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Applied Superconductivity, IEEE Transactions on

Issue 3 • Date Sept. 2004

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Displaying Results 1 - 18 of 18
  • Table of contents

    Page(s): c1
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  • IEEE Transactions on Applied Superconductivity publication information

    Page(s): c2
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  • Fatigue behavior of multifilamentary BSCCO 2223/Ag Superconducting tapes

    Page(s): 1941 - 1947
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3760 KB) |  | HTML iconHTML  

    The mechanical properties and the critical current were studied in three commercial multifilamentary Bi2Sr2Ca2Cu3O10+x/Ag tapes subjected to monotonic and fatigue tension at 77 K in the longitudinal direction. It was found that transport properties were not compromised under monotonic tension if the maximum tensile stress remained below the conventional 0.2% yield strength. This magnitude was reduced by 10% to 20% in the case of fatigue loading, and the service life of the tape was dictated by the mechanical fatigue life. View full abstract»

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  • Investigation of magnetic properties of 2223-BSCCO steel-reinforced tapes

    Page(s): 1948 - 1954
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB) |  | HTML iconHTML  

    Reinforcing multifilamentary Bi2Sr2Ca2Cu3Oy (2223-BSCCO) requires careful evaluation of magnetic losses and, in general, of the quantities related to the hysteresis loop (e.g., coercive field and residual magnetization). In this paper, the results of magnetic quantity measurements performed on superconductive tapes reinforced by both AISI 304 and AISI 316 stainless steel layers are discussed. It is shown that the former kind of steel has power losses higher than the latter. Therefore, from this point of view AISI 316 constitutes a better solution than AISI 304 to reinforce BSCCO-Ag tapes. Comparative measurements performed on the steel layer, the superconductor, and the reinforced tape, separately, allow the different contributions to the total magnetic loss to be singled out. In this way, a relationship between the induced voltages in one single steel layer, in a BSCCO-Ag tape without steel, and in the reinforced structure (BSCCO + 2 steel layers) is derived. View full abstract»

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  • Impact of DC components in transport current and external magnetic field on hysteresis losses in an HTS tape

    Page(s): 1955 - 1958
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    The high-temperature superconductor (HTS) development is presently intensive, and one can expect that HTSs will be used in different electric devices in the future. In some of these devices, e.g., a magnetostrictive actuator, the conductor will be exposed to both ac and dc transport currents and external magnetic fields. One of the most important parameters in the design of electric devices is the power loss. It is, therefore, of importance to develop models that are able to predict the power loss in devices based on HTSs. In this paper, we present an experimental characterization of the hysteresis losses in an HTS tape exposed to ac or dc transport currents in combination with external magnetic fields. The experimental results are compared to some existing models based on the critical state model. The power loss was measured on a multifilamentary Bi-2223 tape at constant temperature (70 K) and frequency (50 Hz). View full abstract»

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  • Magneto-optical visualization of magnetic processes in superconducting strip with the application of magnetic fields and currents

    Page(s): 1959 - 1965
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    The magneto-optical imaging (MOI) technique is widely employed to characterize the magnetic properties of superconductors and other magnetic materials because it can easily show the variation of flux density over a plane with relatively high resolution. In this paper, flux profiles visualized by the MOI technique will be presented for different experimental conditions. The sample investigated is a high-temperature superconducting single strip. Three cases are investigated: 1) application of external currents; 2) application of external magnetic fields; and 3) simultaneous application of external magnetic field and current. The behavior of complicated vortex penetration into the samples for different conditions will be discussed in detail. The magnetic flux profiles are calculated taking into account the sample thickness, as well as the interval between the sample and the MOI indicator film. The calculated and the experimental results are compared and discussed. View full abstract»

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  • Magnetic-shield-type fault current limiter equivalent circuit

    Page(s): 1966 - 1973
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    In order to investigate how a superconducting fault current limiter (SFCL) can enhance the performance of a power system, an accurate circuit model of the device needs to be introduced in power system simulators. In this paper, we present a finite-element numerical model to calculate the time evolution of the voltage across a magnetic-shield-type SFCL, when it is connected to an external circuit. The calculation of the voltage is carried out by using the energy conservation law, and requires the calculation, at any instant, of the current density distribution inside the superconducting tube and magnetization distribution inside the ferromagnetic core of the device. These distributions are determined by means of two coupled equivalent electric and magnetic circuits, whose topology and components are obtained through the spatial integration of quasi-static form of Maxwell equations. Comparisons between numerical and experimental results are shown. View full abstract»

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  • Kinetic inductive model of a millimeter-wave high-temperature superconducting optoelectronic mixer

    Page(s): 1974 - 1982
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB) |  | HTML iconHTML  

    We introduce and analyze an optoelectronic mixer (OEM) based on the kinetic inductive photoresponse in high-temperature superconducting (HTS) films. This device combines photodetection and optoelectronic mixing functions through a nonlinear change in the kinetic inductance of the HTS film when it is irradiated by an optically modulated microwave signal. A comprehensive theoretical analysis is presented using the two-temperature model to describe the nonbolometric (quantum) photoresponse and the kinetic inductance model for the electrical part. Upon the optical irradiation, the change in the electron temperature of the HTS film leads to a parametric change in the kinetic inductance of the photoexcited HTS bridge, which in the presence of a bias current produces a periodic voltage waveform. In order to obtain the temporal behavior and the frequency content of the output voltage in terms of the input local oscillator and modulation frequencies, the kinetic inductance model and Fourier series analysis have been used and their physical consequences have been discussed in detail. The merit characteristics of the kinetic inductive HTS-OEM, such as intrinsic and optical conversion gains and noise temperature, are evaluated and compared with other high-frequency mixers. This is followed by the numerical simulation of the proposed device. View full abstract»

