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Applied Superconductivity, IEEE Transactions on

Issue 2 • Date April 2014

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  • Front cover

    Publication Year: 2014 , Article#: 0000601
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  • IEEE Transactions on Applied Superconductivity publication information

    Publication Year: 2014 , Article#: 0000701
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  • Table of contents

    Publication Year: 2014 , Article#: 0000802
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  • Design of a High-Order Dual-Band Superconducting Filter With Controllable Frequencies and Bandwidths

    Publication Year: 2014 , Article#: 1500205
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    This paper presents the design of an eight-pole dual-band bandpass high-temperature superconducting (HTS) filter with modified stub-loaded resonators (SLRs) and dual-feeding structures. The proposed modified SLRs are found to be advantageous because the even-mode and odd-mode couplings are separated from paths. The two bandwidths can be separately adjusted by two coupling paths. The proposed modified SLRs can conveniently be used to tune the two bandpass frequencies. Therefore, both the frequencies and bandwidths of each bandpass can be easily controlled. Moreover, the proposed modified SLRs can be also used to design high-frequency and high-order dual-band bandpass filters. A dual-feeding structure is adopted to match the external Q factor and internal couplings at two bandpass frequencies simultaneously. An eight-pole HTS dual-band bandpass filter operating at 2.55 and 3.53 GHz is designed and fabricated with a compact size of 18.14 mm × 9.36 mm to demonstrate the proposed design. View full abstract»

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  • Compact High-Temperature Superconducting Filter Using Multimode Stub-Loaded Resonator

    Publication Year: 2014 , Article#: 1500308
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    A simple multimode resonator loaded by open- and short-end stubs is proposed in this paper. Its transmission characteristics and equivalent circuit models are investigated by even-odd mode analysis. In addition, the multiband filter design theory using the proposed resonator is explained, and the desired passbands can be conveniently allocated by properly choosing the dimension parameters of the stub-loaded resonator. For demonstration purposes, a compact high-temperature superconducting (HTS) filter operating at 1.57, 2.6, and 3.50 GHz is designed and fabricated. To sharpen the passband skirts of the filter, a source-load coupling configuration with interdigital structure is arranged to produce several transmission zeros. Then, multipath coupling diagrams are constructed, and the relative phase shifts of each path are studied to explain the responses of the triple-band filter. Furthermore, a grounding technique of the short-end stub is realized by subtly connecting with the metal wall packaging instead of via holes in the substrate. In consideration of the inaccuracy in HTS fabricating and packaging, an optimization scheme is proposed. The results of the sensitivity analysis revealed that the optimization scheme is viable. Finally, measurements are in good agreement with the electromagnetic simulations and verify the circuit design methodology. View full abstract»

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  • Design of Compact Superconducting Diplexer With Spiral Short-Circuited Stubs

    Publication Year: 2014 , Article#: 1500405
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    Three types of impedance-matching structures for diplexer design are analyzed and calculated in this paper. Calculations show that different matching structures should be selected for size reduction, depending on the input impedance of the channel filters in the diplexer. Two channel filters in the superconducting microstrip diplexer at the P-band are designed with spiral resonators and capacitively coupled feedlines. The diplexer is then constructed with an impedance-matching structure of spiral short-circuited stubs. The compact diplexer has a size of 22.9 mm × 21.7 mm on an MgO substrate, which amounts to only 0.101 λg0 ×0.096 λg0, where λg0 is the guided wavelength of the 50- Ω line on the substrate at the midband frequency. The fabricated device exhibits high performance, and its measurements match the simulations well. The experimental insertion loss of both channels is less than 0.13 dB. The common-port return loss is greater than 18.9 dB, and the isolation between the two channels is greater than 60 dB. View full abstract»

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  • A Narrowband Superconducting Quadruplexer With High Isolation

