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Applied Superconductivity, IEEE Transactions on

Issue 3 • Date June 2013

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  • Front Cover

    Publication Year: 2013 , Article#: 0002501
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  • IEEE Transactions on Applied Superconductivity publication information

    Publication Year: 2013 , Article#: 0002601
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  • Table of contents

    Publication Year: 2013 , Article#: 0001808
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  • Finite Element Simulations of Twisted NbTi Conductors

    Publication Year: 2013 , Article#: 6000105
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB) |  | HTML iconHTML  

    Low-temperature superconducting wires, NbTi and Nb3Sn, designed for ac applications, such as CERN and ITER magnets, are composed of twisted multifilament structures. Under time-varying applied magnetic field, twisting decreases the induced electromotive forces between the filaments and is therefore an effective method to reduce interfilamentary coupling. In order to study coupling losses computationally with high precision, 3-D numerical models are needed. In this work, we use 3-D finite-element method simulations to study hysteresis and coupling losses in NbTi superconductors. We investigate the effect of twist pitch on ac losses. In practice, NbTi wires cannot be studied at the filament level due to the extremely complex geometries. However, the manufacturing of these wires is done by using filament bundles. Therefore, we consider wires that consist of homogenized filament bundles embedded in normal conducting matrix. In particular, we consider the effect of barriers around filament bundles and how filaments should be arranged in bundles to minimize the losses. The simulations show that the qualitative behavior of the model is consistent with the analytical results and it can be used, e.g., in optimization processes, where a comparison of wire geometries is needed. Additionally, when considering the coupling of filaments, the barrier plays a very important role in minimizing the losses. View full abstract»

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  • Comparison of Direct Inter-Filament Resistance Measurement on \hbox {Nb}_{3}\hbox {Sn} Strands Between University of Twente and ENEA

    Publication Year: 2013 , Article#: 6000204
    Cited by:  Papers (2)
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    Experimental results of interfilament resistance measurements obtained with different facilities are compared. Two internal tin Nb3Sn strand types are tested at the University of Twente (UT) and ENEA Frascati. The direct interfilament resistance is measured with a standard four-point voltage-current (V- I) method. At the UT, a probe-station is used with micropoint-contact needles as voltage taps and current leads. At ENEA, the results are attained by a setup with microbonded contacts through thin aluminum (Al) wires. To extract values for the filament-to-matrix contact resistance and for the effective transverse resistivity from these experiments, finite element method simulations are required. The results of the experiments are in good agreement. In addition, we correlate the effective transverse resistivity, derived from the direct interfilament resistance measurement, to values measured and calculated from ac coupling loss. View full abstract»

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  • Thermal Conductivity of Industrial \hbox {Nb}_{3} \hbox {Sn} Wires Fabricated by Various Techniques

    Publication Year: 2013 , Article#: 6000404
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    We have developed a new experimental setup specifically designed for measuring thermal conductivity on technical superconductors in the range of temperatures 3-330 K in magnetic fields up to 21 T. Three Nb3Sn wires, produced by the powder-in-tube technique, the bronze route, and the internal tin restacked-rod process, respectively, have been investigated. We show that, due to the complexity of the architecture of these wires, direct measurement of thermal conductivity is required for a correct estimation of thermal stability in superconducting magnets. View full abstract»

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  • Radioactivity of \hbox {Nb}_{3}\hbox {Sn/Cu} Wires After Proton Irradiation

    Publication Year: 2013 , Article#: 6000504
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    Superconducting magnets based on Nb3Sn technology are being developed for the LHC high luminosity upgrade. In this context, irradiation induced changes of the superconducting properties of state-of-the-art Ti and Ta doped Nb3 Sn wires are presently studied. During irradiation tests with protons of 65 MeV at the cyclotron of Université Catholique de Louvain (UCL), 1.4 GeV at the CERN ISOLDE facility, and 24 GeV at the CERN IRRAD1 facility, the superconductor samples become radioactive and their handling must follow the legal specifications for radioactive materials. We have estimated the activation and the resulting ambient dose equivalent rate up to a fluence of 1017 p/cm2 with the Monte-Carlo Code FLUKA. The estimates were verified with experimental activation spectra. Samples for magnetization measurements with a mass of approximately 20 mg have to be considered as radioactive, but they do not have the potential to harm the operators handling them at radiation levels below 1 μSv/h. Larger samples (longer wires and sample holder materials like Cu and TiAl6V4) show correspondingly higher ambient dose equivalent rates and activation levels and they must be handled by radiation workers in designated areas, taking into account the standard precautions for work with radioactive materials. The use of radiation shielding during handling is recommended. View full abstract»

