiduk University, Gyeongju (Korea, Republic of); Choi, Suk Jin [Institute for Basic Science, Daejeon (Korea, Republic of)

    2016-03-15

    In this paper, a hybrid method is proposed to design an air-core superconducting solenoid system for 6 T axial uniform magnetic field using Niobium Titanium (NbTi) superconducting wire. In order to minimize the volume of conductor, the hybrid optimization method including a linear programming and a nonlinear programming was adopted. The feasible space of solenoid is divided by several grids and the magnetic field at target point is approximated by the sum of magnetic field generated by an ideal current loop at the center of each grid. Using the linear programming, a global optimal current distribution in the feasible space can be indicated by non-zero current grids. Furthermore the clusters of the non-zero current grids also give the information of probable solenoids in the feasible space, such as the number, the shape, and so on. Applying these probable solenoids as the initial model, the final practical configuration of solenoids with integer layers can be obtained by the nonlinear programming. The design result illustrates the efficiency and the flexibility of the hybrid method. And this method can also be used for the magnet design which is required the high homogeneity within several ppm (parts per million)

  20. Steady Thermal Field Simulation of Forced Air-cooled Column-type Air-core Reactor

    Institute of Scientific and Technical Information of China (English)

    DENG Qiu; LI Zhenbiao; YIN Xiaogen; YUAN Zhao

    2013-01-01

    Modeling the steady thermal field of the column-type air-core reactor,and further analyzing its distribution regularity,will help optimizing reactor design as well as improving its quality.The operation mechanism and inner insulation structure of a novel current limiting column-type air-core reactor is introduced in this paper.The finite element model of five encapsulation forced air-cooled column type air-core reactor is constructed using Fluent.Most importantly,this paper present a new method that,the steady thermal field of reactor working under forced air-cooled condition is simulated without arbitrarily defining the convection heat transfer coefficient for the initial condition; The result of the thermal field distribution shows that,the maximum steady temperature rise of forced air-cooled columntype air-core reactor happens approximately 5% to its top.The law of temperature distribution indicates:In the 1/3part of the reactor to its bottom,the temperature will rise rapidly to the increasing of height,yet the gradient rate is gradually decreasing; In the 5 % part of the reactor to its top,the temperature will drop rapidly to the increasing of height; In the part between,the temperature will rise slowly to the increasing of height.The conclusion draws that more thermal withstand capacity should be considered at the 5 % part of the reactor to its top to achieve optimal design solution.

  1. ElectroCore separator for particulate air emissions

    Energy Technology Data Exchange (ETDEWEB)

    Easom, B.H.; Smolensky, L.A.; Wysk, S.R.; Altman, R.F.; Olen, K.R.

    1998-07-01

    Coal combustion in fossil energy power systems releases trace amounts of chemical elements identified in the Clean Air Act Amendments of 1990 as hazardous air pollutants (HAPs). Most HAPs exist as solid phase particulate matter and are emitted to the atmosphere in this form. To reduce the emissions of these HAPs, a novel, high efficiency particle collection system known as the ElectroCore is being developed. The concept involves placing a high efficiency particle separator downstream of an underperforming electrostatic precipitator (ESP) that strips the particles from the incoming flow and returns them, along with a small amount of recirculation flow, back to the inlet of the ESP. The main component of the system is the ElectroCore separator. Its design is based on the mechanical Core Separator developed by LSR as a high efficiency centrifugal separator. Enhancing the Core Separator by adding an electrical field improves the separation efficiency of particles in the sub-micron range which is the range where centrifugal separation is ineffective. In the combined system, the centrifugal forces operating on the particles augmented by electrostatic forces so that the ElectroCore has high separation efficiency for particles of all sizes. Field tests have shown that the ElectroCore operating downstream of an underperforming ESP can reduce the particulate emission rate to below 4.3 ng/J (0.01 lb{sub m}/million Btu) even for ESPs with emission rates as high as 260 ng/J (0.6 lb{sub m}/million Btu). The ElectroCore system can perform with most all coal ranks or residual fuel oils (RFO) and has a potentially low capital cost.

  2. Conservation of orbital angular momentum in air core optical fibers

    CERN Document Server

    Gregg, P; Ramachandran, S

    2014-01-01

    Light's orbital angular momentum (OAM) is a conserved quantity in cylindrically symmetric media; however, it is easily destroyed by free-space turbulence or fiber bends, because anisotropic perturbations impart angular momentum. We observe the conservations of OAM even in the presence of strong bend perturbations, with fibers featuring air cores that appropriately sculpt the modal density of states. In analogy to the classical reasoning for the enhanced stability of spinning tops with increasing angular velocity, these states' lifetimes with OAM magnitude. Consequently, contrary to convention wisdom that ground states of systems are the most stable, OAM longevity in air-core fiber increases with mode order. Aided by conservation of this fundamental quantity, we demonstrate fiber propagation of 12 distinct higher-order OAM modes, of which 8 remain low-loss and >98% pure from near-degenerate coupling after km-length propagation. The first realization of long-lived higher-order OAM states, thus far posited to ex...

  3. Stray Capacitances of an Air-Cored Eddy Current Sensor

    Directory of Open Access Journals (Sweden)

    Yi Jia

    2009-12-01

    Full Text Available Stray capacitance of an air-cored eddy current sensor is one of the most crucial issues for successful development of an eddy current based residual stress assessment technology at frequency above 50 MHz. A two dimensional finite element model and an equivalent lumped capacitance network have been developed to accurately quantify overall stray capacitances of an air-cored eddy current sensor with specimen being tested. A baseline model was used to evaluate sensor design parameters, including the effects of pitch distance, trace width, trace thickness, number of turns, inner diameter, substrate thickness, lift-off distance, and dielectric constant of shim on the stray capacitances of the sensor. The results clearly indicate that an appropriate sensor design parameters could reduce the stray capacitance and improve the sensor performance. This research opens up a new design space to minimize stray capacitance effect and improve the sensor sensitivity and its lift-off uncertainty at elevated high frequencies.

  4. Sn/SnOx Core-Shell Nanospheres: Synthesis, Anode Performance in Li Ion Batteries, and Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.L.; Feygenson, M.; Aronson, M.C.; Han, W.-Q.

    2010-09-09

    Sn/SnO{sub x} core?shell nanospheres have been synthesized via a modified polyol process. Their size can be readily controlled by tuning the usage of surface stabilizers and the temperature. Anode performance in Li ion batteries and their superconducting properties is detailed. As anode materials, 45 nm nanospheres outperform both larger and smaller ones. Thus, they exhibit a capacity of about 3443 mAh cm{sup -3} and retain about 88% of after 10 cycles. We propose a model based on the microstructural evolution to explain the size impact on nanosphere performance. Magnetic measurements indicate that the nanospheres become superconducting below the transition temperature T{sub C} = 3.7 K, which is similar to the value obtained in bulk tin. Although T{sub C} does not significantly change with the size of the Sn core, we determined that the critical field H{sub C} of nanospheres can be as much as a factor of 30 larger compared to the bulk value. Alternating current measurements demonstrated that a transition from conventional to filamentary superconducting structure occurs in Sn/SnO{sub x} particles as their size increases. The transition is determined by the relationship between the particle size and the magnetic field penetration depth.

  5. Investigation of residual core ellipticity induced nonreciprocity in air-core photonic bandgap fiber optical gyroscope.

    Science.gov (United States)

    Xu, Xiaobin; Zhang, Zuchen; Zhang, Zhihao; Jin, Jing; Song, Ningfang

    2014-11-01

    Air-core photonic bandgap fiber (PBF) is an excellent choice for fiber optic gyroscope owing to its incomparable adaptability of environment. Strong and continuous polarization mode coupling is found in PBFs with an average intensity of ~-30 dB, but the coupling arrives at the limit when the maximum optical path difference between the primary waves and the polarization-mode-coupling-induced secondary waves reaches ~10mm, which is corresponding to the PBF length of ~110 m according to the birefringence in the PBF. Incident light with the low extinction ratio (ER) can suppress the birth of the polarization-mode-coupling-induced secondary waves, but the low-ER light obtained by the conventional Lyot depolarizers does not work here. Consequently, a large nonreciprocity and a bias error of ~13°/h are caused in the air-core photonic bandgap fiber optical gyroscope (PBFOG) with a PBF coil of ~268 m.

  6. Low-loss air-core polarization maintaining terahertz fiber.

    Science.gov (United States)

    Ren, Guobin; Gong, Yandong; Shum, Ping; Yu, Xia; Hu, JuanJuan; Wang, Guanghui; Ong Ling Chuen, Michael; Paulose, Varghese

    2008-09-01

    We propose a low-loss air-core polarization maintaining polymer fiber for terahertz (THz) wave guiding. The periodic arrangement of square holes with round corners in the cladding offers a bandgap effect for mode guiding. Numerical simulations show that the bandgap effect repels the modal power from the absorbent background polymers, resulting in a significant suppression of absorption loss of the polymers by a factor of more than 25. The phase-index birefringence of the proposed THz fiber is in the order of 10(-3).

  7. Electrically small circularly polarized spherical antenna with air core

    DEFF Research Database (Denmark)

    Kim, O. S.

    2013-01-01

    An electrically small circularly polarized self-resonant spherical antenna with air core is presented. The antenna is a modified multiarm spherical helix exciting TM10 and TE10 spherical modes with equal radiated power, and thus yielding perfect circular polarization over the entire far......-field sphere (except the polar regions, where the radiation is low). The self-resonance is achieved by exciting higher-order TM modes, which provide the necessary electric stored energy in the near-field, while contributing negligibly to the far-field radiation of the antenna. The antenna has electrical size...

  8. Apparatus and method for controlling the temperature of the core of a super-conducting transformer

    Science.gov (United States)

    Golner, Thomas; Pleva, Edward; Mehta, Shirish

    2006-10-10

    An apparatus for controlling the temperature of a core of a transformer is provided that includes a core, a shield surrounding the core, a cast formed between the core and the shield, and tubing positioned on the shield. The cast directs heat from the core to the shield and cooling fluid is directed through the tubing to cool the shield.

  9. Transient Analysis of Air-Core Coils by Moment Method

    Science.gov (United States)

    Fujita, Akira; Kato, Shohei; Hirai, Takao; Okabe, Shigemitu

    In electric power system a threat of lighting surge is decreased by using ground wire and arrester, but the risk of failure of transformer is still high. Winding is the most familiar conductor configuration of electromagnetic field components such as transformer, resistors, reactance device etc. Therefore, it is important that we invest the lighting surge how to advance into winding, but the electromagnet coupling in a winding makes lighting surge analysis difficult. In this paper we present transient characteristics analysis of an air-core coils by moment method in frequency domain. We calculate the inductance from time response and impedance in low frequency, and compare them with the analytical equation which is based on Nagaoka factor.

  10. AirCore Reusable InSitu Sampler for CO2 and Trace Gas Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The AirCore is a simple and novel atmospheric air column sampler to validate satellite observation data of greenhouse gases, using a lightweight, inexpensive coated...

  11. AirCore Reusable InSitu Sampler for CO2 and Trace Gas Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A novel design for an in situ air sampling sensor for CO2 and trace gases is proposed. The sensor, named AirCore, provides the advantages of existing in situ...

  12. Superconductivity in films of Pb/PbSe core/shell nanocrystals.

    Science.gov (United States)

    Zolotavin, Pavlo; Guyot-Sionnest, Philippe

    2012-09-25

    Superconductivity in films of electronically coupled colloidal lead nanocrystals is reported. The coupling between particles is in situ controlled through the conversion of the oxides present on the surface of the nanoparticles to chalcogenides. This transformation allows for a 10(9)-fold increase in the conductivity. The temperature of the onset of the superconductivity was found to depend upon the degree of coupling of the nanoparticles in the vicinity of the insulator-superconductor transition. The critical current density of the best sample of Pb/PbSe nanocrystals at zero magnetic field was determined to be 4 × 10(3) A/cm(2). In turn, the critical field of the sample shows 50-fold enhancement compared to bulk Pb.

  13. Superconducting generators for wind turbines: design considerations

    DEFF Research Database (Denmark)

    Mijatovic, Nenad; Abrahamsen, Asger Bech; Træholt, Chresten

    2010-01-01

    The harmonic content of high temperature superconductors (HTS) field winding in air-core high temperature superconducting synchronous machine (HTS SM) has been addressed in order to investigate tendency of HTS SM towards mechanical oscillation and additional loss caused by higher flux harmonic...

  14. Critical temperatures for superconducting quark matter existence in dense stellar cores

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, J.E. (Inst. Astronomico e Geofisico, Univ. de Sao Paulo, Av. M. Stefano 4200 (04301) Sao Paulo (BR)); Benvenuto, O.G. (Facultad de Ciencias Astronomicas y Geofisicas UNLP, Paseo del Bosque S/N (1900) La Plata (AR)); Vucetich, H. (Dept. di Fisica UNLP, Calle 49 y 115, C.C. 65, (1900) La Plata (AR))

    1992-04-10

    If quark matter is actually a component of compact stars it can probably develop a superconducting phase as a result of QCD interactions. This effect may be harmless for (or dramatically affect) the properties of the star, depending on the actual value of the strong coupling constant {alpha}{sub c}. Explicit expressions for the critical temperature T{sub c} are derived by using some recent results on the long-range behavior of the gluon propagators. In this paper the consequences for the cooling histories of compact stars and possible trends are briefly discussed.

  15. A method for determination of methyl chloride concentration in air trapped in ice cores.

    Science.gov (United States)

    Saito, Takuya; Yokouchi, Yoko; Aoki, Shuji; Nakazawa, Takakiyo; Fujii, Yoshiyuki; Watanabe, Okitsugu

    2006-05-01

    A method for measuring the concentration of methyl chloride (CH3Cl) in air trapped in an ice core was developed. The method combines the air extraction by milling the ice core samples under vacuum and the analysis of the extracted air with a cryogenic preconcentration/gas chromatograph/mass spectrometry system. The method was applied to air from Antarctic ice core samples estimated to have been formed in the pre-industrial and/or early industrial periods. The overall precision of the method deduced from duplicate ice core analyses was estimated to be better than +/-20 pptv. The measured CH3Cl concentration of 528+/-26 pptv was similar to the present-day concentration in the remote atmosphere as well as the CH3Cl concentration over the past 300 years obtained from Antarctic firn air and ice core analyses.

  16. 饱和铁心型超导限流器%Saturated iron - core superconducting fault current limiter

    Institute of Scientific and Technical Information of China (English)

    庞骁刚; 龚伟志; 洪辉; 任安林; 信赢

    2012-01-01

    饱和铁心型超导限流器具有限流功能可靠、输电稳态损耗小、限流恢复时间短等优异特性.根据其工作原理,一方面,用于直流励磁的超导绕组自身不承受短路电流冲击,这避免了其它类型超导限流器中由于超导绕组失超所带来的诸多技术难题;另一方面,其主体电抗器可以借鉴成熟的铁心电抗器技术.因此,饱和铁心型超导限流器的以其优异的性能特性和成熟的工程实现技术,成为迄今为止人们研究的各类超导限流器中的最具实用价值的一种.在电网容量不断扩大,智能化水平不断提高的今天,饱和铁心型超导限流器有非常广阔的应用前景.文中将叙述饱和铁心型超导限流器的基本原理、结构形式、功能特性,并对已在云南普吉变电站挂网运行的35kV/90MVA超导限流器进行简要介绍.%Saturated iron -core superconducting fault current limiters have some superior performance features, such as very low operation loss at normal power transmission, high impedance at fault current limiting, immediately reacting, and fast recovering. Thinks to its working mechanism, there is no risk of quench to the superconductor coil on the impact of the fault current, so complex mechanical, electrical and thermal protection measures can be avoided. The complicity to deal with a quench of superconductor might be a severe technical barrier for other types of superconducting fault current limiiers. In addition, the reactor of the device is mainly composed by iron cores and copper coils, which can be built with the technology for conventional transformers or reactors. For these reasons, this kind of superconducting fault current limiters is considered the most practically viable device in industrial applications. In this paper, the fundamental principles, the structures and the performance features of saturated iron core SFCLs are introduced. The specifications, testing results, and the operational

  17. Influence of filament diameter on superconducting properties of MgB2 multi-core wires

    Science.gov (United States)

    Reissner, M.; Bulla, L.; Husek, I.; Melišek, T.; Kováč, P.

    2013-06-01

    Magnetic behaviour of a series of MgB2 wires, in each case with 19 filaments of superconductor, surrounded by Ti as barrier and reinforced by stainless steel, prepared in the same way but mechanically deformed to different filament diameters ϕ between 58.5 and 17.7 µm, was investigated. Whereas no influence of ϕ on superconducting transition temperature is found, the width of the transition increases with ϕ. Critical current density, irreversibility line and mean effective activation energy U decrease systematically with decreasing ϕ. From a comparison of the field dependence of the pinning force and the temperature dependence of U, it is concluded, that pinning is dominated at low fields by grain boundary pinning and at higher fields by point defect pinning, with a rather broad distribution of pinning energies.

  18. Wireline-rotary air coring of the Bandelier Tuff, Los Alamos, New Mexico

    Science.gov (United States)

    Teasdale, W.E.; Pemberton, R.R.

    1984-01-01

    This paper describes experiments using wireline-rotary air-coring techniques conducted in the Bandelier Tuff using a modified standard wireline core-barrel system. The modified equipment was used to collect uncontaminated cores of unconsolidated ash and indurated tuff at Los Alamos, New Mexico. Core recovery obtained from the 210-foot deep test hole was about 92 percent. A standard HQ-size, triple-tube wireline core barrel (designed for the passage of liquid drilling fluids) was modified for air coring as follows: (1) Air passages were milled in the latch body part of the head assembly; (2) the inside dimension of the outer core barrel tube was machined and honed to provide greater clearance between the inner and outer barrels; (3) oversized reaming devices were added to the outer core barrel and the coring bit to allow more clearance for air and cuttings return; (4) the eight discharge ports in the coring bit were enlarged. To control airborne-dust pollution, a dust-and-cuttings discharge subassembly, designed and built by project personnel, was used. (USGS)

  19. Post-coring entrapment of modern air in polar ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and shallow ice cores

    Directory of Open Access Journals (Sweden)

    M. Aydin

    2010-01-01

    Full Text Available In this study, we report the first measurements of CFC-12 (CCl2F2 in air extracted from shallow ice cores along with firn air CFC-12 measurements from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for presence of modern air entrapped in shallow ice core samples. We propose that this is due to closure of open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our measurements reveal the presence of open porosity below the depth at which firn air samples can be collected and demonstrate how the composition of bubble air in shallow ice cores can be altered during the post-drilling period through purely physical processes. These results have implications for investigations involving trace gas composition of bubbles in shallow ice cores.

  20. Post-coring entrapment of modern air in some shallow ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and ice cores

    Directory of Open Access Journals (Sweden)

    M. Aydin

    2010-06-01

    Full Text Available In this study, we report measurements of CFC-12 (CCl2F2 in firn air and in air extracted from shallow ice cores from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, some of the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for the presence of modern air entrapped in the shallow ice core samples that likely contained open pores at the time of collection. We propose that this is due to closure of the open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our results reveal that open porosity can exist below the maximum depth at which firn air samples can be collected, particularly at sites with lower accumulation rates. CFC-12 measurements demonstrate that post-drilling closure of open pores can lead to a change in the composition of bubble air in shallow ice cores through purely physical processes. The results have implications for investigations involving trace gas composition of bubbles in shallow ice cores collected near the firn-ice transition.

  1. Reusable In Situ AirCore System for CO2 and Trace Gas Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A novel design for an in situ atmospheric sensor for CO2 and trace gases is proposed. The sensor, named AirCore, provides the advantages of existing in situ sensors...

  2. Numerical Analysis of Magnetic Force of Dry-Type Air-Core Reactor

    Institute of Scientific and Technical Information of China (English)

    LIUZhi-gang; GENGYing-san; WANGJian-hua

    2004-01-01

    This paper presents a coupled magnetic-circuit method for computing the magnetic force of air-core reactor under short-time current. The current and the magnetic flux density are computed first and then the magnetic force is obtained. Thus, the dynamic stability performance of air-core reactor can be analyzed at the design stage to reduce experimental cost and shorten the lead-time of product development.

  3. Characterization of a high-temperature superconducting conductor on round core cables in magnetic fields up to 20 T

    Energy Technology Data Exchange (ETDEWEB)

    van der Laan, D. C.; Noyes, P. D.; Miller, G. E.; Weijers, H. W.; Willering, G. P.

    2013-02-13

    The next generation of high-ï¬eld magnets that will operate at magnetic ï¬elds substantially above 20 T, or at temperatures substantially above 4.2 K, requires high-temperature superconductors (HTS). Conductor on round core (CORC) cables, in which RE-Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} (RE = rare earth) (REBCO) coated conductors are wound in a helical fashion on a flexible core, are a practical and versatile HTS cable option for low-inductance, high-field magnets. We performed the first tests of CORC magnet cables in liquid helium in magnetic fields of up to 20 T. A record critical current I{sub c} of 5021 A was measured at 4.2 K and 19 T. In a cable with an outer diameter of 7.5 mm, this value corresponds to an engineering current density J{sub e} of 114 A mm{sup -2} , the highest J{sub e} ever reported for a superconducting cable at such high magnetic fields. Additionally, the first magnet wound from an HTS cable was constructed from a 6 m-long CORC cable. The 12-turn, double-layer magnet had an inner diameter of 9 cm and was tested in a magnetic field of 20 T, at which it had an I{sub c} of 1966 A. The cables were quenched repetitively without degradation during the measurements, demonstrating the feasibility of HTS CORC cables for use in high-field magnet applications.

  4. Characterization of a high-temperature superconducting conductor on round core cables in magnetic fields up to 20 T

    Energy Technology Data Exchange (ETDEWEB)

    van der Laan, D. C.; Noyes, P. D.; Miller, G. E.; Weijers, H. W.; Willering, G. P.

    2013-02-13

    The next generation of high-ï¬eld magnets that will operate at magnetic ï¬elds substantially above 20 T, or at temperatures substantially above 4.2 K, requires high-temperature superconductors (HTS). Conductor on round core (CORC) cables, in which RE-Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} (RE = rare earth) (REBCO) coated conductors are wound in a helical fashion on a flexible core, are a practical and versatile HTS cable option for low-inductance, high-field magnets. We performed the first tests of CORC magnet cables in liquid helium in magnetic fields of up to 20 T. A record critical current I{sub c} of 5021 A was measured at 4.2 K and 19 T. In a cable with an outer diameter of 7.5 mm, this value corresponds to an engineering current density J{sub e} of 114 A mm{sup -2} , the highest J{sub e} ever reported for a superconducting cable at such high magnetic fields. Additionally, the first magnet wound from an HTS cable was constructed from a 6 m-long CORC cable. The 12-turn, double-layer magnet had an inner diameter of 9 cm and was tested in a magnetic field of 20 T, at which it had an I{sub c} of 1966 A. The cables were quenched repetitively without degradation during the measurements, demonstrating the feasibility of HTS CORC cables for use in high-field magnet applications.

  5. Detection of the translational oscillations of the Earth's solid inner core based on the international superconducting gravimeter observations

    Institute of Scientific and Technical Information of China (English)

    SUN Heping; XU Jianqiao; B.Ducarme

    2004-01-01

    Based on the 21 series of the high precision tidal gravity observations recorded using superconducting gravimeters (SG) at 14 stations distributed globally (in totally about 86 years), the translational oscillations of the Earth's solid inner core (ESIC) is detected in this paper. All observations are divided into two groups with G-Ⅰ group (8 relatively longer observational series) and G-Ⅱ group (13 relatively shorter observational series). The detailed corrections to minute original observations for each station are carried out, the error data due to the earthquakes, power supply impulses and some perturbations as change in atmospheric pressure and so on are carefully deleted for the first step, the gravity residuals are obtained after removing further synthetic tidal gravity signals. The Fast Fourier Transform analysis is carried out for each residual series, the estimations of the product spectral densities in the sub-tidal band are obtained by using a multi-station staking technique. The 8 common peaks are found after further removing the remaining frequency dependent pressure signals. The eigenperiods, quality factors and resonant strengths for these peaks are simulated. The numerical results show that the discrepancies of the eigenperiods for 3 of 8 peaks, compared to those of theoretical computation given by Smith, are only 0.4%, -0.4% and 1.0%. This coincidence signifies that the dynamical phenomenon of the Earth's solid inner core can be detected by using high precision ground gravity observations. The reliability of the numerical computation is also checked, the spectral peak splitting phenomenon induced by Earth's rotation and ellipticity is preliminary discussed in this paper.

  6. Numerical simulation and analysis of losses in air-core plastic photonic bandgap fibers

    Institute of Scientific and Technical Information of China (English)

    Tieshan Guan; Mingyang Chen; Zhilong Zhang; Rongjin Yu

    2005-01-01

    @@ The loss properties of air-core plastic photonic bandgap fibers are analyzed by multipole method. Despite the relatively large absorption loss of plastics (PMMA), the contribution of material absorption loss can be reduced significantly through appropriate selection of operating wavelength, number of cladding air-hole rings, radius of air-core, and position of photonic band gap. The transmission loss in this type of fiber can be decreased by an order of magnitude in comparison with that of conventional plastic optical fiber.

  7. Hysteretic method for measuring the flux trapped within the core of a superconducting lead-coated ferromagnetic torus by a linked superconducting tin ring, in a novel Aharonov-Bohm-like effect based on the Feynman path-integral principle

    CERN Document Server

    Chiao, Raymond

    2012-01-01

    A novel kind of nonlocal, macroscopic Aharonov-Bohm effect involving two topologically linked superconducting rings made out of two different materials, namely, lead and tin, is suggested for experimental observation, in which the lead ring is a torus containing a core composed of permanently magnetized ferromagnetic material. It is predicted that the remnant fields in a hysteresis loop induced by the application of a magnetic field imposed by a large external pair of Helmholtz coils upon the tin ring, will be asymmetric with respect to the origin of the loop. An appendix based on Feynman's path-integral principle is the basis for these predictions.

  8. AIRS-observed warm core structures of tropical cyclones over the western North Pacific

    Science.gov (United States)

    Gao, Si; Chen, Baiqing; Li, Tim; Wu, Naigeng; Deng, Wenjian

    2017-03-01

    Atmospheric Infrared Sounder (AIRS) temperature profiles during the period 2003-2013 are used to examine the warm core structures and evolution characteristics associated with the formation and development of western North Pacific (WNP) tropical cyclones (TCs). The warm core with a steady 1.5-K warming in the layer of 500-300 hPa occurs 24 h prior to tropical storm formation. Apparent eye warming extends upward to upper troposphere and downward to near surface after tropical storm formation. TC intensity shows a robust positive correlation with the warm core strength and has a weaker but still significant positive correlation with the warm core height (the weaker correlation is primarily attributed to the scattered warm core heights of weak TCs). Future 24-h intensity change of TCs has little correlation with the warm core height while it has a significant negative correlation with the warm core strength. Weak to moderate warm core at 500-200 hPa may be a necessary but not sufficient initial condition for TC rapid intensification. AIRS-observed warm core structures, in combination with other environmental factors, have the potential to improve the prediction of tropical storm formation and rapid intensification of WNP TCs.

  9. Superconducting material development

    Science.gov (United States)

    1987-09-01

    A superconducting compound was developed that showed a transition to a zero-resistance state at 65 C, or 338 K. The superconducting material, which is an oxide based on strontium, barium, yttrium, and copper, continued in the zero-resistance state similar to superconductivity for 10 days at room temperature in the air. It was also noted that measurements of the material allowed it to observe a nonlinear characteristic curve between current and voltage at 65 C, which is another indication of superconductivity. The research results of the laboratory experiment with the superconducting material will be published in the August edition of the Japanese Journal of Applied Physics.

  10. Design of air-gapped magnetic-core inductors for superimposed direct and alternating currents

    Science.gov (United States)

    Ohri, A. K.; Wilson, T. G.; Owen, H. A., Jr.

    1976-01-01

    Using data on standard magnetic-material properties and standard core sizes for air-gap-type cores, an algorithm designed for a computer solution is developed which optimally determines the air-gap length and locates the quiescent point on the normal magnetization curve so as to yield an inductor design with the minimum number of turns for a given ac voltage and frequency and with a given dc bias current superimposed in the same winding. Magnetic-material data used in the design are the normal magnetization curve and a family of incremental permeability curves. A second procedure, which requires a simpler set of calculations, starts from an assigned quiescent point on the normal magnetization curve and first screens candidate core sizes for suitability, then determines the required turns and air-gap length.

  11. Optimization of Shielded PCB Air-Core Toroids for High-Efficiency DC-DC Converters

    CERN Document Server

    Orlandi, S; Buso, S; Michelis, S; Fuentes, C A; Kayal, M; Faccio, F; Spiazzi, G

    2011-01-01

    The paper describes the design of optimized printed circuit board (PCB) air-core toroids for high-frequency dc-dc converters with strict requirements in terms of volume and noise. The effect of several design parameters on the overall inductor volume, on dc and ac winding resistance, and on the radiated noise will be investigated. PCB toroids are compared to standard air-core solenoids and other state-of-the-art air-core toroids both theoretically and experimentally: at first, using ANSOFT Maxwell and ANSOFT Q3D simulation tools, and subsequently, with laboratory measurements (irradiated noise, efficiency, and frequency response) on several prototypes. These very flexible and rather easy to manufacture inductors appear very attractive for compact high-frequency dc-dc converters where high efficiency, low volume, and low noise are of primary concern.

  12. Air Force Core Values: An Analysis of Mid-Level Career Officers' Values and Their Suitability to Instill Them

    National Research Council Canada - National Science Library

    Keith, Steven

    1997-01-01

    .... To these concerns, this research seeks to evaluate the level of integration of Air Force core values in mid-level career officers, and their subsequent suitability to help instill the core values in subordinates...

  13. Tapered air-core Bragg waveguide spectrometers for lab-on-a-chip applications

    Science.gov (United States)

    Drobot, Brian A.; Melnyk, Aaron D.; Allen, Trevor W.; DeCorby, Ray G.

    2013-05-01

    Lab-on-a-chip and optofluidic micro-systems often rely on bulky off-chip optical components such as lenses and spectrometers for detection. There is a growing demand for compact microspectrometers that can be integrated on-chip, to increase portability and potentially reduce the cost and complexity of these systems. We have previously reported chip-scale microspectrometers based on tapered air-core Bragg waveguides with omnidirectional Bragg claddings. Here, we describe the integration of these air-core waveguide spectrometers with microfluidics, including results for a prototype sensing system based on spectrally-resolved fluorescence detection.

  14. Petrographic Analysis of Portland Cement Concrete Cores from Pease Air National Guard Base, New Hampshire

    Science.gov (United States)

    2016-11-01

    Petrographic Analysis of Portland Cement Concrete Cores from Pease Air National Guard Base, New Hampshire E n g in e e r R e s e a rc h a n d...id, age of the concrete being evaluated and tests performed...4 3 Preface This study was conducted in support of the Air Force Civil Engineer Center (AFCEC) to assess concrete obtained from Pease

  15. Stratospheric measurements of ozone-depleting substances and greenhouse gases using AirCores

    Science.gov (United States)

    Laube, Johannes; Leedham Elvidge, Emma; Kaiser, Jan; Sturges, Bill; Heikkinen, Pauli; Laurila, Tuomas; Hatakka, Juha; Kivi, Rigel; Chen, Huilin; Fraser, Paul; van der Veen, Carina; Röckmann, Thomas

    2017-04-01

    Retrieving air samples from the stratosphere has previously required aircraft or large balloons, both of which are expensive to operate. The novel "AirCore" technique (Karion et al., 2010) enables stratospheric sampling using weather balloons, which is much more cost effective. AirCores are long (up to 200 m) stainless steel tubes which are placed as a payload on a small balloon, can ascend to over 30 km and fill upon descent, collecting a vertical profile of the atmosphere. Retrieved volumes are much smaller though, which presents a challenge for trace gas analysis. To date, only the more abundant trace gases such as carnon dioxide (CO2) and methane (CH4) have been quantified in AirCores. Halogenated trace gases are also important greenhouse gases and many also deplete stratospheric ozone. Their concentrations are however much lower i.e. typically in the part per trillion (ppt) molar range. We here present the first stratospheric measurements of halocarbons in AirCores obtained using UEA's highly sensitive (detection limits of 0.01-0.1 ppt in 10 ml of air) gas chromatography mass spectrometry system. The analysed air originates from a Stratospheric Air Sub-sampler (Mrozek et al., 2016) which collects AirCore segments after the non-destructive CO2 and CH4 analysis. Successfully measured species include CFC-11, CFC-12, CFC-113, CFC-115, H-1211, H-1301, HCFC-22, HCFC-141b, HCFC-142b, HCFC-133a, and sulphur hexafluoride (SF6). We compare the observed mixing ratios and precisions with data obtained from samples collected during various high-altitude aircraft campaigns between 2009 and 2016 as well as with southern hemisphere tropospheric long-term trends. As part of the ERC-funded EXC3ITE (EXploring stratospheric Composition, Chemistry and Circulation with Innovative Techniques) project more than 40 AirCore flights are planned in the next 3 years with an expanded range of up to 30 gases in order to explore seasonal and interannual variability in the stratosphere

  16. Air core detectors for Cerenkov-free scintillation dosimetry of brachytherapy β-sources.

    Science.gov (United States)

    Eichmann, Marion; Thomann, Benedikt

    2017-09-01

    Plastic scintillation detectors are used for dosimetry in small radiation fields with high dose gradients, e.g., provided by β-emitting sources like (106) Ru/(106) Rh eye plaques. A drawback is a background signal caused by Cerenkov radiation generated by electrons passing the optical fibers (light guides) of this dosimetry system. Common approaches to correct for the Cerenkov signal are influenced by uncertainties resulting from detector positioning and calibration procedures. A different approach to avoid any correction procedure is to suppress the Cerenkov signal by replacing the solid core optical fiber with an air core light guide, previously shown for external beam therapy. In this study, the air core concept is modified and applied to the requirements of dosimetry in brachytherapy, proving its usability for measuring water energy doses in small radiation fields. Three air core detectors with different air core lengths are constructed and their performance in dosimetry for brachytherapy β-sources is compared with a standard two-fiber system, which uses a second fiber for Cerenkov correction. The detector systems are calibrated with a (90) Sr/(90) Y secondary standard and tested for their angular dependence as well as their performance in depth dose measurements of (106) Ru/(106) Rh sources. The signal loss relative to the standard detector increases with increasing air core length to a maximum value of 58.3%. At the same time, however, the percentage amount of Cerenkov light in the total signal is reduced from at least 12.1% to a value below 1.1%. There is a linear correlation between induced dose and measured signal current. The air core detectors determine the dose rates for (106) Ru/(106) Rh sources without any form of correction for the Cerenkov signal. The air core detectors show advantages over the standard two-fiber system especially when measuring in radiation fields with high dose gradients. They can be used as simple one-fiber systems and allow

  17. Analysis and Design of Double-sided Air core Linear Servo Motor with Trapezoidal Permanent Magnets

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Yang, Zilong; Yu, Minghu;

    2011-01-01

    In order to reduce the thrust ripple of linear servo system, a double-sided air core permanent magnet linear servo motor with trapezoidal shape permanent magnets (TDAPMLSM) is proposed in this paper. An analytical model of the motor for predicting the magnetic field in the air-gap at no......-load is introduced. This model is derived based on the equivalent magnetization intensity method, and its accuracy is validated by using the results obtained from the finite-element method. The key dimensions that affect the air-gap magnetic field are analyzed based on the analytical model, and the design...

  18. Small-core photonic crystal fibres with weakly disordered air-hole cladding

    DEFF Research Database (Denmark)

    Mortensen, Niels Asger; Nielsen, Martin Dybendal; Folkenberg, Jacob Riis;

    2004-01-01

    Motivated by recent experimental work by Folkenberg et al (2003 Opt. Lett. 28 1882–4) we consider the effect of weak disorder in the air-hole lattice of small-core photonic crystal fibres. We find that the broken symmetry leads to higher-order modes which have generic intensity distributions rese...

  19. Reflection-induced bias error in an air-core photonic bandgap fiber optic gyroscope.

    Science.gov (United States)

    Zhang, Zuchen; Xu, Xiaobin; Zhang, Zhihao; Song, Ningfang; Zhang, Chunxi

    2016-01-15

    Analysis of the bias error induced by reflections in an air-core photonic bandgap fiber gyroscope is performed by both simulation and experiment. The bias error is sinusoidally periodic under modulation, and its intensity is related to the relative positions of the reflection points. A simple and effective method for the suppression of the error is proposed, and it has been verified experimentally.

  20. Investigation, development and verification of printed circuit board embedded air-core solenoid transformers

    DEFF Research Database (Denmark)

    Mønster, Jakob Døllner; Madsen, Mickey Pierre; Pedersen, Jeppe Arnsdorf

    2015-01-01

    A new printed circuit board embedded air-core transformer/coupled inductor is proposed and presented. The transformer is intended for use in power converter applications operating at very high frequency between 30 MHz to 300 MHz. The transformer is based on two or more solenoid structures...

  1. Numerical study of air-core vortex dynamics during liquid draining from cylindrical tanks

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, Sam; Patnaik, B S V [Fluid Mechanics Laboratory, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036 (India); Tharakan, T John, E-mail: bsvp@iitm.ac.in [Flow and Acoustics Group, Liquid Propulsion Systems Centre, Indian Space Research Organization, Trivandrum 695547 (India)

    2014-04-01

    An air core is often formed during liquid draining from cylindrical tanks. An understanding of the mechanism behind its formation and the parameters that accentuate its growth is central to the development of an air-core vortex suppression strategy. In the present study, liquid draining from a cylindrical tank is investigated with the aid of computational fluid dynamics tools. A qualitative and a quantitative comparison of the temporal variation of critical height against available experiments is reported. A systematic investigation has revealed that, drain port shape, size, pressurization, initial rotation, etc, play a vital role in the formation of an air core vortex and its growth. These variables were also observed to influence critical height and total drain time, both of which are of engineering interest. Towards the development of a gas-core suppression strategy, the circular drain port is modified to either a stepped or a bell mouth shape. Although the new drain port shapes have delayed the gas-core from entering the drain-port, they were found to be only marginally advantageous. (paper)

  2. Stratospheric Air Sub-sampler (SAS) and its application to analysis of Δ17O(CO2) from small air samples collected with an AirCore

    Science.gov (United States)

    Janina Mrozek, Dorota; van der Veen, Carina; Hofmann, Magdalena E. G.; Chen, Huilin; Kivi, Rigel; Heikkinen, Pauli; Röckmann, Thomas

    2016-11-01

    We present the set-up and a scientific application of the Stratospheric Air Sub-sampler (SAS), a device to collect and to store the vertical profile of air collected with an AirCore (Karion et al., 2010) in numerous sub-samples for later analysis in the laboratory. The SAS described here is a 20 m long 1/4 inch stainless steel tubing that is separated by eleven valves to divide the tubing into 10 identical segments, but it can be easily adapted to collect smaller or larger samples. In the collection phase the SAS is directly connected to the outlet of an optical analyzer that measures the mole fractions of CO2, CH4 and CO from an AirCore sampler. The stratospheric part (or if desired any part of the AirCore air) is then directed through the SAS. When the SAS is filled with the selected air, the valves are closed and the vertical profile is maintained in the different segments of the SAS. The segments can later be analysed to retrieve vertical profiles of other trace gas signatures that require slower instrumentation. As an application, we describe the coupling of the SAS to an analytical system to determine the 17O excess of CO2, which is a tracer for photochemical processing of stratospheric air. For this purpose the analytical system described by Mrozek et al. (2015) was adapted for analysis of air directly from the SAS. The performance of the coupled system is demonstrated for a set of air samples from an AirCore flight in November 2014 near Sodankylä, Finland. The standard error for a 25 mL air sample at stratospheric CO2 mole fraction is 0.56 ‰ (1σ) for δ17O and 0.03 ‰ (1σ) for both δ18O and δ13C. Measured Δ17O(CO2) values show a clear correlation with N2O in agreement with already published data.

  3. Air core Bragg fibers for delivery of near-infrared laser radiation

    Science.gov (United States)

    Jelínek, Michal; Frank, Milan; Kubeček, Václav; Matějec, Vlastimil; Kašík, Ivan; Podrazký, Ondřej

    2014-12-01

    Optical fibers designed for high power laser radiation delivery represent important tools in medicine, solar systems, or industry. For such purposes several different types of glass optical fibers such as silica, sapphire, or chalcogenide ones as well as hollow-glass fibers, photonic crystal fibers and Bragg fibers have been investigated. Air-core Bragg fibers or photonic crystal fibers offer us the possibility of light transmission in a low dispersive material - air having a high damage threshold and small non-linear coefficient. However, preforms for drawing Bragg fibers can be fabricated by MCVD method similarly as preforms of standard silica fibers. In this paper we present fundamental characteristics of laboratory-designed and fabricated Bragg fibers with air cores intended for delivery of laser radiation at a wavelength range from 0.9 to 1.5 μm. Bragg fibers with different air core diameters of 5, 45 and 73 mm were prepared. The fiber core was surrounded by three pairs of circular Bragg layers. Each pair was composed of one layer with a high and one layer with a low refractive index with a contrast up to 0.03. Several laser sources emitting at 0.975, 1.06, and 1.55 μm were used as radiation sources. Attenuation coefficients, overall transmissions, bending losses, and spatial profiles of output beams from fibers were determined at these wavelengths. The lowest attenuation coefficient of 70 dB/km was determined for the 45 μm and 73 mm air-core fiber when radiation from a laser was launched into the fibers by using optical lenses. However, multimodal transmission has been observed in such condition. It has also been found that bending losses of such fibers are negligible for bending diameters higher than 15 mm.

  4. Accelerator Mass Spectrometric determination of radiocarbon in stratospheric CO2, retrieved from AirCore sampling.

    Science.gov (United States)

    Paul, Dipayan; Been, Henk A.; Chen, Huilin; Kivi, Rigel; Meijer, Harro A. J.

