By Topic

Applied Superconductivity, IEEE Transactions on

Issue 1 • Date March 2007

Filter Results

Displaying Results 1 - 14 of 14
  • Table of contents

    Page(s): C1
    Save to Project icon | Request Permissions | PDF file iconPDF (37 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Applied Superconductivity publication information

    Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (36 KB)  
    Freely Available from IEEE
  • Quench Protection System for the Superconducting Coil of the KSTAR Tokamak

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (659 KB) |  | HTML iconHTML  

    This paper presents two-stage high-power mechanical-thyristor switches developed as 40-kA direct current (dc) circuit breakers for the superconducting coil energy dump system of Korea superconducting Tokamak advanced research (KSTAR). An advanced switching system used in the quench protection should allow multishot mode of operation without maintenance and long lifetime with arcless dc current commutation. The system is designed to combine the advantages of the both mechanical and solid-state power switches. The mechanical stage is to conduct dc current for normal superconducting coil operation and the thyristor stage is to provide fast arcless dc current interruption for quench protection (QP). Compared with the all solid-state switches and vacuum interrupters of equal capabilities the proposed switch is much cheaper than the dc breakers and has lower power dissipation in current conducting state "Kuchinski in Proc. Power Ele., 899-903, 1995;" "Benfatto IEEE Power Del., Vol. 3, No. 4, pp. 1372-1376, Oct. 1998." Also, it is much faster than the vacuum interrupters. The system is designed to break 40-kA dc current within 200 ms. Also, KSTAR device, a configuration of the energy dump system and coil power supplies are presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Investigation of ITER Use Internal-Sn Nb3Sn Superconducting Wire Through Irreversibility Temperature Measurement

    Page(s): 7 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1126 KB) |  | HTML iconHTML  

    By means of a SQUID magnetometer, the irreversibility temperatures and magnetization transitions of an ITER-type internal-Sn Nb3Sn superconducting wire were measured during warming and cooling cycles at a fixed magnetic field. The results obtained show that the irreversibility temperature T*(H) is strongly dependent on A15 phase composition and can be used to optimize the heat treatment process for the internal-Sn Nb3Sn wire. The A15 phase composition in internal-Sn Nb3Sn wire is temperature independent for full-time reaction. From T*(H) and magnetization transition analysis, the heat treatment condition of our ITER use wire is optimized as 675 degC/128 h, which results in the best A15 phase composition suitable for high-field application View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of Additional Reference Current in a Reference Junction-Double Relaxation Oscillation SQUID (RJ-DROS)

    Page(s): 13 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (707 KB) |  | HTML iconHTML  

    A double relaxation oscillation SQUID with a reference junction (RJ-DROS) already has a fixed reference current, so that it holds a fixed flux-to-voltage characteristics when fabricated. When an additional current flows through the reference junction but not through the signal junction in the RJ-DROS, we have obtained the variation of its characteristics. The additional reference current has an effect on reducing the fixed reference current, which results in changing averaged relaxation voltage and transfer coefficient. In particular, while the critical current of the signal SQUID exceeds the reference current, the averaged relaxation voltage at the reference junction is enlarged by the added bias current combined with an additional current and an initial bias current. Therefore the additional reference current can provide the RJ-DROS with variable modulation depth and width within the operating range. Although the characteristics of RJ-DROSs are fixed differently each to each when they are fabricated, the additional current can adjust their characteristics to the same one, which is useful for controlling DROSs in a multichannel DROS system. However, an input-bias current in the preamplifier detecting the outputs at the reference junction, acts as an additional current, and then makes the reference current shift from the optimum current or deviate from the operating range, the input-bias current needs to be regulated within the operating range View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Demagnetization of Trapped Field in High TC Superconductors Using Pulsed Field Methods

    Page(s): 20 - 26
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (979 KB) |  | HTML iconHTML  

    This paper examines the demagnetization of a trapped magnetic field in a high TC superconducting (HTS) monolith using a single, short, high-amplitude field pulse. With a single optimized pulse, the peak trapped field can be reduced to one-third of the maximum saturated value. Alternatively, the spatial average of the trapped field could be fixed very close to zero. After demagnetization, the trapped field has both positive and negative values at various locations in the HTS monolith. Transient responses of the HTS to pulsed fields with different amplitudes are also reported and discussed. It does not appear that the residual trapped field can be reduced to zero throughout the monolith using pulsed field demagnetization methods in a fixed sample/coil geometry. Bean's critical state model is used to explain the measured equilibrium field distributions. Transient response of the HTS to an externally applied field is qualitatively explained by magnetic diffusion. Drive circuit characteristics and design feasibility issues are also addressed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design and Testing of a Superconducting Rotating Machine

