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Applied Superconductivity, IEEE Transactions on

Issue 3 • Date Sept. 1999

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Displaying Results 1 - 8 of 8
  • Superconducting rectifier fluxpump for magnet system of the CMD-2 detector

    Page(s): 4585 - 4590
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (82 KB)  

    A superconducting rectifier fluxpump has been used for the dc power supply of the magnet system of the CMD-2 detector on the VEPP-2M collider at the Budker Institute of Nuclear Physics in Russia since 1989. The fluxpump provides a complete pumping cycle: charging the magnet system, stabilization of the magnetic field, and discharging. The fluxpump consists of an air-core current step-up superconducting transformer and two groups of thermally controlled superconducting switches arranged as a fullwave rectifier. Critical output current during the test was 5.4 kA. The accuracy of the field stabilization provided by the fluxpump is 2.5/spl middot/10/sup -5/. The fluxpump has exhibited reliable and safe operation during its entire history of use. View full abstract»

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  • Toward a systematic design methodology for large multigigahertz rapid single flux quantum circuits

    Page(s): 4591 - 4606
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (689 KB)  

    Rapid single flux quantum (RSFQ) digital circuits have reached the level of medium- to large-scale of integration. At this level, existing design methodologies, developed specifically for RSFQ circuits, have become computationally inefficient. Applying mature semiconductor methodologies to the design of RSFQ circuits, one encounters substantial difficulties originating from the differences between both technologies. In this paper, a new design methodology aimed at large-scale RSFQ circuits is proposed. This methodology is based on a semiconductor semicustom design approach. An established design methodology for small-stale RSFQ digital circuits, based on circuit (junction-level) simulation and device parameter optimization, is used for the design of basic RSFQ cells. A library composed of about 20 basic RSFQ cells has been developed based on this approach. A novel design methodology for large-scale circuits, presented in this paper, is based on logic (gate-level) simulation and timing optimization. This methodology has been implemented around the Cadence integrated design environment and used successfully at the University of Rochester for the design of two large-scale digital circuits. View full abstract»

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  • Accurate calculations of geometrical factors of Hakki-Coleman shielded dielectric resonators

    Page(s): 4607 - 4612
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (113 KB)  

    This paper presents new analytical formulas for the accurate calculation of geometrical factors of Hakki-Coleman shielded dielectric resonators operating in the TE/sub 011/ mode. The new approach is compared numerically with existing semianalytical methods of computing geometrical factors. The results of the comparison show that the new approach of calculating geometrical factors is more accurate. View full abstract»

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  • Improvement on current limiting performance of current limiting devices with damping coils

    Page(s): 4613 - 4618
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (109 KB)  

    An improved model of the current limiting devices such as the high-Tc superconducting fault current limiter (SFCL) and the reactor have been developed. The high-Tc SFCL mainly consists of the primary copper coil, the secondary high-Tc superconducting rings, and the damping coils, which are magnetically coupled through a three-legged magnetic core. Because a portion of the magnetic flux above the saturation point generated by the fault current is cancelled by the damping coil, thereby the magnetic core is prevented from getting into the saturated state. The limiting current level and the saturation of the core could be controlled by the air-gap length of the central leg with the damping coil. A new design of the SFCL is found to increase the effective impedance by about 60 to 70%, compared to the SFCL design without the damping coils. View full abstract»

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  • Newly developed millimeter-sized superconducting linear actuator with superconducting slider

    Page(s): 4619 - 4623
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    A millimeter-sized superconducting linear actuator has been developed. The actuator consists of a superconducting slider, a stator, amplifiers, and a personal computer. Exciting currents for six-phase excitation are applied to the electromagnets of the stator. The experimental results show that the superconducting slider moves over the stator without any mechanical contacts and that the motion resembles a stepping motor. The stable position for the levitating slider depends on the magnetic field produced by the electromagnets. The maximum speed of the slider is more than 10 mm/s. View full abstract»

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  • rf impedance of sintered BSCCO and melt-textured YBCO superconductors

    Page(s): 4624 - 4627
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (90 KB)  

    The authors present the temperature and field dependence of radio frequency response of sintered BSCCO 110-K phase and melt-textured YBCO with Ag and 211 inclusions. The rf resistance and reactance measurements are carried out using a marginal oscillator operating at 11.9 MHz. Melt-textured samples are found to exhibit insignificant low-field losses and hence are potential candidates for applications at radio frequencies. The field induced loss in sintered BSCCO is described by invoking two kinds of weak links. The rf penetration depth of the materials measured is found to be much larger than the London penetration depth and represents the effective screen depth. More importantly, the authors observed an anomaly in the penetration depth of BSCCO which is explained in terms of an interplay between intragranular and Josephson penetration depths. View full abstract»

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  • Electric characteristics of contact junctions between NbTi multifilamentary wires

    Page(s): 4628 - 4632
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    Anomalous current-voltage characteristics have been found for a mechanical contact junction between NbTi superconducting multifilamentary wires. The pressure contact junctions between superconductors were created by either parallel-conductor contact or crossed-conductor contact. The junctions are superconductive over a limited current range. The current-voltage characteristics show switching phenomena, that are both large and very fast, at transitions between zero voltage and resistive states. The switching time is about 2 /spl mu/s. A zero-voltage current of about 60 A was obtained for a 75-mm-long junction at zero applied magnetic field. The current-voltage curve of the junction shows hysteresis that varies with the contact junction's structure. It has been confirmed that mechanical pressure contact junctions can be used as persistent switches without heaters. Additionally, contact junctions may provide uniform current distribution for multistrand cables. View full abstract»

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  • Field solution of a type-II superconducting thin-film planar asymmetric transmission line in the mixed state

    Page(s): 4633 - 4638
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (138 KB)  

    By using the electrodynamic field equations for a type-II superconductor in the mixed state, a sinusoidal wave solution is derived for an asymmetric high-T/sub c/ superconducting transmission line in the presence of vortices. This solution can be used to numerically demonstrate the dependence of the slow mode propagation on the temperature, frequency, and static magnetic field. The effects of vortices on propagation characteristics in a superconducting strip line are thus elucidated. View full abstract»

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Aims & Scope

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

Full Aims & Scope

Meet Our Editors

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