    2015-04-01

    In this decade, understanding the impact of human activities on climate is one of the key issues of discussion globally. The continuous rise in the concentration of greenhouse gases, e.g., CO2, CH4, etc. in the atmosphere, predominantly due to human activities, is alarming and requires continuous monitoring to understand the dynamics. Radiocarbon is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases like CO2 and CH4. Measurement of 14C (or radiocarbon) in atmospheric CO2 generally requires collection of large air samples (few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined. Currently, Accelerator Mass Spectrometry (AMS) is the most precise, reliable and widely used technique for atmospheric radiocarbon detection. However, the regular collection of air samples from troposphere and stratosphere, for example using aircraft, is prohibitively expensive. AirCore is an innovative atmospheric sampling system, developed by NOAA. It comprises of a long tube descending from a high altitude with one end open and the other closed, and has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ~ 30 km) measurements of CH4and CO2(Karion et al. 2010). In Europe, AirCore measurements are being performed on a regular basis near Sodankylä since September 2013. Here we describe the analysis of two such AirCore samples collected in July 2014, Finland, for determining the 14C concentration in stratospheric CO2. The two AirCore samples were collected on consecutive days. Each stratospheric AirCore sample was divided into six fractions, each containing ~ 35 μg CO2 (~9.5 μg C). Each fraction was separately trapped in 1 /4 inch coiled stainless steel tubing for radiocarbon measurements. The procedure for CO2 extraction from the stratospheric air samples; the sample preparation, with samples containing < 10

  5. Chemical signals of past climate and environment from polar ice cores and firn air.

    Science.gov (United States)

    Wolff, Eric W

    2012-10-07

    Chemical and isotopic records obtained from polar ice cores have provided some of the most iconic datasets in Earth system science. Here, I discuss how the different records are formed in the ice sheets, emphasising in particular the contrast between chemistry held in the snow/ice phase, and that which is trapped in air bubbles. Air diffusing slowly through the upper firn layers of the ice sheet can also be sampled in large volumes to give more recent historical information on atmospheric composition. The chemical and geophysical issues that have to be solved to interpret ice core data in terms of atmospheric composition and emission changes are also highlighted. Ice cores and firn air have provided particularly strong evidence about recent changes (last few decades to centuries), including otherwise inaccessible data on increases in compounds that are active as greenhouse gases or as agents of stratospheric depletion. On longer timescales (up to 800,000 years in Antarctica), ice cores reveal major changes in biogeochemical cycling, which acted as feedbacks on the very major changes in climate between glacial and interglacial periods.

  6. Development of Yangbajing Air shower Core detector array for a new EAS hybrid Experiment

    CERN Document Server

    Liu, Jinsheng; Chen, Ding; Zhang, Ying; Zhai, Liuming; Chen, Xu; Hu, Xiaobin; Lin, Yuhui; Zhang, Xueyao; Feng, Cunfeng; Jia, Huanyu; Zhou, Xunxiu; DanZengLuoBu,; Chen, Tianlu; Li, Haijin; Liu, Maoyuan; Yuan, Aifang

    2015-01-01

    Aiming at the observation of cosmic-ray chemical composition at the "knee" energy region, we have been developinga new type air-shower core detector (YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing (90.522$^\\circ$ E, 30.102$^\\circ$ N, 4300 m above sea level, atmospheric depth: 606 g/m$^2$) in Tibet, China. YAC works together with the Tibet air-shower array (Tibet-III) and an underground water cherenkov muon detector array (MD) as a hybrid experiment. Each YAC detector unit consists of lead plates of 3.5 cm thick and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores. The burst size can be measured from 1 MIP (Minimum Ionization Particle) to $10^{6}$ MIPs. The first phase of this experiment, named "YAC-I", consists of 16 YAC detectors each having the size 40 cm $\\times$ 50 cm and distributing in a grid with an effective area of 10 m$^{2}$. YAC-I is used to check hadronic interaction models. The second phase of the experiment,...

  7. Radiocarbon analysis of stratospheric CO2 retrieved from AirCore sampling

    Science.gov (United States)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-10-01

    Radiocarbon (14C) is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases CO2 and CH4. Measurement of radiocarbon in atmospheric CO2 generally requires the collection of large air samples (a few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined using accelerator mass spectrometry (AMS). However, the regular collection of air samples from the stratosphere, for example using aircraft and balloons, is prohibitively expensive. Here we describe radiocarbon measurements in stratospheric CO2 collected by the AirCore sampling method. AirCore is an innovative atmospheric sampling system, which comprises a long tube descending from a high altitude with one end open and the other closed, and it has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ≈ 30 km) measurements of CH4 and CO2. In Europe, AirCore measurements have been being performed on a regular basis near Sodankylä (northern Finland) since September 2013. Here we describe the analysis of samples from two such AirCore flights made there in July 2014, for determining the radiocarbon concentration in stratospheric CO2. The two AirCore profiles were collected on consecutive days. The stratospheric part of the AirCore was divided into six sections, each containing ≈ 35 µg CO2 ( ≈ 9.6 µgC), and stored in a stratospheric air subsampler constructed from 1/4 in. coiled stainless steel tubing ( ≈ 3 m). A small-volume extraction system was constructed that enabled > 99.5 % CO2 extraction from the stratospheric air samples. Additionally, a new small-volume high-efficiency graphitization system was constructed for graphitization of these extracted CO2 samples, which were measured at the Groningen AMS facility. Since the stratospheric samples were very similar in mass, reference samples were also prepared in the same mass range for

  8. Analysis and Design of Double-sided Air core Linear Servo Motor with Trapezoidal Permanent Magnets

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Yang, Zilong; Yu, Minghu

    2011-01-01

    In order to reduce the thrust ripple of linear servo system, a double-sided air core permanent magnet linear servo motor with trapezoidal shape permanent magnets (TDAPMLSM) is proposed in this paper. An analytical model of the motor for predicting the magnetic field in the air-gap at no-load is i......In order to reduce the thrust ripple of linear servo system, a double-sided air core permanent magnet linear servo motor with trapezoidal shape permanent magnets (TDAPMLSM) is proposed in this paper. An analytical model of the motor for predicting the magnetic field in the air-gap at no......-load is introduced. This model is derived based on the equivalent magnetization intensity method, and its accuracy is validated by using the results obtained from the finite-element method. The key dimensions that affect the air-gap magnetic field are analyzed based on the analytical model, and the design...... is optimized by using genetic algorithm. A thrust ripple reduction of 70.6% is achieved by optimization. The proposed analytical model may be used for a quick and reliable design and design optimization of the TDAPMLSM....

  9. Fabrication of solid-cladding photonic band gap fiber with air core

    Science.gov (United States)

    Kujawa, I.; Pysz, D.; Buczyński, R.; Filipkowski, A.; Nowosielski, J.; Stępień, R.

    2008-06-01

    In this paper we report on fabrication of all-Solid photonic Cladding and Air Core fiber (SCAC fiber). As far as we know it is a first reported fabrication of such PCF. Microrods are made of commercially available lead-oxide F2 glass (SCHOTT Inc.) with a refractive index nD=1.619, while as background we use a borosilicate NC21 glass synthesized in-house at ITME with a refractive index nD=1.533. A fabricated fiber has a lattice constant of Λ~7.49μm and microrods diameter of d~4.0μm. Air core has a diameter of DR=3.67μm and total fiber diameter is Dfiber=123.80μm.

  10. Guiding Properties of Silica/Air Hollow-Core Bragg Fibers

    DEFF Research Database (Denmark)

    Foroni, Matteo; Passaro, Davide; Poli, Federica

    2008-01-01

    The guiding properties of realistic silica/air hollow-core Bragg fibers have been investigated by calculating the dispersion curves, the confinement loss spectrum and the field distribution of the guided modes through a full-vector modal solver based on the finite element method. In particular, t...... the different possible applications, the feasibility of a DNA bio-sensor based on a hollow-core Bragg fiber has been demonstrated.......The guiding properties of realistic silica/air hollow-core Bragg fibers have been investigated by calculating the dispersion curves, the confinement loss spectrum and the field distribution of the guided modes through a full-vector modal solver based on the finite element method. In particular......, the silica bridge influence on the fundamental mode has been analyzed, by comparing the properties of an ideal structure, without the silica nano-supports, and of two realistic fibers, with squared off and rounded air-holes. Simulation results have demonstrated the presence of anti-crossing points...

  11. Prepared GdBa2 Cu3Oy Single Domain Superconducting Bulks in Air

    Institute of Scientific and Technical Information of China (English)

    Zheng Minghui; Xiao Ling; Ren Hongtao; Jiao Yulei; Xu Bin; Fang Yuan

    2004-01-01

    The preparation of the single domain GBCO bulk with 25 mm in diameter in air was reported. In order to avoid the Gd ions substituted the Ba sites, different BaCuO2 contents was added into the precursor powders. Tc of the samples achieved 94.3 K. The magnetization hysteresis loops of the samples were measured at 77 K. It is shown that the irreverswas obtained.

  12. Effect of cooling rate on evolution of superconducting phases during decomposition and recrystallization of (Bi,Pb)-2223 core in Ag-sheathed tape

    Institute of Scientific and Technical Information of China (English)

    LI Jingyong; LI Jianguo; ZHENG Huiling; LI Chengshan; LU Yafeng; ZHOU Lian

    2006-01-01

    The reformation of (Bi,Pb)-2223 from the liquid or melt is very important for a melting process of (Bi,Pb)-2223 tape. By combination of quenching experiment with X-ray diffraction (XRD) analysis, the effect of cooling rate on the evolution of three superconducting phases in the (Bi,Pb)-2223 core of Ag-sheathed tape was investigated. The results show that (Bi,Pb)-2223 reformation from the melt seems to experience different routes during slowly cooling at different rates. One is that (Bi,Pb)-2223 phase reformed directly from the melt, and no Bi-2212 participate in this process. The other is that (Bi,Pb)-2223 is converted from the intermediate product, Bi-2212, which formed from the melt during the first cooling stage. Due to the inherent sluggish formation kinetics of (Bi,Pb)-2223 from Bi-2212, only partial (Bi,Pb)-2223 can finally be reformed with the second route.

  13. Vortex core deformation and stepper-motor ratchet behavior in a superconducting aluminum film containing an array of holes.

    Science.gov (United States)

    Van de Vondel, J; Gladilin, V N; Silhanek, A V; Gillijns, W; Tempere, J; Devreese, J T; Moshchalkov, V V

    2011-04-01

    We investigated experimentally the frequency dependence of a superconducting vortex ratchet effect by means of electrical transport measurements and modeled it theoretically using the time-dependent Ginzburg-Landau formalism. We demonstrate that the high frequency vortex behavior can be described as a discrete motion of a particle in a periodic potential, i.e., the so-called stepper-motor behavior. Strikingly, in the more conventional low frequency response a transition takes place from an Abrikosov vortex rectifier to a phase slip line rectifier. This transition is characterized by a strong increase in the rectified voltage and the appearance of a pronounced hysteretic behavior.

  14. 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

  15. Air-clad chirally-coupled-core Yb-fiber femtosecond oscillator with >10W average power

    Directory of Open Access Journals (Sweden)

    Ma Xiuquan

    2013-03-01

    Full Text Available We demonstrate high-power (> 10 W, 300-fs mode-locked oscillators at 83-MHz repetition rate using air-clad Chirally-Coupled-Core Yb-fiber with 37-µm central-core diameter, corresponding to a 30-µm mode-field-diameter.

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

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  17. Development of Electrostatically Enhanced Core Separater for Particulate Air Toxics Control

    Energy Technology Data Exchange (ETDEWEB)

    Eason, B.H.; Smolensky, L.A.; Wysk, S.R.; Altman, R.F.; Harrison, W.A.; Hardman, R.R.

    1997-12-31

    The Clean Air Act Amendments of 1990 have identified 189 chemical elements and compounds as hazardous air pollutants (HAPs). The U.S. Environmental Protection Agency (EPA) has been given the task of evaluating the health risks of these so-called air toxics and determining their acceptable emission rates. The U.S. Department of Energy (DOE), in cooperation with private industry, is sponsoring research into developing new air toxic emission control technologies. Coal typically contains trace amounts of HAPS, the species and amounts vary with coal type and source. Combustion of coal in Fossil Energy Power Systems releases these HAPs into the combustion gas where they flow to the stack by passing through the gas cleanup system. Except for mercury and selenium, the HAPs exist primarily in the solid phase temperatures typical of flue gases so they can be removed by particulate cleanup systems. In fact, these solid phase HAPs are removed with approximately the same efficiency as the other particulate matter. Table 1 shows the removal efficiency of 15 HAPs by an electrostatic precipitator having an efficiency of approximately 99 percent. These results suggest that very high removal efficiencies of particulate HAPs can be achieved by using a very high efficiency particulate collector. Epidemiological studies` suggest that there may be health benefits from reducing concentrations of particulate matter in the ambient air. This paper will discuss the development of a very high efficiency particulate collector called the Electrostatically Enhanced Core Separator (EECS) system that may have the potential to significantly reduce the emission rates of both particulates and particulate air toxics from Fossil Energy Power Systems.

  18. Effect on deformation process of adding a copper core to multifilament MgB2 superconducting wire

    DEFF Research Database (Denmark)

    Hancock, Michael Halloway; Bay, Niels

    2007-01-01

    Using the PIT method, multifilament wire with different packing strategies has been manufactured. In all, three types of wire have been investigated, a 19-filament configuration using ex-situ powder in an Fe-matrix and two 8-filament configurations in an Fe-matrix applying a copper core, one usin...

  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. Possible magnetism in vortex cores of superconducting TmNi{sub 2}B{sub 2}C studied by small angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Abrahamsen, Asger Bech

    2003-11-01

    The compound TmNi{sub 2}B{sub 2}C has previously been studied by Small Angle Neutron Scattering(SANS) with the applied field along the crystalline c-axis and a very rich phase diagram in terms of flux line lattices(FLL) with different symmetries have been observed. One of the FLL transitions is coincident with a magnetic phase transition between two spin density waves. In this thesis additional SANS studies of the FLL phases in TmNi{sub 2}B{sub 2}C are reported and an interpretation of the phase diagram in the paramagnetic region is presented. It is suggested that the square FLL observed is stable in between two transition lines determined by two different length scales. The lower transition field is reached when the distance between the flux lines becomes comparable to the non-locality radius resulting from non-local electrodynamics, whereas the upper transition field is determined from the crossover from intermediate to high flux line density where the vortex cores start to overlap and the superconducting order parameter is suppressed in between the flux lines. A detailed examination of the intensity of the neutron diffraction spots caused by scattering on the flux line lattice in TmNi{sub 2}B{sub 2}C is presented and analyzed on the basis of the form factor of an isolated flux line. This analysis can not provide a good explanation for the observed scattering and it is suggested that the scattering from the Tm ions must be considered. One can argue that the moments of the Tm ions are modulated by the flux line lattice, because the Ruderman-Kittel- Kasuya-Yosida(RKKY) interaction between the Tm ions might be different inside the vortex cores than outside in the superconducting phase. A calculation of the neutron scattering cross section of such a magnetic flux line lattice has been performed and compared to the SANS data. This offers a qualitative explanation of some of the observations, but future work is needed to perform a more quantitative comparison. (au)

  1. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  2. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  3. Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores

    Directory of Open Access Journals (Sweden)

    L. Bazin

    2015-04-01

    Full Text Available Orbital tuning is central for ice core chronologies beyond annual layer counting, available back to 60 ka (i.e. thousand of years before 1950 for Greenland ice cores. While several complementary orbital tuning tools have recently been developed using δ18Oatm, δO2/N2 and air content with different orbital targets, quantifying their uncertainties remains a challenge. Indeed, the exact processes linking variations of these parameters, measured in the air trapped in ice, to their orbital targets are not yet fully understood. Here, we provide new series of δO2/N2 and δ18Oatm data encompassing Marine Isotopic Stage (MIS 5 (between 100–160 ka and the oldest part (380–800 ka of the East Antarctic EPICA Dome C (EDC ice core. For the first time, the measurements over MIS 5 allow an inter-comparison of δO2/N2 and δ18Oatm records from three East Antarctic ice core sites (EDC, Vostok and Dome F. This comparison highlights a site-specific relationship between δO2/N2 and its local summer solstice insolation. Such a relationship increases the uncertainty associated with the use of δO2/N2 as a tool for orbital tuning. Combining records of δ18Oatm and δO2/N2 from Vostok and EDC, we evidence a loss of orbital signature for these two parameters during periods of minimum eccentricity (∼400, ∼720–800 ka. Our dataset reveals a time-varying lag between δO2/N2 and δ18Oatm over the last 800 ka that we interpret as variations of the lag between δ18Oatm and precession. Large lags of ∼5 ka are identified during Terminations I and II, associated with strong Heinrich events. On the opposite, minimal lags (∼1–2 ka are identified during four periods characterized by high eccentricity, intermediate ice volume and no Heinrich events (MIS 6–7, the end of MIS 9, MIS 15 and MIS 17. We therefore suggest that the occurrence of Heinrich events influences the response of δ18Oatm to precession.

  4. Off-resonance frequency operation for power transfer in a loosely coupled air core transformer

    Science.gov (United States)

    Scudiere, Matthew B

    2012-11-13

    A power transmission system includes a loosely coupled air core transformer having a resonance frequency determined by a product of inductance and capacitance of a primary circuit including a primary coil. A secondary circuit is configured to have a substantially same product of inductance and capacitance. A back EMF generating device (e.g., a battery), which generates a back EMF with power transfer, is attached to the secondary circuit. Once the load power of the back EMF generating device exceeds a certain threshold level, which depends on the system parameters, the power transfer can be achieved at higher transfer efficiency if performed at an operating frequency less than the resonance frequency, which can be from 50% to 95% of the resonance frequency.

  5. Air fractionation in plate-like inclusions within the EPICA-DML deep ice core

    Science.gov (United States)

    Nedelcu, A.; Faria, S. H.; Kipfstuhl, S.; Schmidt, B.; Kuhs, W. F.

    2009-04-01

    On ice samples from the ice core recovered in the frame of the European Project for Ice Coring in Antarctica at the deep drilling site in Dronning Maud Land (75°00S; 00°04E) micro-Raman spectrochemical analysis was applied to typical relaxation features appearing after the extraction of an ice core. Essentially, these relaxation microinclusions are little planar polygonal cavities possessing hexagonal symmetry i.e. thin negative crystals lying on the basal plane of the hosting ice crystallite. Usually named plate-like inclusions, PLIs, they tend to change their aspect ratio becoming in general rounder, thicker or thinner depending on the equilibrium established between the structure-composition of the ice and the minute environmental temperature-pressure conditions around a specific PLI, but still preserving a very large aspect ratio (typically 20:1). Muguruma and others (1966) and Mae (1968) have reported studies on plate hexagonal voids, i.e. PLIs, produced (only) in tensile deformation tests of natural and artificial single ice crystals while the first report of PLIs in Antarctic ice cores was presented by Gow (1971). In spite of these early studies and the abundance of PLIs in stored ice core samples, extended investigations of these relaxation features are scarce. We present the results of the first successful study of the chemical composition of PLIs using microfocus Raman spectroscopy (Nedelcu and others, in press). We observe that the relaxation features contain mainly O2 and N2 in their interior, with N2/O2 ratios smaller than 3.7 (the nowadays atmospheric air N2/O2 ratio), indicating a general oxygen enrichment that is not so different from O2 enrichments reported in other investigations on polar ice samples (Nakahara and others, 1988, Ikeda and others, 1999). These results seem to lend support to the current hypothesis that O2 diffuses faster than N2 through the ice matrix (Ikeda-Fukazawa and others, 2001, 2005; Severinghaus and Battle, 2006). More

  6. The impact of drought and air pollution on metal profiles in peat cores.

    Science.gov (United States)

    Souter, Laura; Watmough, Shaun A

    2016-01-15

    Peat cores have long been used to reconstruct atmospheric metal deposition; however, debate remains regarding how well historical depositional patterns are preserved in peat. This study examined peat cores sampled from 14 peatlands in the Sudbury region of Ontario, Canada, which has a well-documented history of acid and metal deposition. Copper (Cu) and lead (Pb) concentrations within individual peat cores were strongly correlated and were elevated in the upper 10 cm, especially in the sites closest to the main Copper Cliff smelter. In contrast, nickel (Ni) and cobalt (Co) concentrations were often elevated at depths greater than 10 cm, indicating much greater post-depositional movement of these metals compared with Cu and Pb. Post-depositional movement of metals is supported by the observation that Ni and Co concentrations in peat pore water increased by approximately 530 and 960% for Ni and Co, respectively between spring and summer due to drought-induced acidification, but there was much less change in Cu concentration. Sphagnum cover and (210)Pb activity measured at 10 cm at the 14 sites significantly increased with distance from Copper Cliff, and the surface peat von Post score decreased with distance from Copper Cliff, indicating the rate of peat formation increases with distance from Sudbury presumably as a result of improved Sphagnum survival. This study shows that the ability of peat to preserve deposition histories of some metals is strongly affected by drought-induced post-depositional movement and that loss of Sphagnum due to air pollution impairs the rate of peat formation, further affecting metal profiles in peatlands.

  7. 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.

  8. Superconductivity and superconductive electronics

    Science.gov (United States)

    Beasley, M. R.

    1990-12-01

    The Stanford Center for Research on Superconductivity and Superconductive Electronics is currently focused on developing techniques for producing increasingly improved films and multilayers of the high-temperature superconductors, studying their physical properties and using these films and multilayers in device physics studies. In general the thin film synthesis work leads the way. Once a given film or multilayer structure can be made reasonably routinely, the emphasis shifts to studying the physical properties and device physics of these structures and on to the next level of film quality or multilayer complexity. The most advanced thin films synthesis work in the past year has involved developing techniques to deposit a-axis and c-axis YBCO/PBCO superlattices and related structures. The in-situ feature is desirable because no solid state reactions with accompanying changes in volume, morphology, etc., that degrade the quality of the film involved.

  9. Measuring air core characteristics of a pressure-swirl atomizer via a transparent acrylic nozzle at various Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun J.; Oh, Sang Youp; Kim, Ho Y.; Yoon, Sam S. [Dept. of Mechanical, Korea University Anamdong, 5-Ga, Sungbukgu, 136-713 Seoul (Korea); James, Scott C. [Thermal/Fluid Science and Engineering, Sandia National Labs, PO Box 969, Livermore, CA 94551 (United States)

    2010-11-15

    Because of thermal fluid-property dependence, atomization stability (or flow regime) can change even at fixed operating conditions when subject to temperature change. Particularly at low temperatures, fuel's high viscosity can prevent a pressure-swirl (or simplex) atomizer from sustaining a centrifugal-driven air core within the fuel injector. During disruption of the air core inside an injector, spray characteristics outside the nozzle reflect a highly unstable, nonlinear mode where air core length, Sauter mean diameter (SMD), cone angle, and discharge coefficient variability. To better understand injector performance, these characteristics of the pressure-swirl atomizer were experimentally investigated and data were correlated to Reynolds numbers (Re). Using a transparent acrylic nozzle, the air core length, SMD, cone angle, and discharge coefficient are observed as a function of Re. The critical Reynolds numbers that distinguish the transition from unstable mode to transitional mode and eventually to a stable mode are reported. The working fluids are diesel and a kerosene-based fuel, referred to as bunker-A. (author)

  10. Stationary rotary force waves on the liquid-air core interface of a swirl atomizer

    Science.gov (United States)

    Chinn, J. J.; Cooper, D.; Yule, A. J.; Nasr, G. G.

    2016-10-01

    A one-dimensional wave equation, applicable to the waves on the surface of the air-core of a swirl atomizer is derived analytically, by analogy to the similar one-dimensional wave equation derivation for shallow-water gravity waves. In addition an analogy to the flow of water over a weir is used to produce an analytical derivation of the flow over the lip of the outlet of a swirl atomizer using the principle of maximum flow. The principle of maximum flow is substantiated by reference to continuity of the discharge in the direction of streaming. For shallow-water gravity waves, the phase velocity is the same expression as for the critical velocity over the weir. Similarly, in the present work, the wave phase velocity on the surface of the air-core is shown to be the same expression as for the critical velocity for the flow at the outlet. In addition, this wave phase velocity is shown to be the square root of the product of the radial acceleration and the liquid thickness, as analogous with the wave phase velocity for shallow water gravity waves, which is the square root of the product of the acceleration due to gravity and the water depth. The work revisits the weirs and flumes work of Binnie et al. but using a different methodology. The results corroborate with the work of Binnie. High speed video, Laser Doppler Anemometry and deflected laser beam experimental work has been carried out on an oversize Perspex (Plexiglas) swirl atomizer. Three distinctive types of waves were detected: helical striations, low amplitude random ripples and low frequency stationary waves. It is the latter wave type that is considered further in this article. The experimentally observed waves appear to be stationary upon the axially moving flow. The mathematical analysis allows for the possibility of a negative value for the phase velocity expression. Therefore the critical velocity and the wave phase velocity do indeed lead to stationary waves in the atomizer. A quantitative comparison

  11. Lateral distribution of high energy hadrons and gamma ray in air shower cores observed with emulsion chambers

    Science.gov (United States)

    Matano, T.; Machida, M.; Kawasumi, N.; Tsushima, I.; Honda, K.; Hashimoto, K.; Navia, C. E.; Matinic, N.; Aquirre, C.

    1985-01-01

    A high energy event of a bundle of electrons, gamma rays and hadronic gamma rays in an air shower core were observed. The bundles were detected with an emulsion chamber with thickness of 15 cm lead. This air shower is estimated to be initiated with a proton with energy around 10 to the 17th power to 10 to the 18th power eV at an altitude of around 100 gmc/2. Lateral distributions of the electromagnetic component with energy above 2 TeV and also the hadronic component of energy above 6 TeV of this air shower core were determined. Particles in the bundle are produced with process of the development of the nuclear cascade, the primary energy of each interaction in the cascade which produces these particles is unknown. To know the primary energy dependence of transverse momentum, the average products of energy and distance for various average energies of secondary particles are studied.

  12. Analysis of an Aircraft Honeycomb Sandwich Panel with Circular Face Sheet/Core Disbond Subjected to Ground-Air Pressurization

    Science.gov (United States)

    Rinker, Martin; Krueger, Ronald; Ratcliffe, James

    2013-01-01

    The ground-air pressurization of lightweight honeycomb sandwich structures caused by alternating pressure differences between the enclosed air within the honeycomb core and the ambient environment is a well-known and controllable loading condition of aerospace structures. However, initial face sheet/core disbonds intensify the face sheet peeling effect of the internal pressure load significantly and can decrease the reliability of the sandwich structure drastically. Within this paper, a numerical parameter study was carried out to investigate the criticality of initial disbonds in honeycomb sandwich structures under ground-air pressurization. A fracture mechanics approach was used to evaluate the loading at the disbond front. In this case, the strain energy release rate was computed via the Virtual Crack Closure Technique. Special attention was paid to the pressure-deformation coupling which can decrease the pressure load within the disbonded sandwich section significantly when the structure is highly deformed.

  13. Advantages of iron core in a tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Bettis, E.S.; Ballou, J.K.; Becraft, W.R.; Peng, Y.K.M.; Watts, H.L.

    1977-01-01

    A quantitative comparison of the iron core vs air core concepts was carried out on a preliminary basis by using a representative tokamak reactor design with the following self-consistent reference parameters. In the area of plasma engineering, poloidal field and MHD equilibrium considerations with an unsaturated iron core is discussed. The question of proper poloidal field coils to maintain D-shaped plasmas of relatively high anti ..beta.. (7%) with a saturated iron core is also discussed. Estimates of the required iron core size, volt seconds, magnetic flux and its influence on force loading on the superconducting toroidal field coils are shown. Conceptual designs of the mechanical structure of an iron core device are presented. Favorable impacts on the OH power supply cost and complexity are indicated.

  14. CFD simulations of a hydrocyclone in absence of an air core

    Directory of Open Access Journals (Sweden)

    Delgadillo J.A.

    2012-01-01

    Full Text Available Computational Fluid Dynamics (CFD is a versatile means to predict the characteristics of flow in fluid mechanics problems under a wide range of design and operating conditions . Applying the CFD in many engineering fields alleviates the problem of the usual engineering design. Recent advance in computational methods and computer technology make CFD an efficient means to study the dynamics of many physical systems. CFD simulations use three dimensional grid and the Reynolds Stress Model (RSM to investigate the flow without air core in a 6˝ hydrocyclone have been conducted using FLUENT. The numerical results are compared with the experimental data related to the Laser Doppler Anemometry (LDA measurements of velocity. In the experimental study, a new procedure is developed to reorient the laser beams that permit one to measure two velocity components at a single point using LDA. The conclusion developed from these experiments enables one to use the LDA directly in the hydrocyclone wall without recourse to auxiliary attachments such as an enclosing box that usually used to minimize the refraction effects of laser beams which are caused by the curved solid wall of the hydrocyclone and the refractive index of the test medium.

  15. Hollow core photonic bandgap fiber with microfluid-infiltrated air holes for slow-light propagation

    Science.gov (United States)

    Ren, Liyong; Liang, Jian; Yun, Maojin

    2012-10-01

    Slow light plays an important role in the fields of all-optical signal processing and integration photonics. It has shown many potential applications, such as realizing optical delay lines or buffers, enhancing linear and nonlinear light-matter interactions, as well as increasing the sensitivity of the interferometers and transducers. In this paper, hollow-core photonic bandgap fibers made from high index glasses are designed by infiltrating microfluid into the air-holes to tailor the fiber dispersion for slow-light propagation under low pulse distortion. In such a fiber made from Si material, group index ng~8 is obtained with a bandwidth up to 30 nm, where the group index fluctuation is restricted in ±10 % of the ng, while ng~6 is obtained with a bandwidth over 100 nm when the chalcogenide material is selected instead. Such a ±10 % criterion determines a regarded flatland region accordingly, and in this region the group velocity dispersion can be negligible. It is found that for the same fiber length the slow-light time delay in the photonic bandgap fiber is much larger as compared with that in the single mode fiber. This kind of photonic bandgap fiber may have many potential applications in short-distance fiber communications and delay lines.

  16. Design and Fabrication of Air-core Inductors for Power Conversion

    DEFF Research Database (Denmark)

    Lê Thanh, Hoà; Mizushima, Io; Tang, Peter Torben

    Microelectromechanical systems (MEMS) inductors are used for e.g. RF MEMS and microelectronics. A new application is for power electronics in switched mode power supplies (SMPS). High-performance power inductors, which can be combined with integrated circuits (IC), are required for future power s...... inductors that are impossible to make by wire-winding technology. As all process temperatures are kept below 200 ºC, the inductors can be integrated into CMOS wafers by MEMS post processing.......Microelectromechanical systems (MEMS) inductors are used for e.g. RF MEMS and microelectronics. A new application is for power electronics in switched mode power supplies (SMPS). High-performance power inductors, which can be combined with integrated circuits (IC), are required for future power...... supply on chip (PwrSoC) [1]. Examples of PwrSoC applications are power adaptors for LED illumination and the “Internet of Things”. We report an air-core MEMS inductor. Our process is scalable and universal for making inductors with versatile geometries e.g. spiral, solenoid, toroid, and advanced...

  17. Towards constraining the stratosphere-troposphere exchange of radiocarbon: strategies of stratospheric 14CO2 measurements using AirCore

    Science.gov (United States)

    Chen, Huilin; Paul, Dipayan; Meijer, Harro; Miller, John; Kivi, Rigel; Krol, Maarten

    2016-04-01

    Radiocarbon (14C) plays an important role in the carbon cycle studies to understand both natural and anthropogenic carbon fluxes, but also in atmospheric chemistry to constrain hydroxyl radical (OH) concentrations in the atmosphere. Apart from the enormous 14C emissions from nuclear bomb testing in the 1950s and 1960s, radiocarbon is primarily produced in the stratosphere due to the cosmogenic production. To this end, better understanding the stratospheric radiocarbon source is very useful to advance the use of radiocarbon for these applications. However, stratospheric 14C observations have been very limited so that there are large uncertainties on the magnitude and the location of the 14C production as well as the transport of radiocarbon from the stratosphere to the troposphere. Recently we have successfully made stratospheric 14C measurements using AirCore samples from Sodankylä, Northern Finland. AirCore is an innovative atmospheric sampling system, which passively collects atmospheric air samples into a long piece of coiled stainless steel tubing during the descent of a balloon flight. Due to the relatively low cost of the consumables, there is a potential to make such AirCore profiling in other parts of the world on a regular basis. In this study, we simulate the 14C in the atmosphere and assess the stratosphere-troposphere exchange of radiocarbon using the TM5 model. The Sodankylä radiocarbon measurements will be used to verify the performance of the model at high latitude. Besides this, we will also evaluate the influence of different cosmogenic 14C production scenarios and the uncertainties in the OH field on the seasonal cycles of radiocarbon and on the stratosphere-troposphere exchange, and based on the results design a strategy to set up a 14C measurement program using AirCore.

  18. Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    OpenAIRE

    2013-01-01

    Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by...

  19. Spray cone angle and air core diameter of hollow cone swirl rocket injector

    Directory of Open Access Journals (Sweden)

    Ahmad Hussein Abdul Hamid

    2011-12-01

    Full Text Available ABSTRACT : Fuel injector for liquid rocket is a very critical component since that small difference in its design can dramatically affect the combustion efficiency. The primary function of the injector is to break the fuel up into very small droplets. The smaller droplets are necessary for fast quiet ignition and to establish a flame front close to the injector head, thus shorter combustion chamber is possible to be utilized. This paper presents an experimetal investigation of a mono-propellant hollow cone swirl injector. Several injectors with different configuration were investigated under cold flow test, where water is used as simulation fluid. This investigation reveals that higher injection pressure leads to higher spray cone angle. The effect of injection pressure on spray cone angle is more prominent for injector with least number of tangential ports. Furthermore, it was found that injector with the most number of tangential ports and with the smallest tangential port diameter produces the widest resulting spray. Experimental data also tells that the diameter of an air core that forms inside the swirl chamber is largest for the injector with smallest tangential port diameter and least number of tangential ports.ABSTRAK : Injektor bahan api bagi roket cecair merupakan satu komponen yang amat kritikal memandangkan perbezaan kecil dalam reka bentuknya akan secara langsung mempengaruhi kecekapan pembakaran. Fungsi utama injektor adalah untuk memecahkan bahan api kepada titisan yang amat kecil. Titisan kecil penting untuk pembakaran pantas secara senyap dan untuk mewujudkan satu nyalaan di hadapan, berhampiran dengan kepala injektor, maka kebuk pembakaran yang lebih pendek berkemungkinan dapat digunakan. Kertas kerja ini mebentangkan satu penyelidikan eksperimental sebuah injektor ekabahan dorong geronggang kon pusar. Beberapa injektor dengan konfigurasi berbeza telah dikaji di bawah ujian aliran sejuk, di mana air digunakan sebagai bendalir

  20. Numerical Analysis of Dynamic Response of Corrugated Core Sandwich Panels Subjected to Near-Field Air Blast Loading

    Directory of Open Access Journals (Sweden)

    Pan Zhang

    2014-01-01

    Full Text Available Three-dimensional fully coupled simulation is conducted to analyze the dynamic response of sandwich panels comprising equal thicknesses face sheets sandwiching a corrugated core when subjected to localized impulse created by the detonation of cylindrical explosive. A large number of computational cases have been calculated to comprehensively investigate the performance of sandwich panels under near-field air blast loading. Results show that the deformation/failure modes of panels depend strongly on stand-off distance. The beneficial FSI effect can be enhanced by decreasing the thickness of front face sheet. The core configuration has a negligible influence on the peak reflected pressure, but it has an effect on the deflection of a panel. It is found that the benefits of a sandwich panel over an equivalent weight solid plate to withstand near-field air blast loading are more evident at lower stand-off distance.

  1. Superconducting electronics

    NARCIS (Netherlands)

    Rogalla, Horst

    1994-01-01

    During the last decades superconducting electronics has been the most prominent area of research for small scale applications of superconductivity. It has experienced quite a stormy development, from individual low frequency devices to devices with high integration density and pico second switching

  2. Fabrication of a polyvinylidene difluoride fiber with a metal core and its application as directional air flow sensor

    Science.gov (United States)

    Bian, Yixiang; Liu, Rongrong; Hui, Shen

    2016-09-01

    We fabricated a sensitive air flow detector that mimic the sensing mechanism found at the tail of some insects. [see Y. Yang, A. Klein, H. Bleckmann and C. Liu, Appl. Phys. Lett. 99(2) (2011); J. J. Heys, T. Gedeon, B. C. Knott and Y. Kim, J. Biomech. 41(5), 977 (2008); J. Tao and X. Yu, Smart Mat. Struct. 21(11) (2012)]. Our bionic airflow sensor uses a polyvinylidene difluoride (PVDF) microfiber with a molybdenum core which we produced with the hot extrusion tensile method. The surface of the fiber is partially coated with conductive silver adhesive that serve as surface electrodes. A third electrode, the metal core is used to polarize polyvinylidene difluoride (PVDF) under the surface electrodes. The cantilever beam structure of the prepared symmetric electrodes of metal core piezoelectric fiber (SMPF) is used as the artificial hair airflow sensor. The surface electrodes are used to measure output voltage. Our theoretical and experimental results show that the SMPF responds fast to air flow changes, the output charge has an exponential correlation with airflow velocity and a cosine relation with the direction of airflow. Our bionic airflow sensor with directional sensing ability can also measure air flow amplitude. [see H. Droogendijk, R. G. P. Sanders and G. J. M. Krijnen, New J. Phys. 15 (2013)]. By using two surface electrodes, our sensing circuit further improves sensitivity.

  3. A new CF-IRMS system for quantifying stable isotopes of carbon monoxide from ice cores and small air samples

    Directory of Open Access Journals (Sweden)

    Z. Wang

    2010-10-01

    Full Text Available We present a new analysis technique for stable isotope ratios (δ13C and δ18O of atmospheric carbon monoxide (CO from ice core samples. The technique is an online cryogenic vacuum extraction followed by continuous-flow isotope ratio mass spectrometry (CF-IRMS; it can also be used with small air samples. The CO extraction system includes two multi-loop cryogenic cleanup traps, a chemical oxidant for oxidation to CO2, a cryogenic collection trap, a cryofocusing unit, gas chromatography purification, and subsequent injection into a Finnigan Delta Plus IRMS. Analytical precision of 0.2‰ (±1δ for δ13C and 0.6‰ (±1δ for δ18O can be obtained for 100 mL (STP air samples with CO mixing ratios ranging from 60 ppbv to 140 ppbv (~268–625 pmol CO. Six South Pole ice core samples from depths ranging from 133 m to 177 m were processed for CO isotope analysis after wet extraction. To our knowledge, this is the first measurement of stable isotopes of CO in ice core air.

  4. Climatic and insolation control on the high-resolution total air content in the NGRIP ice core

    Science.gov (United States)

    Eicher, Olivier; Baumgartner, Matthias; Schilt, Adrian; Schmitt, Jochen; Schwander, Jakob; Stocker, Thomas F.; Fischer, Hubertus

    2016-10-01

    Because the total air content (TAC) of polar ice is directly affected by the atmospheric pressure and temperature, its record in polar ice cores was initially considered as a proxy for past ice sheet elevation changes. However, the Antarctic ice core TAC record is known to also contain an insolation signature, although the underlying physical mechanisms are still a matter of debate. Here we present a high-resolution TAC record over the whole North Greenland Ice Core Project ice core, covering the last 120 000 years, which independently supports an insolation signature in Greenland. Wavelet analysis reveals a clear precession and obliquity signal similar to previous findings on Antarctic TAC, with a different insolation history. In our high-resolution record we also find a decrease of 4-6 % (4-5 mL kg-1) in TAC as a response to Dansgaard-Oeschger events (DO events). TAC starts to decrease in parallel to increasing Greenland surface temperature and slightly before CH4 reacts to the warming but also shows a two-step decline that lasts for several centuries into the warm interstadial. The TAC response is larger than expected considering only changes in air density by local temperature and atmospheric pressure as a driver, pointing to a transient firnification response caused by the accumulation-induced increase in the load on the firn at bubble close-off, while temperature changes deeper in the firn are still small.

  5. Effect of interstitial air holes on Bragg gratings in photonic crystal fibre with a Ge-doped core

    Institute of Scientific and Technical Information of China (English)

    Zhang Hui-Jia; Li Shu-Guang; Hou Lan-Tian

    2009-01-01

    The effect of interstitial air holes on Bragg gratings in photonic crystal fibre (PCF) with a Ge-doped core is numerically investigated by using thc beam propagation method (BPM). It is shown that the interstitial air holes (IAHs) can make Bragg resonance wavelength λ3 shift a little towards short wavelengths and incrcase λB - λ1 (the wavelength spacing between the main peak with Bragg resonance wavelength λB and the first side peak with wavelength λ1) and the coupling coefficient κ of Bragg resonance. Moreover, when the ratio of air hole diameter (d) to pitch (A),d/A, is small, IAHs can suppress the cladding mode resonance. When d/A is large, IAHs increase the number of mode that could strongly interact with the fundamental mode. By comparing the transmission spectral characteristics of PCF-based fibrc Bragg grating (FBG) with IAHs with those without IAtIs at the same air-filling fraction, it is clarified that the change of transmission spectral characteristics of PCF-based FBG with IAHs is not due to a simple change in air-filling fraction. It is also closely related to the distribution of interstitial air holes.

  6. Selecting a Distributed Air-Gap Powder Core For Flyback Transformers

    Institute of Scientific and Technical Information of China (English)

    Magnetics

    2002-01-01

    1 IntroductionFlyback converters are based on the storage of energy in an inductorduring the "on" charging time period ton, and discharge of thisenergy to the load during the "off" time period, toff, as shown inFigure 1. The operation is unipolar and utilizes the first quadrant of the B-Hcurve of a magnetic core (Figure 2). The usable flux density is△B. The ideal core material should have a maximum available △Band low core losses (proportional to the shaded area).For flyback transformers, Magnetics offers:

  7. Highly active and durable core-corona structured bifunctional catalyst for rechargeable metal-air battery application.