    Publication Year: 2014 , Article#: 1500506
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    A manifold-coupled microstrip superconducting quadruplexer with high isolation for S-band communications systems is presented. The problems of channel isolation and common-port impedance matching in the design of the quadruplexer are addressed and studied. An equivalent circuit model for a trial diplexer is built to analyze the isolation between two channel filters with Chebyshev responses. Analyses and simulations show that channel isolation is mainly determined by the resonators that are closest to the noncommon ports. A circuit layout is proposed for the quadruplexer to obtain high isolation. Moreover, a binary matching network is designed to minimize the undesired interactions between the four channel filters in the quadruplexer. The quadruplexer is successfully designed with the proposed methods and fabricated. The measured results show high performance and match well with the simulations. View full abstract»

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  • Proposed FEM-Based Optimization Method for Economical Design of Long Permanent-Magnet Guideways With \hbox {HT}_{\rm c} Superconductors

    Publication Year: 2014 , Article#: 3600609
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    The levitation force between a superconductor disk and a permanent magnet (PM) is the origin for possible industrial applications. The PMs form the most costly part of the permanent-magnet guideways (PMGs), particularly for longer distances. A heuristic optimization method based on simulated annealing has been proposed for the determination of the optimum arrangement and dimensions of PMs in several PMG structures. This optimum design is the most economical PMG design that guarantees the satisfactory levitation performance of the PMG. As part of the optimization process, a FEM-based method has been used, based on the estimation of penetration depth and self-inductance of the superconductor disk, for the calculation of the levitation force. The optimization results contain the PMG structure with minimum PM consumption for a specified levitation height and superconductor disk characteristics and the variation of the most important PMG features, such as its cost and width, versus those distinctive system parameters. These results will provide basic analysis for the design of HTS-PMG levitation systems. Several guideways have been fabricated based on the optimization process outputs and have shown satisfactory results. View full abstract»

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  • Investigation of a Low-Speed Single-Side HTS Linear Induction Motor With Different Primary Structures Used for Linear Metro

    Publication Year: 2014 , Article#: 3600710
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    This paper presents the influence of the primary structures on the performance parameters and critical current of a low-speed single-sided high-temperature superconducting linear induction motor used for the linear metro system. Three types of the primary structures, namely, a slotted iron core, a slotless iron core, and an air core, are set up to evaluate the influence. Developed by the Ag-sheathed Bi-2223 tapes, the exciting windings are distributed with a double-layer concentrated structure. The correction factors and the transverse coefficient are presented to consider the transverse edge effects. The 2-D mathematical model considering the longitudinal end effects is established, and the boundary conditions are given. The transient electromagnetic field of the three schemes is solved by using the time-stepping finite-element method. The experiment carried out on a prototype with a slotted iron core is conducted to validate the accuracy of the established model. The flux density and the performance parameters such as the force characteristics, specific loss, power factor, efficiency, etc., of the machines with three versions of primary structures are compared and analyzed. In addition, the influence of primary structures on the critical current is also investigated. View full abstract»

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  • Lumped-Parameter Model to Describe Dynamic Translational Interaction for High-Temperature Superconducting Bearings

    Publication Year: 2014 , Article#: 3600808
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    This paper discusses a lumped parameter modeling methodology to describe the dynamic vertical and translational force interaction between a bulk superconductor and levitated permanent magnet (PM). The model is formulated to be easily incorporated into larger rigid body system models to aid design of superconducting bearings for flywheel energy storage applications. The proposed modeling technique will significantly reduce the computational expense in order to shorten the design cycle process. The validity of the proposed lumped parameter model is demonstrated by comparing results from finite-element method analysis and measurements of the force displacement interaction between a PM and a bulk high-temperature superconductor. View full abstract»

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  • Magnetic Field Design of a Superconducting Wiggler in the SAGA-LS Storage Ring

    Publication Year: 2014 , Article#: 4102208
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    A magnetic field design for a superconducting (SC) wiggler system, which has been installed in the Saga light source storage ring, was described. The wiggler is a three-pole type, consisting of a 4.0-T SC center magnet and two normal-conducting side magnets; thus, each pole forms a magnet. Since the wiggler consists of isolated magnets, reduction of the first field integral of the center SC magnet was important from the viewpoint of suppression of the orbit displacement. For this purpose, the center SC magnet was designed to have a separated iron core with field clamps and no transverse return yoke. This concept made magnetic field negative regions near the center peak magnetic field on the electron beam orbit to reduce the first field integral and beam meandering. Heat generations due to eddy currents and the magnetic field due to supporting structures were calculated to have ignorable effects. The appropriateness of the design has been confirmed through daily stable operation at the light source. View full abstract»