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  • An FDTD model for calculation of gradient-induced eddy currents in MRI system

    Page(s): 1983 - 1989
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    In most magnetic resonance imaging (MRI) systems, pulsed magnetic gradient fields induce eddy currents in the conducting structures of the superconducting magnet. The eddy currents induced in structures within the cryostat are particularly problematic as they are characterized by long time constants by virtue of the low resistivity of the conductors. This paper presents a three-dimensional (3-D) finite-difference time-domain (FDTD) scheme in cylindrical coordinates for eddy-current calculation in conductors. This model is intended to be part of a complete FDTD model of an MRI system including all RF and low-frequency field generating units and electrical models of the patient. The singularity apparent in the governing equations is removed by using a series expansion method and the conductor-air boundary condition is handled using a variant of the surface impedance concept. The numerical difficulty due to the "asymmetry" of Maxwell equations for low-frequency eddy-current problems is circumvented by taking advantage of the known penetration behavior of the eddy-current fields. A perfectly matched layer absorbing boundary condition in 3-D cylindrical coordinates is also incorporated. The numerical method has been verified against analytical solutions for simple cases. Finally, the algorithm is illustrated by modeling a pulsed field gradient coil system within an MRI magnet system. The results demonstrate that the proposed FDTD scheme can be used to calculate large-scale eddy-current problems in materials with high conductivity at low frequencies. View full abstract»

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  • Superconducting FCL: design and application

    Page(s): 1990 - 2000
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    Design, parameters, and application areas of a superconducting fault current limiter (FCL) are analyzed on the basis of the requirements of power systems. The comparison of resistive and inductive designs is carried out. An example of the effective application of FCLs in distribution substations is considered and the gain from the FCL installation is discussed. It is shown that an FCL not only limits a fault current but also increases the dynamic stability of the synchronous operation of electric machines. The calculation procedure of the parameters of an inductive FCL for a specific application case is described. View full abstract»

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  • Possible application of MPW effect for sensitive acceleration measurements

    Page(s): 2001 - 2007
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    This paper examines the "magnetic potential well" effect by the example of two ring-shaped superconductive coils. This effect allows us to create a noncontact magnetic suspension of one coil and to define its movements by measuring the current in the stationary coil. It is shown that the system of these two coils is unstable with respect to the tilt angle. The new construction of the levitated coil, which allows us to create the completely stable suspension is examined. The solution of the equation of test mass motion and the acceleration-to-current transfer function for low-frequency acceleration are found. The other type of superconducting accelerometer is briefly described for comparison. View full abstract»

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  • A comparison of two design methods for MRI magnets

    Page(s): 2008 - 2014
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    Designs of magnetic resonance imaging (MRI) main magnets obtained from both a functional method and a genetic algorithm method have been compared. While most features in the two approaches are similar, there are several important differences. The functional method leads to fewer coil bundles and a reduced total current, i.e., total ampere turns, (e.g., 6-8 MA) that can be as much as 70% of the total current found with the genetic analysis. While the conclusion about stress is that it is a sensitive function of the choice of wire current density, the designs found with the functional method have a larger hoop stress than that of the genetic design, which may require new or refined manufacturing techniques. Furthermore, the functional approach requires much less computing power (i.e., a personal computer is quite sufficient) while the genetic algorithm method in general demands massively parallel computing techniques. However, in order to search for the optimal magnetic resonance design at a given field strength, it is likely that a combination of these two methods will lead to the best results. View full abstract»

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  • Short-term and long-term mechanical characteristics of BSCCO steel-reinforced tapes

    Page(s): 2015 - 2021
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    An investigation on short-term and long-term mechanical characteristics of Bi2Sr2Ca2Cu3Oy reinforced tapes is presented in this paper. Results of critical current measurements obtained after bending, as well as during application of tensile stress and strain, are shown. Data are processed to provide a threshold model for the bending test, according to which bending on large-diameter mandrels does not provide appreciable damage to superconductor tapes. The values of critical current density derived from tensile stress and strain are investigated by the Weibull cumulative function, showing the existence of two distinct failure modes, determined by different strengths of reinforced tapes. This statistical analysis provides a methodology for a feasible quality control test on superconductive tapes. Long-term behavior evaluation, carried out through life lines derived from tests under different levels of stress and strain, indicate that reinforced tapes show largely improved endurance with respect to nonreinforced ones. View full abstract»

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  • Erratum

    Page(s): 2022
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  • Proceedings of the IEEE celebrating 92 years of in-depth coverage on emerging technologies

    Page(s): 2023
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    Page(s): 2024
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  • Blank page [back cover]

    Page(s): c3
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  • IEEE Transactions on Applied Superconductivity Information for authors

    Page(s): c4
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Aims & Scope

IEEE Transactions on Applied Superconductivity contains articles on the applications of superconductivity and other relevant technology.

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Meet Our Editors

Editor-in-Chief
Britton L. T. Plourde
Syracuse University
bplourde@syr.edu
http://www.phy.syr.edu/~bplourde