    Science.gov (United States)

    Chen, Zhu; Yu, Aiping; Higgins, Drew; Li, Hui; Wang, Haijiang; Chen, Zhongwei

    2012-04-11

    A new class of core-corona structured bifunctional catalyst (CCBC) consisting of lanthanum nickelate centers supporting nitrogen-doped carbon nanotubes (NCNT) has been developed for rechargeable metal-air battery application. The nanostructured design of the catalyst allows the core and corona to catalyze the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. These materials displayed exemplary OER and ORR activity through half-cell testing, comparable to state of the art commercial lanthanum nickelate (LaNiO(3)) and carbon-supported platinum (Pt/C), with added bifunctional capabilities allowing metal-air battery rechargeability. LaNiO(3) and Pt/C are currently the most accepted benchmark electrocatalyst materials for the OER and ORR, respectively; thus with comparable activity toward both of these reactions, CCBC are presented as a novel, inexpensive catalyst component for the cathode of rechargeable metal-air batteries. Moreover, after full-range degradation testing (FDT) CCBC retained excellent activity, retaining 3 and 13 times greater ORR and OER current upon comparison to state of the art Pt/C. Zinc-air battery performances of CCBC is in good agreement with the half-cell experiments with this bifunctional electrocatalyst displaying high activity and stability during battery discharge, charge, and cycling processes. Owing to its outstanding performance toward both the OER and ORR, comparable with the highest performing commercial catalysts to date for each of the respective reaction, coupled with high stability and rechargeability, CCBC is presented as a novel class of bifunctional catalyst material that is very applicable to future generation rechargeable metal-air batteries.

  8. Superfluidity and Superconductivity in Neutron Stars

    Indian Academy of Sciences (India)

    N. Chamel

    2017-09-01

    Neutron stars, the compact stellar remnants of core-collapse supernova explosions, are unique cosmic laboratories for exploring novel phases of matter under extreme conditions. In particular, the occurrence of superfluidity and superconductivity in neutron stars will be briefly reviewed.

  9. On the correlation between air temperature and the core Earth processes: Further investigations using a continuous wavelet analysis

    CERN Document Server

    Sello, Stefano

    2011-01-01

    In a recent article by Dickey, J. O., Marcus, S.L. and O. de Viron, 2011, the authors show evidences for correlations in the multi-decadal variability of Earth's rotation rate [i.e., length of day (LOD)], the angular momentum of the core (CAM), and natural surface air temperature (SAT). Previous investigators have already found that the LOD fluctuations are largely attributed to core-mantle interactions and that the SAT appears strongly anti-correlated with the decadal LOD. As the above authors note, the cause of this common variability needs to be further investigated and studied. In fact, "since temperature cannot affect the CAM or LOD to a sufficient extent, the results favor either a direct effect of Earth's core-generated magnetic field (e.g., through the modulation of charged-particle fluxes, which may impact cloud formation) or a more indirect effect of some other core process on the climate-or yet another process that affects both". The main aim of the present research note is to further support the a...

  10. Nonlinear compression of high energy fiber amplifier pulses in air-filled hypocycloid-core Kagome fiber.

    Science.gov (United States)

    Guichard, Florent; Giree, Achut; Zaouter, Yoann; Hanna, Marc; Machinet, Guillaume; Debord, Benoît; Gérôme, Frédéric; Dupriez, Pascal; Druon, Frédéric; Hönninger, Clemens; Mottay, Eric; Benabid, Fetah; Georges, Patrick

    2015-03-23

    We report on the generation of 34 fs and 50 µJ pulses from a high energy fiber amplifier system with nonlinear compression in an air-filled hypocycloid-core Kagome fiber. The unique properties of such fibers allow bridging the gap between solid core fibers-based and hollow capillary-based post-compression setups, thereby operating with pulse energies obtained with current state-of-the-art fiber systems. The overall transmission of the compression setup is over 70%. Together with Yb-doped fiber amplifier technologies, Kagome fibers therefore appear as a promising tool for efficient generation of pulses with durations below 50 fs, energies ranging from 10 to several hundreds of µJ, and high average powers.

  11. Design and fabrication of a metal core PVDF fiber for an air flow sensor

    Science.gov (United States)

    Bian, Yixiang; Liu, Rongrong; Huang, Xiaomei; Hong, Jin; Huang, Huiyu; Hui, Shen

    2015-10-01

    To track prey or avoid predators, many arthropods can detect variations in airflow and pressure gradients using an array of very thin and sensitive filiform hairs. In this study, metal core piezoelectric poly(vinylidene fluoride) (PVDF) fibers were prepared to mimic such hair sensors. The flexibility of the fibers was very good, which was helpful for overcoming the typical brittleness of piezoelectric ceramic fibers. At the same time, the diameter of the fibers was very small (down to 50 μm in diameter). In order to mimic the insects’ hairs to the maximum extent, which was expected to greatly improve the sensitivity of such PVDF fiber-based sensors, a feasible process to prepare and extract electrodes on the surface of the fibers had to be developed. Compared with stainless steel filament-core fibers, the molybdenum filament-core PVDF fibers were easy to stretch. The molybdenum filament was then covered by a cylindrical PVDF layer with a diameter of 400 μm. One half of the longitudinal surface of the fibers was spray-coated with a conductive silver adhesive. The metal core was then used as one electrode, and the conductive silver adhesive was used as the other electrode. After polarization, a single metal-core PVDF fiber could be used as an airflow sensor. The surface structure and the sections of the PVDF fiber were analyzed by scanning electron microscopy. The results of the mechanical stretching tests showed that the metal core greatly enhanced the mechanical properties of the PVDF fibers. X-ray diffraction revealed that the greater the stretching ratio, the higher the α-to-β-phase conversion rate during the preparation of the PVDF fibers. A single metal-core PVDF fiber was used as a bionic airflow sensor, and a mechanical model of this sensor was derived. The airflow sensing capability of the PVDF fiber was experimentally confirmed in a miniature wind tunnel. The results showed that a cantilevered metal-core PVDF fiber is capable of detecting the range

  12. Monte Carlo simulation for radio detection of Ultra High Energy air shower cores by ANITA-II

    Science.gov (United States)

    Javaid, Amir

    ANITA is a balloon borne radio interferometer, originally built for detection of Ultra High Energy (UHE) neutrinos through Askaryan pulses induced by neutrinos in the deep ice. Besides searching for neutrinos, ANITA has successfully detected geomagnetic radiation from UHE cosmic ray air showers. The present work checks for the possibility of an additional method of UHE cosmic ray detection by ANITA. Highly vertical showers have shower maximum near the ice surface in Antarctica. The compact cores of these shower produce particle cascades inside the ice and consequently Askaryan radio pulses which may be detected by ANITA. A new Monte Carlo simulation SAM (SADE ANITA Monte Carlo) was developed to study this process. SAM includes a full ANITA instrument and flight model as well as two unique components required for the cosmic ray core simulation. 1) A simple model for radio emission by core initiated cascades in the Antarctic firn, including scaling of the RF emission with the shower and medium properties and a CORSIKA derived parametrization for the energy contained inside the core. 2) Due to the different event geometry, cosmic ray core induced RF signals are reflected from the bedrock and suffer more attenuation than the neutrino induced signals. Accordingly a Pan- Antarctic geo-statistical frequency dependent 3D RF attenuation model was developed based on temperature, chemistry and other physical properties of Antarctic ice. Using the aperture determined from SAM, an Auger UHE cosmic ray flux is expected to produce 7.4×10 -4 < 0.13 < 0.44 events during an ANITA-II flight exposure. There are considerable uncertainties in this estimate.

  13. AirCore-HR: a high-resolution column sampling to enhance the vertical description of CH4 and CO2

    Directory of Open Access Journals (Sweden)

    O. Membrive

    2017-06-01

    Full Text Available An original and innovative sampling system called AirCore was presented by NOAA in 2010 (Karion et al., 2010. It consists of a long (>  100 m and narrow (<  1 cm stainless steel tube that can retain a profile of atmospheric air. The captured air sample has then to be analyzed with a gas analyzer for trace mole fraction. In this study, we introduce a new AirCore aiming to improve resolution along the vertical with the objectives to (i better capture the vertical distribution of CO2 and CH4, (ii provide a tool to compare AirCores and validate the estimated vertical resolution achieved by AirCores. This (high-resolution AirCore-HR consists of a 300 m tube, combining 200 m of 0.125 in. (3.175 mm tube and a 100 m of 0.25 in. (6.35 mm tube. This new configuration allows us to achieve a vertical resolution of 300 m up to 15 km and better than 500 m up to 22 km (if analysis of the retained sample is performed within 3 h. The AirCore-HR was flown for the first time during the annual StratoScience campaign from CNES in August 2014 from Timmins (Ontario, Canada. High-resolution vertical profiles of CO2 and CH4 up to 25 km were successfully retrieved. These profiles revealed well-defined transport structures in the troposphere (also seen in CAMS-ECMWF high-resolution forecasts of CO2 and CH4 profiles and captured the decrease of CO2 and CH4 in the stratosphere. The multi-instrument gondola also carried two other low-resolution AirCore-GUF that allowed us to perform direct comparisons and study the underlying processing method used to convert the sample of air to greenhouse gases vertical profiles. In particular, degrading the AirCore-HR derived profiles to the low resolution of AirCore-GUF yields an excellent match between both sets of CH4 profiles and shows a good consistency in terms of vertical structures. This fully validates the theoretical vertical resolution achievable by AirCores. Concerning CO2 although a

  14. AirCore-HR: a high-resolution column sampling to enhance the vertical description of CH4 and CO2

    Science.gov (United States)

    Membrive, Olivier; Crevoisier, Cyril; Sweeney, Colm; Danis, François; Hertzog, Albert; Engel, Andreas; Bönisch, Harald; Picon, Laurence

    2017-06-01

    An original and innovative sampling system called AirCore was presented by NOAA in 2010 (Karion et al., 2010). It consists of a long (> 100 m) and narrow (air. The captured air sample has then to be analyzed with a gas analyzer for trace mole fraction. In this study, we introduce a new AirCore aiming to improve resolution along the vertical with the objectives to (i) better capture the vertical distribution of CO2 and CH4, (ii) provide a tool to compare AirCores and validate the estimated vertical resolution achieved by AirCores. This (high-resolution) AirCore-HR consists of a 300 m tube, combining 200 m of 0.125 in. (3.175 mm) tube and a 100 m of 0.25 in. (6.35 mm) tube. This new configuration allows us to achieve a vertical resolution of 300 m up to 15 km and better than 500 m up to 22 km (if analysis of the retained sample is performed within 3 h). The AirCore-HR was flown for the first time during the annual StratoScience campaign from CNES in August 2014 from Timmins (Ontario, Canada). High-resolution vertical profiles of CO2 and CH4 up to 25 km were successfully retrieved. These profiles revealed well-defined transport structures in the troposphere (also seen in CAMS-ECMWF high-resolution forecasts of CO2 and CH4 profiles) and captured the decrease of CO2 and CH4 in the stratosphere. The multi-instrument gondola also carried two other low-resolution AirCore-GUF that allowed us to perform direct comparisons and study the underlying processing method used to convert the sample of air to greenhouse gases vertical profiles. In particular, degrading the AirCore-HR derived profiles to the low resolution of AirCore-GUF yields an excellent match between both sets of CH4 profiles and shows a good consistency in terms of vertical structures. This fully validates the theoretical vertical resolution achievable by AirCores. Concerning CO2 although a good agreement is found in terms of vertical structure, the comparison between the various AirCores yields a large and

  15. DC Characterization of the Coaxial Superconducting Cable

    Science.gov (United States)

    Šouc, J.; Gömöry, F.; Vojenčiak, M.; Frolek, L.; Isfort, D.; Ehrenberg, J.; Bock, J.

    2008-01-01

    Coaxial cable model with superconducting core and superconducting shield conductor was constructed and tested in DC regime. While the core was already examined in our previous works, in this contribution the detailed study of the superconducting shield conductor in DC conditions is presented. It consists of 16 ReBCO coated tapes with critical current 35 A each connected in parallel. Using shunts with known values placed in series the currents in individual tapes were possible to measure. Distribution of the total cable current into the individual tapes was monitored and its influence on critical current of the cable is discussed.

  16. Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    Directory of Open Access Journals (Sweden)

    E. Capron

    2013-05-01

    Full Text Available Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI and semi-coastal (TALDICE and EPICA Dronning Maud Land, EDML Antarctic regions. Combined with available ice core air-δ15N measurements from the EPICA Dome C (EDC site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ15N profiles reveal a heterogeneous response of the firn structure to glacial–interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ15N variations, they systematically fail to capture the large millennial-scale δ15N variations measured at BI and the δ15N glacial levels measured at JRI and EDML – a mismatch previously reported for central East Antarctic ice cores. New constraints of the EDML gas–ice depth offset during the Laschamp event (~41 ka and the last deglaciation do not favour the hypothesis of a large convective zone within the firn as the explanation of the glacial firn model–δ15N data mismatch for this site. While we could not conduct an in-depth study of the influence of impurities in snow for firnification from the existing datasets, our detailed comparison between the δ15N profiles and firn model simulations under different temperature and accumulation rate scenarios suggests that the role of accumulation rate may have been underestimated in the current description of firnification

  17. Hadronic- and electromagnetic cores of air-showers observed by hybrid experiments at high mountains

    CERN Document Server

    Tamada, M

    2010-01-01

    Characteristics of the high energy families (bundle of high energy e, gamma) and hadrons in the air-showers detected in the hybrid experiment together with emulsion chamber and AS-array at Mt.Chacaltaya are studied in detail by comparing with those of CORSIKA simulations using interaction models of QGSJET and EPOS. Because the atmospheric families and hadron component have more direct information of the nuclear interaction, correlations between atmospheric families and burst (hadron component of air-showers) accompanied to air-showers are more sensitive to the mechanism of the the cosmic-ray interactions. The burst size dependence of the family energy is compared with those of simulations. It is found that the family energy accompanied by the air-showers with the larger burst-size is systematically smaller than that expected in the simulated events. The experimental results can not be described simply by changing the chemical composition of primary cosmic-rays and this indicates that the x-distribution of sec...

  18. Radiocarbon analysis of stratospheric CO2 retrieved from AirCore sampling

    NARCIS (Netherlands)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-01-01

    Radiocarbon (C-14) is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases CO2 and CH4. Measurement of radiocarbon in atmospheric CO2 generally requires the collection of large air samples (a few liters) from

  19. Radiocarbon analysis of stratospheric CO2 retrieved from AirCore sampling

    NARCIS (Netherlands)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-01-01

    Radiocarbon (C-14) is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases CO2 and CH4. Measurement of radiocarbon in atmospheric CO2 generally requires the collection of large air samples (a few liters) from w

  20. Influence of air pressure on soliton formation in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Roberts, Peter John

    2009-01-01

    Abstract Soliton formation during dispersive compression of chirped few-picosecond pulses at the microjoule level in a hollow-core photonic bandgap (HC-PBG) fiber is studied by numerical simulations. Long-pass filtering of the emerging frequency-shifted solitons is investigated with the objective...... at high powers. This allows a scaling of the output pulse energy toward the microjoule level. © 2009 Optical Society of America...

  1. A Centrifuge-Based Technique for Dry Extraction of Air for Ice Core Studies of Carbon Dioxide.

    Science.gov (United States)

    Grachev, A. M.; Brook, E. J.

    2008-12-01

    High resolution CO2 data from the Law Dome ice core document an abrupt ~10 ppm drop in CO2 at about 1600 AD (MacFarling Meure et al., Geophys. Res Lett., v. 33, L14810), which has been attributed to changes in human activities. CO2 measurements in ice cores are difficult, however, making verification of this feature an important task. We are undertaking a high-resolution study of CO2 between 1400 and 1800 AD in the WAIS Divide (Antarctica) ice core with a new dry extraction technique. The need for a dry extraction technique as opposed to a melt-refreeze technique in studies of CO2 from ice cores arises because of the well-documented artifacts in CO2 imposed by the presence of liquid water. Three dry-extraction methods have been employed by previous workers to measure CO2: needle-crushing method, ball-bearings method, and cheese-grater method (B. Stauffer, in: Encyclopedia of Quaternary Science, p. 1181, Elsevier 2007). Each has limitations, and we propose a simpler dry extraction technique, based on a large-capacity refrigerated centrifuge (the "centrifuge technique"), which eliminates the need to employ cryogenic temperatures to collect extracted gas and is more compatible with high sample throughput. The technique is now being tested on ~25-gram WAIS Divide samples in conjunction with CO2 measurements with a gas chromatograph. The technique employs a Beckman J- 6B centrifuge, in which evacuated stainless steel flask is placed: the flask has a weight inside positioned directly over a tall-standing piece of ice whose cross-section is small compared to that of the flask. Upon acceleration to 3000 rpm the weight moves down and presses the ice sample into a thin tablet covering flask's bottom, yielding the air extraction efficiency of ~80%. Preliminary tests suggest that precision and accuracy can be achieved at the level of ~1 ppm once the system is fine-tuned.

  2. Superconducting Microelectronics.

    Science.gov (United States)

    Henry, Richard W.

    1984-01-01

    Discusses superconducting microelectronics based on the Josephson effect and its advantages over conventional integrated circuits in speed and sensitivity. Considers present uses in standards laboratories (voltage) and in measuring weak magnetic fields. Also considers future applications in superfast computer circuitry using Superconducting…

  3. Glacial-interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    Directory of Open Access Journals (Sweden)

    R. Mulvaney

    2012-12-01

    Full Text Available Correct estimate of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice cores studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: output of a firn densification model and measurements of δ15N of N2 in air trapped in ice core. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI and semi coastal (TALDICE and EPICA Dronning Maud Land, EDML Antarctic regions. Combined with available δ15N measurements performed from the EPICA Dome C (EDC site, the studied regions encompass a large range of surface accumulation rate and temperature conditions. While firn densification simulations are able to correctly represent most of the δ15N trends over the last deglaciation measured in the EDC, BI, TALDICE and EDML ice cores, they systematically fail to capture BI and EDML δ15N glacial levels, a mismatch previously seen for Central East Antarctic ice cores. Using empirical constraints of the EDML gas-ice depth offset during the Laschamp event (~ 41 ka, we can rule out the existence of a large convective zone as the explanation of the glacial firn model-δ15N data mismatch for this site. The good match between modelled and measured δ15N at TALDICE as well as the lack of any clear correlation between insoluble dust concentration in snow and δ15N records in the different ice cores suggest that past changes in loads of impurities are not the only main driver of glacial-interglacial changes in firn lock-in depth. We conclude that firn densification dynamics may instead be driven mostly by accumulation rate changes. The mismatch between modelled and measured δ15N may be due to inaccurate reconstruction of past accumulation rate or underestimated influence of accumulation rate in firnification models.

  4. Robust two-dimensional superconductivity and vortex system in Bi2Te3/FeTe heterostructures.

    Science.gov (United States)

    Liu, Hong-Chao; Li, Hui; He, Qing Lin; Sou, Iam Keong; Goh, Swee K; Wang, Jiannong

    2016-05-17

    The discovery of two-dimensional superconductivity in Bi2Te3/FeTe heterostructures provides a new platform for the search of Majorana fermions in condensed matter systems. Since Majorana fermions are expected to reside at the core of the vortices, a close examination of the vortex dynamics in superconducting interface is of paramount importance. Here, we report the robustness of the interfacial superconductivity and 2D vortex dynamics in four as-grown and aged Bi2Te3/FeTe heterostructure with different Bi2Te3 epilayer thickness (3, 5, 7, 14 nm). After two years' air exposure, superconductivity remains robust even when the thickness of Bi2Te3 epilayer is down to 3 nm. Meanwhile, a new feature at ~13 K is induced in the aged samples, and the high field studies reveal its relevance to superconductivity. The resistance of all as-grown and aged heterostructures, just below the superconducting transition temperature follows the Arrhenius relation, indicating the thermally activated flux flow behavior at the interface of Bi2Te3 and FeTe. Moreover, the activation energy exhibits a logarithmic dependence on the magnetic field, providing a compelling evidence for the 2D vortex dynamics in this novel system. The weak disorder associated with aging-induced Te vacancies is possibly responsible for these observed phenomena.

  5. An Optimized Air-Core Coil Sensor with a Magnetic Flux Compensation Structure Suitable to the Helicopter TEM System

    Directory of Open Access Journals (Sweden)

    Chen Chen

    2016-04-01

    Full Text Available The air-core coil sensor (ACS is widely used as a transducer to measure the variation in magnetic fields of a helicopter transient electromagnetic (TEM system. A high periodic emitting current induces the magnetic field signal of the underground medium. However, such current also generates a high primary field signal that can affect the received signal of the ACS and even damage the receiver. To increase the dynamic range of the received signal and to protect the receiver when emitting current rises/falls, the combination of ACS with magnetic flux compensation structure (bucking coil is necessary. Moreover, the optimized ACS, which is composed of an air-core coil and a differential pre-amplifier circuit, must be investigated to meet the requirements of the helicopter TEM system suited to rapid surveying for shallow buried metal mine in rough topography. Accordingly, two ACSs are fabricated in this study, and their performance is verified and compared inside a magnetic shielding room. Using the designed ACSs, field experiments are conducted in Baoqing County. The field experimental data show that the primary field response can be compensated when the bucking coil is placed at an appropriate point in the range of allowed shift distance beyond the center of the transmitting coil and that the damage to the receiver induced by the over-statured signal can be solved. In conclusion, a more suitable ACS is adopted and is shown to have better performance, with a mass of 2.5 kg, resultant effective area of 11.6 m2 (i.e., diameter of 0.496 m, 3 dB bandwidth of 66 kHz, signal-to-noise ratio of 4 (i.e., varying magnetic field strength of 0.2 nT/s, and normalized equivalent input noise of 3.62 nV/m2.

  6. Temperature insensitive one-dimensional bending vector sensor based on eccentric-core fiber and air cavity Fabry-Perot interferometer

    Science.gov (United States)

    Kong, Jing; Zhou, Ai; Yuan, Libo

    2017-04-01

    A temperature insensitive directional bending sensor based on an eccentric-core fiber (ECF) cascaded with an air-cavity Fabry–Perot (F-P) interferometer is presented and demonstrated. The ECF-based air cavity F-P interferometer is fabricated by fuse splicing a piece of hollow-core fiber (HCF) in between an ECF and a multi-mode fiber (MMF). The bending sensitivities of the sensor at the two opposite most sensitive directions are 79.5 pm/m‑1 and ‑81.5 pm/m‑1, respectively. The temperature sensitivity of the proposed structure is as low as 1 pm °C‑1.

  7. Coexistence of ferromagnetism and superconductivity in YBCO nanoparticles.

    Science.gov (United States)

    Zhu, Zhonghua; Gao, Daqiang; Dong, Chunhui; Yang, Guijin; Zhang, Jing; Zhang, Jinlin; Shi, Zhenhua; Gao, Hua; Luo, Honggang; Xue, Desheng

    2012-03-21

    Nanoparticles of superconducting YBa(2)Cu(3)O(7-δ) were synthesized via a citrate pyrolysis technique. Room temperature ferromagnetism was revealed in the samples by a vibrating sample magnetometer. Electron spin resonance spectra at selected temperatures indicated that there is a transition from the normal to the superconducting state at temperatures below 100 K. The M-T curves with various applied magnetic fields showed that the superconducting transition temperatures are 92 K and 55 K for the air-annealed and the post-annealed samples, respectively. Compared to the air-annealed sample, the saturation magnetization of the sample by reheating the air-annealed one in argon atmosphere is enhanced but its superconductivity is weakened, which implies that the ferromagnetism maybe originates from the surface oxygen defects. By superconducting quantum interference device measurements, we further confirmed the ferromagnetic behavior at high temperatures and interesting upturns in field cooling magnetization curves within the superconducting region are found. We attributed the upturn phenomena to the coexistence of ferromagnetism and superconductivity at low temperatures. Room temperature ferromagnetism of superconducting YBa(2)Cu(3)O(7-δ) nanoparticles has been observed in some previous related studies, but the issue of the coexistence of ferromagnetism and superconductivity within the superconducting region is still unclear. In the present work, it will be addressed in detail. The cooperation phenomena found in the spin-singlet superconductors will help us to understand the nature of superconductivity and ferromagnetism in more depth.

  8. 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.

  9. Large superconducting wind turbine generators

    DEFF Research Database (Denmark)

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

    2012-01-01

    and the rotation speed is lowered in order to limit the tip speed of the blades. The ability of superconducting materials to carry high current densities with very small losses might facilitate a new class of generators operating with an air gap flux density considerably higher than conventional generators...... and 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...

  10. SUPERCONDUCTING PHOTOCATHODES.

    Energy Technology Data Exchange (ETDEWEB)

    SMEDLEY, J.; RAO, T.; WARREN, J.; SEKUTOWICZ, LANGNER, J.; STRZYZEWSKI, P.; LEFFERS, R.; LIPSKI, A.

    2005-10-09

    We present the results of our investigation of lead and niobium as suitable photocathode materials for superconducting RF injectors. Quantum efficiencies (QE) have been measured for a range of incident photon energies and a variety of cathode preparation methods, including various lead plating techniques on a niobium substrate. The effects of operating at ambient and cryogenic temperatures and different vacuum levels on the cathode QE have also been studied.

  11. Theoretical and Experimental Evaluation of the Temperature Distribution in a Dry Type Air Core Smoothing Reactor of HVDC Station

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2017-05-01

    Full Text Available The outdoor ultra-high voltage (UHV dry-type air-core smoothing reactors (DASR of High Voltage Direct Current systems are equipped with a rain cover and an acoustic enclosure. To study the convective heat transfer between the DASR and the surrounding air, this paper presents a coupled model of the temperature and fluid field based on the structural features and cooling manner. The resistive losses of encapsulations calculated by finite element method (FEM were used as heat sources in the thermal analysis. The steady fluid and thermal field of the 3-D reactor model were solved by the finite volume method (FVM, and the temperature distribution characteristics of the reactor were obtained. Subsequently, the axial and radial temperature distributions of encapsulation were investigated separately. Finally, an optical fiber temperature measurement scheme was used for an UHV DASR under natural convection conditions. Comparative analysis showed that the simulation results are in good agreement with the experimental data, which verifies the rationality and accuracy of the numerical calculation. These results can serve as a reference for the optimal design and maintenance of UHV DASRs.

  12. A preliminary investigation into the use of Red Pine (Pinus Resinosa) tree cores as historic passive samplers of POPs in outdoor air

    Science.gov (United States)

    Rauert, Cassandra; Harner, Tom

    2016-09-01

    The suitability of Red Pine trees (Pinus Resinosa) to act as passive samplers for persistent organic pollutants (POPs) in outdoor air and to provide historic information on air concentration trends was demonstrated in this preliminary investigation. Red Pine tree cores from Toronto, Canada, were tested for polycyclic aromatic hydrocarbon (PAHs), alkylated-PAHs, nitro and oxy-PAHs, polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (novel BFRs). The PBDEs and novel BFRs demonstrated a similar relative contribution in cores representing 30 years of tree growth, to that reported in contemporary air samples. Analysis of tree ring segments of 5-15 years resulted in detectable concentrations of some PAHs and alk-PAHs and demonstrated a transition from petrogenic sources to pyrogenic sources over the period 1960-2015. A simple uptake model was developed that treats the tree rings as linear-phase passive air samplers. The bark infiltration factor, IFBARK, is a key parameter of the model that reflects the permeability of the bark to allow chemicals to be transferred from ambient air to the outer tree layer (cambium). An IFBARK of about 2% was derived for the Red Pine trees based on tree core and air monitoring data.

  13. Geometric structures in hadronic cores of extensive air showers observed by KASCADE

    CERN Document Server

    Kampert, K H; Apel, W D; Badea, F; Bekk, K; Bercuci, A; Blümer, H; Bozdog, H; Brancus, I M; Büttner, C; Chilingarian, A A; Daumiller, K; Doll, P; Engel, R; Engler, J; Fessler, F; Gils, H J; Glasstetter, R; Haungs, A; Heck, D; Hörandel, J R; Klages, H O; Maier, G; Mathes, H J; Mayer, H J; Milke, J; Müller, M; Obenland, R; Oehlschläger, J; Ostapchenko, S; Petcu, M; Plewnia, S; Rebel, H; Risse, A; Risse, M; Roth, M; Schatz, G; Schieler, H; Scholz, J; Stumpert, M; Thouw, T; Ulrich, H; Van Buren, J; Vardanyan, A; Weindl, A; Wochele, J; Zabierowski, J; Zagromski, S

    2005-01-01

    The geometric distribution of high-energy hadrons >100 GeV in shower cores measured with the KASCADE calorimeter is analyzed. The data are checked for sensitivity to hadronic interaction features and indications of new physics as discussed in the literature. The angular correlation of the most energetic hadrons and in particular the fraction of events with hadrons being aligned are quantified by means of the commonly used parameter lambda_4. The analysis shows that the observed lambda_4 distribution is compatible with that predicted by simulations and is not linked to an angular correlation from hadronic jet production at high energy. Another parameter, d_4^max, describing distances between hadrons measured in the detector, is found to be sensitive both to the transverse momenta in secondary hadron production and the primary particle type. Transverse momenta in high-energy hadron interactions differing by a factor two or more from what is assumed in the standard simulations are disfavoured by the measured d_4...

  14. Air-core microcavities and metal-dielectric filters - building blocks for optofluidic microsystems

    Science.gov (United States)

    Allen, Trevor Warren

    This thesis describes a study on two optical devices intended to be building blocks for the creation of integrated optical/microfluidic lab-on-a-chip systems. First, arrays of curved-mirror dome-shaped microcavities were fabricated by buckling self-assembly of a-Si/SiO2 multilayers. This novel technique employs controlled, stress-induced film delamination to form highly symmetric cavities with minimal roughness defects or geometrical imperfections. Measured cavity heights were in good agreement with predictions from elastic buckling theory. Also, the measured finesse (> 103) and quality factor (> 104 in the 1550-nm range) were close to reflectance-limited predictions, indicating low defects and roughness. Hermite- and Laguerre-Gaussian modes were observable, indicating a high degree of cylindrical symmetry. In the second part of the research, transmittance in periodic metal-dielectric multilayer structures was studied. Metal-dielectric stacks have many potential applications in optofluidic microsystems, including as transmission filters, superlenses, and substrates for surface plasmon sensors. In this work, we showed that potential transmittance theory provides a good method for describing the tunneling of photons through metal-dielectric stacks, for both Fabry-Perot and surface plasmon resonances. This approach explains the well-known fact that for a given thickness of metal, subdividing the metal into several thin films can increase the maximum transmittance. Conditions for admittance matching of dielectric-metal-dielectric unit cells to an external air medium were explored for Fabry-Perot based tunneling, revealing that thicker metal films require higher-index dielectrics for optimal admittance matching. It was also shown for the first time that potential transmittance theory can be used to predict the maximum possible transmittance in surface-plasmon-mediated tunneling. In a subsequent study, potential transmittance was used to derive an expression for

  15. 饱和铁芯型超导限流器研究进展综述%Summarization of R&D on DC biased iron core type superconductive fault current limiter

    Institute of Scientific and Technical Information of China (English)

    金涛; 徐颖; 周世平; 何清; 任丽

    2013-01-01

    电力系统短路电流对系统的稳定安全运行造成了极大的威胁,超导故障限流器是一种将超导技术、电力技术相结合产生的故障限流装置,能有效地限制短路电流.饱和铁芯型超导限流器是产业化前景较好的一种超导限流器,在对此类型的故障限流器进行了深入调研和广泛收集资料的基础上,介绍了饱和铁芯型超导限流器的工作原理,分析了它的优缺点,阐述了饱和铁芯型超导限流器的国内外发展现状,归纳了其在设计过程中的关键技术和制约其工业化应用的主要问题,并提出了技术建议,最后展望了饱和铁芯型超导限流的应用前景.%The continuous enlargement of fault current has great influence on the stability and safety of power system. Super-conductive Fault Current Limiter (SFCL) is a current - limiting device which combines the superconducting technology with the electric technology, which is a effective way to solve the problem. And DC biased iron core type SFCL has the better application prospect. According to the investigation and extensive collection of fundamental data, the operating principle of this type SFCL was introduced in this paper. Through analyzing the research and development situation at home and abroad, its advantages and disadvantages were compared. The key technologies in design procedure and main problems constraining its industrial application were summarized. Finally, technical proposal of the DC biased iron core type SFCL was proposed, and the application prospect of it was predicted.

  16. Stabilized soliton self-frequency shift and 0.1- PHz sideband generation in a photonic-crystal fiber with an air-hole-modified core.

    Science.gov (United States)

    Liu, Bo-Wen; Hu, Ming-Lie; Fang, Xiao-Hui; Li, Yan-Feng; Chai, Lu; Wang, Ching-Yue; Tong, Weijun; Luo, Jie; Voronin, Aleksandr A; Zheltikov, Aleksei M

    2008-09-15

    Fiber dispersion and nonlinearity management strategy based on a modification of a photonic-crystal fiber (PCF) core with an air hole is shown to facilitate optimization of PCF components for a stable soliton frequency shift and subpetahertz sideband generation through four-wave mixing. Spectral recoil of an optical soliton by a red-shifted dispersive wave, generated through a soliton instability induced by high-order fiber dispersion, is shown to stabilize the soliton self-frequency shift in a highly nonlinear PCF with an air-hole-modified core relative to pump power variations. A fiber with a 2.3-microm-diameter core modified with a 0.9-microm-diameter air hole is used to demonstrate a robust soliton self-frequency shift of unamplified 50-fs Ti: sapphire laser pulses to a central wavelength of about 960 nm, which remains insensitive to variations in the pump pulse energy within the range from 60 to at least 100 pJ. In this regime of frequency shifting, intense high- and low-frequency branches of dispersive wave radiation are simultaneously observed in the spectrum of PCF output. An air-hole-modified-core PCF with appropriate dispersion and nonlinearity parameters is shown to provide efficient four-wave mixing, giving rise to Stokes and anti-Stokes sidebands whose frequency shift relative to the pump wavelength falls within the subpetahertz range, thus offering an attractive source for nonlinear Raman microspectroscopy.

  17. Core temperature in super-Gaussian pumped air-clad photonic crystal fiber lasers compared with double-clad fiber lasers

    Indian Academy of Sciences (India)

    P Elahi; H Nadgaran; F Kalantarifard

    2007-03-01

    In this paper we investigate the core temperature of air-clad photonic crystal fiber (PCF) lasers pumped by a super-Gaussian (SG) source of order four. The results are compared with conventional double-clad fiber (DCF) lasers pumped by the same super-Gaussian and by top-hat pump profiles.

  18. Variations in air temperature during the last 100 years revealed by δ18 O in the Malan ice core from the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Ninglian; YAO Tandong; PU Jianchen; ZHANG Yongliang; SUN Weizhen; WANG Youqing

    2003-01-01

    By comprehensive analyses, it was found that the variations in δ18O recorded in Malan ice core from the Kekexili Region on the Tibetan Plateau could represent the changes in air temperature during the summer half year (from May to October) over the Kekexili Region and the northern margin of the Tibetan Plateau. The general increase trend in δ18O in this ice core during the past century indicated climate warming, and it was estimated that air temperature during the summer half-year rose about 1.2℃over there then. However, this ice core record documented that the study area has been cooling while most of the world has been dramatically warming since the late 1970s. A teleconnection was found between the variations in δ18O in the Malan ice core and the North Atlantic Oscillation. Moreover,the variations in δ18O in this ice core were similar to that in the summer half-year air temperature over the southern Tibetan Plateau on the centurial time scale, but opposite on the multidecadal time scale.

  19. A centrifugal ice microtome for measurements of atmospheric CO2 on air trapped in polar ice cores

    Directory of Open Access Journals (Sweden)

    H. Fischer

    2012-10-01

    Full Text Available For atmospheric CO2 reconstructions using ice cores, the technique to release the trapped air from the ice samples is crucial for the precision and accuracy of the measurements. We present here a new dry extraction technique in combination with a new gas analytical system that together show significant improvements with respect to current systems. Ice samples (3–15 g are pulverized using a novel Centrifugal Ice Microtome (CIM by shaving the ice in a cooled vacuum chamber (−27 °C in which no friction occurs due to the use of magnetic bearings. Both, the shaving principle of the CIM and the use of magnetic bearings have not been applied so far in this field. Shaving the ice samples produces finer ice powder and releases a minimum of 90% of the trapped air compared to 50%–70% when needle crushing is employed. In addition, the friction-free motion with an optimized design to reduce contaminations of the inner surfaces of the device result in a reduced system offset of about 2.0 ppmv compared to 4.9ppmv. The gas analytical part shows a factor two higher precision than our corresponding part of the previous system and all processes except the loading and cleaning of the CIM now run automatically. Compared to our previous system the new system shows a 3 times better measurement reproducibility of about 1.1 ppmv (1σ which is similar to the best reproducibility of other systems applied in this field. With this high reproducibility, replicate measurements are not required anymore for most prospective measurement campaigns resulting in a possible output of 12–20 measurements per day compared to a maximum of 6 with other systems.

  20. Experimental study on two-phase flow natural circulation in a core catcher cooling channel for EU-APR1400 using air-water system

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki Won [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Korea Atomic Energy Research Institute, Daejeon 34057 (Korea, Republic of); Nguyen, Thanh Hung [School of Nuclear Engineering, Purdue University, West Lafayette, IN 47906 (United States); Ha, Kwang Soon; Kim, Hwan Yeol; Song, Jinho [Korea Atomic Energy Research Institute, Daejeon 34057 (Korea, Republic of); Park, Hyun Sun [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Revankar, Shripad T., E-mail: shripad@postech.ac.kr [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); School of Nuclear Engineering, Purdue University, West Lafayette, IN 47906 (United States); Kim, Moo Hwan [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Korea Institute of Nuclear Safety, Daejeon 305-338 (Korea, Republic of)

    2017-05-15

    Highlights: • Two-phase flow regimes and transition behavior were observed in the coolant channel. • Test were conducted for natural circulation with air-water. • Data were obtained on flow regime, void fraction, flow rates and re-wetting time. • The data were related to a cooling capability of core catcher system. - Abstract: Ex-vessel core catcher cooling system driven by natural circulation is designed using a full scaled air-water system. A transparent half symmetric section of a core catcher coolant channel of a pressurized water reactor was designed with instrumentations for local void fraction measurement and flow visualization. Two designs of air-water top separator water tanks are studied including one with modified ‘super-step’ design which prevents gas entrainment into down-comer. In the experiment air flow rates are set corresponding to steam generation rate for given corium decay power. Measurements of natural circulation flow rate, spatial local void fraction distribution and re-wetting time near the top wall are carried out for various air flow rates which simulate boiling-induced vapor generation. Since heat transfer and critical heat flux are strongly dependent on the water mass flow rate and development of two-phase flow on the heated wall, knowledge of two-phase flow characteristics in the coolant channel is essential. Results on flow visualization showing two phase flow structure specifically near the high void accumulation regions, local void profiles, rewetting time, and natural circulation flow rate are presented for various air flow rates that simulate corium power levels. The data are useful in assessing the cooling capability of and safety of the core catcher system.

  1. Superconducting Electric Machines for Ship Propulsion.

    Science.gov (United States)

    1977-02-14

    ship propulsion applications. These concepts evolved from previous work at MIT on superconducting AC machines. The superconducting machines considered were: (1) multipole, low-speed motors, (2) torque compensated motors, (3) high-speed generator, (4) rotating air-gap armature induction motor, (5) thyristor switched AC motors. The first four machine types were studied theoretically while experimental models were constructed of the last two. Preliminary designs were completed...of the five mahcines for an appropriate ship ... propulsion application. In

  2. Temperature dependence of beat-length and confinement loss in an air-core photonic band-gap fiber

    Science.gov (United States)

    Xu, Zhenlong; Li, Xuyou; Hong, Yong; Liu, Pan; Yang, Hanrui; Ling, Weiwei

    2016-05-01

    The temperature dependence of polarization-maintaining (PM) property and loss in a highly-birefringent air-core photonic band-gap fiber (PBF) is investigated. The effects of temperature variation on the effective index, beat-length and confinement loss are studied numerically by using the full-vector finite element method (FEM). It is found that, the PM property of this PBF is insensitive to the temperature, and the temperature-dependent beat-length coefficient can be as low as 2.86×10-8 m/°C, which is typically 200 times less than those of conventional panda fibers, the PBF has a stable confinement loss of 0.01 dB/m over the temperature range of -30 to 20 °C for the slow axis at the wavelength of 1.55 μm. The PBF with ultra-low temperature-dependent PM property and low loss can reduce the thermally induced polarization instability apparently in interferometric applications such as resonant fiber optic gyroscope (RFOG), optical fiber sensors, and so on.

  3. Small field diode correction factors derived using an air core fibre optic scintillation dosimeter and EBT2 film.

    Science.gov (United States)

    Ralston, Anna; Liu, Paul; Warrener, Kirbie; McKenzie, David; Suchowerska, Natalka

    2012-05-07

    There is no commercially available real-time dosimeter that can accurately measure output factors for field sizes down to 4 mm without the use of correction factors. Silicon diode detectors are commonly used but are not dosimetrically water equivalent, resulting in energy dependence and fluence perturbation. In contrast, plastic scintillators are nearly dosimetrically water equivalent. A fibre optic dosimeter (FOD) with a 0.8 mm(3) plastic scintillator coupled to an air core light guide was used to measure the output factors for Novalis/BrainLab stereotactic cones of diameter 4-30 mm and Novalis MLC fields of width 5-100 mm. The FOD data matched the output factors measured by a 0.125 cm(3) Semiflex ion chamber for the MLC fields above 30 mm and those measured with the EBT2 radiochromic film for the cones and MLC fields below 30 mm. Relative detector readings were obtained with four diode types (IBA SFD, EFD, PFD, PTW 60012) for the same fields. Empirical diode correction factors were determined by taking the ratio of FOD output factors to diode relative detector readings. The diodes were found to over-respond by 3%-16% for the smallest field. There was good agreement between different diodes of the same model number.

  4. 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...