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  • Transformation Heat Treatment of Rapidly Quenched  \hbox {Nb}_{3}\hbox {Al} Precursor Monitored In Situ by High Energy Synchrotron Diffraction

    Publication Year: 2013 , Article#: 6000604
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    Nb3Al superconductors are studied for use in high field magnets. Fine-grained Nb3Al with nearly stoichiometric Al content is obtained by a rapid heating quenching and transformation process. We describe a nondestructive in situ study of the transformation process step of a rapid heating quenching Nb3Al precursor wire with ramp rates of either 120 °C/h or 800 °C/h. High-energy synchrotron X-ray diffraction measurements show the transformation from a Nb(Al)SS supersaturated solid solution into Nb3Al. When heating with a ramp rate of 120 °C/h, a strong reduction of the Nb(Al)SS (110) diffraction peak component is observed when the temperature exceeds 660 °C. Additional diffraction peaks are detectable in the approximate temperature interval 610 °C -750 °C and significant Nb3Al growth is observed above 730 °C. View full abstract»

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  • Effect of Thermal Cycle on the Lattice Structure in  \hbox {RHQ-Nb}_{3}\hbox {Al} Superconducting Wire

    Publication Year: 2013 , Article#: 6000704
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    In A15 superconducting wires, it is known that the critical current has a dependence on the strain in a magnetic field. Therefore, RHQ-Nb3Al wires are being studied to develop a high field magnet. Since the wire is usually composed of three or more materials, residual strain is induced by the different coefficients of thermal expansion in the materials in the cooling process after A15 phase transformation. In neutron diffraction measurements at room temperature, we previously reported that the residual strain of Nb3Al filaments in the wire is tensile. We also reported that the difference of the residual strain in Nb3Al filaments, as obtained at room temperature, has an effect on the tensile strain dependence of the critical current. In this study, we effectively reduced the residual strain by using a thermal cycle method after A15 phase transformation. By applying one thermal cycle process, the tensile residual strain was decreased by approximately 0.08%. This is the first investigation of the thermal cycle effect on the residual strain in the RHQ-Nb3Al wire. Studies on the thermal cycle are necessary to understand the mechanical properties of the wire. In this paper, we report the details of the thermal cycle method, its effect on the lattice structures of Nb3Al and Cu at room temperature, and the analysis results from the perspective of material strength in strain recovery and its hysteresis. View full abstract»

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  • Applicability of Reel-to-Reel RHQ Treatments to  \hbox {Nb}_{3}\hbox {Al} Precursors With a Ta/Cu/Ta Three-Layer Filament-Barrier Structure

    Publication Year: 2013 , Article#: 6000805
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    A tension-free rapid heating and quenching (RHQ) simulator was previously employed to demonstrate that a ductile and normal-conducting Cu layer can suppress a magnetic field instability and improve bending strain tolerance. However, a molten Cu barrier caused the filament to be shifted from the original location, and excess heating caused the Cu to locally corrode a Ta layer, through which it diffused into the filament, thereby embrittling the resulting wire. In some cases, the swelling molten-Cu tore the Ta skin. Fabrication of a long piece of Ta/Cu/Ta barrier Nb3Al wire is attempted using reel-to-reel RHQ treatment of a modified precursor with a thicker Ta skin that would tolerate both tension forces in a section of the wire between electrodes and pressure from the swelling of molten-Cu. In the optimum RHQ condition (VRHQ: 9.5 V), a 50-m piece of Ta/Cu/Ta barrier precursor was successfully reel-to-reel RHQ treated to form a bcc supersaturated-solid solution (Nb(Al)ss) without bursting of the Ta skin. Microstructural analysis revealed that the molten Cu, into which Ta dissolved, diffused into the jelly-roll filament, mainly through a region of partially melted Al-rich Nb( Al)ss. The critical current density of the filament Jc (18 T, 4.2 K) was optimized by the deformation of Nb(Al)ss and compared favorably with the conventional precursor. View full abstract»