    Page(s): 27 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1778 KB) |  | HTML iconHTML  

    We have designed, constructed and tested an eight-pole superconducting rotating machine, based on an unconventional topology that could potentially lead to a significant increase in power density. Calculations have been carried out in two steps: estimation of the magnetic scalar potential from a Coulomb formulation using the Markov chain Monte Carlo (MCMC) method, and the calculation of the flux density by derivation of the potential using a regularization method. The use of the MCMC method enables the calculation of the magnetic scalar potential in selected regions of the discrete geometry, which is an important factor to minimize the computation time. The principle of the operation has been validated by a successful testing of the motor showing this novel configuration of an electrical motor as very promising View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Synchrotron Tomography for the Study of Void Formation in Internal Tin Nb3Sn Superconductors

    Page(s): 34 - 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (599 KB) |  | HTML iconHTML  

    Synchrotron absorption tomography has been applied for the study of voids formed during the thermal treatment of internal tin Nb3 Sn strands. Possible void formation mechanisms and in particular the effect of Sn phase transformations and melting are discussed based on a quantitative void description. Sn melting changes mainly the shape and volume of the individual voids but does not increase the total void volume in the strand View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fabrication of YBa2Cu3O7−x Superconducting Films Using Low-Fluorine-Content Solution

    Page(s): 40 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1171 KB) |  | HTML iconHTML  

    A new solution for fabrication of YBa2Cu3O 7-x (YBCO) superconducting films has been developed of Ba-TFA with nonfluorine Y and Cu organic salts being used as precursors. This new solution contains only 30% of the fluorine in an all-TFA solution, and duration of heat-treatment cycles is much shorter than that when an all-TFA solution is used. New YBCO-films are characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. The results indicate that the as-prepared YBCO-films using the low-fluorine-content solution exhibit good textures and retain high oxygen content. Samples of these YBCO-films have good superconducting properties including high critical transition temperature Tc=90.5 K, sharp transition temperature DeltaTC<0.9 K, and enhanced critical current density Jc=3 MA/cm2 View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Some Considerations About the Cooling of the Rotor of a Superconducting Motor

    Page(s): 44 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (731 KB) |  | HTML iconHTML  

    This paper deals with the cooling of the rotor of a superconducting motor. We consider three cooling systems: a cold insert, circulation of a cool gas and boiling of a cool liquid. For each case, we study the use of three different gases: hydrogen, helium, neon, and two liquids: hydrogen and neon. For each case of cooling, we define the best gases in term of cooling efficiency View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetic Field Coils for Gradiometer Balancing

    Page(s): 52 - 59
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (283 KB) |  | HTML iconHTML  

    We present a design of a compact set of biplanar coils which produces magnetic fields of eight different profiles for the purpose of gradiometer balancing. The magnetic field profiles correspond to uniform magnetic fields in three orthogonal directions and five linearly independent first-order gradients. The coils are made by etching square printed circuit boards that have dimensions of 0.5 m times 0.5 m. The typical inhomogeneity of the magnetic fields and gradients produced by the ideally assembled coil set in a cylindrically shaped volume that measures 50 mm in diameter and 225 mm in height is of the order of 10 -5. The coils yield uniform fields and first-order gradients of at least 1(muT/A) and 1(muT/Amiddotm), respectively. The influence of manufacturing tolerances on the performance of the set is investigated by means of Monte Carlo simulations. Based on these simulations, we concluded that the coil set needs to be assembled with a tolerance of 0.1 mm in order to reach a required uniformity of order of 10-5-10-4 View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Order form for reprints

    Page(s): 60
    Save to Project icon | Request Permissions | PDF file iconPDF (345 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Applied Superconductivity upcoming special conference issues

    Page(s): C3
    Save to Project icon | Request Permissions | PDF file iconPDF (24 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Applied Superconductivity Information for authors

    Page(s): C4
    Save to Project icon | Request Permissions | PDF file iconPDF (28 KB)  
    Freely Available from IEEE

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