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  • Manufacturing of ITER PF5 and CC Sample Conductors

    Publication Year: 2014 , Article#: 4202905
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    The design of poloidal field (PF) coils and correction coils (CCs) for the International Thermonuclear Experimental Reactor (ITER) relies on the use of 45-kA NbTi cable-in-conduit conductors. All PF5 and CC conductors are produced in China. Research and development programs are needed to acquire knowledge on the behavior of such conductors. Since the conductors are new, full-size copper dummy conductors have been produced in advance for testing the cabling parameters, the definition of the automatic tungsten-inert-gas welding of a seamless jacket section, the elaboration of cable insertion, compaction, etc. Then, two short qualification conductor samples (the PF5 and the CC) are manufactured at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), Hefei, China, with the NbTi advanced strands produced by the Western Superconducting Technologies Company, Ltd. In this paper, the manufacturing procedures for the two PF5 and CC conductor samples are described in detail. View full abstract»

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  • Cold Mass Design of the Superconducting Outsert for the 40-T Hybrid Magnet

    Publication Year: 2014 , Article#: 4301905
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    A 40-T hybrid magnet is under construction at the High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences (CHMFL), Hefei, China. It includes a superconducting outsert magnet that can provide a central field of 11 T and a warm bore of Ø 800 mm for the insertion of a water-cooled magnet. This superconducting magnet has three superconducting coils, all of which are wound with Nb3Sn cable-in-conduit conductors (CICCs). The structural design of the superconducting outsert's cold mass has been worked out starting from the design of the conductors and the configuration of the coils. In this paper, we present the considerations and designs for the major components of the cold mass, i.e., the winding pack, the preload structure, the CICC lead support structures, and the cooling circuit. In addition, the design of the support structure of the coils is introduced and discussed. This is a key element and a special component with the function to support the cold mass and to transfer the fault loads from the coils to the base plate of the cryostat while its heat load to the cryogenic side remains as low as possible. View full abstract»

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  • Development of an 8-T Conduction—Cooled Superconducting Magnet With 300-mm Warm Bore for Material Processing Application

    Publication Year: 2014 , Article#: 4701605
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    A wide-bore conduction-cooled superconducting magnet was designed, fabricated, and tested for material processing applications. The superconducting magnet has a large clear warm bore of Ø300 mm, the maximum center field of 8 T, the homogeneity of 97% in homogeneous regions of Ø300 mm × 50 mm. The magnet is composed of three coaxial coils made with NbTi low-temperature superconducting wires. All the coils were connected in series and will be operated with a current of 82.2 A with a high level of stored energy, i.e., about 2.13 MJ. A passive protection based on a subdivided scheme is adopted to protect the magnet from damage caused by a quench. Two two-stage GM cryocoolers with the second-stage cooling power of 1.5 W is used to cool the superconducting magnet from room temperature to 4.2 K. In this paper, magnetic design, stress and strain analysis, quench protection, fabrication, and test are presented. View full abstract»

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  • Performance Improvement and Optimization of New High-Temperature Superconducting Coil Assembly

    Publication Year: 2014 , Article#: 4901104
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    To practically use high-temperature superconducting (HTS) coils, it is necessary to reduce the total length of the HTS tape while maintaining a large amount of stored energy and small magnetic field leakage. In this paper, we propose a new HTS coil assembly, which is distinct from solenoid and toroid coils. Using the typical r- z axes of cylindrical coordinates, several small coils having rectangular cross sections are placed such that they form a circle in the r- z plane. Note that these small coils are coaxial along the z -axis. To form the solid structure, these cross sections are rotated about the z-axis. The analysis of the coil assembly allowed for performance improvements and optimization. The performance improvement resulted from the large modification of the magnetic field angles, which are achieved by the cancelation of Br magnetic field components from each element coil. The critical current of the optimized assembly is greater than that of a normal rectangular solenoid by 1.6 times. As a result, the optimized assembly results in 78% increase in stored energy and a large reduction in the magnetic field leakage, as compared with a normal rectangular solenoid coil with the same HTS tape length. View full abstract»