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  • Design of Transformation-Processed \hbox {Nb}_{3} \hbox {Al} Conductors to Balance Drawability and Inter-Filament Decoupling

    Publication Year: 2013 , Article#: 6001004
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    Transformation-processed Nb3Al superconductors should be used in conjunction with a high-melting-point matrix material such as Nb. However, Nb is superconductive below 9 K, which causes low-field instability due to magnetic interfilament coupling at liquid He temperature. One alternative matrix material is Ta. However, the use of Ta sacrifices the drawability of the precursor wires, increasing the risk of wire breakage during drawing. In this work, a new layout intended to balance drawability and interfilament decoupling is proposed. In this new layout, Nb barrier filaments are concentrated around the central dummy core, and Ta barrier filaments are located so as to magnetically decouple the Nb barrier filaments in the outer filamentary region. The drawability and magnetization behavior of the newly designed Nb3Al wires are compared with those of conventional wires. View full abstract»

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  • Superconducting Strand and Cable Development for the LHC Upgrades and Beyond

    Publication Year: 2013 , Article#: 6001112
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2492 KB) |  | HTML iconHTML  

    Fermilab and CERN have started the development of 11 T Nb3Sn dipoles to replace a number of Large Hadron Collider (LHC) NbTi dipole magnets and free space for the additional collimators anticipated for the LHC luminosity upgrades. An essential step in the design of these magnets is the development of the 40-strand, high aspect ratio cable needed to achieve the nominal field of 11 T at the LHC operating current of 11.85 kA. To investigate conductors suited for this and other high-field magnet applications, a larger Superconducting Strand and Cable R&D lab was established at FNAL's Technical Division. Keystoned cables with and without a stainless steel core were developed and produced using 0.7 mm Nb3Sn strands made by Oxford Superconducting Technology with 127 (baseline) and 169 (advanced) restacks using the Restacked-Rod-Process. The electrical performance of these two strands is compared in cables made with different processes and geometries. Some of the effects of a cross-over in the cable were measured. Finally, it is shown how finite element modeling can be used as an aid in Rutherford-type cable design. View full abstract»

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  • Status of Conductor Qualification for the ITER Central Solenoid

    Publication Year: 2013 , Article#: 6001208
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (802 KB) |  | HTML iconHTML  

    The ITER central solenoid (CS) must be capable of driving inductively 30 000 15 MA plasma pulses with a burn duration of 400 s. This implies that during the lifetime of the machine, the CS, comprised of six independently powered coil modules, will have to sustain severe and repeated electromagnetic cycles to high current and field conditions. The design of the CS calls for the use of cable-in-conduit conductors made up of and pure copper strands, assembled in a five-stage, rope-type cable around a central cooling spiral that is inserted into a circle-in-square jacket made up of a special grade of high manganese stainless steel. Since cable-in-conduit conductors are known to exhibit electromagnetic cycling degradation, prior to the launch of production, the conductor design and potential suppliers must be qualified through the successful testing of full-size conductor samples. These tests are carried out at the SULTAN test facility. In this paper, we report the results of the on-going CS conductor performance qualification and we present the options under consideration for the different modules constituting the CS coil. View full abstract»

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  • J_{\rm c}(B, T) Characterization of Commercial NbTi Strands for the ITER Poloidal Field Coils by Transport and Magnetization Methods

    Publication Year: 2013 , Article#: 6001304
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (479 KB) |  | HTML iconHTML  