  5. 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

  6. Low cost, formable, high T(sub c) superconducting wire

    Science.gov (United States)

    Smialek, James L. (Inventor)

    1991-01-01

    A ceramic superconductivity part such as a wire is produced through the partial oxidation of a specially formulated copper alloy in the core. The alloys contain low level quantities of rare earth and alkaline earth dopant elements. Upon oxidation at high temperature, superconducting oxide phases are formed as a thin film.

  7. Induced Magnetism in Color-Superconducting Media

    CERN Document Server

    Ferrer, Efrain J

    2009-01-01

    The dense core of compact stars is the natural medium for the realization of color superconductivity. A common characteristic of such astrophysical objects is their strong magnetic fields, especially those of the so called magnetars. In this talk, I discuss how a color superconducting core can generate or/and enhance the stellar magnetic field independently of a magnetohydrodynamic dynamo mechanism. The magnetic field generator is in this case a gluonic current which circulates to stabilize the color superconductor in the presence of a strong magnetic field or under the pairing stress produced in the medium by the neutrality and $\\beta$-equilibrium constraints.

  8. High field superconducting magnets

    Science.gov (United States)

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

    2011-01-01

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

  9. Optimum coil shape for a given volume of conductor to obtain maximum central field in an air core solenoid

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, P. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    This paper is an expansion of engineering notes prepared in 1961 to address the question of how to wind circular coils so as to obtain the maximum axial field with the minimum volume of conductor. At the time this was a germain question because of the advent of superconducting wires which were in very limited supply, and the rapid push for generation of very high fields, with little concern for uniformity.

  10. Theory of superconductivity

    CERN Document Server

    Crisan, Mircea

    1989-01-01

    This book discusses the most important aspects of the theory. The phenomenological model is followed by the microscopic theory of superconductivity, in which modern formalism of the many-body theory is used to treat most important problems such as superconducting alloys, coexistence of superconductivity with the magnetic order, and superconductivity in quasi-one-dimensional systems. It concludes with a discussion on models for exotic and high temperature superconductivity. Its main aim is to review, as complete as possible, the theory of superconductivity from classical models and methods up t

  11. NSGA-II Algorithm with a Local Search Strategy for Multiobjective Optimal Design of Dry-Type Air-Core Reactor

    Directory of Open Access Journals (Sweden)

    Chengfen Zhang

    2015-01-01

    Full Text Available Dry-type air-core reactor is now widely applied in electrical power distribution systems, for which the optimization design is a crucial issue. In the optimization design problem of dry-type air-core reactor, the objectives of minimizing the production cost and minimizing the operation cost are both important. In this paper, a multiobjective optimal model is established considering simultaneously the two objectives of minimizing the production cost and minimizing the operation cost. To solve the multi-objective optimization problem, a memetic evolutionary algorithm is proposed, which combines elitist nondominated sorting genetic algorithm version II (NSGA-II with a local search strategy based on the covariance matrix adaptation evolution strategy (CMA-ES. NSGA-II can provide decision maker with flexible choices among the different trade-off solutions, while the local-search strategy, which is applied to nondominated individuals randomly selected from the current population in a given generation and quantity, can accelerate the convergence speed. Furthermore, another modification is that an external archive is set in the proposed algorithm for increasing the evolutionary efficiency. The proposed algorithm is tested on a dry-type air-core reactor made of rectangular cross-section litz-wire. Simulation results show that the proposed algorithm has high efficiency and it converges to a better Pareto front.

  12. Relationships between Organizational Commitment, Core Job Characteristics, and Organizational Citizenship Behaviors in United States Air Force Organizations

    Science.gov (United States)

    2006-06-01

    fact, former Secretary of the Air Force James Roche made retaining Air Force personnel the Air Force’s number one priority and made the retention of...could therefore be used to redesign health organizations in Malaysia to promote commitment (Pearson & Chong, 1997). Although feedback was found not

  13. In situ electrical transport measurement of superconductive ultrathin films

    Institute of Scientific and Technical Information of China (English)

    刘灿华; 贾金锋

    2015-01-01

    The discovery of an extraordinarily superconductive large energy gap in SrTiO3 supported single-layer FeSe films has recently initiated a great deal of research interests in surface-enhanced superconductivity and superconductive ultrathin films fabricated on crystal surfaces. On account of the instability of ultra-thin films in air, it is desirable to perform elec-trical transport measurement in ultra-high vaccum (UHV). Here we review the experimental techniques of in situ electrical transport measurement and their applications on superconductive ultrathin films.

  14. Progress report on a new search for free e/3 quarks in the cores of 10(15) - 10(16) eV air showers

    Science.gov (United States)

    Hodson, A. L.; Bull, R. M.; Taylor, R. S.; Belford, C. H.

    1985-01-01

    The Leeds 3 sq m Wilson cloud chamber is being used in a new search for free e/3 quarks close to the axes of 10 to the 15th power - 10 to the 16th power eV air showers. A ratio trigger circuit is used to detect the incidence of air shower cores; the position of the shower center and the axis direction are determined from photographs of current-limited spark chambers. It is thus possible, for the first time, to know where we have looked for quarks in air showers and to select for scanning only those cloud chamber photographs where we have good evidence that the shower axis was close to the chamber. 250 g/sq cm of lead/concrete absorber above the cloud chamber serve to reduce particle densities and make a quark search possible very close to the shower axes. The current status of the search is given.

  15. Dating the 800 ka - long EPICA DC ice core by tuning the air content and δO2/N2 records on local summer insolation.

    Science.gov (United States)

    Raynaud, D.; Lipenkov, V.; Loutre, M.-F.; Landais, A.; Capron, E.

    2012-04-01

    A new method of dating the long glacial-interglacial ice core records has emerged during the last 10 years. It is based on properties measured on the air extracted from the ice that are used as proxies of local summer insolation. This dating method is referred to as "local orbital tuning dating". It's an almost absolute dating, providing we better understand the link between the influence of the local summer insolation on the snow grains at the surface and the measured properties in the ice, namely the content and the δO2/N2 ratio of the air enclosed in the ice. Changes in these two properties have already shown convincing correlations with orbitally forced local summer insolation on several Antarctic and Greenland long ice core records. Moreover, both δO2/N2 and air content have recently been measured for the first time on the same ice core (Vostok). The same methods of spectral analysis were applied on these records. The two experimentally independent local insolation proxies lead to orbital timescales that agree well together (within less than 1ka on average). We present here new air content (V) data obtained along the Antarctic EPICA DC ice cores. These data extent the existing record, which covers the last 430,000 years, to about 800,000 years, i.e. they add four glacial-interglacial cycles. The new record has a time resolution of 2,000 years on average. The spectral properties of the new 430 - 800 kyr V record are primarily obtained by continuous wavelet transform (CWT) analysis. It confirms and refines the results from the Blackman-Tukey (BT) and Multi-Taper Method (MTM analysis). The spectral signature of V is compared to its specific Integrated Summer Insolation (ISI) target and the time delay between the V signal and its ISI target is used to propose a V chronology for the oldest part of the record (800-430 kyr BP). The spectral signatures of V and the insolation targets will be compared between the 800 -430 ka BP period (this work) and the 430 - 0 ka

  16. Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction.

    Science.gov (United States)

    Li, J Jack; Wang, Y Andrew; Guo, Wenzhuo; Keay, Joel C; Mishima, Tetsuya D; Johnson, Matthew B; Peng, Xiaogang

    2003-10-15

    Successive ion layer adsorption and reaction (SILAR) originally developed for the deposition of thin films on solid substrates from solution baths is introduced as a technique for the growth of high-quality core/shell nanocrystals of compound semiconductors. The growth of the shell was designed to grow one monolayer at a time by alternating injections of air-stable and inexpensive cationic and anionic precursors into the reaction mixture with core nanocrystals. The principles of SILAR were demonstrated by the CdSe/CdS core/shell model system using its shell-thickness-dependent optical spectra as the probes with CdO and elemental S as the precursors. For this reaction system, a relatively high temperature, about 220-240 degrees C, was found to be essential for SILAR to fully occur. The synthesis can be readily performed on a multigram scale. The size distribution of the core/shell nanocrystals was maintained even after five monolayers of CdS shell (equivalent to about 10 times volume increase for a 3.5 nm CdSe nanocrystal) were grown onto the core nanocrystals. The epitaxial growth of the core/shell structures was verified by optical spectroscopy, TEM, XRD, and XPS. The photoluminescence quantum yield (PL QY) of the as-prepared CdSe/CdS core/shell nanocrystals ranged from 20% to 40%, and the PL full-width at half-maximum (fwhm) was maintained between 23 and 26 nm, even for those nanocrystals for which the UV-vis and PL peaks red-shifted by about 50 nm from that of the core nanocrystals. Several types of brightening phenomena were observed, some of which can further boost the PL QY of the core/shell nanocrystals. The CdSe/CdS core/shell nanocrystals were found to be superior in comparison to the highly luminescent CdSe plain core nanocrystals. The SILAR technique reported here can also be used for the growth of complex colloidal semiconductor nanostructures, such as quantum shells and colloidal quantum wells.

  17. Simple Superconducting "Permanent" Electromagnet

    Science.gov (United States)

    Israelson, Ulf E.; Strayer, Donald M.

    1992-01-01

    Proposed short tube of high-temperature-superconducting material like YBa2Cu3O7 acts as strong electromagnet that flows as long as magnetic field remains below critical value and temperature of cylinder maintained sufficiently below superconducting-transition temperature. Design exploits maximally anisotropy of high-temperature-superconducting material.

  18. 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.

  19. Superconductivity of lead

    Energy Technology Data Exchange (ETDEWEB)

    Boorse, H.A.; Cook, D.B.; Zemansky, W.M.

    1950-06-01

    Numerous determinations of the zero-field transition temperature of lead have been made. All of these observations except that of Daunt were made by the direct measurement of electrical resistance. Daunt`s method involved the shielding effect of persistent currents in a hollow cylinder. In the authors work on columbium to be described in a forthcoming paper an a.c. induction method was used for the measurement of superconducting transitions. The superconductor was mounted as a cylindrical core of a coil which functioned as the secondary of a mutual inductance. The primary coil was actuated by an oscillator which provided a maximum a.c. field within the secondary of 1.5 oersteds at a frequency of 1000 cycles per second. The secondary e.m.f. which was dependent for its magnitude on the permeability of the core was amplified, rectifie, and observed on a recording potentiometer. During the application of this method to the study of columbium it appeared that a further check on the zero-field transition temperature of lead would be worth while especially if agreement between results for very pure samples could be obtained using this method. Such result would help in establishing the lead transition temperature as a reasonably reproducible reference point in the region between 4 deg and 10 deg K.

  20. Superconductivity in Medicine

    Science.gov (United States)

    Alonso, Jose R.; Antaya, Timothy A.

    2012-01-01

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

  1. Enhanced superconductivity of fullerenes

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-06-20

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

  2. 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.

  3. Protective link for superconducting coil

    Science.gov (United States)

    Umans, Stephen D.

    2009-12-08

    A superconducting coil system includes a superconducting coil and a protective link of superconducting material coupled to the superconducting coil. A rotating machine includes first and second coils and a protective link of superconducting material. The second coil is operable to rotate with respect to the first coil. One of the first and second coils is a superconducting coil. The protective link is coupled to the superconducting coil.

  4. Characterization of rapid climate changes through isotope analyses of ice and entrapped air in the NEEM ice core

    DEFF Research Database (Denmark)

    Guillevic, Myriam

    Greenland ice core have revealed the occurrence of rapid climatic instabilities during the last glacial period, known as Dansgaard-Oeschger (DO) events, while marine cores from the North Atlantic have evidenced layers of ice rafted debris deposited by icebergs melt, caused by the collapse...... four Greenland deep ice cores (GRIP, GISP2, NGRIP and NEEM) are investigated over a series of Dansgaard– Oeschger events (DO 8, 9 and 10). Combined with firn modeling, δ15N data allow us to quantify abrupt temperature increases for each drill site (1σ = 0.6°C for NEEM, GRIP and GISP2, 1.5°C for NGRIP...

  5. Design of single-winding energy-storage reactors for dc-to-dc converters using air-gapped magnetic-core structures

    Science.gov (United States)

    Ohri, A. K.; Wilson, T. G.; Owen, H. A., Jr.

    1977-01-01

    A procedure is presented for designing air-gapped energy-storage reactors for nine different dc-to-dc converters resulting from combinations of three single-winding power stages for voltage stepup, current stepup and voltage stepup/current stepup and three controllers with control laws that impose constant-frequency, constant transistor on-time and constant transistor off-time operation. The analysis, based on the energy-transfer requirement of the reactor, leads to a simple relationship for the required minimum volume of the air gap. Determination of this minimum air gap volume then permits the selection of either an air gap or a cross-sectional core area. Having picked one parameter, the minimum value of the other immediately leads to selection of the physical magnetic structure. Other analytically derived equations are used to obtain values for the required turns, the inductance, and the maximum rms winding current. The design procedure is applicable to a wide range of magnetic material characteristics and physical configurations for the air-gapped magnetic structure.

  6. Ultra-large number of transmission channels in space division multiplexing using few-mode multi-core fiber with optimized air-hole-assisted double-cladding structure.

    Science.gov (United States)

    Watanabe, Tatsuhiko; Kokubun, Yasuo

    2014-04-07

    The ultimate number of transmission channels in a fiber for the space division multiplexing (SDM) is shown by designing an air-hole-assisted double-cladding few-mode multi-core fiber. The propagation characteristics such as the dispersion and the mode field diameter are almost equalized for all cores owing to the double cladding structure, and the crosstalk between adjacent cores is extremely suppressed by the heterogeneous arrangement of cores and the air holes surrounding the cores. Optimizing the structure of the air-hole-assisted double-cladding, ultra dense core arrangements, e.g. 129 cores in a core accommodated area with 200 μm diameter, can be realized with low crosstalk of less than -34.3 dB at 100km transmission. In this design, each core supports 3 modes i.e. LP(01), LP(11a), and LP(11b) as the transmission channels, so that the number of transmission channels can be 3-hold greater than the number of cores. Therefore, 387 transmission channels can be realized.

  7. A new CF-IRMS system for the quantification of the stable isotopes of carbon monoxide from ice cores and small air samples

    Directory of Open Access Journals (Sweden)

    Z. Wang

    2009-10-01

    Full Text Available A new simultaneous analysis technique for stable isotope ratios (δ13C and δ18O of atmospheric carbon monoxide (CO from ice core samples and small air samples is presented, based on an on-line cryogenic vacuum extraction followed by continuous-flow isotope ratio mass spectrometry (CF-IRMS. The CO extraction system includes two multi-loop cryogenic cleanup traps, a chemical oxidant for oxidation to CO2, a cryogenic collection trap, a cryofocusing unit, purification by gas chromatography, and subsequent injection into a Finnigan Delta Plus IRMS. Analytical precision of 0.2‰(±1σ for δ13C and 0.6‰(±1σ for δ18O can be obtained for 100 mL (STP air sample with CO mixing ratio ranging from 60 to 140 ppbv (~268–625 pmol CO. Six South Pole ice core samples with depth ranging from 133 to 177 m are also processed for CO isotope analysis based on a wet extraction line attached to the above cryogenic vacuum system. This is the first report on measuring isotope ratios of CO in ice core samples.

  8. Superconductivity in transition metals.

    Science.gov (United States)

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

    2015-03-13

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

  9. Cryogenic Characteristics of the ATLAS Barrel Toroid Superconducting Magnet

    CERN Document Server

    Pengo, R; Delruelle, N; Pezzetti, M; Pirotte, O; Passardi, Giorgio; Dudarev, A; ten Kate, H

    2008-01-01

    ATLAS, one of the experiments of the LHC accelerator under commissioning at CERN, is equipped with a large superconducting magnet the Barrel Toroid (BT) that has been tested at nominal current (20500 A). The BT is composed of eight race-track superconducting coils (each one weights about 45 tons) forming the biggest air core toroidal magnet ever built. By means of a large throughput centrifugal pump, a forced flow (about 10 liter/second at 4.5 K) provides the indirect cooling of the coils in parallel. The paper describes the results of the measurements carried out on the complete cryogenic system assembled in the ATLAS cavern situated 100 m below the ground level. The measurements include, among other ones, the static heat loads, i.e., with no or constant current in the magnet, and the dynamic ones, since additional heat losses are produced, during the current ramp-up or slow dump, by eddy currents induced on the coil casing.

  10. A Compact Fiber Inclinometer Using a Thin-Core Fiber with Incorporated an Air-Gap Microcavity Fiber Interferometer

    Directory of Open Access Journals (Sweden)

    Jiacheng Li

    2016-01-01

    Full Text Available A compact fiber-optic inclinometer is proposed and experimentally demonstrated based on a Fabry-Perot interference (FFPI. The sensing head consists of a short segment of thin-core fiber (TCF following with a piece of hollow-core fiber (HCF. High-order cladding modes have been excited because of core diameter mismatch. A clear interference spectrum has been obtained as the consequence of interference among the reflected core modes and cladding modes. Fringe contrast of the interference spectrum is highly sensitive to fiber bending with direction independence, and good linearity has been observed during the bending range from 1° to 3° with a sensitivity of 2.71 dB/deg.

  11. Face Sheet/Core Disbond Growth in Honeycomb Sandwich Panels Subjected to Ground-Air-Ground Pressurization and In-Plane Loading

    Science.gov (United States)

    Chen, Zhi M.; Krueger, Ronald; Rinker, Martin

    2015-01-01

    Typical damage modes in light honeycomb sandwich structures include face sheet/core disbonding and core fracture, both of which can pose a threat to the structural integrity of a component. These damage modes are of particular interest to aviation certification authorities since several in-service occurrences, such as rudder structural failure and other control surface malfunctions, have been attributed to face sheet/core disbonding. Extensive studies have shown that face sheet/core disbonding and core fracture can lead to damage propagation caused by internal pressure changes in the core. The increasing use of composite sandwich construction in aircraft applications makes it vitally important to understand the effect of ground-air-ground (GAG) cycles and conditions such as maneuver and gust loads on face sheet/core disbonding. The objective of the present study was to use a fracture mechanics based approach developed earlier to evaluate the loading at the disbond front caused by ground-air-ground pressurization and in-plane loading. A honeycomb sandwich panel containing a circular disbond at one face sheet/core interface was modeled with three-dimensional (3D) solid finite elements. The disbond was modeled as a discrete discontinuity and the strain energy release rate along the disbond front was computed using the Virtual Crack Closure Technique (VCCT). Special attention was paid to the pressure-deformation coupling which can decrease the pressure load within the disbonded sandwich section significantly when the structure is highly deformed. The commercial finite element analysis software, Abaqus/Standard, was used for the analyses. The recursive pressure-deformation coupling problem was solved by representing the entrapped air in the honeycomb cells as filled cavities in Abaqus/Standard. The results show that disbond size, face sheet thickness and core thickness are important parameters that determine crack tip loading at the disbond front. Further, the pressure

  12. Characterization of rapid climate changes through isotope analyses of ice and entrapped air in the NEEM ice core

    DEFF Research Database (Denmark)

    Guillevic, Myriam

    Greenland ice core have revealed the occurrence of rapid climatic instabilities during the last glacial period, known as Dansgaard-Oeschger (DO) events, while marine cores from the North Atlantic have evidenced layers of ice rafted debris deposited by icebergs melt, caused by the collapse...... of Northern hemisphere ice sheets, known as Heinrich events. The imprint of DO and Heinrich events is also recorded at mid to low latitudes in different archives of the northern hemisphere. A detailed multi-proxy study of the sequence of these rapid instabilities is essential for understanding the climate...... mechanisms at play. Recent analytical developments have made possible to measure new paleoclimate proxies in Greenland ice cores. In this thesis we first contribute to these analytical developments by measuring the new innovative parameter 17O-excess at LSCE (Laboratoire des Sciences du Climatet de l...

  13. Non-linear Dynamic Analysis of Steel Hollow I-core Sandwich Panel under Air Blast Loading

    Directory of Open Access Journals (Sweden)

    Asghar Vatani Oskouei

    2015-12-01

    Full Text Available In this paper, the non-linear dynamic response of novel steel sandwich panel with hollow I-core subjected to blast loading was studied. Special emphasis is placed on the evaluation of midpoint displacements and energy dissipation of the models. Several parameters such as boundary conditions, strain rate, mesh dependency and asymmetrical loading are considered in this study. The material and geometric non-linearities are also considered in the numerical simulation. The results obtained are compared with available experimental data to verify the developed FE model. Modeling techniques are described in detail. According to the results, sandwich panels with hollow I-core allowed more plastic deformation and energy dissipation and less midpoint displacement than conventional I-core sandwich panels and also equivalent solid plate with the same weight and material.

  14. Frontiers in Superconducting Materials

    CERN Document Server

    Narlikar, Anant V

    2005-01-01

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

  15. Superconducting energy recovery linacs

    Science.gov (United States)

    Ben-Zvi, Ilan

    2016-10-01

    High-average-power and high-brightness electron beams from a combination of laser photocathode electron guns and a superconducting energy recovery linac (ERL) is an emerging accelerator science with applications in ERL light sources, high repetition rate free electron lasers , electron cooling, electron ion colliders and more. This paper reviews the accelerator physics issues of superconducting ERLs, discusses major subsystems and provides a few examples of superconducting ERLs.

  16. High-Temperature Superconductivity

    Science.gov (United States)

    Tanaka, Shoji

    2006-12-01

    A general review on high-temperature superconductivity was made. After prehistoric view and the process of discovery were stated, the special features of high-temperature superconductors were explained from the materials side and the physical properties side. The present status on applications of high-temperature superconductors were explained on superconducting tapes, electric power cables, magnets for maglev trains, electric motors, superconducting quantum interference device (SQUID) and single flux quantum (SFQ) devices and circuits.

  17. Internalization of Air Force Core Values Among Company Grade Officers: Where are We and Where are We Going?

    Science.gov (United States)

    1997-03-01

    re–inforce their social perception of those core values our senior leadership have articulated. According to Kurt Lewin , “lectures and other abstract...motivated because life in the company has meaning for them.1 —Terrence E. Deal and Allan A. Kennedy Corporate Cultures Kurt Lewin defines re–education as

  18. 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

  19. Superconductive imaging surface magnetometer

    Science.gov (United States)

    Overton, Jr., William C.; van Hulsteyn, David B.; Flynn, Edward R.

    1991-01-01

    An improved pick-up coil system for use with Superconducting Quantum Interference Device gradiometers and magnetometers involving the use of superconducting plates near conventional pick-up coil arrangements to provide imaging of nearby dipole sources and to deflect environmental magnetic noise away from the pick-up coils. This allows the practice of gradiometry and magnetometry in magnetically unshielded environments. One embodiment uses a hemispherically shaped superconducting plate with interior pick-up coils, allowing brain wave measurements to be made on human patients. another embodiment using flat superconducting plates could be used in non-destructive evaluation of materials.

  20. Superconducting optical modulator

    Science.gov (United States)

    Bunt, Patricia S.; Ference, Thomas G.; Puzey, Kenneth A.; Tanner, David B.; Tache, Nacira; Varhue, Walter J.

    2000-12-01

    An optical modulator based on the physical properties of high temperature superconductors has been fabricated and tested. The modulator was constructed form a film of Yttrium Barium Copper Oxide (YBCO) grown on undoped silicon with a buffer layer of Yttria Stabilized Zirconia. Standard lithographic procedures were used to pattern the superconducting film into a micro bridge. Optical modulation was achieved by passing IR light through the composite structure normal to the micro bridge and switching the superconducting film in the bridge region between the superconducting and non-superconducting states. In the superconducting state, IR light reflects from the superconducting film surface. When a critical current is passed through the micro bridge, it causes the film in this region to switch to the non-superconducting state allowing IR light to pass through it. Superconducting materials have the potential to switch between these two states at speeds up to 1 picosecond using electrical current. Presently, fiber optic transmission capacity is limited by the rate at which optical data can be modulated. The superconducting modulator, when combined with other components, may have the potential to increase the transmission capacity of fiber optic lines.

  1. Basic Study of Superconductive Actuator

    OpenAIRE

    涌井, 和也; 荻原, 宏康

    2000-01-01

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

  2. Constraints on N2O budget changes since pre-industrial time from new firn air and ice core isotope measurements

    Directory of Open Access Journals (Sweden)

    S. Bernard

    2006-01-01

    Full Text Available A historical record of changes in the N2O isotope composition is important for a better understanding of the global N2O atmospheric budget. Here we have combined measurements of trapped gases in the firn and in ice cores of one Arctic site (North GReenland Ice core Project - NGRIP and one Antarctic site (Berkner Island. We have performed measurements of the 18O and position dependent 15N isotopic composition of N2O. By comparing these data to simulations carried out with a firn air diffusion model, we have reconstructed the temporal evolution of the N2O isotope signatures since pre-industrial times. The decrease observed for all signatures is consistent from one pole to the other. Results obtained from the air occluded in the ice suggest a decrease of about -2.8, -2.4, -3.2 and -1.6 for δ15N, 1δ15N, 2δ15N and δ18O, respectively, since 1700 AD. Firn air data imply a decrease of about -1.1, -1.2, -1.0 and -0.6 for δ15N, 1δ15N, 2δ15N and δ18O, respectively, since 1970 AD. These results imply consistent trends from firn and ice measurements for δ15N and δ18O. The trends for the intramolecular distribution of 15N are less well constrained than the bulk 15N trends because of the larger experimental error for the position dependent 15N measurements. The decrease in the heavy isotope content of atmospheric N2O can be explained by the increasing importance of agriculture for the present atmospheric N2O budget.

  3. The in the Guliya shallow ice core during the prevailing summer monsoons and sea-air interactions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The correlations of the δ18Omax in the shallow ice core from the Guliya ice cap on the Tibetan Plateau with the global sea surface temperatures (SST) and height at the 500 hPa over the Northern Hemisphere were analyzed. The correlated regions on oceans that have a significant influence on the δ18Omax in the Guliya ice core are all located in ocean currents, or convergent regions of currents. They are the eastern Equatorial Pacific, the Northern Pacific Current, the Hot Pool in the eastern Indian Ocean, the Mozambique Current, the Northern Atlantic Current, the Canary Current and the Atlantic Equatorial Current. The δ18Omax in the Guliya ice core has negative correlations with the SST located in the lower latitudes, and positive correlations with the SST in the middle latitudes. The correlated areas at the 500 hPa that have a great impact on the δ8Omax are located in the subtropical highs over the mid-low-latitude oceans and the long-wave trough area over Balkhash Lake, where there are marked negative correlations between the heights in those areas and the δ18Omax. The influencing mechanism is displayed by the diversity of the vapor origins transported to the Guliya region. The strengths of the European ridge and the ridge over Baikal Lake have notable positive correlations with the 8180max. The two systems indirectly influence the vapor transportation towards the Guliya region by the adjustment of long-wave trough and ridge.

  4. Heterodyne spectroscopy with superconducting single-photon detector

    Science.gov (United States)

    Lobanov, Yu. V.; Shcherbatenko, M. L.; Semenov, A. V.; Kovalyuk, V. V.; Korneev, A. A.; Goltsman, G. N.

    2016-12-01

    We demonstrate successful operation of a Superconducting Single Photon Detector (SSPD) as the core element in a heterodyne receiver. Irradiating the SSPD by both a local oscillator power and signal power simultaneously, we observed beat signal at the intermediate frequency of a few MHz. Gain bandwidth was found to coincide with the detector single pulse width, where the latter depends on the detector kinetic inductance, determined by the superconducting nanowire length.

  5. Heterodyne spectroscopy with superconducting single-photon detector

    Directory of Open Access Journals (Sweden)

    Lobanov Yu.V.

    2017-01-01

    Full Text Available We demonstrate successful operation of a Superconducting Single Photon Detector (SSPD as the core element in a heterodyne receiver. Irradiating the SSPD by both a local oscillator power and signal power simultaneously, we observed beat signal at the intermediate frequency of a few MHz. Gain bandwidth was found to coincide with the detector single pulse width, where the latter depends on the detector kinetic inductance, determined by the superconducting nanowire length.

  6. Analysis of Air Gap Value in Iron Core Reactor Design%铁心电抗器设计中气隙取值的分析

    Institute of Scientific and Technical Information of China (English)

    吴红波

    2016-01-01

    基于产品计算和制造实际经验,介绍了一种铁心电抗器设计中气隙数量的取值方法,通过气隙数量的计算分析和对铁饼工艺偏差、气隙排布等情况的分析,得到相对合理的气隙取值。结果表明该取值方法有助于提高铁心电抗器电抗值的一次性合格率和提高生产效率。%Based on product calculation and practical experience of manufacture, this paper introduced a kind of air gap valuing method in iron core reactor design. After calculation analysis of air gap value, discus technology bias and gas conifguration, this paper obtained the relative reasonable air gap value. The results show that this method helps to improve the disposable pass rates of reactance value and production efif-ciency.

  7. Banded transformer cores

    Science.gov (United States)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  8. Graphene: Carbon's superconducting footprint

    Science.gov (United States)

    Vafek, Oskar

    2012-02-01

    Graphene exhibits many extraordinary properties, but superconductivity isn't one of them. Two theoretical studies suggest that by decorating the surface of graphene with the right species of dopant atoms, or by using ionic liquid gating, superconductivity could yet be induced.

  9. 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.

  10. 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...

  11. Experimental study of vortex with air core in front of side crest outlet gate%边表孔闸前吸气旋涡试验研究

    Institute of Scientific and Technical Information of China (English)

    马飞; 王宇

    2016-01-01

    Large free-surface vortex with air-core easily occurs in front of gate at the side crest outlets. A series of physical model tests were conducted to observe the flow patterns, analyze the cause of vortex formation, study the influences of operating head, gate opening, distance from side pier to the reservoir bank and the operation conditions of crest outlet adjacent to side crest outlet on vortex, and discuss the effect of vortex on pressure of crest outlet surface. The results demonstrate that, the large vortex with air-core is mainly generated by flow around side pier, which is a special hydraulic phenomenon occurring at the side crest outlets. The air-core diameter of vortex decreases with the increase of gate opening, and increases with increasing operating head and distance from side pier to the reservoir bank; moreover, the vortex is larger when the gate of crest outlet adjacent to side crest outlet in fully opening than in partially opening conditions; the vortex leads to the occurrence of sub-pressure at the sidewall and even cavitation damage, so it should be controlled for practical engineering.%针对多泄洪表孔的边表孔闸前极易产生强烈的吸气旋涡的问题,试验观察了边表孔闸前水流流态,分析了旋涡成因,并详细研究了工作水头、闸门开度、绕流距离及相邻表孔运行方式对吸气旋涡的影响以及吸气旋涡对表孔侧墙压力的影响。结果表明:该吸气旋涡主要是由边墩绕流效应引起,是发生在边表孔的特殊水流现象;旋涡涡心直径随工作水头和绕流距离的增大而增大,随闸门开度的增大而减小;相邻表孔全开与局部开启相比,边表孔闸前漩涡更大;吸气旋涡导致表孔下游侧墙出现负压,可能造成侧墙空蚀破坏,在实际工程中应注意对此类旋涡进行控制。

  12. Superconductivity in carbon nanomaterials

    Science.gov (United States)

    Dlugon, Katarzyna

    The purpose of this thesis is to explain the phenomenon of superconductivity in carbon nanomaterials such as graphene, fullerenes and carbon nanotubes. In the introductory chapter, there is a description of superconductivity and how it occurs at critical temperature (Tc) that is characteristic and different to every superconducting material. The discovery of superconductivity in mercury in 1911 by Dutch physicist Heike Kamerlingh Onnes is also mentioned. Different types of superconductors, type I and type II, low and high temperatures superconductors, as well as the BCS theory that was developed in 1957 by Bardeen, Cooper, and Schrieffer, are also described in detail. The BCS theory explains how Cooper's pairs are formed and how they are responsible for the superconducting properties of many materials. The following chapters explain superconductivity in doped fullerenes, graphene and carbon nanotubes, respectively. There is a thorough explanation followed by many examples of different types of carbon nanomaterials in which small changes in chemical structure cause significant changes in superconducting properties. The goal of this research was not only to take into consideration well known carbon based superconductors but also to search for the newest available materials such as the fullerene nanowhiskers discovered quite recently. There is also a presentation of fairly new ideas about inducing superconductivity in a monolayer of graphene which is more challenging than inducing superconductivity in graphite by simply intercalating metal atoms between its graphene sheets. An effort has been taken to look for any available information about carbon nanomaterials that have the potential to superconduct at room temperature, mainly because discovery of such materials would be a real revolution in the modern world, although no such materials have been discovered yet.

  13. Dual-core antiresonant hollow core fibers.

    Science.gov (United States)

    Liu, Xuesong; Fan, Zhongwei; Shi, Zhaohui; Ma, Yunfeng; Yu, Jin; Zhang, Jing

    2016-07-25

    In this work, dual-core antiresonant hollow core fibers (AR-HCFs) are numerically demonstrated, based on our knowledge, for the first time. Two fiber structures are proposed. One is a composite of two single-core nested nodeless AR-HCFs, exhibiting low confinement loss and a circular mode profile in each core. The other has a relatively simple structure, with a whole elliptical outer jacket, presenting a uniform and wide transmission band. The modal couplings of the dual-core AR-HCFs rely on a unique mechanism that transfers power through the air. The core separation and the gap between the two cores influence the modal coupling strength. With proper designs, both of the dual-core fibers can have low phase birefringence and short modal coupling lengths of several centimeters.

  14. CO sub 2 -climate relationship as deduced from the Vostok ice core: a re-examination based on new measurements and on a re-evaluation of the air dating

    Energy Technology Data Exchange (ETDEWEB)

    Barnola, J.M.; Pimienta, P.; Raynaud, D. (Laboratoire de Glaciologie et Geophysique et de l' Environment, Cedex (FR)); Korotkevich, Y.S. (Arctic and Antarctic Research Inst., Leningrad (SU))

    1991-01-01

    Interpretation of the past CO{sub 2} variations recorded in polar ice during the large climatic transitions requires an accurate determination of the air-ice age difference. For the Vostok core, the age differences resulting from different assumptions on the firn densification process are compared and a new procedure is proposed to date the air trapped in this core. The penultimate deglaciation is studied on the basis of this new air dating and new CO{sub 2} measurements. These measurements and results obtained on other ice cores indicate that at the beginning of the deglaciations, the CO{sub 2} increase is either in phase or lags by less than about 1000 years with respect to the Antarctic temperature, while it clearly lags the temperature at the onset of the last glaciation. (orig.) (21 refs., 3 figs., 1 tab.).

  15. 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.

  16. Measuring the triple O2 isotopic composition of air trapped in ice cores and quantifying thecauses of δ18Oatm Millennial Scale Variations

    DEFF Research Database (Denmark)

    Reutenauer, Corentin

    , a region of the world which still lacks of climatic reconstructions and whose role is widely debated in the context of millennial-scale climate variations. Atmospheric O2 is enriched in heavy isotopologues (δ17O , δ18O ) relative to O2 in ocean water, the ultimate source of O2 for photosynthesis...... in atmospheric δ18O and 17Δ (17Δatm= ln(δ17Oatm)−0.516 · ln(δ18Oatm). We review the current understanding of pastorbital and millennial time-scale variations of atmospheric O2 isotopes. We also give a description of air transport and associated processes in the firn, which alte rthe climatic signal preserved...... in ice core bubbles. Second, a very high analytical precision and accuracy is required to measure the past variations of δ18Oatm and especially 17Δatm preserved in ice core bubbles. One must primarily have the ability to measure variations as small as 10 permeg (0.01 ‰), corresponding to the millennial...

  17. 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.

  18. Superconductivity in doped insulators

    Energy Technology Data Exchange (ETDEWEB)

    Emery, V.J. [Brookhaven National Lab., Upton, NY (United States); Kivelson, S.A. [California Univ., Los Angeles, CA (United States). Dept. of Physics

    1995-12-31

    It is shown that many synthetic metals, including high temperature superconductors are ``bad metals``, with such a poor conductivity that the usual meanfield theory of superconductivity breaks down because of anomalously large classical and quantum fluctuations of the phase of the superconducting order parameter. It is argued that the supression of a first order phase transition (phase separation) by the long-range Coulomb interaction leads to high temperature superconductivity accompanied by static or dynamical charge inhomogeneIty. Evidence in support of this picture for high temperature superconductors is described.

  19. DEVELOPMENT OF A HYDRODYNAMIC MODEL OF A HYDROCYCLONE INCLUDING THE SIMULATION OF AIR-CORE EFFECT, USING THE FINITE VOLUME METHOD

    Directory of Open Access Journals (Sweden)

    Gabriel Felipe Aguilera

    2014-07-01

    Full Text Available The hydrocyclone is one of the most used classification equipment in industry, particularly in mineral processing. Maybe its main characteristic is to be a hydrodynamic separation equipment, whereby it has a high production capability and different levels of efficiency are depending on the geometrical configuration, operational parameters and the type of material to be processed. Nevertheless, there are a few successful studies regarding the modelling and simulation of its hydrodynamic principles, because the flow behavior inside is quite complex. Most of the current models are empirical and they are not applicable to all cases and types of minerals. One of the most important problems to be solved, besides the cut size and the effect of the physical properties of the particles, is the distribution of the flow inside the hydrocyclone, because if the work of the equipment is at low slurry densities, very clear for small hydrocyclones, its mechanic behavior is a consequence of the kind of liquid used as continuous phase, being water the most common liquid. This work shows the modelling and simulation of the hydrodynamic behavior of a suspension inside a hydrocyclone, including the air core effect, through the use of finite differences method. For the developing of the model, the Reynolds Stress Model (RSM for the evaluation of turbulence, and the Volume of Fluid (VOF to study the interaction between water and air were used. Finally, the model shows to be significant for experimental data, and for different conditions of an industrial plant.

  20. Method of forming low cost, formable High T(subc) superconducting wire

    Science.gov (United States)

    Smialek, James L. (Inventor)

    1989-01-01

    A ceramic superconductivity part, such as a wire, is produced through the partial oxidation of a specially formulated copper alloy in a core. The alloys contains low level of quantities of rare earth and alkaline earth dopant elements. Upon oxidation at high temperatures, and superconducting oxide phases are formed as a thin film.

  1. Muscle, skin and core temperature after -110°c cold air and 8°c water treatment.

    Science.gov (United States)

    Costello, Joseph Thomas; Culligan, Kevin; Selfe, James; Donnelly, Alan Edward

    2012-01-01

    The aim of this investigation was to elucidate the reductions in muscle, skin and core temperature following exposure to -110°C whole body cryotherapy (WBC), and compare these to 8°C cold water immersion (CWI). Twenty active male subjects were randomly assigned to a 4-min exposure of WBC or CWI. A minimum of 7 days later subjects were exposed to the other treatment. Muscle temperature in the right vastus lateralis (n=10); thigh skin (average, maximum and minimum) and rectal temperature (n=10) were recorded before and 60 min after treatment. The greatest reduction (Pmuscle (mean ± SD; 1 cm: WBC, 1.6 ± 1.2°C; CWI, 2.0 ± 1.0°C; 2 cm: WBC, 1.2 ± 0.7°C; CWI, 1.7 ± 0.9°C; 3 cm: WBC, 1.6 ± 0.6°C; CWI, 1.7 ± 0.5°C) and rectal temperature (WBC, 0.3 ± 0.2°C; CWI, 0.4 ± 0.2°C) were observed 60 min after treatment. The largest reductions in average (WBC, 12.1 ± 1.0°C; CWI, 8.4 ± 0.7°C), minimum (WBC, 13.2 ± 1.4°C; CWI, 8.7 ± 0.7°C) and maximum (WBC, 8.8 ± 2.0°C; CWI, 7.2 ± 1.9°C) skin temperature occurred immediately after both CWI and WBC (Pmuscle and core temperature to a similar level of those experienced after CWI. Although both treatments significantly reduced skin temperature, WBC elicited a greater decrease compared to CWI. These data may provide information to clinicians and researchers attempting to optimise WBC and CWI protocols in a clinical or sporting setting.

  2. Muscle, Skin and Core Temperature after −110°C Cold Air and 8°C Water Treatment

    Science.gov (United States)

    Costello, Joseph Thomas; Culligan, Kevin; Selfe, James; Donnelly, Alan Edward

    2012-01-01

    The aim of this investigation was to elucidate the reductions in muscle, skin and core temperature following exposure to −110°C whole body cryotherapy (WBC), and compare these to 8°C cold water immersion (CWI). Twenty active male subjects were randomly assigned to a 4-min exposure of WBC or CWI. A minimum of 7 days later subjects were exposed to the other treatment. Muscle temperature in the right vastus lateralis (n = 10); thigh skin (average, maximum and minimum) and rectal temperature (n = 10) were recorded before and 60 min after treatment. The greatest reduction (Pmuscle (mean ± SD; 1 cm: WBC, 1.6±1.2°C; CWI, 2.0±1.0°C; 2 cm: WBC, 1.2±0.7°C; CWI, 1.7±0.9°C; 3 cm: WBC, 1.6±0.6°C; CWI, 1.7±0.5°C) and rectal temperature (WBC, 0.3±0.2°C; CWI, 0.4±0.2°C) were observed 60 min after treatment. The largest reductions in average (WBC, 12.1±1.0°C; CWI, 8.4±0.7°C), minimum (WBC, 13.2±1.4°C; CWI, 8.7±0.7°C) and maximum (WBC, 8.8±2.0°C; CWI, 7.2±1.9°C) skin temperature occurred immediately after both CWI and WBC (Pmuscle and core temperature to a similar level of those experienced after CWI. Although both treatments significantly reduced skin temperature, WBC elicited a greater decrease compared to CWI. These data may provide information to clinicians and researchers attempting to optimise WBC and CWI protocols in a clinical or sporting setting. PMID:23139763

  3. Air-snow transfer of nitrate on the East Antarctic Plateau - Part 2: An isotopic model for the interpretation of deep ice-core records

    Science.gov (United States)

    Erbland, J.; Savarino, J.; Morin, S.; France, J. L.; Frey, M. M.; King, M. D.