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  • Fast and Precise Method for Inductance Calculation of Coaxial Circular Coils With Rectangular Cross Section Using the One-Dimensional Integration of Elementary Functions Applicable to Superconducting Magnets

    Publication Year: 2014 , Article#: 4901309
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    A new and extremely fast and precise method for calculating mutual inductance between coaxial circular coils in air with rectangular cross section and uniform current densities is presented. It is thoroughly compared with all recently published methods in the same computing environment, and the results confirm the aforementioned. Along with the high accuracy and low computational time, the emphasis is put on the easiness of implementing the method, using only the elementary functions. The method can be used in all combinations of the coils' radii and heights, from narrow coils to coils with extremely large radii, such as the coils used in superconducting magnets. Excellent numerical stability and agreement with professional software was found in all testing cases. View full abstract»

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  • Thermal Analysis of 10-MW-Class Wind Turbine HTS Synchronous Generator

    Publication Year: 2014 , Article#: 5202209
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    In this paper, the thermal performance of a 10-MW-class wind turbine-based high-temperature superconducting (HTS) synchronous generator is studied. The proposed generator is designed and modeled through a finite-element method (FEM), and the generator losses, including iron losses and electrical losses, are obtained. As the output power substantially depends on thermal rising of the generator, heat transfer analysis of the proposed HTS generator is carried out using both lumped parameters network (LPN) and FEM analysis. Then, temperature distribution of the components of the machine is evaluated and discussed for different generator speeds. The proper temperature distribution guarantees the desirable operation of the generator. This paper shows that it is feasible to design a 10-MW-class HTS synchronous generator from thermal analysis point of view. View full abstract»

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  • Testing and Demonstration of a 10-kA HTS DC Power Cable

    Publication Year: 2014 , Article#: 5400104
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    A 10-kA/360-m high-temperature superconducting (HTS) dc power cable has been developed and installed in 2012 in central China. The cable is connecting a rectifier at a substation to a bus bar of an aluminum electrolysis plant. Before operating in the power grid, a series of testing on the performance of the cable was conducted. The testing results show that the performance meets the operational requirements and that the critical current of the cable exceeds 12.5 kA. The 10-kA HTS cable was successfully energized at the Henan Zhongfu Industrial Company Ltd., Gongyi, China, on September 26, 2012. Since then, the cable has been stably and reliably supplying power for the company's aluminum electrolyzing plant. View full abstract»

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  • Multiphysics Approach in HTS Transformers With Different Winding Schemes

    Publication Year: 2014 , Article#: 55003018
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    This paper elaborates the results of our previous study by delving into time-step multiphysical simulations juxtaposing electromagnetic and thermal characteristics of a high-temperature superconducting (HTS) transformer. This is attainable by using multiphysical coupling of the Kirchhoff laws, the Maxwell equations, and thermal equilibrium. The electrical behavior of the superconductor is described by means of a B-dependent modified E- J power-law relation. Moreover, a precise calculation of the mechanical force components created by the interaction between current and leakage flux density of each winding scheme is the further objective of this paper. The multiphysical processes are carefully scrutinized for normal and fault conditions in an exemplary HTS transformer by analytical and finite-element analyses of 3-D FLUX software in steady-state and transient modes. View full abstract»

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  • Growth of NdFeAsO Films by a Combination of Metal–Organic Chemical Vapor Deposition and Arsenic Diffusion Processes