    Commercial multifilamentary NbTi strands produced by the Russian Federation Domestic Agency for the ITER poloidal field (PF) coils PF1 and PF6 were characterized regarding by magnetization and transport measurements. The results of critical current measurements at magnetic fields in the wide range from 2 to 10 T and at temperatures from 3.5 to 7.5 K are presented. The experimental results were obtained at two laboratories; the two sets of data show a good match and demonstrate the high reproducibility of data. The current sharing temperature of the strands is between 5.9 and 6 K at 6.4 T at an operating current of 33 A. These results enable finding strand characteristic parameters for fits and lead to a database, which is essential for the future analysis of experimental data for the PF conductor performance. View full abstract»

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  • Feasibility Studies of 0.7 mm \hbox {Nb}_{3}\hbox {Al} Strands and Rutherford Cable

    Publication Year: 2013 , Article#: 6001404
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    We are planning to demonstrate a quadrupole magnet with magnetic mirror structure by using 0.7-mm Nb3Al strands. As feasibility studies for this program, we investigated an influence of the diameter reduction of Cu-stabilized Nb3Al strands from 1.0 to 0.7 mm. Wire breakages and Cu separations did not happen with applying the cold die-drawing. The non-Cu Jc and n-values of the 0.7 mm strands did not degrade and could keep the same performance of the 1.0 mm strands. Although irregular deformations of Nb-Al filaments slightly occurred, magnetization properties of the 0.7 mm strands are almost the same as those of the 1.0 mm strands. Ta interfilament matrix of the 0.7 mm strands was also effective to improve the low field instability at 4.2 K. In addition, 27 strands Rutherford cable has been made by using the 0.7 mm F1 strand without any troubles. All of 27 extracted strands taken from the F1 cable showed very uniform Ic performance at 4.2 K. View full abstract»

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  • Analytical Study of Degradation of CIC Conductor Performance Due to Strand Bending and Buckling

    Publication Year: 2013 , Article#: 6001505
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    Critical current of cable-in-conduit conductors for ITER TF coils was measured using a pair of short cable-in-conduit conductors, which are electrically connected from each other at the bottom joint. It was found from these test results that the measured critical current was lower than that evaluated from the critical current performance of a single strand. One of the explanations for this phenomenon is a nonuniform current distribution due to local degradation caused by strand buckling. To study the influence on the conductor performance, the author developed a new analysis model for the calculation of bending strain due to buckling and then, combined this with the electrical circuit model, which consists of lumped and distributed circuits for the conductor and upper/bottom joints, respectively. Simulation results show that when local degradation exists, nonuniform current distribution is established. This indicated that conductor performance can be degraded by local degradation such as strand buckling. View full abstract»

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  • Pulsed Magnetic Field Assisted Technique for Joining  \hbox {MgB}_{2} Conductors for Persistent Mode MRI Magnets

    Publication Year: 2013 , Article#: 6200104
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    The commercial availability of long lengths of MgB2 conductor with an increasingly attractive price-to-performance ratio encourages its use in cryogen-free magnetic resonance imaging magnets. For such a magnet operating in persistent mode, connections between MgB2 wires must be completely superconducting to ensure long-term magnetic field stability. A new electromagnetically assisted technique for joining MgB2 conductors is proposed. An electrically conducting tube is electromagnetically formed around the wires to provide mechanical coupling. Mg + 2B powder is placed inside this tube between the wire ends with exposed MgB2 cores. Pulsed magnetic field compression of the tube densifies the joint powder, which is also redistributed into better contact with wire cores, and forms the tube to the shape of the joined wires. Cu powder has also been added into the Mg + 2B joint powder to minimize the reactive diffusion between Mg and Cu components. Finite element modeling of the deformation process will be presented, along with critical current measurements performed on a joint and on the individual wire for comparison. The applicability of this method for joining wires in reacted and unreacted form for magnet applications will be discussed. View full abstract»

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  • Critical Current Density and Current Transfer Length of Multifilamentary \hbox {MgB}_{2} Strands of Various Design

    Publication Year: 2013 , Article#: 6200204
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (575 KB) |  | HTML iconHTML  