    2015-10-01

    Unraveling the modern budget of reactive nitrogen on the Antarctic Plateau is critical for the interpretation of ice-core records of nitrate. This requires accounting for nitrate recycling processes occurring in near-surface snow and the overlying atmospheric boundary layer. Not only concentration measurements but also isotopic ratios of nitrogen and oxygen in nitrate provide constraints on the processes at play. However, due to the large number of intertwined chemical and physical phenomena involved, numerical modeling is required to test hypotheses in a quantitative manner. Here we introduce the model TRANSITS (TRansfer of Atmospheric Nitrate Stable Isotopes To the Snow), a novel conceptual, multi-layer and one-dimensional model representing the impact of processes operating on nitrate at the air-snow interface on the East Antarctic Plateau, in terms of concentrations (mass fraction) and nitrogen (δ15N) and oxygen isotopic composition (17O excess, Δ17O) in nitrate. At the air-snow interface at Dome C (DC; 75° 06' S, 123° 19' E), the model reproduces well the values of δ15N in atmospheric and surface snow (skin layer) nitrate as well as in the δ15N profile in DC snow, including the observed extraordinary high positive values (around +300 ‰) below 2 cm. The model also captures the observed variability in nitrate mass fraction in the snow. While oxygen data are qualitatively reproduced at the air-snow interface at DC and in East Antarctica, the simulated Δ17O values underestimate the observed Δ17O values by several per mill. This is explained by the simplifications made in the description of the atmospheric cycling and oxidation of NO2 as well as by our lack of understanding of the NOx chemistry at Dome C. The model reproduces well the sensitivity of δ15N, Δ17O and the apparent fractionation constants (15ϵapp, 17Eapp) to the snow accumulation rate. Building on this development, we propose a framework for the interpretation of nitrate records

  4. Electrostatic separation of superconducting particles from non-superconducting particles and improvement in fuel atomization by electrorheology

    Science.gov (United States)

    Chhabria, Deepika

    particles are smaller than 45mum. One always come across multiphase superconducting materials where most superconducting grains are much smaller than 45mum. On the other hand, since our technology is based on the surface effect, it gets stronger when the particles become smaller. Our technology is thus perfect for small superconducting particles and for fabrication of HTSC materials. The area of superconductivity is expected to be very important for 21 st Century energy industry. The key for this development is the HTSC materials. We, therefore, expect that our technology will have strong impact in the area. (2) Improving engine efficiency and reducing pollutant emissions are extremely important. Here we report our fuel injection technology based on new physics principle that proper application of electrorheology can reduce the viscosity of petroleum fuels. A small device is thus introduced just before the fuel injection for the engine, producing a strong electric field to reduce the fuel viscosity, resulting in much smaller fuel droplets in atomization. As combustion starts at the interface between fuel and air and most harmful emissions are coming from incomplete burning, reducing the size of fuel droplets would increase the total surface area to start burning, leading to a cleaner and more efficient engine. This concept has been widely accepted as the discussions about future engine for efficient and clean combustion are focused on ultra-dilute mixtures at extremely high pressure to produce much finer mist of fuel for combustion. The technology is expected to have broad applications, applicable to current internal combustion engines and future engines as well.

  5. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

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

    2010-01-01

    , the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10...... offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However...... MW generator and it is concluded that the present production capacity of coated conductors must be increased by a factor of 36 by 2020, resulting in a ten times lower price of the tape in order to reach a realistic price level for the superconducting drive train....

  6. 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...

  7. Superconductivity fundamentals and applications

    CERN Document Server

    Buckel, Werner

    2004-01-01

    This is the second English edition of what has become one of the definitive works on superconductivity in German -- currently in its sixth edition. Comprehensive and easy to understand, this introductory text is written especially with the non-specialist in mind. The authors, both long-term experts in this field, present the fundamental considerations without the need for extensive mathematics, describing the various phenomena connected with the superconducting state, with liberal insertion of experimental facts and examples for modern applications. While all fields of superconducting phenomena are dealt with in detail, this new edition pays particular attention to the groundbreaking discovery of magnesium diboride and the current developments in this field. In addition, a new chapter provides an overview of the elements, alloys and compounds where superconductivity has been observed in experiments, together with their major characteristics. The chapter on technical applications has been considerably expanded...

  8. Superconductivity and symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Sarasua, L.G., E-mail: sarasua@fisica.edu.uy [Instituto de Fisica, Facultad de Ciencias, Universidad de la Republica, Montevideo (Uruguay)

    2012-02-15

    In the present work we consider the relation between superconductivity and spontaneous gauge symmetry breaking (SGBS). We show that ODLRO does not require in principle SBGS, even in the presence of particle number fluctuations, by examining exact solutions of a fermionic pairing model. The criteria become equivalent if a symmetry breaking field is allowed, which can be attributed to the interaction with the environment. However, superconducting states without SBGS are not forbidden.

  9. 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.

  10. Emergent Higgsless Superconductivity

    Directory of Open Access Journals (Sweden)

    Cristina Diamantini M.

    2017-01-01

    Full Text Available We present a new Higgsless model of superconductivity, inspired from anyon superconductivity but P- and T-invariant and generalizable to any dimension. While the original anyon superconductivity mechanism was based on incompressible quantum Hall fluids as average field states, our mechanism involves topological insulators as average field states. In D space dimensions it involves a (D-1-form fictitious pseudovector gauge field which originates from the condensation of topological defects in compact lowenergy effective BF theories. There is no massive Higgs scalar as there is no local order parameter. When electromagnetism is switched on, the photon acquires mass by the topological BF mechanism. Although the charge of the gapless mode (2 and the topological order (4 are the same as those of the standard Higgs model, the two models of superconductivity are clearly different since the origins of the gap, reflected in the high-energy sectors are totally different. In 2D thi! s type of superconductivity is explicitly realized as global superconductivity in Josephson junction arrays. In 3D this model predicts a possible phase transition from topological insulators to Higgsless superconductors.

  11. 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.

  12. High temperature interfacial superconductivity

    Science.gov (United States)

    Bozovic, Ivan [Mount Sinai, NY; Logvenov, Gennady [Port Jefferson Station, NY; Gozar, Adrian Mihai [Port Jefferson, NY

    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.

  13. The superconducting spin valve and triplet superconductivity

    Science.gov (United States)

    Garifullin, I. A.; Leksin, P. V.; Garif`yanov, N. N.; Kamashev, A. A.; Fominov, Ya. V.; Schumann, J.; Krupskaya, Y.; Kataev, V.; Schmidt, O. G.; Büchner, B.

    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 CoOx/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.

  14. Development of superconducting power devices in Europe

    Science.gov (United States)

    Tixador, Pascal

    2010-11-01

    Europe celebrated last year (2008) the 100-year anniversary of the first liquefaction of helium by H. Kammerling Onnes in Leiden. It led to the discovery of superconductivity in 1911. Europe is still active in the development of superconducting (SC) devices. The discovery of high critical temperature materials in 1986, again in Europe, has opened a lot of opportunities for SC devices by broking the 4 K cryogenic bottleneck. Electric networks experience deep changes due to the emergence of dispersed generation (renewable among other) and to the advances in ICT (Information Communication Technologies). The networks of the future will be “smart grids”. Superconductivity will offer “smart” devices for these grids like FCL (Fault Current Limiter) or VLI (Very Low Inductance) cable and would certainly play an important part. Superconductivity also will participate to the required sustainable development by lowering the losses and enhancing the mass specific powers. Different SC projects in Europe will be presented (Cable, FCL, SMES, Flywheel and Electrical Machine) but the description is not exhaustive. Nexans has commercialized the first two FCLs without public funds in the European grid (UK and Germany). The Amsterdam HTS cable is an exciting challenge in term of losses for long SC cables. European companies (Nexans, Air Liquide, Siemens, Converteam, …) are also very active for projects outside Europe (LIPA, DOE FCL, …).

  15. Engineering status of the superconducting end cap toroid magnets for the ATLAS experiment at LHC

    CERN Document Server

    Baynham, D Elwyn; Carr, F S; Courthold, M J D; Cragg, D A; Densham, C J; Evans, D; Holtom, E; Rochford, J; Sole, D; Towndrow, Edwin F; Warner, G P

    2000-01-01

    The ATLAS experiment at LHC, CERN will utilise a large, superconducting, air-cored toroid magnet system for precision muon measurements. The magnet system will consist of a long barrel and two end-cap toroids. Each end-cap toroid will contain eight racetrack coils mounted as a single cold mass in cryostat vessel of ~10 m diameter. The project has now moved from the design/specification stage into the fabrication phase. This paper presents the engineering status of the cold masses and vacuum vessels that are under fabrication in industry. Final designs of cold mass supports, cryogenic systems and control/protection systems are presented. Planning for toroid integration, test and installation is described. (3 refs).

  16. Superconducting state parameters of ternary metallic glasses

    Indian Academy of Sciences (India)

    Aditya M Vora

    2011-12-01

    The well-known empty core (EMC) model potential of Ashcroft was used to study the theoretical investigation of the superconducting state parameters (SSP) viz. electron–phonon coupling strength , Coulomb pseudopotential $\\mu^{\\ast}$, transition temperature $T_{C}$, isotope effect exponent and effective interaction strength $N_{O}V$ of some ternary metallic glasses. Most recent local field correction function due to Sarkar et al is used to study the screening influence on the aforesaid properties. Quadratic $T_{C}$ equations have been proposed and found successful. Also, the present findings are found to be in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the ternary superconductors. The pseudo-alloy-atom (PAA) model was applied for the first time instead of Vegard’s law.

  17. Nanoscience and Engineering in Superconductivity

    CERN Document Server

    Moshchalkov, Victor; Lang, Wolfgang

    2010-01-01

    For emerging energy saving technologies, superconducting materials with superior performance are needed. Such materials can be developed by manipulating the 'elementary building blocks' through nanostructuring. For superconductivity the 'elementary blocks' are Cooper pair and fluxon (vortex). This book presents new ways how to modify superconductivity and vortex matter through nanostructuring and the use of nanoscale magnetic templates. The basic nano-effects, vortex and vortex-antivortex patterns, vortex dynamics, Josephson phenomena, critical currents, and interplay between superconductivity

  18. Seasonal air temperature variations retrieved from a Geladaindong ice core, Tibetan Plateau%青藏高原各拉丹冬冰芯记录的季节气温变化

    Institute of Scientific and Technical Information of China (English)

    张拥军; 康世昌; 秦大河; 任贾文; 张玉兰; Bjorn GRIGHOLM4; Paul MAYEWSKI

    2007-01-01

    A 70-year history of precipitation δ18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier (33(o)34′37.8″ N, 91(o)10′35.3″ E, 5720 m a.s.l.) on Mt. Geladaindong (the source region of Yangtze River) during October and November, 2005. Based on the seasonality of δ18O records and the significant positive relationships between monsoon/non-monsoon δ18O values and summer/spring air temperature from the nearby meteorological stations, the history of summer and spring air temperature have been reconstructed for the last 70 years. The results show that both summer and spring air temperature variations present similar trends during the last 70 years. Regression analysis indicates that the slope of the temperature-δ18O relationship is 1.3℃/‰ for non-monsoon δ18O values and spring air temperature, and 0.4℃/‰ for monsoon δ18O values and summer air temperature. Variation of air temperature recorded in the ice core is consistent with that in the Northern Hemisphere (NH), however, the warming trend in the Geladaindong region is more intense than that in the NH, reflecting a higher sensitivity to global warming in the high elevation regions. In addition, warming trend is greater in spring than in summer.

  19. Analysis of specific absorption rate and internal electric field in human biological tissues surrounding an air-core coil-type transcutaneous energy transmission transformer.

    Science.gov (United States)

    Shiba, Kenji; Zulkifli, Nur Elina Binti; Ishioka, Yuji

    2017-06-01

    In this study, we analyzed the internal electric field E and specific absorption rate (SAR) of human biological tissues surrounding an air-core coil transcutaneous energy transmission transformer. Using an electromagnetic simulator, we created a model of human biological tissues consisting of a dry skin, wet skin, fat, muscle, and cortical bone. A primary coil was placed on the surface of the skin, and a secondary coil was located subcutaneously inside the body. The E and SAR values for the model representing a 34-year-old male subject were analyzed using electrical frequencies of 0.3-1.5 MHz. The transmitting power was 15 W, and the load resistance was 38.4 Ω. The results showed that the E values were below the International Commission on Non-ionizing Radiation Protection (ICNIRP) limit for the general public exposure between the frequencies of 0.9 and 1.5 MHz, and SAR values were well below the limit prescribed by the ICNIRP for the general public exposure between the frequencies of 0.3 and 1.2 MHz.

  20. Interface high-temperature superconductivity

    Science.gov (United States)

    Wang, Lili; Ma, Xucun; Xue, Qi-Kun

    2016-12-01

    Cuprate high-temperature superconductors consist of two quasi-two-dimensional (2D) substructures: CuO2 superconducting layers and charge reservoir layers. The superconductivity is realized by charge transfer from the charge reservoir layers into the superconducting layers without chemical dopants and defects being introduced into the latter, similar to modulation-doping in the semiconductor superlattices of AlGaAs/GaAs. Inspired by this scheme, we have been searching for high-temperature superconductivity in ultra-thin films of superconductors epitaxially grown on semiconductor/oxide substrates since 2008. We have observed interface-enhanced superconductivity in both conventional and unconventional superconducting films, including single atomic layer films of Pb and In on Si substrates and single unit cell (UC) films of FeSe on SrTiO3 (STO) substrates. The discovery of high-temperature superconductivity with a superconducting gap of ∼20 meV in 1UC-FeSe/STO has stimulated tremendous interest in the superconductivity community, for it opens a new avenue for both raising superconducting transition temperature and understanding the pairing mechanism of unconventional high-temperature superconductivity. Here, we review mainly the experimental progress on interface-enhanced superconductivity in the three systems mentioned above with emphasis on 1UC-FeSe/STO, studied by scanning tunneling microscopy/spectroscopy, angle-resolved photoemission spectroscopy and transport experiments. We discuss the roles of interfaces and a possible pairing mechanism inferred from these studies.

  1. 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.

  2. Large Superconducting Magnet Systems

    CERN Document Server

    Védrine, P.

    2014-07-17

    The increase of energy in accelerators over the past decades has led to the design of superconducting magnets for both accelerators and the associated detectors. The use of Nb−Ti superconducting materials allows an increase in the dipole field by up to 10 T compared with the maximum field of 2 T in a conventional magnet. The field bending of the particles in the detectors and generated by the magnets can also be increased. New materials, such as 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.

  3. Failed theories of superconductivity

    CERN Document Server

    Schmalian, Joerg

    2010-01-01

    Almost half a century passed between the discovery of superconductivity by Kammerlingh Onnes and the theoretical explanation of the phenomenon by Bardeen, Cooper and Schrieffer. During the intervening years the brightest minds in theoretical physics tried and failed to develop a microscopic understanding of the effect. A summary of some of those unsuccessful attempts to understand superconductivity not only demonstrates the extraordinary achievement made by formulating the BCS theory, but also illustrates that mistakes are a natural and healthy part of the scientific discourse, and that inapplicable, even incorrect theories can turn out to be interesting and inspiring.

  4. Superconducting magnetic quadrupole

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-08-01

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

  5. 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).

  6. Superconducting magnetic bearings for machine tools. Phase 1, SBIR program. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Anastas, G.; Bennett, A.; Downer, J.; Hockney, R.

    1988-01-01

    The research was directed toward investigating the role of superconducting materials in a magnetic bearing system. Superconducting magnetic bearings are shown to offer the potential for vastly improved performance. These bearings are expected to be especially applicable to rotors which have extremely tight position tolerances. The development of superconducting magnetic bearing technology is also expected to allow a number of novel approaches in the development of machinery and systems. Researchers studied an alternative bearing design which employs a superconducting coil and eliminates all conventional magnetic structures. The study has resulted in a design definition and detailed analysis for a superconducting bearing system which is sized to roughly duplicate the air bearing system of an existing air-bearing spindle.

  7. Lightweight MgB2 superconducting 10 MW wind generator

    Science.gov (United States)

    Marino, I.; Pujana, A.; Sarmiento, G.; Sanz, S.; Merino, J. M.; Tropeano, M.; Sun, J.; Canosa, T.

    2016-02-01

    The offshore wind market demands a higher power rate and more reliable turbines in order to optimize capital and operational costs. The state-of-the-art shows that both geared and direct-drive conventional generators are difficult to scale up to 10 MW and beyond due to their huge size and weight. Superconducting direct-drive wind generators are considered a promising solution to achieve lighter weight machines. This work presents an innovative 10 MW 8.1 rpm direct-drive partial superconducting generator using MgB2 wire for the field coils. It has a warm iron rotor configuration with the superconducting coils working at 20 K while the rotor core and the armature are at ambient temperature. A cooling system based on cryocoolers installed in the rotor extracts the heat from the superconducting coils by conduction. The generator's main parameters are compared against a permanent magnet reference machine, showing a significant weight and size reduction. The 10 MW superconducting generator concept will be experimentally validated with a small-scale magnetic machine, which has innovative components such as superconducting coils, modular cryostats and cooling systems, and will have similar size and characteristics as the 10 MW generator.

  8. A superconducting transformer system for high current cable testing.

    Science.gov (United States)

    Godeke, A; Dietderich, D R; Joseph, J M; Lizarazo, J; Prestemon, S O; Miller, G; Weijers, H W

    2010-03-01

    This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10,464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples.

  9. Superconducting Magnets for Particle Accelerators

    CERN Document Server

    Rossi, L

    2012-01-01

    Superconductivity has been the most influential technology in the field of accelerators in the last 30 years. Since the commissioning of the Tevatron, which demonstrated the use and operability of superconductivity on a large scale, superconducting magnets and rf cavities have been at the heart of all new large accelerators. Superconducting magnets have been the invariable choice for large colliders, as well as cyclotrons and large synchrotrons. In spite of the long history of success, superconductivity remains a difficult technology, requires adequate R&D and suitable preparation, and has a relatively high cost. Hence, it is not surprising that the development has also been marked by a few setbacks. This article is a review of the main superconducting accelerator magnet projects; it highlights the main characteristics and main achievements, and gives a perspective on the development of superconducting magnets for the future generation of very high energy colliders.

  10. Spin-orbit-coupled superconductivity.

    Science.gov (United States)

    Lo, Shun-Tsung; Lin, Shih-Wei; Wang, Yi-Ting; Lin, Sheng-Di; Liang, C-T

    2014-06-25

    Superconductivity and spin-orbit (SO) interaction have been two separate emerging fields until very recently that the correlation between them seemed to be observed. However, previous experiments concerning SO coupling are performed far beyond the superconducting state and thus a direct demonstration of how SO coupling affects superconductivity remains elusive. Here we investigate the SO coupling in the critical region of superconducting transition on Al nanofilms, in which the strength of disorder and spin relaxation by SO coupling are changed by varying the film thickness. At temperatures T sufficiently above the superconducting critical temperature T(c), clear signature of SO coupling reveals itself in showing a magneto-resistivity peak. When T superconductivity. By studying such magneto-resistivity peaks under different strength of spin relaxation, we highlight the important effects of SO interaction on superconductivity.

  11. 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.

  12. Superconducting Technology Assessment

    Science.gov (United States)

    2005-08-01

    of Nb/Al- Nx /NbTiN junctions for SIS mixer applications,” IEEE Trans. Appl. Superconduct., vol. 11, pp. 76–79, Mar. 2001. [48] M. Gurvitch, W. A...Another connector developed by IBM for commercial applications using a dendritic interposer technology. A “beam-on-pad” approach developed by Siemens

  13. 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.

  14. 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)

  15. 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.

  16. Niobium superconducting cavity

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.

  17. LHC Superconducting Magnets

    CERN Document Server

    Jean Leyder

    2000-01-01

    The LHC is the next step in CERN's quest to unravel the mysteries of the Universe. It will accelerate protons to energies never before achieved in laboratories, and to hold them on course it will use powerful superconducting magnets on an unprecedented scale.

  18. 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

  19. Superconducting Quantum Circuits

    NARCIS (Netherlands)

    Majer, J.B.

    2002-01-01

    This thesis describes a number of experiments with superconducting cir- cuits containing small Josephson junctions. The circuits are made out of aluminum islands which are interconnected with a very thin insulating alu- minum oxide layer. The connections form a Josephson junction. The current trough

  20. Checking BEBC superconducting magnet

    CERN Multimedia

    1974-01-01

    The superconducting coils of the magnet for the 3.7 m Big European Bubble Chamber (BEBC) had to be checked, see Annual Report 1974, p. 60. The photo shows a dismantled pancake. By December 1974 the magnet reached again the field design value of 3.5 T.

  1. Nonequilibrium superconducting detectors

    Science.gov (United States)

    Cristiano, R.; Ejrnaes, M.; Esposito, E.; Lisitskyi, M. P.; Nappi, C.; Pagano, S.; Perez de Lara, D.

    2006-03-01

    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.

  2. Nonequilibrium superconducting detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cristiano, R [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Ejrnaes, M [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); INFN Sezione di Napoli, 80126 Naples (Italy); Esposito, E [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Lisitskyi, M P [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Nappi, C [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Pagano, S [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Dipartimento di Fisica, Universita di Salerno, 84081 Baronissi (Saudi Arabia) (Italy); Perez de Lara, D [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy)

    2006-03-15

    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.

  3. 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.

  4. 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.

  5. Nonlinearities in Microwave Superconductivity

    OpenAIRE

    Ledenyov, Dimitri O.; Ledenyov, Viktor O.

    2012-01-01

    The research is focused on the modeling of nonlinear properties of High Temperature Superconducting (HTS) thin films, using Bardeen, Cooper, Schrieffer and Lumped Element Circuit theories, with purpose to enhance microwave power handling capabilities of microwave filters and optimize design of microwave circuits in micro- and nano- electronics.

  6. 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

  7. 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)

  8. 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)

  9. 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.

  10. High temperature interface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gozar, A., E-mail: adrian.gozar@yale.edu [Yale University, New Haven, CT 06511 (United States); Bozovic, I. [Yale University, New Haven, CT 06511 (United States); Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2016-02-15

    Highlight: • This review article covers the topic of high temperature interface superconductivity. • New materials and techniques used for achieving interface superconductivity are discussed. • We emphasize the role played by the differences in structure and electronic properties at the interface with respect to the bulk of the constituents. - Abstract: High-T{sub c} superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T{sub c} Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  11. Covalent Electron Transfer Theory of Superconductivity

    Science.gov (United States)

    1992-06-19

    where n. and n, converge to establish the threshold density for the onset of superconductivity. 41 Comparison of ne(t) Inse (O) versus t for W = 0.5, 1...all temperatures according to ne(T) = n(7) - nt(T) , (58) where n() = n(Tc)[ I - nse(T) Inse (O)]. Thus, the fractional contribution of the threshold...approximately -1/2, thereby suggesting that Kerr- v,6t 2. For the transition metals with largely unpolarizable cores of closed p6 shells (i.e., noble gases

  12. Observation of Superconductivity in Tetragonal FeS.

    Science.gov (United States)

    Lai, Xiaofang; Zhang, Hui; Wang, Yingqi; Wang, Xin; Zhang, Xian; Lin, Jianhua; Huang, Fuqiang

    2015-08-19

    The possibility of superconductivity in tetragonal FeS has attracted considerable interest because of its similarities to the FeSe superconductor. However, all efforts made to pursue superconductivity in tetragonal FeS have failed so far, and it remains controversial whether tetragonal FeS is metallic or semiconducting. Here we report the observation of superconductivity at 5 K in tetragonal FeS that is synthesized by the hydrothermal reaction of iron powder with sulfide solution. The obtained samples are highly crystalline and less air-sensitive, in contrast to those reported in the literature, which are meta-stable and air-sensitive. Magnetic and electrical properties measurements show that the samples behave as a paramagnetic metal in the normal state and exhibit superconductivity below 5 K. The high crystallinity and the stoichiometry of the samples play important roles in the observation of superconductivity. The present results demonstrate that tetragonal FeS is a promising new platform to realize high-temperature superconductors.

  13. 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...

  14. 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 ...

  15. 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 ...

  16. Superconducting switch pack

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, V.C.; Wollan, J.J.

    1990-07-24

    This patent describes a superconducting switch pack at least one switch element. The switch element including a length of superconductive wire having a switching portion and two lead portions, the switching portion being between the lead portions; means for supporting the switching portion in a plane in a common mold; hardened resin means encapsulating the switching portion in the plane in a solid body; wherein the solid body has an exterior surface which is planar and substantially parallel with and spaced apart from the plane in which the switching portion is positioned. The exterior surface being exposed to the exterior of the switch pack and the resin means filling the space between the exterior surface and the plane of the switching portion so as to provide uninterrupted thermal communication between the plane of the switching portion and the exterior of the switch pack; and a heater element in thermal contact with the switching portion.

  17. Tunable superconducting nanoinductors

    Energy Technology Data Exchange (ETDEWEB)

    Annunziata, Anthony J; Santavicca, Daniel F; Frunzio, Luigi; Rooks, Michael J; Prober, Daniel E [Department of Applied Physics, Yale University, New Haven, CT 06511 (United States); Catelani, Gianluigi [Department of Physics, Yale University, New Haven, CT 06511 (United States); Frydman, Aviad, E-mail: anthony.annunziata@yale.edu, E-mail: daniel.prober@yale.edu [Department of Physics, Bar-Ilan University, Ramat Gan 52900 (Israel)

    2010-11-05

    We characterize inductors fabricated from ultra-thin, approximately 100 nm wide strips of niobium (Nb) and niobium nitride (NbN). These nanowires have a large kinetic inductance in the superconducting state. The kinetic inductance scales linearly with the nanowire length, with a typical value of 1 nH {mu}m{sup -1} for NbN and 44 pH {mu}m{sup -1} for Nb at a temperature of 2.5 K. We measure the temperature and current dependence of the kinetic inductance and compare our results to theoretical predictions. We also simulate the self-resonant frequencies of these nanowires in a compact meander geometry. These nanowire inductive elements have applications in a variety of microwave frequency superconducting circuits.

  18. 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.

  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. Topological confinement and superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Al-hassanieh, Dhaled A [Los Alamos National Laboratory; Batista, Cristian D [Los Alamos National Laboratory

    2008-01-01

    We derive a Kondo Lattice model with a correlated conduction band from a two-band Hubbard Hamiltonian. This mapping allows us to describe the emergence of a robust pairing mechanism in a model that only contains repulsive interactions. The mechanism is due to topological confinement and results from the interplay between antiferromagnetism and delocalization. By using Density-Matrix-Renormalization-Group (DMRG) we demonstrate that this mechanism leads to dominant superconducting correlations in aID-system.

  1. 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)

  2. Helical superconducting black holes.

    Science.gov (United States)

    Donos, Aristomenis; Gauntlett, Jerome P

    2012-05-25

    We construct novel static, asymptotically five-dimensional anti-de Sitter black hole solutions with Bianchi type-VII(0) symmetry that are holographically dual to superconducting phases in four spacetime dimensions with a helical p-wave order. We calculate the precise temperature dependence of the pitch of the helical order. At zero temperature the black holes have a vanishing entropy and approach domain wall solutions that reveal homogenous, nonisotropic dual ground states with an emergent scaling symmetry.

  3. Silicon superconducting quantum interference device

    Energy Technology Data Exchange (ETDEWEB)

    Duvauchelle, J. E.; Francheteau, A.; Marcenat, C.; Lefloch, F., E-mail: francois.lefloch@cea.fr [Université Grenoble Alpes, CEA - INAC - SPSMS, F-38000 Grenoble (France); Chiodi, F.; Débarre, D. [Université Paris-sud, CNRS - IEF, F-91405 Orsay - France (France); Hasselbach, K. [Université Grenoble Alpes, CNRS - Inst. Néel, F-38000 Grenoble (France); Kirtley, J. R. [Center for probing at nanoscale, Stanford University, Palo Alto, California 94305-4045 (United States)

    2015-08-17

    We have studied a Superconducting Quantum Interference Device (SQUID) made from a single layer thin film of superconducting silicon. The superconducting layer is obtained by heavily doping a silicon wafer with boron atoms using the gas immersion laser doping technique. The SQUID is composed of two nano-bridges (Dayem bridges) in a loop and shows magnetic flux modulation at low temperature and low magnetic field. The overall behavior shows very good agreement with numerical simulations based on the Ginzburg-Landau equations.

  4. Superconducting Qubit Optical Transducer (SQOT)

    Science.gov (United States)

    2015-08-05

    SECURITY CLASSIFICATION OF: The SQOT (Superconducting Qubit Optical Transducer ) project proposes to build a novel electro-optic system which can...Apr-2015 Approved for Public Release; Distribution Unlimited Final Report: "Superconducting Qubit Optical Transducer " (SQOT) The views, opinions and...journals: Number of Papers published in non peer-reviewed journals: Final Report: "Superconducting Qubit Optical Transducer " (SQOT) Report Title The

  5. Economical Aspects of Superconducting Cable

    Science.gov (United States)

    Ohya, Masayoshi

    High-temperature superconducting (HTS) cables are expected to resolve technical problems with power grids because they put large-capacity, low-loss power transmission into a compact package. One problem is replacing old 275-kV oil filled (OF) cables with cross-linked polyethylene insulated vinyl sheath cables (XLPE cables). This is difficult because XLPE cable has a lower transmission capacity than OF cable. In addition, the high concentration of public infrastructure underground makes it extremely difficult to build new ones. However, if 66-kV HTS cables can be installed inside existing underground conduits and can achieve a power capacity equivalent to conventional 275-kV cables, construction costs could be significantly reduced. Moreover, if XLPE cables are used for a 1,000 MVA-class transmission line, then three circuits of nine 275-kV single-core cables would be required, which would incur a transmission loss of 90 W/m/cct. Three circuits of three 66-kV Three-in-One HTS cables, however, with an AC loss of 1 W/m/ph@3 kA, heat invasion of 2 W/m, and cooling system efficiency of 0.1, would reduce transmission loss to less than three-fifths that of XLPE cables.

  6. 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...

  7. Navy superconductivity efforts

    Science.gov (United States)

    Gubser, D. U.

    1990-04-01

    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.

  8. 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.

  9. 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.

  10. Superconductivity in CVD diamond films.

    Science.gov (United States)

    Takano, Yoshihiko

    2009-06-24

    A beautiful jewel of diamond is insulator. However, boron doping can induce semiconductive, metallic and superconducting properties in diamond. When the boron concentration is tuned over 3 × 10(20) cm(-3), diamonds enter the metallic region and show superconductivity at low temperatures. The metal-insulator transition and superconductivity are analyzed using ARPES, XAS, NMR, IXS, transport and magnetic measurements and so on. This review elucidates the physical properties and mechanism of diamond superconductor as a special superconductivity that occurs in semiconductors.

  11. 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.

  12. 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.

  13. 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.

  14. Constraints on N2O budget changes since pre-industrial time from new firn air and ice core isotope measurements

    NARCIS (Netherlands)

    Bernard, S.; Röckmann, T.; Kaiser, J.; Barnola, j.m.; Fischer, H; Blunier, T.; Chappellaz, J.

    2006-01-01

    A historical record of changes in the N2O isotope composition is important for a better understanding of the global N2O atmospheric budget. Here we have combined measurements of trapped gases in the firn and in ice cores of one Arctic site (North GReenland Ice core Project – NGRIP) and one Antarctic

  15. Optimization of superconducting tiling pattern for superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL)

    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.

  16. A flux pumping method applied to the magnetization of YBCO superconducting coils: frequency, amplitude and waveform characteristics

    Science.gov (United States)

    Fu, Lin; Matsuda, Koichi; Lecrevisse, Thibault; Iwasa, Yukikazu; Coombs, Tim

    2016-04-01

    This letter presents a flux pumping method and the results gained when it was used to magnetize a range of different YBCO coils. The pumping device consists of an iron magnetic circuit with eight copper coils which apply a traveling magnetic field to the superconductor. The copper poles are arranged vertically with an air gap length of 1 mm and the iron cores are made of laminated electric steel plates to minimize eddy-current losses. We have used this arrangement to investigate the best possible pumping result when parameters such as frequency, amplitude and waveform are varied. We have successfully pumped current into the superconducting coil up to a value of 90% of I c and achieved a resultant magnetic field of 1.5 T.

  17. Superconductivity-like phenomena in an ferrimagnetic endohedral fullerene with diluted magnetic surface

    Science.gov (United States)

    Kantar, Ersin

    2017-09-01

    The hysteretic properties of a Ising-type endohedral fullerene (EF) with a doped magnetic spin-1/2 particle confined within a spherical cage (by diluted magnetic spin-1 particles) are investigated by using the effective-field theory with correlations. The extrinsic and intrinsic parameters dependencies of the magnetic hysteresis curves and superconductivity-like phenomena in the Ising-type EF system have investigated. We have reported that doped magnetic core atom is chiefly responsible of the occurrence of the superconductivity-like phenomena in the system. Moreover, three superconductivity series have been presented by the temperature, surface composition and crystal field.

  18. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in a...

  19. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in...

  20. Theory analysis of critical-current degeneration in bended superconducting tapes of multifilament composite Bi2223/Ag

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Peifeng; Wang, Xingzhe, E-mail: xzwang@lzu.edu.cn

    2015-10-15

    Highlights: • We proposed an empirical model to describe carrying-current degradation of bent Bi2223/Ag tapes. • Asymmetric damage of superconductor multifilament is taken into account. • Both the loading and unloading processes of bend deformation are captured. • Carrying-current property can be improved by designing configuration of the multifilament core. - Abstract: This paper proposed a degradation model to explore the influence of the mechanical bending deformation on the critical-current of superconducting composite Bi2223/Ag tape taking into account the asymmetric mechanical damage. With the aid of Weibull distribution function of statistical damage of filaments, the critical-current dependence upon bending strain of the superconducting tape in processes of loading and unloading is characterized. The degradation profile of critical-current in the superconducting composite tape is theoretically investigated by the proposed model for different critical damage strains and configurations of superconducting multifilament core at the cross-section. It is shown that the theoretical predictions are in reasonably good agreement with the experimental data, and the configuration of the multifilament core of the superconducting composite tape has a significant influence on the critical-current degradation. The superconducting multifilament core located near the compression region of the cross-section remarkably improves the mechanical and carrying-current capabilities of the superconducting composite tape.

  1. 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...

  2. 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...

  3. 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.

  4. Superconductivity in a chiral nanotube

    Science.gov (United States)

    Qin, F.; Shi, W.; Ideue, T.; Yoshida, M.; Zak, A.; Tenne, R.; Kikitsu, T.; Inoue, D.; Hashizume, D.; Iwasa, Y.

    2017-02-01

    Chirality of materials are known to affect optical, magnetic and electric properties, causing a variety of nontrivial phenomena such as circular dichiroism for chiral molecules, magnetic Skyrmions in chiral magnets and nonreciprocal carrier transport in chiral conductors. On the other hand, effect of chirality on superconducting transport has not been known. Here we report the nonreciprocity of superconductivity--unambiguous evidence of superconductivity reflecting chiral structure in which the forward and backward supercurrent flows are not equivalent because of inversion symmetry breaking. Such superconductivity is realized via ionic gating in individual chiral nanotubes of tungsten disulfide. The nonreciprocal signal is significantly enhanced in the superconducting state, being associated with unprecedented quantum Little-Parks oscillations originating from the interference of supercurrent along the circumference of the nanotube. The present results indicate that the nonreciprocity is a viable approach toward the superconductors with chiral or noncentrosymmetric structures.

  5. 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)

  6. Superconducting dipole electromagnet

    Science.gov (United States)

    Purcell, John R.

    1977-07-26

    A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.

  7. 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

  8. TOPICAL REVIEW: Superconducting bearings

    Science.gov (United States)

    Hull, John R.

    2000-02-01

    The physics and technology of superconducting bearings is reviewed. Particular attention is given to the use of high-temperature superconductors (HTSs) in rotating bearings. The basic phenomenology of levitational forces is presented, followed by a brief discussion of the theoretical models that can be used for conceptual understanding and calculations. The merits of various HTS bearing designs are presented, and the behaviour of HTS bearings in typical situations is discussed. The article concludes with a brief survey of various proposed applications for HTS bearings.

  9. Conventional and unconventional superconductivity

    Science.gov (United States)

    Fernandes, R. M.

    2012-02-01

    Superconductivity has been one of the most fruitful areas of research in condensed matter physics, bringing together researchers with distinct interests in a collaborative effort to understand from its microscopic basis to its potential for unprecedented technological applications. The concepts, techniques, and methods developed along its centennial history have gone beyond the realm of condensed matter physics and influenced the development of other fascinating areas, such as particle physics and atomic physics. These notes, based on a set of lectures given at the 2011 Advanced Summer School of Cinvestav, aim to motivate the young undergraduate student in getting involved in the exciting world of conventional and unconventional superconductors.

  10. Superconductivity from correlated hopping

    CERN Document Server

    Batista, C D; Aligia, A A

    1995-01-01

    We consider a chain described by a next-nearest-neighbor hopping combined with a nearest-neighbor spin flip. In two dimensions this three-body term arises from a mapping of the three-band Hubbard model for CuO$_2$ planes to a generalized $t-J$ model and for large O-O hopping favors resonance-valence-bond superconductivity of predominantly $d$-wave symmetry. Solving the ground state and low-energy excitations by analytical and numerical methods we find that the chain is a Luther-Emery liquid with correlation exponent $K_{\\rho} = (2-n)^2/2$, where $n$ is the particle density.

  11. 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

  12. 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

  13. Superconducting Electronic Film Structures

    Science.gov (United States)

    1991-02-14

    cubic, yttria stabilized, zirconia (YSZ) single crystals with (100) orientation and ao = 0.512 to 0.516 nm. Films were magnetron-sputtered... Crown by Solid-State and Vapor-Phase Epitaxy," IEEE Trans. Uagn. 25(2), 2538 (1989). 6. J. H. Kang, R. T. Kampwirth, and K. E. Gray, "Superconductivity...summarized in Fig. 1, are too high for SrTiO3 or yttria- stabilized zirconia (YSZ) to be used in rf applications. MgO, LaAIO 3 , and LaGaO3 have a tan 6

  14. Heavy fermion superconductivity

    Science.gov (United States)

    Brison, Jean-Pascal; Glémot, Loı̈c; Suderow, Hermann; Huxley, Andrew; Kambe, Shinsaku; Flouquet, Jacques

    2000-05-01

    The quest for a precise identification of the symmetry of the order parameter in heavy fermion systems has really started with the discovery of the complex superconducting phase diagram in UPt 3. About 10 years latter, despite numerous experiments and theoretical efforts, this is still not achieved, and we will quickly review the present status of knowledge and the main open question. Actually, the more forsaken issue of the nature of the pairing mechanism has been recently tackled by different groups with macroscopic or microscopic measurement, and significant progress have been obtained. We will discuss the results emerging from these recent studies which all support non-phonon-mediated mechanisms.

  15. Nano-engineered pinning centres in YBCO superconducting films

    Science.gov (United States)

    Crisan, A.; Dang, V. S.; Mikheenko, P.

    2017-02-01

    For practical applications of superconducting materials in applied magnetic fields, artificial pinning centres in addition to natural ones are required to oppose the Lorentz force. These pinning centres are actually various types of defects in the superconductor matrix. The pinning centres can be categorised on their dimension (volume, surface or point) and on their character (normal cores or Δκ cores). Different samples have been produced by Pulsed Laser Deposition, with various thicknesses, temperatures and nanostructured additions to the superconducting matrix. They have been characterized by SQUID Magnetic Properties Measurement System and Physical Properties Measurement System, as well as by Transmission Electron Microscopy (TEM). Correlations between pinning architecture, TEM images, and critical currents at various fields and field orientations will be shown for a large number of YBa2Cu3Ox films with various types and architectures of artificial pinning centres.

  16. Effect of annealing on superconductivity in Fe1+y(Te1-xSx) system

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We have synthesized polycrystalline samples of Fe1.11(Te1-xSx) and single crystals of Fe1+y(Te0.88S0.12),and characterized their properties.Our results show that the solid solution of S in the Fe1.11Te tetragonal lattice is limited,~10%.We observed superconductivity at ~8 K in both polycrystalline samples and single crystals.Magnetization measurements reveal that the volume fraction is small for this superconducting phase in both polycrystalline samples as-synthesized and single crystals as-grown.It is found that annealing in air enhances the superconducting fraction;the maximum fraction is almost 100% in the single crystals annealed in air at 300°C.We discuss the effect of annealing on superconductivity and transport properties at the normal state in the Fe1+y(Te1-xSx) system in terms of decrease of the excess Fe.

  17. A sublimation technique for high-precision measurements of δ13CO2 and mixing ratios of CO2 and N2O from air trapped in ice cores

    Directory of Open Access Journals (Sweden)

    H. Fischer

    2011-07-01

    Full Text Available In order to provide high precision stable carbon isotope ratios (δ13CO2 or δ13C of CO2 from small bubbly, partially and fully clathrated ice core samples we developed a new method based on sublimation coupled to gas chromatography-isotope ratio mass spectrometry (GC-IRMS. In a first step the trapped air is quantitatively released from ~30 g of ice and CO2 together with N2O are separated from the bulk air components and stored in a miniature glass tube. In an off-line step, the extracted sample is introduced into a helium carrier flow using a minimised tube cracker device. Prior to measurement, N2O and organic sample contaminants are gas chromatographically separated from CO2. Pulses of a CO2/N2O mixture are admitted to the tube cracker and follow the path of the sample through the system. This allows an identical treatment and comparison of sample and standard peaks. The ability of the method to reproduce δ13C from bubble and clathrate ice is verified on different ice cores. We achieve reproducibilities for bubble ice between 0.05 ‰ and 0.07 ‰ and for clathrate ice between 0.05 ‰ and 0.09 ‰ (dependent on the ice core used. A comparison of our data with measurements on bubble ice from the same ice core but using a mechanical extraction device shows no significant systematic offset. In addition to δ13C, the CO2 and N2O mixing ratios can be volumetrically derived with a precision of 2 ppmv and 8 ppbv, respectively.

  18. 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 ...

  19. 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...

  20. Superconducting magnets for MRI

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.E.