    Publication Year: 2014 , Article#: 7300106
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    NdFeAsO films have been grown by a two-step method. First, precursor films that contain a mixture of Nd and Fe oxides were grown by metal-organic chemical vapor deposition. Afterward, the arsenic is incorporated during annealing of these precursor films in the presence of a NdFeAsO0.75F0.25 pellet. The X-ray diffraction and the scanning electron microscopy show that the formation of the quaternary NdFeAsO phase is prevented by the stability of the rare-earth oxides and rare-earth oxyfluorides and that it is synthesized only if the annealing temperature is higher than 1050 °C. Although the pellet creates a reaction atmosphere to synthesize the superconducting phase, the fluorine is not incorporated into the quaternary NdFeAsO phase. View full abstract»

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  • Magnetic Field Evaluation of a Thin Type-II Superconducting Circular Washer Carrying a Radial Transport Current

    Publication Year: 2014 , Article#: 8000304
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    We calculate the magnetic field and sheet-current density distribution for a thin-film superconducting circular washer carrying a radial transport current. Our calculations show that applying a radial transport current to a washer containing remanent flux in zero field will cause the magnetic flux to be expelled from the sample. Moreover, the magnetic flux profiles of several superconducting washers of different radii are compared. The two components of the magnetic flux densities on the top of the washer for several radial currents are also presented. View full abstract»

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  • A Time-Harmonic Approach to Numerically Model Losses in the Metal Matrix in Twisted Superconductors in External Magnetic Field

    Publication Year: 2014 , Article#: 8200909
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    The first NbTi superconductor was developed in 1962 at Westinghouse. During 50 years, the manufacturing process of NbTi wires became highly optimized, and complex wire structures, which are needed in reducing ac losses, can be produced these days. Twisted multifilamentary structures generate many challenges from the modeler's point of view. Considering numerical modeling, NbTi wires are too complicated to model with filament-level details. This is due to the high number and very nonlinear resistivity of filaments. Consequently, simplified approaches are needed for wire modeling. In this paper, a time-harmonic approach to model losses in the metal matrix is introduced. It is based on the linear approximation of filaments. The method to determine the linear resistivity of filaments is based on the definition of the skin depth and the radius of filaments. This can be done in advance without solving a nonlinear problem in 3-D. The suitability of the time-harmonic approach is benchmarked against the H-formulated 3-D eddy current model (ECM) with power-law resistivity. According to simulations, the losses in the metal matrix predicted by the time-harmonic approach agreed well with the nonlinear ECM when the filaments were uncoupled. The results achieved with the proposed approach similarly followed the effects of geometrical changes in the wire structure on losses as the nonlinear ECM and predicted the circumstances where the filaments became partially coupled. The simulation times were considerably lower with the new approach. From the manufacturer's perspective, it is important to design conductors where the filaments stay uncoupled and have low ac losses in such a situation. Thus, the new approach can provide an effective design tool in developing new superconductors. View full abstract»

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  • Dual-Band Superconducting Bandpass Filter Using Quadruple-Mode Resonator

    Publication Year: 2014 , Article#: 4901204
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    A dual-band high-temperature superconducting (HTS) bandpass filter (BPF) using a quadruple-mode resonator is realized in this paper. The resonator consists of a half-wavelength uniform impedance resonator, an open stub in a symmetrical plane, and two spiral open stubs at the two sides of the symmetrical plane. Distinct characteristics of the quadruple-mode resonator are investigated by using even/odd mode theory, and the design graphs are given to analyze the dual-band filter. A dual-band HTS BPF with central frequencies of 1.8 GHz for GSM applications and 2.4 GHz for wireless local area network applications is designed using the proposed quadruple-mode resonator, which is fabricated by depositing YBCO films on a 0.5-mm-thick MgO substrate. Its size occupies only 13 mm × 17 mm. Measured results demonstrate that an insertion loss within the passbands is less than 0.25 dB. In addition, a transmission zero is achieved in-between two passbands, and two transmission zeros are realized in the upper stopband of the higher passband, which improve the skirt selectivity and stopband characteristics of the filter. View full abstract»

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  • Publish your article in IEEE Access

    Publication Year: 2014 , Article#: 9800201
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  • Open Access

    Publication Year: 2014 , Article#: 9800301
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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