    1984-08-01

    Three types of magnets are currently used to provide the background field required for magnet resonance imaging (MRI). (i) Permanent magnets produce fields of up to 0.3 T in volumes sufficient for imaging the head or up to 0.15 T for whole body imaging. Cost and simplicity of operation are advantages, but relatively low field, weight (up to 100 tonnes) and, to a small extent, instability are limitations. (ii) Water-cooled magnets provide fields of up to 0.25 T in volumes suitable for whole body imaging, but at the expense of power (up to 150 kW for 0.25 T) and water-cooling. Thermal stability of the field requires the maintenance of constant temperature through periods both of use and of quiescence. (iii) Because of the limitations imposed by permanent and resistive magnets, particularly on field strength, the superconducting magnet is now most widely used to provide background fields of up to 2 T for whole body MRI. It requires very low operating power and that only for refrigeration. Because of the constant low temperature, 4.2 K, at which its stressed structure operates, its field is stable. The following review deals principally with superconducting magnets for MRI. However, the sections on field analysis apply to all types of magnet and the description of the source terms of circular coils and of the principals of design of solenoids apply equally to resistive solenoidal magnets.

  1. CDF modeling of flow and transport processes in the reactor core of a modular high temperature reactor during an air ingress accident; CFD-Modellierung der Stroemungs- und Transportprozesse im Reaktorkern eines modularen Hochtemperaturreaktors waehrend eines Lufteinbruchstoerfalls

    Energy Technology Data Exchange (ETDEWEB)

    Baggemann, Johannes

    2015-05-22

    Generation IV of reactor design is supposed to include inherent safety systems that allow accident management using passive processes (without external energy). The VTR (very high temperature reactor) is graphite moderated with helium cooling. The design concept assumes that in any operational situation the after heat is removed by thermal conduction and radiation. Air ingress is beyond-design accident assuming a leak in the primary circuit triggering oxygen reaction with the hot graphite that could damage the barriers for fission product release. Using 3D CFD (computational fluid dynamics) codes the air ingress scenario is simulated, the flow and transport processes in the reactor core are analyzed. For validation of the modeling heat transport processes were investigated in specific test facilities.

  2. 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.

  3. 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.)

  4. Operational Merits of Maritime Superconductivity

    Science.gov (United States)

    Ross, R.; Bosklopper, J. J.; van der Meij, K. H.

    The perspective of superconductivity to transfer currents without loss is very appealing in high power applications. In the maritime sector many machines and systems exist in the roughly 1-100 MW range and the losses are well over 50%, which calls for dramatic efficiency improvements. This paper reports on three studies that aimed at the perspectives of superconductivity in the maritime sector. It is important to realize that the introduction of superconductivity comprises two technology transitions namely firstly electrification i.e. the transition from mechanical drives to electric drives and secondly the transition from normal to superconductive electrical machinery. It is concluded that superconductivity does reduce losses, but its impact on the total energy chain is of little significance compared to the investments and the risk of introducing a very promising but as yet not proven technology in the harsh maritime environment. The main reason of the little impact is that the largest losses are imposed on the system by the fossil fueled generators as prime movers that generate the electricity through mechanical torque. Unless electric power is supplied by an efficient and reliable technology that does not involve mechanical torque with the present losses both normal as well as superconductive electrification of the propulsion will hardly improve energy efficiency or may even reduce it. One exception may be the application of degaussing coils. Still appealing merits of superconductivity do exist, but they are rather related to the behavior of superconductive machines and strong magnetic fields and consequently reduction in volume and mass of machinery or (sometimes radically) better performance. The merits are rather convenience, design flexibility as well as novel applications and capabilities which together yield more adequate systems. These may yield lower operational costs in the long run, but at present the added value of superconductivity rather seems more

  5. Technical report series on global modeling and data assimilation. Volume 5: Documentation of the AIRES/GEOS dynamical core, version 2

    Science.gov (United States)

    Suarez, Max J. (Editor); Takacs, Lawrence L.

    1995-01-01

    A detailed description of the numerical formulation of Version 2 of the ARIES/GEOS 'dynamical core' is presented. This code is a nearly 'plug-compatible' dynamics for use in atmospheric general circulation models (GCMs). It is a finite difference model on a staggered latitude-longitude C-grid. It uses second-order differences for all terms except the advection of vorticity by the rotation part of the flow, which is done at fourth-order accuracy. This dynamical core is currently being used in the climate (ARIES) and data assimilation (GEOS) GCMs at Goddard.

  6. 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.

  7. Superconducting interfaces between insulating oxides.

    Science.gov (United States)

    Reyren, N; Thiel, S; Caviglia, A D; Kourkoutis, L Fitting; Hammerl, G; Richter, C; Schneider, C W; Kopp, T; Rüetschi, A-S; Jaccard, D; Gabay, M; Muller, D A; Triscone, J-M; Mannhart, J

    2007-08-31

    At interfaces between complex oxides, electronic systems with unusual electronic properties can be generated. We report on superconductivity in the electron gas formed at the interface between two insulating dielectric perovskite oxides, LaAlO3 and SrTiO3. The behavior of the electron gas is that of a two-dimensional superconductor, confined to a thin sheet at the interface. The superconducting transition temperature of congruent with 200 millikelvin provides a strict upper limit to the thickness of the superconducting layer of congruent with 10 nanometers.

  8. Superconducting cable connections and methods

    Energy Technology Data Exchange (ETDEWEB)

    van der Laan, Daniel Cornelis

    2017-09-05

    Superconducting cable connector structures include a terminal body (or other structure) onto which the tapes from the superconducting cable extend. The terminal body (or other structure) has a diameter that is sufficiently larger than the diameter of the former of the superconducting cable, so that the tapes spread out over the outer surface of the terminal body. As a result, gaps are formed between tapes on the terminal body (or other structure). Those gaps are filled with solder (or other suitable flowable conductive material), to provide a current path of relatively high conductivity in the radial direction. Other connector structures omit the terminal body.

  9. Domain wall description of superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Brito, F.A. [Departamento de Física, Universidade Federal de Campina Grande, Caixa Postal 10071, 58109-970 Campina Grande, Paraíba (Brazil); Freire, M.L.F. [Departamento de Física, Universidade Estadual da Paraíba, 58109-753 Campina Grande, Paraíba (Brazil); Mota-Silva, J.C. [Departamento de Física, Universidade Federal de Campina Grande, Caixa Postal 10071, 58109-970 Campina Grande, Paraíba (Brazil); Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-970 João Pessoa, Paraíba (Brazil)

    2014-01-20

    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.

  10. Aspects of Color Superconductivity

    CERN Document Server

    Hong, D K

    2001-01-01

    I discuss some aspects of recent developments in color superconductivity in high density quark matter. I calculate the Cooper pair gap and the critical points at high density, where magnetic gluons are not screened. The ground state of high density QCD with three light flavors is shown to be a color-flavor locking state, which can be mapped into the low-density hadronic phase. The meson mass at the CFL superconductor is also calculated. The CFL color superconductor is bosonized, where the Fermi sea is identified as a $Q$-matter and the gapped quarks as topological excitations, called superqualitons, of mesons. Finally, as an application of color supercoductivity, I discuss the neutrino interactions in the CFL color superconductor.

  11. Superconducting Hadron Linacs

    CERN Document Server

    Ostroumov, Peter

    2013-01-01

    This article discusses the main building blocks of a superconducting (SC) linac, the choice of SC resonators, their frequencies, accelerating gradients and apertures, focusing structures, practical aspects of cryomodule design, and concepts to minimize the heat load into the cryogenic system. It starts with an overview of design concepts for all types of hadron linacs differentiated by duty cycle (pulsed or continuous wave) or by the type of ion species (protons, H-, and ions) being accelerated. Design concepts are detailed for SC linacs in application to both light ion (proton, deuteron) and heavy ion linacs. The physics design of SC linacs, including transverse and longitudinal lattice designs, matching between different accelerating–focusing lattices, and transition from NC to SC sections, is detailed. Design of high-intensity SC linacs for light ions, methods for the reduction of beam losses, preventing beam halo formation, and the effect of HOMs and errors on beam quality are discussed. Examples are ta...

  12. 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.

  13. Anyon Superconductivity of Sb

    Science.gov (United States)

    Maksoed, Wh-; Parengkuan, August

    2016-10-01

    In any permutatives to Pedro P. Kuczhynski from Peru, for anyon superconductivity sought EZ Kuchinskii et al.: ``Anion height dependence of Tc & d.o.s of Fe-based Superconductors'', 2010 as well as ``on the basis of electron microscopy & AFM measurements, these phenomena are quantified with focus on fractal dimension, particle perimeter & size of the side branch(tip width) in bert Stegemann et al.:Crystallization of Sb nanoparticles-Pattern Formation & Fractal Growth'', J.PhysChem B., 2004. For dendritic & dendrimer fractal characters shown further: ``antimony denrites were found to be composed of well-crystallized nanoflakes with size 20-4 nm''- Bou Zhau, et al., MaterialLetters, 59 (2005). The alkyl triisopropyl attached in TIPSb those includes in DNA, haemoglobin membrane/fixed-bed reactor for instance quotes in Dragony Fu, Nature Review Cancer, 12 (Feb 2012). Heartfelt Gratitudes to HE. Mr. Prof. Ir. Handojo.

  14. Superconductivity of columbium

    Energy Technology Data Exchange (ETDEWEB)

    Cook, D.B.; Zemansky, M.W.; Boorse, H.A.

    1950-11-15

    Isothermal critical magnetic field curves and zero field transitions for several annealed specimens of columbium have been measured by an a.c. mutual inductance method at temperatures from 5.1 deg K to the zero field transition temperature. The H-T curve was found to fit the usual parabolic relationship H = H{sub 0}(1-T(2)/T(2){sub 0}) with H{sub 0} = 8250 oersteds and T{sub 0} = 8.65 deg K. The initial slope of the curve was 1910 oersteds/deg. The electronic specific heat in the normal state calculated from the thermodynamic equations is 0.0375T and the approximate Debye characteristic temperature in the superconducting state, 67 deg K. Results on a different grade of columbium with a tantalum impurity of 0.4 percent, according to neutron scattering measurements, were in agreement, with the data obtained from columbium of 0.2 percent maximum tantalum impurity.

  15. Superconducting pulsed magnets

    CERN Document Server

    CERN. Geneva

    2006-01-01

    Lecture 1. Introduction to Superconducting Materials Type 1,2 and high temperature superconductors; their critical temperature, field & current density. Persistent screening currents and the critical state model. Lecture 2. Magnetization and AC Loss How screening currents cause irreversible magnetization and hysteresis loops. Field errors caused by screening currents. Flux jumping. The general formulation of ac loss in terms of magnetization. AC losses caused by screening currents. Lecture 3. Twisted Wires and Cables Filamentary composite wires and the losses caused by coupling currents between filaments, the need for twisting. Why we need cables and how the coupling currents in cables contribute more ac loss. Field errors caused by coupling currents. Lecture 4. AC Losses in Magnets, Cooling and Measurement Summary of all loss mechanisms and calculation of total losses in the magnet. The need for cooling to minimize temperature rise in a magnet. Measuring ac losses in wires and in magnets. Lecture 5. Stab...

  16. Overview on superconducting photoinjectors

    Directory of Open Access Journals (Sweden)

    A. Arnold

    2011-02-01

    Full Text Available 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 (2004PSISDG0277-786X10.1117/12.557378] 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 operation was demonstrated at FZD [R. Xiang et al., in Proceedings of the 31st International Free Electron Laser Conference (FEL 09, Liverpool, UK (STFC Daresbury Laboratory, Warrington, 2009, p. 488]. In the near future SRF guns are expected to play an important role for linac-driven FEL facilities. In this paper we will review the concepts, the design parameters, and the status of the major SRF gun projects.

  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. Mixed-mu superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Mulcahy, Thomas M. (Western Springs, IL)

    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.

  19. 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

  20. Search for superconductivity in micrometeorites.

    Science.gov (United States)

    Guénon, S; Ramírez, J G; Basaran, Ali C; Wampler, J; Thiemens, M; Taylor, S; Schuller, Ivan K

    2014-12-05

    We have developed a very sensitive, highly selective, non-destructive technique for screening inhomogeneous materials for the presence of superconductivity. This technique, based on phase sensitive detection of microwave absorption is capable of detecting 10(-12) cc of a superconductor embedded in a non-superconducting, non-magnetic matrix. For the first time, we apply this technique to the search for superconductivity in extraterrestrial samples. We tested approximately 65 micrometeorites collected from the water well at the Amundsen-Scott South pole station and compared their spectra with those of eight reference materials. None of these micrometeorites contained superconducting compounds, but we saw the Verwey transition of magnetite in our microwave system. This demonstrates that we are able to detect electro-magnetic phase transitions in extraterrestrial materials at cryogenic temperatures.

  1. 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 6...

  2. 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.

  3. 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...

  4. Cryogenic Systems and Superconductive Power

    Science.gov (United States)

    The report defines, investigates, and experimentally evaluates the key elements of a representative crogenic turborefrigerator subsystem suitable for providing reliable long-lived cryogenic refrigeration for a superconductive ship propulsion system.

  5. Recent advances in fullerene superconductivity

    CERN Document Server

    Margadonna, S

    2002-01-01

    Superconducting transition temperatures in bulk chemically intercalated fulleride salts reach 33 K at ambient pressure and in hole-doped C sub 6 sub 0 derivatives in field-effect-transistor (FET) configurations, they reach 117 K. These advances pose important challenges for our understanding of high-temperature superconductivity in these highly correlated organic metals. Here we review the structures and properties of intercalated fullerides, paying particular attention to the correlation between superconductivity and interfullerene separation, orientational order/disorder, valence state, orbital degeneracy, low-symmetry distortions, and metal-C sub 6 sub 0 interactions. The metal-insulator transition at large interfullerene separations is discussed in detail. An overview is also given of the exploding field of gate-induced superconductivity of fullerenes in FET electronic devices.

  6. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  7. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  8. 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).

  9. Y-Ba Superconducting Ceramics

    Science.gov (United States)

    Shunbao, Tian; Xiaofei, Li; Tinglian, Wen; Zuxiang, Lin; Shichun, Li; Huijun, Yu

    Polycrystalline Y-Ba-Cu-O superconducting materials have been studied. It was found that chemical composition and processing condition may play an important role in the final structure and superconducting properties. The density has been determined and compared with the calculated value according to the structure model reported by Bell Labs. The grain size and the morphology of the materials were observed by SEM.

  10. Composite conductor containing superconductive wires

    Energy Technology Data Exchange (ETDEWEB)

    Larson, W.L.; Wong, J.

    1974-03-26

    A superconductor cable substitute made by coworking multiple rods of superconductive niobium--titanium or niobium--zirconium alloy with a common copper matrix to extend the copper and rods to form a final elongated product which has superconductive wires distributed in a reduced cross-section copper conductor with a complete metallurgical bond between the normal-conductive copper and the superconductor wires contained therein is described. The superconductor cable can be in the form of a tube.

  11. Entanglement witnessing in superconducting beamsplitters

    Science.gov (United States)

    Soller, H.; Hofstetter, L.; Reeb, D.

    2013-06-01

    We analyse a large class of superconducting beamsplitters for which the Bell parameter (CHSH violation) is a simple function of the spin detector efficiency. For these superconducting beamsplitters all necessary information to compute the Bell parameter can be obtained in Y-junction setups for the beamsplitter. Using the Bell parameter as an entanglement witness, we propose an experiment which allows to verify the presence of entanglement in Cooper pair splitters.

  12. 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....

  13. Recent developments in superconducting materials including ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Tachikawa, Kyoji

    1987-06-01

    This report describes the history of superconduction starting in 1911, when the superconducting phenomenon was first observed in murcury, until the recent discovery of superconducting materials with high critical temperatures. After outlining the BCS theory, basic characteristics are discussed including the critical temperature, magnetic field and current density to be reached for realizing the superconducting state. Various techniques for practical superconducting materials are discussed, including methods for producing extra fine multiconductor wires from such superconducting alloys as Nb-Ti, intermetallic Nb/sub 3/Sn compound and V/sub 3/Ga, as well as methods for producing wires of Nb/sub 3/Al, Nb/sub 3/(Al, Ge) and Nb/sub 3/Ge such as continuous melt quenching, electron beam irradiation, laser beam irradiation and chemical evaporation. Characteristics of superconducting ceramics are described, along with their applications including superconducting magnets and superconducting elements. (15 figs, 1 tab, 19 refs)

  14. Computer Simulation and Experimental Development of An Air Shower Core Detector%空气簇射轴芯探测器的计算机模拟和实验开发

    Institute of Scientific and Technical Information of China (English)

    杨振; 张颖; 邵静; 翟留名; 李万杰; 黄晶

    2011-01-01

    为了验证10 TeV及以上能区朝前区强子作用模型,我们完成了详细的计算机蒙特卡洛模拟.在计算机蒙卡模拟的基础上,我们设计并开发了空气簇射轴芯探测器(Yangbajing Air shower Core array,YAC),并使其与西藏羊八井ASgamma实验的外围广延大气簇射阵列(Tibet-Ⅲ)成功地联合运行.根据计算机模拟的结果显示,这样的YAC探测器共124台,摆成格子状结构,中间10×10阵列,外围24台,经过3年,我们可观测到10 TeV以上,满足我们要求的高能轴芯事例为5.6×107例.利用(Tibet -Ⅲ+ YAC)的联合实验,可记录10 TeV及以上能区的宇宙线空气簇射高能轴芯区所包含的100 GeV以上的电子和光子,测量其数目、横向分布等信息.由于该能区原初宇宙线的成分和能谱已有直接观测的结果,因此,根据YAC观测到的上述参量与计算机模拟结果的比较,我们可以对现有的强子作用模型进行验证.%In order to check the hadronic interaction models in the forward region at primary energies of above 10 TeV, a detailed computer simulation and an experimental development of the Yangbajing Air shower Core detector array ( YAC) is described. YAC, consisting of 124 detectors for which 100 are arranged into 10 x 10 grid and 24 are surrounded, will be operated together with the Tibet - Asgamma Extensive Air Shower array (Tibet - III). By using the hybrid experiment ( Tibet - III + YAC) , the high energy electromagnetic particles in the core region of air showers with primary energies higher than 10 TeV can be recorded. Their number distribution , their energy distribution, their lateral spread distribution and other information, together with the primary energy estimated by the accompanied air shower event recorded by the Tibet - III array, can provide important information in checking the interaction models in the corresponding energy region. A sufficient big data sample of about 5.6 × 107 high energy core events in three

  15. The road to superconducting spintronics

    Science.gov (United States)

    Eschrig, Matthias

    Energy efficient computing has become a major challenge, with the increasing importance of large data centres across the world, which already today have a power consumption comparable to that of Spain, with steeply increasing trend. Superconducting computing is progressively becoming an alternative for large-scale applications, with the costs for cooling being largely outweighed by the gain in energy efficiency. The combination of superconductivity and spintronics - ``superspintronics'' - has the potential and flexibility to develop into such a green technology. This young field is based on the observation that new phenomena emerge at interfaces between superconducting and other, competing, phases. The past 15 years have seen a series of pivotal predictions and experimental discoveries relating to the interplay between superconductivity and ferromagnetism. The building blocks of superspintronics are equal-spin Cooper pairs, which are generated at the interface between superconducting and a ferromagnetic materials in the presence of non-collinear magnetism. Such novel, spin-polarised Cooper pairs carry spin-supercurrents in ferromagnets and thus contribute to spin-transport and spin-control. Geometric Berry phases appear during the singlet-triplet conversion process in structures with non-coplanar magnetisation, enhancing functionality of devices, and non-locality introduced by superconducting order leads to long-range effects. With the successful generation and control of equal-spin Cooper pairs the hitherto notorious incompatibility of superconductivity and ferromagnetism has been not only overcome, but turned synergistic. I will discuss these developments and their extraordinary potential. I also will present open questions posed by recent experiments and point out implications for theory. This work is supported by the Engineering and Physical Science Research Council (EPSRC Grant No. EP/J010618/1).

  16. High temperature superconducting compounds

    Science.gov (United States)

    Goldman, Allen M.

    1992-11-01

    The major accomplishment of this grant has been to develop techniques for the in situ preparation of high-Tc superconducting films involving the use of ozone-assisted molecular beam epitaxy. The techniques are generalizable to the growth of trilayer and multilayer structures. Films of both the DyBa2Cu3O(7-x) and YBa2Cu3O(7-x) compounds as well as the La(2-x)Sr(x)CuO4 compound have been grown on the usual substrates, SrTiO3, YSZ, MgO, and LaAlO3, as well as on Si substrates without any buffer layer. A bolometer has been fabricated on a thermally isolated SiN substrate coated with YSZ, an effort carried out in collaboration with Honeywell Inc. The deposition process facilitates the fabrication of very thin and transparent films creating new opportunities for the study of superconductor-insulator transitions and the investigation of photo-doping with carriers of high temperature superconductors. In addition to a thin film technology, a patterning technology has been developed. Trilayer structures have been developed for FET devices and tunneling junctions. Other work includes the measurement of the magnetic properties of bulk single crystal high temperature superconductors, and in collaboration with Argonne National Laboratory, measurement of electric transport properties of T1-based high-Tc films.

  17. The Superconducting TESLA Cavities

    CERN Document Server

    Aune, B.; Bloess, D.; Bonin, B.; Bosotti, A.; Champion, M.; Crawford, C.; Deppe, G.; Dwersteg, B.; Edwards, D.A.; Edwards, H.T.; Ferrario, M.; Fouaidy, M.; Gall, P-D.; Gamp, A.; Gössel, A.; Graber, J.; Hubert, D.; Hüning, M.; Juillard, M.; Junquera, T.; Kaiser, H.; Kreps, G.; Kuchnir, M.; Lange, R.; Leenen, M.; Liepe, M.; Lilje, L.; Matheisen, A.; Möller, W-D.; Mosnier, A.; Padamsee, H.; Pagani, C.; Pekeler, M.; Peters, H-B.; Peters, O.; Proch, D.; Rehlich, K.; Reschke, D.; Safa, H.; Schilcher, T.; Schmüser, P.; Sekutowicz, J.; Simrock, S.; Singer, W.; Tigner, M.; Trines, D.; Twarowski, K.; Weichert, G.; Weisend, J.; Wojtkiewicz, J.; Wolff, S.; Zapfe, K.

    2000-01-01

    The conceptional design of the proposed linear electron-positron colliderTESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with anaccelerating gradient of Eacc >= 25 MV/m at a quality factor Q0 > 5E+9. Thedesign goal for the cavities of the TESLA Test Facility (TTF) linac was set tothe more moderate value of Eacc >= 15 MV/m. In a first series of 27industrially produced TTF cavities the average gradient at Q0 = 5E+9 wasmeasured to be 20.1 +- 6.2 MV/m, excluding a few cavities suffering fromserious fabrication or material defects. In the second production of 24 TTFcavities additional quality control measures were introduced, in particular aneddy-current scan to eliminate niobium sheets with foreign material inclusionsand stringent prescriptions for carrying out the electron-beam welds. Theaverage gradient of these cavities at Q0 = 5E+9 amounts to 25.0 +- 3.2 MV/mwith the exception of one cavity suffering from a weld defect. Hence only amoderate improvement in production and preparation technique...

  18. Comparison of 10 MW superconducting generator topologies for direct-drive wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2015-01-01

    proposed to address the problem with generator size, because the electrical machines with superconducting windings are capable of achieving a higher torque density of an electrical machine. However, the topology to be adopted for superconducting wind generators has not yet been settled, since the high...... magnetic field excitation allows for lightweight non-magnetic composite materials for machine cores instead of iron. A topology would probably not be a good option for an offshore wind turbine generator if it demands a far more expensive active material cost than others, even if it has other advantages...... such as light weight or small iron losses. This paper is to provide a preliminary quantitative comparison of 10 MW superconducting MgB2 generator topologies from the perspective of active material. The results show that iron-cored topologies have a cheaper active material and their sizes are relatively smaller...

  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. Atmospheric abundance and global emissions of perfluorocarbons CF4, C2F6 and C3F8 since 1800 inferred from ice core, firn, air archive and in situ measurements

    Science.gov (United States)

    Trudinger, Cathy M.; Fraser, Paul J.; Etheridge, David M.; Sturges, William T.; Vollmer, Martin K.; Rigby, Matt; Martinerie, Patricia; Mühle, Jens; Worton, David R.; Krummel, Paul B.; Steele, L. Paul; Miller, Benjamin R.; Laube, Johannes; Mani, Francis S.; Rayner, Peter J.; Harth, Christina M.; Witrant, Emmanuel; Blunier, Thomas; Schwander, Jakob; O'Doherty, Simon; Battle, Mark

    2016-09-01

    Perfluorocarbons (PFCs) are very potent and long-lived greenhouse gases in the atmosphere, released predominantly during aluminium production and semiconductor manufacture. They have been targeted for emission controls under the United Nations Framework Convention on Climate Change. Here we present the first continuous records of the atmospheric abundance of CF4 (PFC-14), C2F6 (PFC-116) and C3F8 (PFC-218) from 1800 to 2014. The records are derived from high-precision measurements of PFCs in air extracted from polar firn or ice at six sites (DE08, DE08-2, DSSW20K, EDML, NEEM and South Pole) and air archive tanks and atmospheric air sampled from both hemispheres. We take account of the age characteristics of the firn and ice core air samples and demonstrate excellent consistency between the ice core, firn and atmospheric measurements. We present an inversion for global emissions from 1900 to 2014. We also formulate the inversion to directly infer emission factors for PFC emissions due to aluminium production prior to the 1980s. We show that 19th century atmospheric levels, before significant anthropogenic influence, were stable at 34.1 ± 0.3 ppt for CF4 and below detection limits of 0.002 and 0.01 ppt for C2F6 and C3F8, respectively. We find a significant peak in CF4 and C2F6 emissions around 1940, most likely due to the high demand for aluminium during World War II, for example for construction of aircraft, but these emissions were nevertheless much lower than in recent years. The PFC emission factors for aluminium production in the early 20th century were significantly higher than today but have decreased since then due to improvements and better control of the smelting process. Mitigation efforts have led to decreases in emissions from peaks in 1980 (CF4) or early-to-mid-2000s (C2F6 and C3F8) despite the continued increase in global aluminium production; however, these decreases in emissions appear to have recently halted. We see a temporary reduction of around

  1. Superconductive articles including cerium oxide layer

    Science.gov (United States)

    Wu, Xin D.; Muenchausen, Ross E.

    1993-01-01

    A ceramic superconductor comprising a metal oxide substrate, a ceramic high temperature superconductive material, and a intermediate layer of a material having a cubic crystal structure, said layer situated between the substrate and the superconductive material is provided, and a structure for supporting a ceramic superconducting material is provided, said structure comprising a metal oxide substrate, and a layer situated over the surface of the substrate to substantially inhibit interdiffusion between the substrate and a ceramic superconducting material deposited upon said structure.

  2. 4. MESOSCOPIC SUPERCONDUCTIVITY: Proximity Action theory of superconductive nanostructures

    Science.gov (United States)

    Skvortsov, M. A.; Larkin, A. I.; Feigel'man, M. V.

    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.

  3. Impact of eigenvalues on the pseudopotential calculation of superconducting parameters of metals Ga, Cd and In

    Science.gov (United States)

    Yadav, Jayprakash; Rafique, S. M.; Kumari, Shanti

    2009-10-01

    In the present paper some superconducting (SC) state parameters of metals Ga, Cd and In have been studied through Harrison's First Principle [HFP] pseudopotential technique using McMillan's formalism. The impact of choosing two different sets of core energy eigenvalues viz. Herman-Skillman and Clementi (or Experimental) has been studied.

  4. 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.

  5. Gifts from the superconducting curiosity shop

    Institute of Scientific and Technical Information of China (English)

    David Mandrus

    2011-01-01

    Superconductivity has just celebrated its 100th birthday,and yet despite its advanced age it has never been more alive.Given that most subfields of materials physics have a half-life of about seven years,what accounts for the enduring popularity of superconductivity? What is it about superconductivity that continues to fascinate?

  6. LLNL superconducting magnets test facility

    Energy Technology Data Exchange (ETDEWEB)

    Manahan, R; Martovetsky, N; Moller, J; Zbasnik, J

    1999-09-16

    The FENIX facility at Lawrence Livermore National Laboratory was upgraded and refurbished in 1996-1998 for testing CICC superconducting magnets. The FENIX facility was used for superconducting high current, short sample tests for fusion programs in the late 1980s--early 1990s. The new facility includes a 4-m diameter vacuum vessel, two refrigerators, a 40 kA, 42 V computer controlled power supply, a new switchyard with a dump resistor, a new helium distribution valve box, several sets of power leads, data acquisition system and other auxiliary systems, which provide a lot of flexibility in testing of a wide variety of superconducting magnets in a wide range of parameters. The detailed parameters and capabilities of this test facility and its systems are described in the paper.

  7. Superconductivity, antiferromagnetism, and neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Tranquada, John M., E-mail: jtran@bnl.gov; Xu, Guangyong; Zaliznyak, Igor A.

    2014-01-15

    High-temperature superconductivity in both the copper-oxide and the iron–pnictide/chalcogenide systems occurs in close proximity to antiferromagnetically ordered states. Neutron scattering has been an essential technique for characterizing the spin correlations in the antiferromagnetic phases and for demonstrating how the spin fluctuations persist in the superconductors. While the nature of the spin correlations in the superconductors remains controversial, the neutron scattering measurements of magnetic excitations over broad ranges of energy and momentum transfers provide important constraints on the theoretical options. We present an overview of the neutron scattering work on high-temperature superconductors and discuss some of the outstanding issues. - Highlights: • High-temperature superconductivity is closely associated with antiferromagnetism. • Antiferromagnetic spin fluctuations coexist with the superconductivity. • Neutron scattering is essential for characterising the full spectrum of spin excitations.

  8. 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.

  9. Domain wall description of superconductivity

    CERN Document Server

    Brito, F A; Silva, J C M

    2012-01-01

    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 as the parameter to move type I to type II domain walls. Alternatively, this means that the domain wall surface is suffering an acceleration as one goes from one type to another. On the other hand, changing from type I to type II state means a formation of a condensate what is in perfect sense of lowering the temperature around the superconductor. One can think of this scenario as an analog of holographic scenarios where this set up is replaced by a black hole near the domain wall.

  10. The contrasting magnetic fields of superconducting pulsars and magnetars

    CERN Document Server

    Lander, S K

    2013-01-01

    We study equilibrium magnetic field configurations in a neutron star whose core has type-II superconducting protons. Unlike normal matter, whose equations do not involve any special field strength, those for superconductors contain the lower critical field, of order 10^{15} G. We find that the ratio between this critical field and the smooth-averaged stellar magnetic field at the crust-core boundary is the key feature dictating the field geometry. Our results suggest that pulsar and magnetar-strength fields have notably different configurations. Field decay for neutron stars with B_{pole}\\sim 10^{14} G could thus result in substantial internal rearrangements, with the toroidal field component being pushed out of the core; this may be related to observed magnetar activity.

  11. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2010-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  12. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2008-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  13. Stripes and superconductivity in cuprates

    Science.gov (United States)

    Tranquada, John M.

    2012-06-01

    Holes doped into the CuO2 planes of cuprate parent compounds frustrate the antiferromagnetic order. The development of spin and charge stripes provides a compromise between the competing magnetic and kinetic energies. Static stripe order has been observed only in certain particular compounds, but there are signatures which suggest that dynamic stripe correlations are common in the cuprates. Though stripe order is bad for superconducting phase coherence, stripes are compatible with strong pairing. Ironically, magnetic-field-induced stripe order appears to enhance the stability of superconducting order within the planes.

  14. Stripes and superconductivity in cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Tranquada, John M., E-mail: jtran@bnl.gov [Condensed Matter Physics and Materials Science Dept., Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)

    2012-06-01

    Holes doped into the CuO{sub 2} planes of cuprate parent compounds frustrate the antiferromagnetic order. The development of spin and charge stripes provides a compromise between the competing magnetic and kinetic energies. Static stripe order has been observed only in certain particular compounds, but there are signatures which suggest that dynamic stripe correlations are common in the cuprates. Though stripe order is bad for superconducting phase coherence, stripes are compatible with strong pairing. Ironically, magnetic-field-induced stripe order appears to enhance the stability of superconducting order within the planes.

  15. Geneva University - Superconducting flux quantum bits: fabricated quantum objects

    CERN Multimedia

    2007-01-01

    Ecole de physique Département de physique nucléaire et corspusculaire 24, Quai Ernest-Ansermet 1211 GENEVE 4 Tél: (022) 379 62 73 Fax: (022) 379 69 92 Lundi 29 janvier 2007 COLLOQUE DE LA SECTION DE PHYSIQUE 17 heures - Auditoire Stueckelberg Superconducting flux quantum bits: fabricated quantum objects Prof. Hans Mooij / Kavli Institute of Nanoscience, Delft University of Technology The quantum conjugate variables of a superconductor are the charge or number of Cooper pairs, and the phase of the order parameter. In circuits that contain small Josephson junctions, these quantum properties can be brought forward. In Delft we study so-called flux qubits, superconducting rings that contain three small Josephson junctions. When a magnetic flux of half a flux quantum is applied to the loop, there are two states with opposite circulating current. For suitable junction parameters, a quantum superposition of those macroscopic states is possible. Transitions can be driven with resonant microwaves. These quantum ...

  16. The helium cryogenic plant for the CMS superconducting magnet

    CERN Document Server

    Perinic, G; Dagut, F; Dauguet, P; Hirel, P

    2002-01-01

    A new helium refrigeration plant with a cooling capacity of 800 W at 4.45 K, 4500 W between 60 K and 80 K, and 4 g/s liquefaction simultaneously has been designed and is presently being constructed by Air Liquide for CERN. The refrigeration plant will provide the cooling power for the cool down and the operation of the CMS (Compact Muon Solenoid) superconducting coil whose cold mass weighs 225 t. The refrigeration plant will at first be installed in a surface building for the tests of the superconducting magnet. On completion of the tests the cold box will be moved to its final underground position next to the CMS experimental cavern. This paper presents the process design, describes the main components and explains their selection. (4 refs).

  17. Investigation of EAS cores

    Science.gov (United States)

    Shaulov, S. B.; Beyl, P. F.; Beysembaev, R. U.; Beysembaeva, E. A.; Bezshapov, S. P.; Borisov, A. S.; Cherdyntceva, K. V.; Chernyavsky, M. M.; Chubenko, A. P.; Dalkarov, O. D.; Denisova, V. G.; Erlykin, A. D.; Kabanova, N. V.; Kanevskaya, E. A.; Kotelnikov, K. A.; Morozov, A. E.; Mukhamedshin, R. A.; Nam, R. A.; Nesterova, N. M.; Nikolskaya, N. M.; Pavluchenko, V. P.; Piskal, V. V.; Puchkov, V. S.; Pyatovsky, S. E.; Ryabov, V. A.; Sadykov, T. Kh.; Schepetov, A. L.; Smirnova, M. D.; Stepanov, A. V.; Uryson, A. V.; Vavilov, Yu. N.; Vildanov, N. G.; Vildanova, L. I.; Zayarnaya, I. S.; Zhanceitova, J. K.; Zhukov, V. V.

    2017-06-01

    The development of nuclear-electromagnetic cascade models in air in the late forties have shown informational content of the study of cores of extensive air showers (EAS). These investigations were the main goal in different experiments which were carried out over many years by a variety of methods. Outcomes of such investigations obtained in the HADRON experiment using an X-ray emulsion chamber (XREC) as a core detector are considered. The Ne spectrum of EAS associated with γ-ray families, spectra of γ-rays (hadrons) in EAS cores and the Ne dependence of the muon number, ⟨Nμ⟩, in EAS with γ-ray families are obtained for the first time at energies of 1015-1017 eV with this method. A number of new effects were observed, namely, an abnormal scaling violation in hadron spectra which are fundamentally different from model predictions, an excess of muon number in EAS associated with γ-ray families, and the penetrating component in EAS cores. It is supposed that the abnormal behavior of γ-ray spectra and Ne dependence of the muon number are explained by the emergence of a penetrating component in the 1st PCR spectrum `knee' range. Nuclear and astrophysical explanations of the origin of the penetrating component are discussed. The necessity of considering the contribution of a single close cosmic-ray source to explain the PCR spectrum in the knee range is noted.

  18. Investigation of EAS cores

    Directory of Open Access Journals (Sweden)

    Shaulov S.B.

    2017-01-01

    Full Text Available The development of nuclear-electromagnetic cascade models in air in the late forties have shown informational content of the study of cores of extensive air showers (EAS. These investigations were the main goal in different experiments which were carried out over many years by a variety of methods. Outcomes of such investigations obtained in the HADRON experiment using an X-ray emulsion chamber (XREC as a core detector are considered. The Ne spectrum of EAS associated with γ-ray families, spectra of γ-rays (hadrons in EAS cores and the Ne dependence of the muon number, ⟨Nμ⟩, in EAS with γ-ray families are obtained for the first time at energies of 1015–1017 eV with this method. A number of new effects were observed, namely, an abnormal scaling violation in hadron spectra which are fundamentally different from model predictions, an excess of muon number in EAS associated with γ-ray families, and the penetrating component in EAS cores. It is supposed that the abnormal behavior of γ-ray spectra and Ne dependence of the muon number are explained by the emergence of a penetrating component in the 1st PCR spectrum ‘knee’ range. Nuclear and astrophysical explanations of the origin of the penetrating component are discussed. The necessity of considering the contribution of a single close cosmic-ray source to explain the PCR spectrum in the knee range is noted.

  19. 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.

  20. Air-Stable, Near- to Mid-Infrared Emitting Solids of PbTe/CdTe Core-Shell Colloidal quantum dots.

    Science.gov (United States)

    Protesescu, Loredana; Zünd, Tanja; Bodnarchuk, Maryna I; Kovalenko, Maksym V

    2016-03-03

    Light emitters and detectors operating in the near- and mid-infrared spectral regions are important to many applications, such as telecommunications, high-resolution gas analysis, atmospheric pollution monitoring, medical diagnostics, and night vision. Various lead chalcogenides (binary, ternary, and quaternary alloys) in the form of quantum dots (QDs) or quantum wells provide narrow bandgap energies that cover the broad infrared region corresponding to wavelengths of 1-30 μm. Here, we report an inexpensive, all-solution-based synthesis strategy to thin-film solids consisting of 5-16 nm PbTe QDs encapsulated by CdTe shells. Colloidally synthesized PbTe QDs were first converted into core-shell PbTe/CdTe QDs, and then deposited as thin films. The subsequent fusion of the CdTe shells is achieved by ligand removal and annealing in the presence of CdCl2 . Contrary to highly unstable bare PbTe QDs, PbTe/CdTe QD solids exhibit bright and stable near- to mid-infrared emission at wavelengths of 1-3 μm, which is also retained upon prolonged storage at ambient conditions for one year.

  1. Superconductivity in highly disordered dense carbon disulfide.

    Science.gov (United States)

    Dias, Ranga P; Yoo, Choong-Shik; Struzhkin, Viktor V; Kim, Minseob; Muramatsu, Takaki; Matsuoka, Takahiro; Ohishi, Yasuo; Sinogeikin, Stanislav

    2013-07-16

    High pressure plays an increasingly important role in both understanding superconductivity and the development of new superconducting materials. New superconductors were found in metallic and metal oxide systems at high pressure. However, because of the filled close-shell configuration, the superconductivity in molecular systems has been limited to charge-transferred salts and metal-doped carbon species with relatively low superconducting transition temperatures. Here, we report the low-temperature superconducting phase observed in diamagnetic carbon disulfide under high pressure. The superconductivity arises from a highly disordered extended state (CS4 phase or phase III[CS4]) at ~6.2 K over a broad pressure range from 50 to 172 GPa. Based on the X-ray scattering data, we suggest that the local structural change from a tetrahedral to an octahedral configuration is responsible for the observed superconductivity.

  2. Phase slips in superconducting weak links

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Gregory; Glatz, Andreas; Aranson, Igor S.

    2017-01-01

    Superconducting vortices and phase slips are primary mechanisms of dissipation in superconducting, superfluid, and cold-atom systems. While the dynamics of vortices is fairly well described, phase slips occurring in quasi-one- dimensional superconducting wires still elude understanding. The main reason is that phase slips are strongly nonlinear time-dependent phenomena that cannot be cast in terms of small perturbations of the superconducting state. Here we study phase slips occurring in superconducting weak links. Thanks to partial suppression of superconductivity in weak links, we employ a weakly nonlinear approximation for dynamic phase slips. This approximation is not valid for homogeneous superconducting wires and slabs. Using the numerical solution of the time-dependent Ginzburg-Landau equation and bifurcation analysis of stationary solutions, we show that the onset of phase slips occurs via an infinite period bifurcation, which is manifested in a specific voltage-current dependence. Our analytical results are in good agreement with simulations.

  3. 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 ...

  4. Power applications for superconducting cables

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Hansen, Steen; Jørgensen, Preben

    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...

  5. Superconductivity by kinetic energy saving?

    NARCIS (Netherlands)

    Van der Marel, D; Molegraaf, HJA; Presura, C; Santoso, [No Value; Hewson, AC; Zlatic,

    2003-01-01

    A brief introduction is given in the generic microscopic framework of superconductivity. The consequences for the temperature dependence of the kinetic energy, and the correlation energy are discussed for two cases: The BCS scenario and the non-Fermi liquid scenario. A quantitative comparison is mad

  6. 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.

  7. 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.

  8. Superconductivity by kinetic energy saving?

    NARCIS (Netherlands)

    Van der Marel, D; Molegraaf, HJA; Presura, C; Santoso, [No Value; Hewson, AC; Zlatic,

    2003-01-01

    A brief introduction is given in the generic microscopic framework of superconductivity. The consequences for the temperature dependence of the kinetic energy, and the correlation energy are discussed for two cases: The BCS scenario and the non-Fermi liquid scenario. A quantitative comparison is

  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. Collaring of Po Superconducting Dipole

    CERN Multimedia

    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

  11. Superconductivity resulting from antiferromagnetic states

    Energy Technology Data Exchange (ETDEWEB)

    Feng Shi-Ping (Department of Physics, Beijing Normal University (CN))

    1989-09-01

    When the dopping is low enough, the holes obey Bose statistics, Bose-Einstein condensation of these holes may lead to occurance of superconductivity. In this framework, we have calculated some physical quantities, the results are in qualitative agreement with experiments.

  12. Superconductivity by kinetic energy saving?

    NARCIS (Netherlands)

    Van der Marel, D; Molegraaf, HJA; Presura, C; Santoso, [No Value; Hewson, AC; Zlatic,

    2003-01-01

    A brief introduction is given in the generic microscopic framework of superconductivity. The consequences for the temperature dependence of the kinetic energy, and the correlation energy are discussed for two cases: The BCS scenario and the non-Fermi liquid scenario. A quantitative comparison is mad

  13. 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.

  14. 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.

  15. Fireballs from superconducting cosmic strings

    Science.gov (United States)

    Gruzinov, Andrei; Vilenkin, Alexander

    2017-01-01

    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.

  16. Superconducting Qubits and Quantum Resonators

    NARCIS (Netherlands)

    Forn-Díaz, P.

    2010-01-01

    Superconducting qubits are fabricated "loss-free" electrical circuits on a chip with size features of tens of nanometers. If cooled to cryogenic temperatures below -273 °C they behave as quantum elements, similar to atoms and molecules. Such a qubit can be manipulated by fast-oscillating magnetic fi

  17. Tutorial on Superconducting Accelerator Magnets

    Science.gov (United States)

    Ball, M. J. Penny; Goodzeit, Carl L.

    1997-05-01

    A multimedia CD-ROM tutorial on the physics and engineering concepts of superconducting magnets for particle accelerators is being developed under a U.S. Dept. of Energy SBIR grant. The tutorial, scheduled for distribution this summer, is targeted to undergraduate junior or senior level science students. However, its unified presentation of the broad range of issues involved in the design of superconducting magnets for accelerators and the extensive detail about the construction process (including animations and video clips) will also be of value to staff of research institutes and industrial concerns with an interest in applied superconductivity or magnet development. The source material, which is based on the world-wide R and D programs to develop superconducting accelerator magnets, is organized in five units with the following themes: Introduction to magnets and accelerators; (2) Superconductors for accelerator magnets; (3) Magnetic design methods for accelerator magnets; (4) Electrical, mechanical, and cryogenic considerations for the final magnet package; (5) Performance characteristics and measurement methods. A detailed outline and examples will be shown.

  18. 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.

  19. Photon-detecting superconducting resonators

    NARCIS (Netherlands)

    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

  20. Ice Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

  1. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  2. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  3. Core benefits

    National Research Council Canada - National Science Library

    Keith, Brian W

    2010-01-01

    This SPEC Kit explores the core employment benefits of retirement, and life, health, and other insurance -benefits that are typically decided by the parent institution and often have significant governmental regulation...

  4. Superconductivity: The persistence of pairs

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, Alex; Littlewood, Peter

    2015-05-20

    Superconductivity stems from a weak attraction between electrons that causes them to form bound pairs and behave much like bosons. These so-called Cooper pairs are phase coherent, which leads to the astonishing properties of zero electrical resistance and magnetic flux expulsion typical of superconducting materials. This coherent state may be qualitatively understood within the Bose–Einstein condensate (BEC) model, which predicts that a gas of interacting bosons will become unstable below a critical temperature and condense into a phase of matter with a macroscopic, coherent population in the lowest energy state, as happens in 4He or cold atomic gases. The successful theory proposed by Bardeen, Cooper and Schrieffer (BCS) predicts that at the superconducting transition temperature Tc, electrons simultaneously form pairs and condense, with no sign of pairing above Tc. Theorists have long surmised that the BCS and BEC models are opposite limits of a single theory and that strong interactions or low density can, in principle, drive the system to a paired state at a temperature Tpair higher than Tc, making the transition to the superconducting state BEC-like (Fig. 1). Yet most superconductors to date are reasonably well described by BCS theory or its extensions, and there has been scant evidence in electronic materials for the existence of pairing independent of the full superconducting state (though an active debate rages over the cuprate superconductors). Writing in Nature, Jeremy Levy and colleagues have now used ingenious nanostructured devices to provide evidence for electron pairing1. Perhaps surprisingly, the material they have studied is a venerable, yet enigmatic, low-temperature superconductor, SrTiO3.

  5. Honeycomb Core Permeability Under Mechanical Loads

    Science.gov (United States)

    Glass, David E.; Raman, V. V.; Venkat, Venki S.; Sankaran, Sankara N.

    1997-01-01

    A method for characterizing the air permeability of sandwich core materials as a function of applied shear stress was developed. The core material for the test specimens was either Hexcel HRP-3/16-8.0 and or DuPont Korex-1/8-4.5 and was nominally one-half inch thick and six inches square. The facesheets where made of Hercules' AS4/8552 graphite/epoxy (Gr/Ep) composites and were nominally 0.059-in. thick. Cytec's Metalbond 1515-3M epoxy film adhesive was used for co-curing the facesheets to the core. The permeability of the specimens during both static (tension) and dynamic (reversed and non-reversed) shear loads were measured. The permeability was measured as the rate of air flow through the core from a circular 1-in2 area of the core exposed to an air pressure of 10.0 psig. In both the static and dynamic testing, the Korex core experienced sudden increases in core permeability corresponding to a core catastrophic failure, while the URP core experienced a gradual increase in the permeability prior to core failure. The Korex core failed at lower loads than the HRP core both in the transverse and ribbon directions.

  6. Effects of rolling deformation processes on the properties of Ag-sheathed Sr1-xKxFe2As2 superconducting tapes

    Science.gov (United States)

    Huang, He; Zhang, Xianping; Yao, Chao; Dong, Chiheng; Zhang, Qianjun; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2016-06-01

    The powder-in-tube method is widely used in fabricating iron-based superconducting wires and tapes. To make tapes, a multi-pass rolling process is usually adopted. However, the multi-pass rolling process limits the efficiency of tapes. In this work, rolling deformation technique was studied systematically by fabricating Sr1-xKxFe2As2 superconducting tapes. The total rolling reduction ratio is about 80% and the difference of superconducting performance of tapes rolled by 2, 3, 5 and 7 passes has been investigated. The critical current density Jc, Vickers micro-hardness and microstructure of the superconducting core indicate that tapes after 2, 3, 5 and 7 rolling passes exhibit a similar trend. The width of the tapes and the area of superconducting cores increase with decreasing the number of rolling passes, but the transport Jc of tapes after different rolling passes seems to be the same, except for the tape rolled by 2 passes, whose transport Jc is lower than the other tapes. Concerning the geometry uniformity for the superconducting cores, the sausaging phenomenon was not observed from the photograph of longitudinal cross-section of all the samples. "Lobes" phenomenon on transverse cross-section can be suppressed through decreasing the rolling passes. Therefore, we can obtain uniform and high-performance Ag-sheathed iron-based superconducting tapes by cutting the number of rolling passes down to 3, which is more advantageous to the large-scale producing in the future.

  7. Performance of current measurement system in poloidal field power supply for Experimental Advanced Superconducting Tokamak

    Science.gov (United States)

    Liu, D. M.; Li, J.; Wan, B. N.; Lu, Z.; Wang, L. S.; Jiang, L.; Lu, C. H.; Huang, J.

    2016-11-01

    As one of the core subsystems of the Experimental Advanced Superconducting Tokamak (EAST), the poloidal field power system supplies energy to EAST's superconducting coils. To measure the converter current in the poloidal field power system, a current measurement system has been designed. The proposed measurement system is composed of a Rogowski coil and a newly designed integrator. The results of the resistor-inductor-capacitor discharge test and the converter equal current test show that the current measurement system provides good reliability and stability, and the maximum error of the proposed system is less than 1%.

  8. Heat deposition into the superconducting central column of a spherical tokamak fusion plant

    Science.gov (United States)

    Windsor, C. G.; Morgan, J. G.; Buxton, P. F.

    2015-02-01

    A key challenge in designing a fusion power plant is to manage the heat deposition into the central core containing superconducting toroidal field coils. Spherical tokamaks have limited space for shielding the central core from fast neutrons produced by fusion and the resulting gamma rays. This paper reports a series of three-dimensional computations using the Monte Carlo N-particle code to calculate the heat deposition into the superconducting core. For a given fusion power, this is considered as a function of plasma major radius R0, core radius rsc and shield thickness d. Computations over the ranges 0.6 m ⩽ R0 ⩽ 1.6 m, 0.15 m ⩽ rsc ⩽ 0.25 m and 0.15 m ⩽ d ⩽ 0.4 m are presented. The deposited power shows an exponential dependence on all three variables to within around 2%. The additional effects of source profile, the outer shield and shield material are all considered. The results can be interpolated to 2% accuracy and have been successfully incorporated into a system code. A possible pilot plant with 174 MW of fusion is shown to lead to a heat deposition into the superconducting core of order 30 kW. An estimate of 1.7 MW is made for the cryogenic plant power necessary for heat removal, and of 88 s running time for an adiabatic experiment where the heat deposition is absorbed by a 10 K temperature rise.

  9. Superconducting-magnetic heterostructures: a method of decreasing AC losses and improving critical current density in multifilamentary conductors.

    Science.gov (United States)

    Glowacki, B A; Majoros, M

    2009-06-24

    Magnetic materials can help to improve the performance of practical superconductors on the macroscale/microscale as magnetic diverters and also on the nanoscale as effective pinning centres. It has been established by numerical modelling that magnetic shielding of the filaments reduces AC losses in self-field conditions due to decoupling of the filaments and, at the same time, it increases the critical current of the composite. This effect is especially beneficial for coated conductors, in which the anisotropic properties of the superconductor are amplified by the conductor architecture. However, ferromagnetic coatings are often chemically incompatible with YBa(2)Cu(3)O(7) and (Pb,Bi)(2)Sr(2)Ca(2)Cu(3)O(9) conductors, and buffer layers have to be used. In contrast, in MgB(2) conductors an iron matrix may remain in direct contact with the superconducting core. The application of superconducting-magnetic heterostructures requires consideration of the thermal and electromagnetic stability of the superconducting materials used. On one hand, magnetic materials reduce the critical current gradient across the individual filaments but, on the other hand, they often reduce the thermal conductivity between the superconducting core and the cryogen, which may cause destruction of the conductor in the event of thermal instability. A possible nanoscale method of improving the critical current density of superconducting conductors is the introduction of sub-micron magnetic pinning centres. However, the volumetric density and chemical compatibility of magnetic inclusions has to be controlled to avoid suppression of the superconducting properties.

  10. Test and Coupling Calculation of Temperature Field for UHV Dry-Type Air-Core Smoothing Reactor%特高压干式空心平波电抗器温度场耦合计算与试验

    Institute of Scientific and Technical Information of China (English)

    姜志鹏; 文习山; 王羽; 陈瑞珍; 曹继丰; 陈图腾

    2015-01-01

    为了研究特高压干式空心平波电抗器的温升分布特性,该文基于计算流体力学和传热学理论,建立了电抗器稳态流体与固体耦合温度场的数学计算模型.采用有限容积法对三维模型进行稳态流体场与温度场直接求解,获得其温度场分布特性,研究了包封轴向及径向温度分布规律.最后采用光纤测温法对自然对流下的电抗器进行温升测量.对比分析表明,计算与试验结果吻合较好,验证温度场数值计算的合理性和准确性,为特高压干式空心平波电抗器温升监测提供参考.%To research the distribution characteristics of temperature rise for UHV dry-type air-core smoothing reactor, according to computational fluid dynamics and heat transfer theory, this paper presented the mathematical model of temperature field coupling steady fluid and solid for the reactor. The finite volume method was employed to solve the steady flow and temperature fields of 3D model directly, and the temperature distribution characteristics of the reactor were obtained. Then the axial and radial temperature distributions of encapsulations were studied separately. Finally, optical fiber temperature measurement method was used to test temperature rise for the reactor under natural convection condition. Comparative analysis shows that the calculated results are in good agreement with the experiment, which verifies the rationality and accuracy of the temperature field numerical calculation. And it can provide references for the temperature rise monitoring of UHV dry-type air-core smoothing reactor.

  11. Research on turbulent mixing of the bypass and core flows for air-turbo-rocket%空气涡轮火箭发动机内外涵气流掺混研究

    Institute of Scientific and Technical Information of China (English)

    李平; 李文龙; 何国强

    2012-01-01

    A numerical calculation on the flow field of mixing combustion chamber without chemical reaction was carried out for hydrazine monopropellant air-turbo-rocket under uniform inlet flows. The induction and decay evolution of streamwise and normal vortices were obtained,and an analysis was made on the influence of this course on turbulent mixing efficiency of the bypass and core flows. A quantitative analysis revealed that streamwise vortices induced by a spanwise array of large scale secondary flows at trailing edge play a dominant role in the downstream mixing process of the bypass and core flows. It is preferable to employ scarfed lobed mixers with large lobe penetration rate. A preliminary analysis of turbulent mixing efficiency was also made between computational and experimental data for two mixing schemes including three kinds of lobed mixer,and results show that nonuniform inlet flow conditions have a significant impact upon turbulent mixing and combustion efficiency for small dimension air-turbo-rocket.%通过无化学反应、均匀进气条件下肼单组元空气涡轮火箭发动机混流燃烧室内流场的数值计算,得到了流向涡与正交涡系产生、衰减演变过程及其对内外涵气流掺混效率的影响规律.结果表明,大尺度阵列二次环流诱导形成的流向涡对内外涵气流掺混起主导作用,大波瓣穿透率的斜切波瓣混流器的综合性能较优.结合热试车结果,分析了包括波瓣混流器在内的两类掺混方案的强化掺混效率.分析表明,非均匀进气条件对小尺寸空气涡轮火箭发动机掺混燃烧效率影响很大.

  12. Towards high efficiency air-processed near-infrared responsive photovoltaics: bulk heterojunction solar cells based on PbS/CdS core-shell quantum dots and TiO2 nanorod arrays.

    Science.gov (United States)

    Gonfa, Belete Atomsa; Kim, Mee Rahn; Delegan, Nazar; Tavares, Ana C; Izquierdo, Ricardo; Wu, Nianqiang; El Khakani, My Ali; Ma, Dongling

    2015-06-14

    Near infrared (NIR) PbS quantum dots (QDs) have attracted significant research interest in solar cell applications as they offer several advantages, such as tunable band gaps, capability of absorbing NIR photons, low cost solution processability and high potential for multiple exciton generation. Nonetheless, reports on solar cells based on NIR PbS/CdS core-shell QDs, which are in general more stable and better passivated than PbS QDs and thus more promising for solar cell applications, remain very rare. Herein we report high efficiency bulk heterojunction QD solar cells involving hydrothermally grown TiO2 nanorod arrays and PbS/CdS core-shell QDs processed in air (except for a device thermal annealing step) with a photoresponse extended to wavelengths >1200 nm and with a power conversion efficiency (PCE) as high as 4.43%. This efficiency was achieved by introducing a thin, sputter-deposited, uniform TiO2 seed layer to improve the interface between the TiO2 nanorod arrays and the front electrode, by optimizing TiO2 nanorod length and by conducting QD annealing treatment to enhance charge carrier transport. It was found that the effect of the seed layer became more obvious when the TiO2 nanorods were longer. Although photocurrent did not change much, both open circuit voltage and fill factor clearly changed with TiO2 nanorod length. This was mainly attributed to the variation of charge transport and recombination processes, as evidenced by series and shunt resistance studies. The optimal PCE was obtained at the nanorod length of ∼450 nm. Annealing is shown to further increase the PCE by ∼18%, because of the improvement of charge carrier transport in the devices as evidenced by considerably increased photocurrent. Our results clearly demonstrate the potential of the PbS/CdS core-shell QDs for the achievement of high PCE, solution processable and NIR responsive QD solar cells.

  13. Numerical simulation of anti-explosion performance of U-type core sandwich panel under air explosion%空爆载荷下U型夹层板抗爆性能数值仿真研究

    Institute of Scientific and Technical Information of China (English)

    张延昌; 赵卉

    2012-01-01

    Sandwich panels with superior mechanical properties have been widely used in transportation system such as the aircraft and the high-speed train. To investigate damage properties of the U-type core sandwich panel, MSC. Dytran was applied to analyze the deformation modes, coupling forces, velocity, acceleration and energy absorption of the sandwich panel under air explosion. The results were compared with the stiffened plate. Orthogonal experimental method was applied to analyze the affect of structural parameters on the anti-explosion performance and better combination of sizes. Analysis shows the top and bottom face of the U-type core sandwich panel exihibit membrane tensile and wave deformation. Easily crushed core reduces the impact on the top faces and has high energy absorption efficiency, making deformation of the top face reduced significantly. The deformations, speeds, and accelerations of the top and bottom faces are less than those of the stiffened plate. The U-type core sandwich panel shows superior antiknock performance. The influence of structural parameters on the anti-explosion performance of the sandwich panel in a diminishing order is; inclination angle, top face sheet thickness, width of sandwich core member, bottom face sheet thickness. The antiknock performance of the sandwich panel with optimal combination of sizes is improved significantly.%力学性能优越的夹层板结构在飞机、高速列车等交通运输领域得到广泛应用.为研究U型夹层板空爆载荷下的损伤特性,利用有限元软件MSC.Dytran分析U型夹层板空爆载荷下的损伤变形模式、耦合力、结构位移、速度、加速度、吸能,并与加筋板架对比;应用正交试验设计方法分析结构参数对抗爆性能的影响程度及较优的尺寸组合.分析表明:冲击载荷下U型夹层板上下面板的变形模式为膜拉伸,产生波浪式变形;夹芯层易于压皱变形,减少了对上面板冲击载荷的传递,同时夹芯

  14. 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.

  15. Superconducting Josephson vortex flow transistors

    CERN Document Server

    Tavares, P A C

    2002-01-01

    The work reported in this thesis focuses on the development of high-temperature superconducting Josephson vortex-flow transistors (JVFTs). The JVFT is a particular type of superconducting transistor, i.e. an electromagnetic device capable of delivering gain while keeping the control and output circuits electrically isolated. Devices were fabricated from (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta thin films grown by Pulsed Laser Deposition on 24 deg magnesium oxide and strontium titanate bicrystals. The design of the JVFTs was guided by numerical simulations and the devices were optimised for current gain. Improvements were made to the fabrication process in order to accurately pattern the small structures required. The devices exhibited current gains higher than 60 in liquid nitrogen. Gains measured at lower temperatures were significantly higher. As part of the work a data acquisition suite was developed for the characterisation of three-terminal devices and, in particular, of JVFTs.

  16. 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.

  17. Superconducting wires and fractional flux

    Science.gov (United States)

    Sá de Melo, C. A. R.

    1996-05-01

    The quantization of flux quanta in superconductors is revisited and analyzed in a new geometry. The system analyzed is a superconducting wire. The geometry is such that the superconducting wire winds N times around an insulating cylinder and that the wire has its end connected back to its beginning, thus producing an N-loop short circuited solenoid. The winding number N acts as a topological index that controls flux quantization. In this case, fractional flux quanta can be measured through the center of the insulating cylinder, provided that the cylinder radius is small enough. The Little-Parks experiment for an identical geometry is discussed. The period of oscillation of the transition temperature of the wire is found to vary as 1/N in units of flux Φ relative to the flux quantum Φ0. When a SQUID is made in such a geometry the maximal current through the SQUID varies with period Φ0/N.

  18. Stripes and Superconductivity in Cuprates

    OpenAIRE

    Tranquada, John M.

    2011-01-01

    Holes doped into the CuO2 planes of cuprate parent compounds frustrate the antiferromagnetic order. The development of spin and charge stripes provides a compromise between the competing magnetic and kinetic energies. Static stripe order has been observed only in certain particular compounds, but there are signatures which suggest that dynamic stripe correlations are common in the cuprates. Though stripe order is bad for superconducting phase coherence, stripes are compatible with strong pair...

  19. Superconducting Qubits: A Short Review

    OpenAIRE

    Devoret, M. H.; Wallraff, A.; Martinis, J. M.

    2004-01-01

    Superconducting qubits are solid state electrical circuits fabricated using techniques borrowed from conventional integrated circuits. They are based on the Josephson tunnel junction, the only non-dissipative, strongly non-linear circuit element available at low temperature. In contrast to microscopic entities such as spins or atoms, they tend to be well coupled to other circuits, which make them appealling from the point of view of readout and gate implementation. Very recently, new designs ...

  20. Inelastic tunneling in superconducting junctions

    Energy Technology Data Exchange (ETDEWEB)

    Hlobil, Patrik Christian

    2016-06-10

    In this dissertation a theoretical formalism of elastic and inelastic tunneling spectroscopy is developed for superconductors. The underlying physical processes behind the different two tunneling channels and their implications for the interpretation of experimental tunneling data are investigated in detail, which can explain the background conductance seen in the cuprate and iron-based superconductors. Further, the properties of the emitted light from a superconducting LED are investigated.

  1. 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.

  2. 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.

  3. Activities on RF superconductivity at DESY

    Energy Technology Data Exchange (ETDEWEB)

    Matheisen, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); TESLA Collaboration

    1996-01-01

    At DESY the HERA electron storage ring is supplied with normal and superconducting cavities. The superconducting system transfers up to 1 MW klystron power to the beam. Experiences are reported on luminosity and machine study runs. Since 1993 one major activity in the field of RF superconducting cavities is the installation of the TESLA Test Facility. Set-up of hardware and first tests of s.c. resonators are presented. (R.P.). 11 refs.

  4. Enhanced superconductivity in aluminum-based hyperbolic metamaterials

    CERN Document Server

    Smolyaninova, V N; Zimmerman, W; Prestigiacomo, J C; Osofsky, M S; Kim, H; Xing, Z; Qazilbash, M M; Smolyaninov, I I

    2016-01-01

    One of the most important goals of condensed matter physics is materials by design, i.e. the ability to reliably predict and design materials with a set of desired properties. A striking example is the deterministic enhancement of the superconducting properties of materials. Recent experiments have demonstrated that the metamaterial approach is capable of achieving this goal, such as tripling the critical temperature Tc in Al-Al2O3 epsilon near zero (ENZ) core-shell metamaterial superconductors. However, transport properties of such metamaterials remained much worse compared to conventional superconductors. Here, we demonstrate that an Al/Al2O3 hyperbolic metamaterial geometry is capable of a similar Tc enhancement, while having superior transport and magnetic properties compared to the core-shell metamaterial superconductors. This result opens up numerous new possibilities for metamaterial enhancement of Tc in other practically important simple superconductors, such as niobium and MgB2. It also indicates tha...

  5. Enhanced superconductivity in aluminum-based hyperbolic metamaterials

    Science.gov (United States)

    Smolyaninova, Vera N.; Jensen, Christopher; Zimmerman, William; Prestigiacomo, Joseph C.; Osofsky, Michael S.; Kim, Heungsoo; Bassim, Nabil; Xing, Zhen; Qazilbash, Mumtaz M.; Smolyaninov, Igor I.

    2016-01-01

    One of the most important goals of condensed matter physics is materials by design, i.e. the ability to reliably predict and design materials with a set of desired properties. A striking example is the deterministic enhancement of the superconducting properties of materials. Recent experiments have demonstrated that the metamaterial approach is capable of achieving this goal, such as tripling the critical temperature TC in Al-Al2O3 epsilon near zero (ENZ) core-shell metamaterial superconductors. Here, we demonstrate that an Al/Al2O3 hyperbolic metamaterial geometry is capable of a similar TC enhancement, while having superior transport and magnetic properties compared to the core-shell metamaterial superconductors. PMID:27658850

  6. Enhanced superconductivity in aluminum-based hyperbolic metamaterials

    Science.gov (United States)

    Smolyaninova, Vera N.; Jensen, Christopher; Zimmerman, William; Prestigiacomo, Joseph C.; Osofsky, Michael S.; Kim, Heungsoo; Bassim, Nabil; Xing, Zhen; Qazilbash, Mumtaz M.; Smolyaninov, Igor I.

    2016-09-01

    One of the most important goals of condensed matter physics is materials by design, i.e. the ability to reliably predict and design materials with a set of desired properties. A striking example is the deterministic enhancement of the superconducting properties of materials. Recent experiments have demonstrated that the metamaterial approach is capable of achieving this goal, such as tripling the critical temperature TC in Al-Al2O3 epsilon near zero (ENZ) core-shell metamaterial superconductors. Here, we demonstrate that an Al/Al2O3 hyperbolic metamaterial geometry is capable of a similar TC enhancement, while having superior transport and magnetic properties compared to the core-shell metamaterial superconductors.

  7. Rapid rotational crust-core relaxation in magnetars

    CERN Document Server

    Sedrakian, Armen

    2016-01-01

    If a magnetar interior $B$-field exceeds $10^{15}$ G it will unpair the proton superconductor in the star's core by inducing diamagnetic currents which destroy the Cooper pair coherence. Then, the $P$-wave neutron superfluid in these non-superconducting regions will couple to the stellar plasma by scattering of protons off the quasiparticles confined in the cores of neutron vortices via the strong (nuclear) force. The dynamical time-scales associated with this interaction span from several minutes at the crust-core interface to a few seconds in the deep core. We show that (a) the rapid crust-core coupling is incompatible with oscillation models of magnetars which decouple completely the core superfluid from the crust and (b) magnetar precession is damped by the coupling of normal fluids to the superfluid core and, if observed, needs to be forced or continuously excited by seismic activity.

  8. 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.

  9. Attenuation in Superconducting Circular Waveguides

    Directory of Open Access Journals (Sweden)

    K. H. Yeap

    2016-09-01

    Full Text Available We present an analysis on wave propagation in superconducting circular waveguides. In order to account for the presence of quasiparticles in the intragap states of a superconductor, we employ the characteristic equation derived from the extended Mattis-Bardeen theory to compute the values of the complex conductivity. To calculate the attenuation in a circular waveguide, the tangential fields at the boundary of the wall are first matched with the electrical properties (which includes the complex conductivity of the wall material. The matching of fields with the electrical properties results in a set of transcendental equations which is able to accurately describe the propagation constant of the fields. Our results show that although the attenuation in the superconducting waveguide above cutoff (but below the gap frequency is finite, it is considerably lower than that in a normal waveguide. Above the gap frequency, however, the attenuation in the superconducting waveguide increases sharply. The attenuation eventually surpasses that in a normal waveguide. As frequency increases above the gap frequency, Cooper pairs break into quasiparticles. Hence, we attribute the sharp rise in attenuation to the increase in random collision of the quasiparticles with the lattice structure.

  10. Ballistic superconductivity in semiconductor nanowires

    Science.gov (United States)

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

    2017-07-01

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

  11. Analysis of Discharge Fault in 35 kV Dry-type Air-Core Reactor%一起35 kV干式空心电抗器放电故障分析

    Institute of Scientific and Technical Information of China (English)

    张宁; 李洪伟

    2014-01-01

    本文介绍了一起500 kV变电站35 kV干式空心电抗器在运行当中发生放电烧损的故障情况,通过现场检查、试验,结合故障电抗器的解体检查结果,对故障原因进行了深入分析,发现故障的主要原因是由于在强磁场下涡流产生温升,破坏了电抗器本身绝缘,本文对防止同类故障的发生具有一定的借鉴意义。%In this paper, a fault of burn-out of 35 kV dry-type air-core reactor due to discharge in the operation at 500 kV substation is introduced. The reason of the fault is analyzed through site inspec-tion, test and disassembly inspection result of the faulty reactor. It is caused by high temperature rise caused by eddy current at strong magnetic field resulting to insulation damage of the reactor it-self. The analysis result has a definite reference to similar fault to be prevented.

  12. 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.

  13. Anisotropic superconductivity driven by kinematic interaction

    Science.gov (United States)

    Ivanov, V. A.

    2000-11-01

    We have analysed the effect of kinematic pairing on the symmetry of superconducting order parameter for a square lattice in the frame of the strongly correlated Hubbard model. It is argued that in the first perturbation order the kinematic interaction renormalizes the Hubbard-I dispersions and provides at low doping the mixed singlet (s + s*)-wave superconductivity, giving way at higher doping to the triplet p-wave superconductivity. The obtained phase diagram depends only on the hopping integral parameter. The influence of the Coulomb repulsion on the kinematic superconducting pairing has been estimated. The (s + s*)-wave gap and the thermodynamic critical magnetic field have been derived.

  14. 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.

  15. 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

  16. Impact of core-cladding boundary shape on the waveguide properties of hollow core microstructured fibers

    Science.gov (United States)

    Pryamikov, A. D.; Alagashev, G. K.; Kosolapov, A. F.; Biriukov, A. S.

    2016-12-01

    In this paper we consider an interaction between the air core modes (ACMs) of hollow core waveguide microstructures and core-cladding boundary walls in various shapes. The analysis is based on well-established models such as the ARROW (anti-resonant reflecting optical waveguide) model and on the models proposed for the first time. In particular, we consider the dynamics of light localization in the polygonal core cladding boundary wall as dependant on the type of its discrete rotational symmetry. Based on our findings we analyze the mechanisms of light localization in the core-cladding boundary walls of negative curvature hollow core microstructured fibers (NC HCMFs).

  17. Topological superconductivity induced by ferromagnetic metal chains

    Science.gov (United States)

    Li, Jian; Chen, Hua; Drozdov, Ilya K.; Yazdani, A.; Bernevig, B. Andrei; MacDonald, A. H.

    2014-12-01

    Recent experiments have provided evidence that one-dimensional (1D) topological superconductivity can be realized experimentally by placing transition-metal atoms that form a ferromagnetic chain on a superconducting substrate. We address some properties of this type of system by using a Slater-Koster tight-binding model to account for important features of the electronic structure of the transition-metal chains on the superconducting substrate. We predict that topological superconductivity is nearly universal when ferromagnetic transition-metal chains form straight lines on superconducting substrates and that it is possible for more complex chain structures. When the chain is weakly coupled to the substrate and is longer than superconducting coherence lengths, its proximity-induced superconducting gap is ˜Δ ESO/J where Δ is the s -wave pair potential on the chain, ESO is the spin-orbit splitting energy induced in the normal chain state bands by hybridization with the superconducting substrate, and J is the exchange splitting of the ferromagnetic chain d bands. Because of the topological character of the 1D superconducting state, Majorana end modes appear within the gaps of finite length chains. We find, in agreement with the experiment, that when the chain and substrate orbitals are strongly hybridized, Majorana end modes are substantially reduced in amplitude when separated from the chain end by less than the coherence length defined by the p -wave superconducting gap. We conclude that Pb is a particularly favorable substrate material for ferromagnetic chain topological superconductivity because it provides both strong s -wave pairing and strong Rashba spin-orbit coupling, but that there is an opportunity to optimize properties by varying the atomic composition and structure of the chain. Finally, we note that in the absence of disorder, a new chain magnetic symmetry, one that is also present in the crystalline topological insulators, can stabilize multiple

  18. Core Java

    CERN Document Server

    Horstmann, Cay S

    2013-01-01

    Fully updated to reflect Java SE 7 language changes, Core Java™, Volume I—Fundamentals, Ninth Edition, is the definitive guide to the Java platform. Designed for serious programmers, this reliable, unbiased, no-nonsense tutorial illuminates key Java language and library features with thoroughly tested code examples. As in previous editions, all code is easy to understand, reflects modern best practices, and is specifically designed to help jumpstart your projects. Volume I quickly brings you up-to-speed on Java SE 7 core language enhancements, including the diamond operator, improved resource handling, and catching of multiple exceptions. All of the code examples have been updated to reflect these enhancements, and complete descriptions of new SE 7 features are integrated with insightful explanations of fundamental Java concepts.

  19. Superconductivity in the Sn-Ba-Sr-Y-Cu-O system

    Science.gov (United States)

    Aleksandrov, K. S.; Khrustalev, B. P.; Krivomazov, S. N.; Petrov, M. I.; Vasilyev, A. D.; Zwegintsev, S. A.

    1991-01-01

    After the discovery of high-T(sub c) superconductivity in the La-Ba-Cu-O compound, several families of superconducting oxides were synthesized. Here, researchers report the results of the search for superconductivity in the compounds based on tin which has a lone electron pair like Bi, Tl, and Pb. The following compounds were synthesized: Sn1Ba1Sr1Cu3O(sub x), Sn1Ba1Ca1Cu3O(sub x), Sn1Ba1Mg1Cu3O(sub x), Sn1Sr1Ca1Cu3O(sub x), Sn1Sr1Mg1Cu3O(sub x), and Sn1Ca1Mg1Cu3O(sub x). The initial components were oxides and carbonates of the appropriate elements. A standard firing-grinding procedure was used. Final heating was carried out at 960 C during 12 hours. Then the samples were cooled inside the furnace. All the synthesis cycles were carried out in air atmosphere. Among the synthesized compounds only Sn1Ba1Sr1Cu3O(sub x) showed remarkable conductivity. Other compounds were practically dielectrics. Presence of a possible superconductivity in Sn1Ba1Sr1Cu3O(sub x) was defined by using the Meissner effect. At low temperature a deviation from paramagnetic behavior is observed. The hysteresis loops obtained at lower temperature undoubtly testify to the presence of a superconductive phase in the sample. However, the part of the superconductive phase in the Sn1Ba1Sr1Cu3O(sub x) ceramic turned out to be small, less than 2 percent, which agrees with the estimation from magnetic data. In order to increase the content of the superconductive phase, two-valent cations Ba and Sr were partially substituted by univalent (K) and three-valent ones (Y).

  20. Short sample testing facility for the Superconducting Super Collider

    Energy Technology Data Exchange (ETDEWEB)

    Zbasnik, J.; Scanlan, R.; Taylor, C.; Peters, C.; Pope, W.; Royet, J. (Lawrence Berkeley Lab., CA (USA))

    1989-06-01

    In this paper we present the system requirements of the apparatus measuring the short sample critical current of the cable for the Superconducting Super Collider (SSC), and the current status of our development work. Key features of the system presented here are: a sample holder which clamps the samples sufficiently well such that no training quenches are required to perform critical current measurements and another which may allow for faster sample mounting; voltage tap boards using a printed-circuit technique which eliminates the necessity of soldering wires for the voltage measurements; a 1-m ling, 5-cm-bore dipole magnet with close-in iron designed to produce 7.5 T with a 6000 A excitation current; and an air-lock system that allows repeated sample changes without the magnet chamber being contaminated with air and other impurities. 7 refs., 6 figs.

  1. Superconducting integrated submillimeter receiver for TELIS

    NARCIS (Netherlands)

    Koshelets, Valery P.; Ermakov, Andrey B.; Filippenko, Lyudmila V.; Khudchenko, Andrey V.; Kiselev, Oleg S.; Sobolev, Alexander S.; Torgashin, Mikhail Yu.; Yagoubov, Pavel A.; Hoogeveen, Ruud W. M.; Wild, Wolfgang

    2007-01-01

    In this report an overview of the results on the development of a single-chip superconducting integrated receiver for the Terahertz Limb Sounder (TELIS) balloon project intended to measure a variety of stratosphere trace gases is presented. The Superconducting Integrated Receiver (SIR) comprises in

  2. Insulation systems for superconducting transmission cables

    DEFF Research Database (Denmark)

    Tønnesen, Ole

    1996-01-01

    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...

  3. 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.

  4. Superconducting magnets. Citations from NTIS data base

    Science.gov (United States)

    Reimherr, G. W.

    1980-10-01

    The cited reports discuss research on materials studies, theory, design and applications of superconducting magnets. Examples of applications include particle accelerators, MHD power generation, superconducting generators, nuclear fusion research devices, energy storage systems, and magnetic levitation. This updated bibliography contains 218 citations, 88 of which are new entries to the previous edition.

  5. Superconducting Materials, Magnets and Electric Power Applications

    Science.gov (United States)

    Crabtree, George

    2011-03-01

    The surprising discovery of superconductivity a century ago launched a chain of convention-shattering innovations and discoveries in superconducting materials and applications that continues to this day. The range of large-scale applications grows with new materials discoveries - low temperature NbTi and Nb3 Sn for liquid helium cooled superconducting magnets, intermediate temperature MgB2 for inexpensive cryocooled applications including MRI magnets, and high temperature YBCO and BSSCO for high current applications cooled with inexpensive liquid nitrogen. Applications based on YBCO address critical emerging challenges for the electricity grid, including high capacity superconducting cables to distribute power in urban areas; transmission of renewable electricity over long distances from source to load; high capacity DC interconnections among the three US grids; fast, self-healing fault current limiters to increase reliability; low-weight, high capacity generators enabling off-shore wind turbines; and superconducting magnetic energy storage for smoothing the variability of renewable sources. In addition to these grid applications, coated conductors based on YBCO deposited on strong Hastelloy substrates enable a new generation of all superconducting high field magnets capable of producing fields above 30 T, approximately 50% higher than the existing all superconducting limit based on Nb3 Sn . The high fields, low power cost and the quiet electromagnetic and mechanical operation of such magnets could change the character of high field basic research on materials, enable a new generation of high-energy colliding beam experiments and extend the reach of high density superconducting magnetic energy storage.

  6. Superconducting chip receivers for imaging application

    NARCIS (Netherlands)

    Shitov, SV; Koshelets, VP; Ermakov, AB; Filippenko, LV; Baryshev, AM; Luinge, W; Gao, [No Value

    1999-01-01

    Experimental details of a unique superconducting imaging array receiver are discussed. Each pixel contains an internally pumped receiver chip mounted on the back of the elliptical microwave lens. Each chip comprises a quasi-optical SIS mixer integrated with a superconducting flux-flow oscillator (FF

  7. Diagram of a LEP superconducting cavity

    CERN Multimedia

    1991-01-01

    This diagram gives a schematic representation of the superconducting radio-frequency cavities at LEP. Liquid helium is used to cool the cavity to 4.5 degrees above absolute zero so that very high electric fields can be produced, increasing the operating energy of the accelerator. Superconducting cavities were used only in the LEP-2 phase of the accelerator, from 1996 to 2000.

  8. 17th International Conference on RF Superconductivity

    CERN Document Server

    Laxdal, Robert E.; Schaa, Volker R.W.

    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.

  9. Josephson plasma resonance in superconducting multilayers

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Sakai, S

    1998-01-01

    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...

  10. Research progresses shed light on superconductivity mechanism

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The spring of 2008 saw substantial breakthroughs in superconductivity research. Four groups of physicists, one after another, achieved remarkable progresses in the study of iron-based materials after the breakthrough made by H. Hosono's group in Japan, providing renewed insights into the fundamental mechanism of high-temperature superconductivity (HTSC), a perplexing enigma on the frontier of condensed matter physics.

  11. 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...

  12. Interfacing superconducting qubits and single optical photons

    NARCIS (Netherlands)

    Das, Sumanta; Faez, Sanli; 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

  13. Interaction between ionic lattices and superconducting condensates

    OpenAIRE

    2007-01-01

    The interaction of the ionic lattice with the superconducting condensate is treated in terms of the electrostatic force in superconductors. It is shown that this force is similar but not identical to the force suggested by the volume difference of the normal and superconducting states. The BCS theory shows larger deviations than the two-fluid model.

  14. Superconducting-electromagnetic hybrid bearing using YBCO bulk locks for passive axial levitation

    Energy Technology Data Exchange (ETDEWEB)

    Nicolsky, R. [Instituto de Fisica, UFRJ, Cx. P. 68528, Rio de Janeiro 21945-970 (Brazil). E-mail: nicolsky at if.ufrj.br; Andrade, R. de Jr. [DEE/EE/UFRJ, Cx. P. 68515, Rio de Janeiro 21945-970 (Brazil); Ripper, A.; Stephan, R.M. [PEM/COPPE/UFRJ, Cx. P. 68504, Rio de Janeiro 21945-970 (Brazil); David, D.F.B.; Santisteban, J.A. [Engenharia/UFF, Rua Passo da Patria 156, Niteroi 24210-240 (Brazil); Gawalek, W.; Habisreuther, T.; Strasser, T. [Institut fuer Physikalische Hoch Technologie (IPHT), Helmhotzweg 4, D07743, Jena (Germany)

    2000-06-01

    A superconducting/electromagnetic hybrid bearing has been designed using active radial electromagnetic positioning and a superconducting passive axial levitator. This bearing has been tested for an induction machine with a vertical shaft. The prototype was conceived as a four-pole, two-phase induction machine using specially designed stator windings for delivering torque and radial positioning simultaneously. The radial bearing uses four eddy-current sensors, displaced 90 deg. from each other, for measuring the shaft position and a PID control system for feeding back the currents. The stator windings have been adapted from the ones of a standard induction motor. The superconducting axial bearing has been assembled with commercial NdFeB permanent magnets and a set of seven top-seeded-melt-textured YBCO large-grain cylindrical blocks. The bearing set-up was previously simulated by a finite element method for different permanent magnet-superconductor block configurations. The stiffness of the superconducting axial bearing has been investigated by measuring by a dynamic method the vertical and transversal elastic constants for different field cooling processes. The resulting elastic constants show a linear dependence on the air gap, i.e. the clearance between the permanent magnet assembly and the set of superconducting large-grain blocks, which is dependent on cooling distance. (author)

  15. Analysis of reflection-coefficient by wireless power transmission using superconducting coils

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, In Sung; Choi, Hyo Sang [Chosun University, Gwangju (Korea, Republic of); Chung, Dong Chul [Korea Institute of Carbon Convergence Technology, Jeonju (Korea, Republic of)

    2017-06-15

    The use of electronic devices such as mobile phones and tablet PCs has increased of late. However, the power which is supplied through wires has a limitation of the free use of devices and portability. Magnetic-resonance wireless power transfer (WPT) can achieve increased transfer distance and efficiency compared to the existing electromagnetic inductive coupling. A superconducting coil can be applied to increase the efficiency and distance of magnetic-resonance WPT. As superconducting coils have lower resistance than copper coils, they can increase the quality factor (Q-factor) and can overcome the limitations of magnetic-resonance WPT. In this study, copper coils were made from ordinary copper under the same condition as the superconducting coils for a comparison experiment. Superconducting coils use liquid nitrogen to keep the critical temperature. As there is a difference of medium between liquid nitrogen and air, liquid nitrogen was also used in the normal conductor coil to compare the experiment with under the same condition. It was confirmed that superconducting coils have a lower reflection-coefficient(S11) than the normal conductor coils.

  16. Superconductivity in compensated and uncompensated semiconductors.

    Science.gov (United States)

    Yanase, Youichi; Yorozu, Naoyuki

    2008-12-01

    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.

  17. 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.

  18. 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....

  19. Superconducting Radio Frequency Technology: An Overview

    Energy Technology Data Exchange (ETDEWEB)

    Peter Kneisel

    2003-06-01

    Superconducting RF cavities are becoming more often the choice for larger scale particle accelerator projects such as linear colliders, energy recovery linacs, free electron lasers or storage rings. Among the many advantages compared to normal conducting copper structures, the superconducting devices dissipate less rf power, permit higher accelerating gradients in CW operation and provide better quality particle beams. In most cases these accelerating cavities are fabricated from high purity bulk niobium, which has superior superconducting properties such as critical temperature and critical magnetic field when compared to other superconducting materials. Research during the last decade has shown, that the metallurgical properties--purity, grain structure, mechanical properties and oxidation behavior--have significant influence on the performance of these accelerating devices. This contribution attempts to give a short overview of the superconducting RF technology with emphasis on the importance of the material properties of the high purity niobium.

  20. 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.

  1. Stripes and superconductivity in cuprate superconductors

    Science.gov (United States)

    Tranquada, J. M.

    2005-08-01

    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.

  2. Free-standing oxide superconducting articles

    Science.gov (United States)

    Wu, Xin D.; Muenchausen, Ross E.

    1993-01-01

    A substrate-free, free-standing epitaxially oriented superconductive film including a layer of a template material and a layer of a ceramic superconducting material is provided together with a method of making such a substrate-free ceramic superconductive film by coating an etchable material with a template layer, coating the template layer with a layer of a ceramic superconductive material, coating the layer of ceramic superconductive material with a protective material, removing the etchable material by an appropriate means so that the etchable material is separated from a composite structure including the template lay This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  3. Development of Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

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

    2012-01-01

    (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......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...... to somewhere between 4K and 50K, depending on what type of superconductor is employed, which poses a significant challenge both from a construction and operation point of view. The high temperature superconductors can facilitate a higher operation temperature and simplified cooling, but the current price...

  4. Quantum Memristors with Superconducting Circuits

    Science.gov (United States)

    Salmilehto, J.; Deppe, F.; di Ventra, M.; Sanz, M.; Solano, E.

    2017-02-01

    Memristors are resistive elements retaining information of their past dynamics. They have garnered substantial interest due to their potential for representing a paradigm change in electronics, information processing and unconventional computing. Given the advent of quantum technologies, a design for a quantum memristor with superconducting circuits may be envisaged. Along these lines, we introduce such a quantum device whose memristive behavior arises from quasiparticle-induced tunneling when supercurrents are cancelled. For realistic parameters, we find that the relevant hysteretic behavior may be observed using current state-of-the-art measurements of the phase-driven tunneling current. Finally, we develop suitable methods to quantify memory retention in the system.

  5. Superconductivity in Metals and Alloys

    Science.gov (United States)

    1963-02-01

    sintered material (Reed, Gatos , LaFleur, and Roddy, 1962). It has great importance for any materials work, since generalizations based only on stoichio...1961),Phys. Rev. Letters 6, 597. Goodman, B. B., (1962) IBM J. Research and Development 6, 63. Gor’kov, L. P., (1960), Soy . Phys. JETP 10, 998...34Superconductivity in Metals and Alloys-Technical Documentary Report No. ASD-TDR-62-269, Contract No. AF 33(616)-640 5. Reed, T. B., Gatos , H. C., LaFleur, W. j

  6. The crystallography of color superconductivity

    CERN Document Server

    Bowers, J A; Bowers, Jeffrey A.; Rajagopal, Krishna

    2003-01-01

    We describe the crystalline phase of color superconducting quark matter. This phase may occur in quark matter at densities relevant for compact star physics, with possible implications for glitch phenomena in pulsars. We use a Ginzburg-Landau approach to determine that the crystal has a face-centered-cubic (FCC) structure. Moreover, our results indicate that the phase is robust, with gaps, critical temperature, and free energy comparable to those of the color-flavor-locked (CFL) phase. Our calculations also predict ``crystalline superfluidity'' in ultracold gases of fermionic atoms.

  7. Superconductivity, antiferromagnetism, and neutron scattering

    Science.gov (United States)

    Tranquada, John M.; Xu, Guangyong; Zaliznyak, Igor A.

    2014-01-01

    High-temperature superconductivity in both the copper-oxide and the iron-pnictide/chalcogenide systems occurs in close proximity to antiferromagnetically ordered states. Neutron scattering has been an essential technique for characterizing the spin correlations in the antiferromagnetic phases and for demonstrating how the spin fluctuations persist in the superconductors. While the nature of the spin correlations in the superconductors remains controversial, the neutron scattering measurements of magnetic excitations over broad ranges of energy and momentum transfers provide important constraints on the theoretical options. We present an overview of the neutron scattering work on high-temperature superconductors and discuss some of the outstanding issues.

  8. Superconductivity a very short introduction

    CERN Document Server

    Blundell, Stephen

    2009-01-01

    Superconductivity is one of the most exciting areas of research in physics today. Outlining the history of its discovery, and the race to understand its many mysterious and counter-intuitive phenomena, this Very Short Introduction explains in accessible terms the theories that have been developed, and how they have influenced other areas of science, including the Higgs boson of particle physics and ideas about the early Universe. It is an engaging and informative accountof a fascinating scientific detective story, and an intelligible insight into some deep and beautiful ideas of physics

  9. Quantum Memristors with Superconducting Circuits

    Science.gov (United States)

    Salmilehto, J.; Deppe, F.; Di Ventra, M.; Sanz, M.; Solano, E.

    2017-01-01

    Memristors are resistive elements retaining information of their past dynamics. They have garnered substantial interest due to their potential for representing a paradigm change in electronics, information processing and unconventional computing. Given the advent of quantum technologies, a design for a quantum memristor with superconducting circuits may be envisaged. Along these lines, we introduce such a quantum device whose memristive behavior arises from quasiparticle-induced tunneling when supercurrents are cancelled. For realistic parameters, we find that the relevant hysteretic behavior may be observed using current state-of-the-art measurements of the phase-driven tunneling current. Finally, we develop suitable methods to quantify memory retention in the system. PMID:28195193

  10. Superconductive Signal-Processing Circuits

    Science.gov (United States)

    1994-08-01

    September 1991. 13. P. H. Xiao, E. Charbon , A. Sangiovanni-Vincentelli, T. Van Duzer,and S.W. Whiteley, "INDEX: An inductance extractor for superconducting...wideband analog-to-digital to a useful binary representation. In order to achieve an N-bit converter reported earlier [1]. The original design has been...rises, the SQUID Parameter Original Modified switches to the voltage state, and the output goes high. Ic(J1) 337 367 I tA S gaicGate: The comparator

  11. 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.)

  12. Terahertz superconducting plasmonic hole array

    CERN Document Server

    Tian, Zhen; Han, Jiaguang; Gu, Jianqiang; Xing, Qirong; Zhang, Weili

    2010-01-01

    We demonstrate thermally tunable superconductor hole array with active control over their resonant transmission induced by surface plasmon polaritons . The array was lithographically fabricated on high temperature YBCO superconductor and characterized by terahertz-time domain spectroscopy. We observe a clear transition from the virtual excitation of the surface plasmon mode to the real surface plasmon mode. The highly tunable superconducting plasmonic hole arrays may have promising applications in the design of low-loss, large dynamic range amplitude modulation, and surface plasmon based terahertz devices.

  13. Investigation of the bulk pinning force in YBCO superconducting films with nano-engineered pinning centres

    Science.gov (United States)

    Crisan, A.; Dang, V. S.; Yearwood, G.; Mikheenko, P.; Huhtinen, H.; Paturi, P.

    2014-08-01

    For practical applications of superconducting materials in applied magnetic fields, artificial pinning centres in addition to natural ones are required to oppose the Lorentz force. These pinning centres are actually various types of defects in the superconductor matrix. The pinning centres can be categorised on their dimension (volume, surface, or point) and on their character (normal cores or Δκ cores). We have used the Dew Hughes approach to determine the types of pinning centres present in various samples, with various thicknesses, temperatures and nanostructured additions to the superconducting matrix. Results show that normal surface pinning centres are present throughout almost all the samples, as dominant pinning mechanism. Such 2D extended pinning centres are mainly due to dislocations, grain boundaries, nanorods. Strong normal point pinning centres were found to be common in BZO doped YBCO samples. Other types of pinning centres, in various (minor) concentrations were also found in some of the samples.

  14. 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...

  15. Recent developments in superconducting receivers

    Science.gov (United States)

    Richards, Paul L.

    1990-09-01

    A description is given of recent work at Berkeley on superconducting mixers and detectors for infrared and millimeter wavelengths. The first report is a review article which summarizes the status of development of superconducting components for infrared and millimeter wave receivers. The next report describes accurate measurements and also theoretical modeling of an SIS quasiparticle waveguide mixer for W-band which uses very high quality Ta junctions. The best mixer noise is only 1.3 times the quantum limit. Both the mixer gain and the noise are in quantitative agreement with the quantum theory. Next, a report is given on measurements and theoretical modeling of the absorptivity (surface resistance) of high quality epitaxial films of the high Tc superconductor YBCO from 750 GHz to 21 THz. Finally, there are reports on the design and experimental performance of two different types of high Tc bolometric detectors. One is a conventional bolometer with a gold-black absorber. The other is an antenna coupled microbolometer.

  16. Superconducting rf development at ATLAS

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, K.W.; Kedzie, M.; Clifft, B.E. [Argonne National Lab., IL (United States); Roy, A.; Potukuchi, P. [Nuclear Science Centre, New Delhi (India); Givens, J.; Potter, J.; Crandall, K. [AccSys Technology, Inc., Pleasanton, CA (United States); Added, N. [Sao Paulo Univ., SP (Brazil)

    1993-12-31

    The ATLAS superconducting heavy-ion linac began operation in 1978 and has operated nearly continuously since that time, while undergoing a series of upgrades and expansions, the most recent being the ``uranium upgrade`` completed earlier this year and described below. In its present configuration the ATLAS linac consists of an array of 64 resonant cavities operating from 48 to 145 MHz, which match a range of particle velocities .007 < {beta} = v/c < .2. The linac provides approximately 50 MV of effective accelerating potential for ions of q/m > 1/10 over the entire periodic table. Delivered beams include 5 {minus} 7 pnA of {sup 238}U{sup 39+} at 1535 MeV. At present more than 10{sup 6} cavity-hours of operation at surface electric fields of 15 MV/m have been accumulated. Superconducting structure development at ATLAS is aimed at improving the cost/performance of existing low velocity structures both for possible future ATLAS upgrades, and also for heavy-ion linacs at other institutions. An application of particular current interest is to develop structures suitable for accelerating radioactive ion beams. Such structures must accelerate very low charge to mass ratio beams and must also have very large transverse acceptance.

  17. DC superconducting fault current limiter

    Science.gov (United States)

    Tixador, P.; Villard, C.; Cointe, Y.

    2006-03-01

    There is a lack of satisfying solutions for fault currents using conventional technologies, especially in DC networks, where a superconducting fault current limiter could play a very important part. DC networks bring a lot of advantages when compared to traditional AC ones, in particular within the context of the liberalization of the electric market. Under normal operation in a DC network, the losses in the superconducting element are nearly zero and only a small, i.e. a low cost, refrigeration system is then required. The absence of zero crossing of a DC fault current favourably accelerates the normal zone propagation. The very high current slope at the time of the short circuit in a DC grid is another favourable parameter. The material used for the experiments is YBCO deposited on Al2O3 as well as YBCO coated conductors. The DC limitation experiments are compared to AC ones at different frequencies (50-2000 Hz). Careful attention is paid to the quench homogenization, which is one of the key issues for an SC FCL. The University of Geneva has proposed constrictions. We have investigated an operating temperature higher than 77 K. As for YBCO bulk, an operation closer to the critical temperature brings a highly improved homogeneity in the electric field development. The material can then absorb large energies without degradation. We present tests at various temperatures. These promising results are to be confirmed over long lengths.

  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. Three-flavor color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Malekzadeh, H.

    2007-12-15

    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 {sup 3}He), the A and A{sup *} 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{sup *} phase is favored. It is shown that the 2SC phase is identical to the A{sup *} 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.)

  20. Thermal Field Calculation and Analysis of an Air-core Compulsator%空心补偿脉冲发电机温度场计算与分析

    Institute of Scientific and Technical Information of China (English)

    赵伟铎; 崔淑梅; 刘庆; 吴绍朋

    2011-01-01

    空心补偿脉冲发电机采用新型复合材料替代传统的铁心,在提高电机的功率密度同时,也带来了一些新的问题。由于复合材料导热性能较差,导致电机整体的散热性能不佳,因而连续放电运行时电机的热性能预估显得十分重要。针对该问题,建立了空心脉冲发电机的温度场有限元模型,对绕组和气隙进行了合理的等效简化,提出一种计算电机内空气温度的迭代算法,并通过实验验证了仿真模型的正确性,为同类电机的温度场计算提供了方法。提出利用电磁场有限元仿真计算电机热源损耗的方法,分析了其驱动轨道炮负载时的温度场,讨论了不同放电周期下电机的温度分布特点及变化规律,计算出样机连续运行的安全放电周期,为后续指导电机的负载实验和优化设计奠定了基础。%In order to maximize power densities, compulsators are designed as an air-core prototype. However, new problems have also been brought out by the new structure. Due to the poor thermal conductivity of composite materials, heat dissipation of the machine is severe, and heat performance estimate becomes vital during continuous discharges. In this paper, transient FEM thermal field analysis model had been built, on the basis of equivalent winding and air gap model. An iterative method to calculate the air temperature inside the machine had been proposed as well, and the results had been verified by experiments. When analyzing the compulsator under a typical railgun load, a loss calculation method based on FEM electromagnetic had been proposed. The temperature distributions under different operation conditions had been discussed, and the safe continuous discharge period had been calculated. The research process mentioned provides the theoretical and experimental guides for optimization and discharge experiments in the future.

  1. 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

  2. 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.

    2016-03-01

    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.

  3. Visualizing domain wall and reverse domain superconductivity.

    Science.gov (United States)

    Iavarone, M; Moore, S A; Fedor, J; Ciocys, S T; Karapetrov, G; Pearson, J; Novosad, V; Bader, S D

    2014-08-28

    In magnetically coupled, planar ferromagnet-superconductor (F/S) hybrid structures, magnetic domain walls can be used to spatially confine the superconductivity. In contrast to a superconductor in a uniform applied magnetic field, the nucleation of the superconducting order parameter in F/S structures is governed by the inhomogeneous magnetic field distribution. The interplay between the superconductivity localized at the domain walls and far from the walls leads to effects such as re-entrant superconductivity and reverse domain superconductivity with the critical temperature depending upon the location. Here we use scanning tunnelling spectroscopy to directly image the nucleation of superconductivity at the domain wall in F/S structures realized with Co-Pd multilayers and Pb thin films. Our results demonstrate that such F/S structures are attractive model systems that offer the possibility to control the strength and the location of the superconducting nucleus by applying an external magnetic field, potentially useful to guide vortices for computing application.

  4. Sample of superconducting wiring (Niobium Titanium)

    CERN Multimedia

    About NbTi cable: The cable consists of 36 strands of superconducting wire, each strand has a diameter of 0.825 mm and houses 6300 superconducting filaments of niobium-titanium (Nb-Ti, a superconducting alloy). Each filament has a diameter of about 0.006 mm, i.e. 10 times smaller than a typical human hair. The filaments are embedded in a high-purity copper matrix. Copper is a normal conducting material. The filaments are in the superconductive state when the temperature is below about -263ºC (10.15 K). When the filaments leave the superconductive state, the copper acts as conductor transports the electrical current. Each strand of The NbTi cable (at superconducting state) has a current density of up to above 2000 A/mm2 at 9 T and -271ºC (2.15 K). A cable transport a current of about 13000 A at 10 T and -271ºC (2.15 K). About LHC superconducting wiring: The high magnetic fields needed for the LHC can only be reached using superconductors. At very low temperatures, superconductors have no electrical resista...

  5. Sample of superconducting wiring (Niobium Titanium)

    CERN Multimedia

    About NbTi cable: The cable consists of 36 strands of superconducting wire, each strand has a diameter of 0.825 mm and houses 6300 superconducting filaments of niobium-titanium (Nb-Ti, a superconducting alloy). Each filament has a diameter of about 0.006 mm, i.e. 10 times smaller than a typical human hair. The filaments are embedded in a high-purity copper matrix. Copper is a normal conducting material. The filaments are in the superconductive state when the temperature is below about -263ºC (10.15 K). When the filaments leave the superconductive state, the copper acts as conductor transports the electrical current. Each strand of The NbTi cable (at superconducting state) has a current density of up to above 2000 A/mm2 at 9 T and -271ºC (2.15 K). A cable transport a current of about 13000 A at 10 T and -271ºC (2.15 K). About LHC superconducting wiring: The high magnetic fields needed for the LHC can only be reached using superconductors. At very low temperatures, superconductors have no electrical resistan...

  6. Superconducting phase transition in STM tips

    Energy Technology Data Exchange (ETDEWEB)

    Eltschka, Matthias; Jaeck, Berthold; Assig, Maximilian; Etzkorn, Markus; Ast, Christian R. [Max Planck Institute for Solid State Research, Stuttgart (Germany); Kern, Klaus [Max Planck Institute for Solid State Research, Stuttgart (Germany); Ecole Polytechnique Federale de Lausanne (Switzerland)

    2015-07-01

    The superconducting properties of systems with dimensions comparable to the London penetration depth considerably differ from macroscopic systems. We have studied the superconducting phase transition of vanadium STM tips in external magnetic fields. Employing Maki's theory we extract the superconducting parameters such as the gap or the Zeeman splitting from differential conductance spectra. While the Zeeman splitting follows the theoretical description of a system with s=1/2 and g=2, the superconducting gaps as well as the critical fields depend on the specific tip. For a better understanding of the experimental results, we solve a one dimensional Usadel equation modeling the superconducting tip as a cone with the opening angle α in an external magnetic field. We find that only a small region at the apex of the tip is superconducting in high magnetic fields and that the order of the phase transition is directly determined by α. Further, the spectral broadening increases with α indicating an intrinsic broadening mechanism due to the conical shape of the tip. Comparing these calculations to our experimental results reveals the order of the superconducting phase transition of the STM tips.

  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

    2016-03-16

    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.

  8. 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.

  9. Dimensionality of high temperature superconductivity in oxides

    Science.gov (United States)

    Chu, C. W.

    1989-01-01

    Many models have been proposed to account for the high temperature superconductivity observed in oxide systems. Almost all of these models proposed are based on the uncoupled low dimensional carrier Cu-O layers of the oxides. Results of several experiments are presented and discussed. They suggest that the high temperature superconductivity observed cannot be strictly two- or one-dimensional, and that the environment between the Cu-O layers and the interlayer coupling play an important role in the occurrence of such high temperature superconductivity. A comment on the very short coherence length reported is also made.

  10. Downsized superconducting magnetic energy storage systems

    Science.gov (United States)

    Palmer, David N.

    Scaled-down superconductive magnetic energy storage systems (DSMES) and superconductive magnetic energy power sources (SMEPS) are proposed for residential, commercial/retail, industrial off-peak and critical services, telephone and other communication systems, computer operations, power back-up/energy storages, power sources for space stations, and in-field military logistics/communication systems. Recent advances in high-Tc superconducting materials technology are analyzed. DSMES/SMEPS concepts are presented, and design, materials, and systems requirements are discussed. Problems ar identified, and possible solutions are offered. Comparisons are made with mechanical and primary and secondary energy storage and conversion systems.

  11. 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)

  12. Energizer keep going: 100 years of superconductivity

    Institute of Scientific and Technical Information of China (English)

    Pengcheng Dai; Xing-jiang Zhou; Dao-xin Yao

    2011-01-01

    It has been 100 years since Heike Kamerlingh Onnes discovered superconductivity on April 8,1911.Amazingly,this field is still very active and keeps booming,like a magic.A lot of new phenomena and materials have been found,and superconductors have been used in many different fields to improve our lives.Onnes won the Nobel Prize for this incredible discovery in 1913 and used the word superconductivity for the first time.Onnes believed that quantum mechanics would explain the effect,but he could not produce a theory at that time.Now we know superconductivity is a macroscopic quantum phenomenon.

  13. Magnetism and superconductivity in heavy fermion systems

    Energy Technology Data Exchange (ETDEWEB)

    Flouquet, J. (DRFMC, C.E.N.G., 38 - Grenoble (France)); Brison, J.P.; Hasselbach, K.; Taillefer, L. (C.N.R.S., 38 - Grenoble (France)); Behnia, K.; Jaccard, D. (DPMC, Geneva Univ. (Switzerland)); Visser, A. de (Natuurkundig Lab., Univ. van Amsterdam (Netherlands))

    1991-12-01

    The normal and superconducting properties of heavy fermion compounds are reviewed. The discussion is focus on the three uranium compounds: UBe{sub 13}, UPt{sub 3} and URu{sub 2}Si{sub 2}. Special attention is given: 1) to unusual (H.T) superconducting phase diagram as discovered in UPt{sub 3} where two successive superconducting phases seem to occur in zero magnetic field; 2) to the role of long range ordering as found in URu{sub 2}Si{sub 2} and UPt{sub 3}. (orig.).

  14. 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.

  15. Impact of core cladding boundary shape on the waveguide properties of hollow core microstructured fibers

    CERN Document Server

    Pryamikov, A D; Biriukov, A S

    2016-01-01

    In this paper we consider an interaction between the air core modes of hollow core waveguide microstructures and core cladding boundary walls in various shapes. The analysis is based on well established models such as the anti-resonant reflecting optical waveguide model and on the models proposed for the first time. In particular, we consider the dynamics of light localization in the polygonalcore cladding boundary wall as dependant on the type of its discrete rotational symmetry. Based on our findings we analyze the mechanisms of light localization in the core cladding boundary walls of negative curvature hollow core microstructured fibers.

  16. Superconductive coil characterization for next dipoles and quadrupoles generation

    CERN Document Server

    Khalil, Malathe

    2016-01-01

    The LHC is the most sophisticated scientific machine ever built as a device that allows the scientists to explore the universe and its origin. Scientists from all over the world are working to upgrade the LHC to open the door for new physics. HL-LHC (high luminosity LHC) project is the core project at CERN which was approved in 2013 by CERN’s council. In order to increase the integrated luminosity up to 3000 fb-1 within this decade. To do so it is crucial to design cutting edge superconducting magnets that can elevate the magnetic field up to 20T, which is Nb3Sn. However this material is brittle when it functions as superconductor, which makes it hard to be used as a cold magnet. So in this report the fabrication of 10 stacks of Nb3Sn superconducting multifilament wires was investigated as well as primary test using experimental setup and creating material model for Nb3Sn with the finite element analysis [ANSYS] is carried out.

  17. The metallization and superconductivity of dense hydrogen sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yinwei, E-mail: yinwei-li@jsnu.edu.cn; Hao, Jian; Li, Yanling [School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116 (China); Liu, Hanyu [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatchewan S7N 5E2 (Canada); Ma, Yanming, E-mail: mym@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)

    2014-05-07

    Hydrogen sulfide (H{sub 2}S) is a prototype molecular system and a sister molecule of water (H{sub 2}O). The phase diagram of solid H{sub 2}S at high pressures remains largely unexplored arising from the challenges in dealing with the pressure-induced weakening of S–H bond and larger atomic core difference between H and S. Metallization is yet achieved for H{sub 2}O, but it was observed for H{sub 2}S above 96 GPa. However, the metallic structure of H{sub 2}S remains elusive, greatly impeding the understanding of its metallicity and the potential superconductivity. We have performed an extensive structural study on solid H{sub 2}S at pressure ranges of 10–200 GPa through an unbiased structure prediction method based on particle swarm optimization algorithm. Besides the findings of candidate structures for nonmetallic phases IV and V, we are able to establish stable metallic structures violating an earlier proposal of elemental decomposition into sulfur and hydrogen [R. Rousseau, M. Boero, M. Bernasconi, M. Parrinello, and K. Terakura, Phys. Rev. Lett. 85, 1254 (2000)]. Our study unravels a superconductive potential of metallic H{sub 2}S with an estimated maximal transition temperature of ∼80 K at 160 GPa, higher than those predicted for most archetypal hydrogen-containing compounds (e.g., SiH{sub 4}, GeH{sub 4}, etc.)

  18. Test of a cryogenic set-up for a 10 meter long liquid nitrogen cooled superconducting power cable

    DEFF Research Database (Denmark)

    Træholt, Chresten; Rasmussen, Carsten; Kühle (fratrådt), Anders Van Der Aa;

    2000-01-01

    High temperature superconducting power cables may be cooled by a forced flow of sub-cooled liquid nitrogen. One way to do this is to circulate the liquid nitrogen (LN2) by means of a mechanical pump through the core of the cable and through a sub-cooler.Besides the cooling station, the cryogenics...... cable. We report on our experimental set-up for testing a 10 meter long high temperature superconducting cable with a critical current of 3.2 kA at 77K. The set-up consists of a custom designed cable end termination, current lead, coolant feed-through, liquid nitrogen closed loop circulation system...

  19. X-ray Photoelectron Spectroscopy on Superconducting Tl2CaBa2Cu2O8 Thin Film

    Science.gov (United States)

    Zeng, Wensheng; Qiu, Ping; Yan, Shaolin; Li, Zengfa; Zhang, Guangyin

    1991-06-01

    We have prepared single-phase superconducting Tl2CaBa2Cu2O8 thin film by dc magnetron sputtering process and measured x-ray photoelectron spectra of the film at room and liquid nitrogen temperatures. From the relative intensities of the Ba3d, Tl4f. O1s and Cu2p spectra taken at different take-off angles, we have concluded that there is an adventitious contamination (nonsuperconducting phase) surface layer. After excluding contributions from these spurious phases, we have tentatively assigned which core-level shifts should be caused by the superconducting phase transition.

  20. Vortex cores and vortex motion in superconductors with anisotropic Fermi surfaces

    Science.gov (United States)

    Galvis, J. A.; Herrera, E.; Guillamón, I.; Vieira, S.; Suderow, H.

    2017-02-01

    Explaning static and dynamic properties of the vortex lattice in anisotropic superconductors requires a careful characterization of vortex cores. The vortex core contains Andreev bound states whose spatial extension depends on the anisotropy of the electronic band-structure and superconducting gap. This might have an impact on the anisotropy of the superconducting properties and on vortex dynamics. Here we briefly summarize basic concepts to understand anisotropic vortex cores and review vortex core imaging experiments. We further discuss moving vortex lattices and the influence of vortex core shape in vortex motion. We find vortex motion in highly tilted magnetic fields. We associate vortex motion to the vortex entry barrier and the screening currents at the surface. We find preferential vortex motion along the main axis of the vortex lattice. After travelling integers of the intervortex distance, we find that vortices move more slowly due to the washboard potential of the vortex lattice.

  1. Coexistence of superconductivity and antiferromagnetism in (Li0.8Fe0.2)OHFeSe.

    Science.gov (United States)

    Lu, X F; Wang, N Z; Wu, H; Wu, Y P; Zhao, D; Zeng, X Z; Luo, X G; Wu, T; Bao, W; Zhang, G H; Huang, F Q; Huang, Q Z; Chen, X H

    2015-03-01

    Iron selenide superconductors exhibit a number of unique characteristics that are helpful for understanding the mechanism of superconductivity in high-Tc iron-based superconductors more generally. However, in the case of AxFe2Se2 (A = K, Rb, Cs), the presence of an intergrown antiferromagnetic insulating phase makes the study of the underlying physics problematic. Moreover, FeSe-based systems intercalated with alkali metal ions, NH3 molecules or organic molecules are extremely sensitive to air, which prevents the further investigation of their physical properties. It is therefore desirable to find a stable and easily accessible FeSe-based superconductor to study its physical properties in detail. Here, we report the synthesis of an air-stable material, (Li0.8Fe0.2)OHFeSe, which remains superconducting at temperatures up to ~40 K, by means of a novel hydrothermal method. The crystal structure is unambiguously determined by a combination of X-ray and neutron powder diffraction and nuclear magnetic resonance. Moreover, antiferromagnetic order is shown to coexist with superconductivity. This synthetic route opens a path for exploring superconductivity in other related systems, and confirms the appeal of iron selenides as a platform for understanding superconductivity in iron pnictides more broadly.

  2. 多喷头喷气静电纺纳米纤维包芯纱制备%Nanofiber core-spun yarn produced by multi-nozzle air jet electro-spinning

    Institute of Scientific and Technical Information of China (English)

    王鹏; 周玉嫚; 管声启; 何健新; 赵霆; 谭卫琳

    2015-01-01

    An multi‐nozzle air jet electro‐spinning device for fabricating continuously twisted vis‐cose filament/polyinylidenefluorid (PVDF) nanofiber core‐spun yarn was designed to signifi‐cantly improve nanofiber production based on the theory that solution bubble is broken to form multiple jet flows .Nanofibers ejected from multiple nozzles were gathered and bundled by con‐jugate electro‐spinning ,and then twisted on the surface of core filament yarn through the rota‐ting of metal funnel .The core‐spun yarn of viscose filament coated by PVDF nanofibers were prepared and the morphology ,mechanical property and hydrophobic property of the yarn w ere analyzed .T he results show s that PVDF nanofibers are coated on core filament surface perfectly with good orientation and uniform twist distribution .In addition ,the mechanical property of yarn has a significant improvement through coating twisted PVDF nanofeibers ,and the stress and strain increases from 19.39M Pa and 15.83% to 30.82M Pa and 19.81% , respectively . Lastly ,PVDF nanofiber core‐spun yarn has good hydrophobicity with 150° surface contact an‐g le .%为了提高纳米纤维的产量,利用气泡破裂形成多射流的原理,设计了一种多喷头喷气静电纺制备连续有捻的聚偏氟乙烯(PVDF)纳米纤维包芯纱装置.通过双重共轭静电纺的原理集聚纳米纤维,利用金属喇叭的旋转对纳米纤维加捻并包缠在芯纱表面.制备了以粘胶束为芯纱外包PVDF纳米纤维的纳米纤维包芯纱,并研究了该纱线的形貌、力学性能和疏水性能.结果显示, PVDF纳米纤维在芯纱表面包覆比较均匀,且包覆在芯纱表面的纤维有较好的取向和均匀的捻回分布.PVDF纳米纤维包芯纱的力学性能较之芯纱显著提高,断裂强度和伸长率分别达到30.82M Pa和19.81%,且具有良好的疏水性,表面接触角达到150°.

  3. Coherent controlization using superconducting qubits.

    Science.gov (United States)

    Friis, Nicolai; Melnikov, Alexey A; Kirchmair, Gerhard; Briegel, Hans J

    2015-01-01

    Coherent controlization, i.e., coherent conditioning of arbitrary single- or multi-qubit operations on the state of one or more control qubits, is an important ingredient for the flexible implementation of many algorithms in quantum computation. This is of particular significance when certain subroutines are changing over time or when they are frequently modified, such as in decision-making algorithms for learning agents. We propose a scheme to realize coherent controlization for any number of superconducting qubits coupled to a microwave resonator. For two and three qubits, we present an explicit construction that is of high relevance for quantum learning agents. We demonstrate the feasibility of our proposal, taking into account loss, dephasing, and the cavity self-Kerr effect.

  4. Pairing theory of striped superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Loder, Florian; Kampf, Arno P.; Kopp, Thilo; Graser, Siegfried [Center for Electronic Correlations and Magnetism, Institute of Physics, Augsburg (Germany)

    2011-07-01

    Striped high-T{sub c} superconductors such as La{sub 7/8}Ba{sub 1/8}CuO{sub 4} 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.

  5. 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.

  6. 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.

  7. Towards inducing superconductivity into graphene

    Science.gov (United States)

    Efetov, Dmitri K.

    Graphenes transport properties have been extensively studied in the 10 years since its discovery in 2004, with ground-breaking experimental observations such as Klein tunneling, fractional quantum Hall effect and Hofstadters butterfly. Though, so far, it turned out to be rather poor on complex correlated electronic ground states and phase transitions, despite various theoretical predictions. The purpose of this thesis is to help understanding the underlying theoretical and experimental reasons for the lack of strong electronic interactions in graphene, and, employing graphenes high tunability and versatility, to identify and alter experimental parameters that could help to induce stronger correlations. In particular graphene holds one last, not yet experimentally discovered prediction, namely exhibiting intrinsic superconductivity. With its vanishingly small Fermi surface at the Dirac point, graphene is a semi-metal with very weak electronic interactions. Though, if it is doped into the metallic regime, where the size of the Fermi surface becomes comparable to the size of the Brillouin zone, the density of states becomes sizeable and electronic interactions are predicted to be dramatically enhanced, resulting in competing correlated ground states such as superconductivity, magnetism and charge density wave formation. Following these predictions, this thesis first describes the creation of metallic graphene at high carrier doping via electrostatic doping techniques based on electrolytic gates. Due to graphenes surface only properties, we are able to induce carrier densities above n>1014 cm-2 (epsilonF>1eV) into the chemically inert graphene. While at these record high carrier densities we yet do not observe superconductivity, we do observe fundamentally altered transport properties as compared to semi-metallic graphene. Here, detailed measurements of the low temperature resistivity reveal that the electron-phonon interactions are governed by a reduced, density

  8. Durability Evaluation of Superconducting Magnets

    Science.gov (United States)

    Inoue, Akihiko; Ogata, Masafumi; Nakauchi, Masahiko; Asahara, Tetsuo; Herai, Toshiki; Nishikawa, Yoichi

    2006-06-01

    It is one of the most essential things to verify the durability of devices and components of JR-Maglev system to realize the system into the future inauguration. Since the load requirements were insufficient in terms of the durability under vibrations under mere running tests carried out on Yamanashi Maglev Test Line hereinafter referred to YMTL, we have developed supplemental method with bench tests. Superconducting magnets hereinafter referred to SCM as used in the experimental running for the last seven years on the YMTL were brought to Kunitachi Technical Research Institute; we conducted tests to evaluate the durability of SCM up to a period of the service life in commercial use. The test results have indicated that no irregularity in each part of SCM proving that SCM are sufficiently durable for the practical application.

  9. Nonclassical correlations in superconducting circuits

    Energy Technology Data Exchange (ETDEWEB)

    Migliore, Rosanna [Dipartimento di Scienze Fisiche ed Astronomiche, Universita di Palermo (Italy); CNR-INFM, UdR CNISM di Palermo, Palermo (Italy); Scala, Matteo [Dipartimento di Scienze Fisiche ed Astronomiche, Universita di Palermo (Italy); Departamento de Optica, Facultad de Fisica, Universidad Complutense, Madrid (Spain); Guccione, Marina; Sanchez-Soto, Luis L. [Dipartimento di Scienze Fisiche ed Astronomiche, Universita di Palermo (Italy); Messina, Antonino [Departamento de Optica, Facultad de Fisica, Universidad Complutense, Madrid (Spain)

    2009-05-15

    A key step on the road map to solid-state quantum information processing (and to a deeper understanding of many counterintuitive aspects of quantum mechanics) is the generation and manipulation of nonclassical correlations between different quantum systems. Within this framework, we analyze the possibility of generating maximally entangled states in a system of two superconducting flux qubits, as well as the effectof their own environments on the entanglement dynamics. The analysis reported here confirms that the phenomena of sudden birth and sudden death of the entanglement do not depend on the particular measure of the entanglement adopted (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Gapless superconductivity and string theory

    CERN Document Server

    Khlebnikov, S

    2014-01-01

    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. From the theoretical perspective, 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.

  11. Superconducting magnets and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.E.C. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Francis Bitter National Magnet Lab.)

    1989-08-01

    Superconducting magnets are now being used in applications as diverse as medical imaging, fusion research, and power conditioning. The steady improvement in the understanding of instability and quenching has allowed increases in current density and compactness of winding. The reduction in winding size that has thus followed has allowed the construction of economic magnets for imaging, for acceleration, and for high-resolution spectrometers. Large magnets for fusion and energy applications have been made possible by composite conductors containing large fractions of copper or aluminum. The advent of high-temperature superconductors may hold the promise, eventually, of very-high-field magnets. Meanwhile low-temperature superconductors capable of generating fields up to 30 T have been developed.

  12. 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.

  13. More superconductivity questions than answers.

    Science.gov (United States)

    Robinson, A L

    1987-07-17

    Although making liquid nitrogen-temperature superconductors is easy enough that high school science projects already feature them, researchers still have little idea how the new ceramic oxides work and therefore little guidance for improving them. At the International Workshop on Novel Mechanisms of Superconductivity, held from 22 to 26 June in Berkeley, California, theorists reviewed a host of competing explanations of how these materials come by their remarkable properties, but they could not, get far in sifting through the candidates for the best one. One cause of the unsettled situation is that theorists have not yet pushed their models far enough to make many specific predictions about physical properties and therefore to provide a reason to choose one theory over another. But experimental data for comparison with theory are lacking, too. For example, experimentalists are just now succeeding in being able to grow single crystals and thin films of the ceramic oxide superconductors, whose properties were shown at the workshop to be highly anisotropic. Measurements already made on the polycrystalline sintered material available up to now are difficult to interpret and therefore need to be repeated on good-quality crystals and films, where the variation of properties with crystallographic orientation can be mapped out. Given the high level of Japanese activity in the field, it was surprising that no researchers from industrial laboratories in Japan presented their findings at the workshop. In the light of a budding international competition in commercializing superconductors, some American scientists interpreted the absence as an attempt to protect proprietary advances. A more pleasant surprise was the attendance of a delegation of six Soviet scientists, although one of the fathers of superconductivity theory, Vitaly Ginzburg of the P.N.Lebedev Institute of Physics in Moscow, who was expected, did not come.

  14. Vortex cores and vortex motion in superconductors with anisotropic Fermi surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Galvis, J.A. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Departamento de Ciencias Naturales, Facultad de ingeniería y Ciencias Básicas, Universidad Central, Bogotá (Colombia); National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States); Herrera, E.; Guillamón, I.; Vieira, S. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Unidad Asociada de Altos Campos Magnéticos y Bajas Temperaturas, UAM, CSIC, Madrid (Spain); Suderow, H., E-mail: hermann.suderow@uam.es [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Unidad Asociada de Altos Campos Magnéticos y Bajas Temperaturas, UAM, CSIC, Madrid (Spain)

    2017-02-15

    Highlights: • The observation of vortex cores is reviewed, with emphasis in new experiments. • Vortex cores are follow superconducting gap and Fermi surface shapes. • The vortex core shape influences vortex dynamics. - Abstract: Explaning static and dynamic properties of the vortex lattice in anisotropic superconductors requires a careful characterization of vortex cores. The vortex core contains Andreev bound states whose spatial extension depends on the anisotropy of the electronic band-structure and superconducting gap. This might have an impact on the anisotropy of the superconducting properties and on vortex dynamics. Here we briefly summarize basic concepts to understand anisotropic vortex cores and review vortex core imaging experiments. We further discuss moving vortex lattices and the influence of vortex core shape in vortex motion. We find vortex motion in highly tilted magnetic fields. We associate vortex motion to the vortex entry barrier and the screening currents at the surface. We find preferential vortex motion along the main axis of the vortex lattice. After travelling integers of the intervortex distance, we find that vortices move more slowly due to the washboard potential of the vortex lattice.

  15. Experimental determination of LMFBR seismic equivalent core model

    Energy Technology Data Exchange (ETDEWEB)

    Fontaine, B.; Buland, P.; Fegeant, O.; Gantenbein, F. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1995-12-31

    The main phenomena which influence an LMFBR core seismic response are the fluid structure interaction and the impacts between subassemblies. To study the core behaviour seismic tests and calculations have been performed on the core mock-up RAPSODIE in air or in water and for different excitation levels. (author). 2 refs., 6 figs.

  16. High Tc superconducting small loop antenna

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.; Mehler, M.J.; Maclean, T.S.M.; Lancaster, M.J.; Gough, C.E. (Univ. of Birmingham (UK)); Alford, N. (I.C.I. Advanced Materials Div., Runcorn (UK))

    1989-12-01

    The improvement in the radiation efficiency of an electrically small loop antenna is analysed when it is fabricated from a superconductor, and experimental results for a liquid nitrogen cooled, ceramic superconducting loop at 450MHz are presented. (orig.).

  17. 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.

  18. Superconducting gap structure of FeSe.

    Science.gov (United States)

    Jiao, Lin; Huang, Chien-Lung; Rößler, Sahana; Koz, Cevriye; Rößler, Ulrich K; Schwarz, Ulrich; Wirth, Steffen

    2017-03-07

    The microscopic mechanism governing the zero-resistance flow of current in some iron-based, high-temperature superconducting materials is not well understood up to now. A central issue concerning the investigation of these materials is their superconducting gap symmetry and structure. Here we present a combined study of low-temperature specific heat and scanning tunnelling microscopy measurements on single crystalline FeSe. The results reveal the existence of at least two superconducting gaps which can be represented by a phenomenological two-band model. The analysis of the specific heat suggests significant anisotropy in the gap magnitude with deep gap minima. The tunneling spectra display an overall "U"-shaped gap close to the Fermi level away as well as on top of twin boundaries. These results are compatible with the anisotropic nodeless models describing superconductivity in FeSe.

  19. Simulation of an HTS Synchronous Superconducting Generator

    DEFF Research Database (Denmark)

    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, 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 resistivity, thus making the computation...... of heating losses a cumbersome task. Furthermore, the high aspect ratio of the superconducting materials involved adds a penalty in the time required to perform simulations. The chosen strategy for simulation is as follows: A mechanical torque signal together with an electric load is used to drive the finite...

  20. 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...... resistivity, thus making the computation of heating losses a cumbersome task. Furthermore, the high aspect ratio of the superconducting materials involved adds a penalty in the time required to perform simulations. The chosen strategy for simulation is as follows: A mechanical torque signal together...