    In this paper, a series of high-performing powder-in-tube MgB2 strands have been prepared. Transport voltage-current measurements were performed to determine the effects of C doping and strand geometry such as filament numbers. The best Jc for our samples was 1.0 × 105 A/cm2 at 4.2 K, 7 T, for a strand using B powder with 3% C addition. The current transfer length was also measured for MgB2 short wires with Nb chemical barrier and Monel outer sheath. The current transfer length ranged from 2 to 12 mm, and had a correlation with the filament numbers. View full abstract»

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  • Monofilament \hbox {MgB}_{2} Wire for a Whole-Body MRI Magnet: Superconducting Joints and Test Coils

    Publication Year: 2013 , Article#: 6200304
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (815 KB) |  | HTML iconHTML  

    This paper presents recent results from our continued development of a 0.5 T whole-body MRI magnet at the Francis Bitter Magnet Laboratory. HyperTech Research Corp. (Columbus, OH) manufactures the MgB2 conductor for this project. During the past year, we have found that our technique, originally developed successfully to splice unreacted multifilament MgB2 wires, works much better, i.e., of higher reliability, with unreacted monofilament MgB2 wires. This has led us to wind the entire coil components in our persistent-mode MRI magnet with unreacted monofilament MgB2 wire, having a MgB2 core of 0.4 mm in diameter, an overall diameter of 0.8 mm bare, 1 mm S-glass insulated. To verify that these coils would not suffer from flux jumping, as they would if wound with monofilament NbTi wire, magnetization studies were performed on monofilament wires of MgB2 and NbTi (as a reference) at 4.2 K. For the monofilament MgB2 wire, the results were affirmative. To further ensure the absence of flux jumping that may quench these current-carrying coils, two test coils were wound with unreacted monofilament MgB2 wire. One MgB2 coil was operated in driven mode, while the other MgB2 coil, equipped with a persistent current switch and terminated with a superconducting joint, was operated in persistent mode. The operating temperature range was 4.2-15 K for these MgB2 coils. The driven mode coil was operated in self-field. The persistent mode coil achieved a persistent current of 100 A, corresponding to a self-field of ~ 1 T in the winding, for 1 hour with no measurable decay. Both test coils were operated quench free. View full abstract»

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  • Improved Critical Current Density in \hbox {\it Ex S\itu} Processed Carbon-Substituted \hbox {MgB}_{2} Tapes by Mg-Addition

    Publication Year: 2013 , Article#: 6200405
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    Grain coupling and critical current density (Jc) property were improved in ex situ processed MgB2 tapes by using a mixture of MgB2 and Mg powders with a planetary ball-milling treatment with mineral and silicon oils. The milling process with the oils chemically and mechanically probably peels off the damaged surface layers of the filling powder. The mineral oil is much more effective for the carbon substitution than the silicon oil. Nearly all of the residual mineral oil after drying the filling powder is used for a source for a carbon substitution for B in MgB2, whereas the residual silicon oil hardly reacts with MgB2. Although the B released from MgB2 on the substitution reaction works as obstacles to the supercurrent path, the carbon substitution raises the upper critical field (Bc2), bringing about Jc enhancement. Mg-addition to the filling powder brings about the grain coupling and further Jc enhancement, probably because of the consumption of the released B. The optimized amount of Mg added to the filling powder is MgB2: Mg = 10: 1 in molar ratio. View full abstract»

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  • Improved Performances of \hbox {MgB}_{2} Conductor by Using of Innovative Amorphous and Nano-Structurated Boron

    Publication Year: 2013 , Article#: 6200504
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    In this paper, we report about improved performances of amorphous and nano-structurated boron in MgB2 critical current density of wires and tapes. The boron produced by magnesiothermic reaction, using nano-structurated boron oxide, is used to synthesize nano-structurated MgB2 powders. These powders are used to produce several wires by ex-situ P.I.T. method. Here we applied only the ex-situ technique, in which our group is very well skilled. The same procedure can be applied to obtain in-situ P.I.T. tapes and wires as well. The boron and the MgB2 powders are characterized both from a physical-chemical point of view and from the superconductive point of view. We performed X-ray analysis to compare the home-made boron crystalline degree with respect to the commercial one. SQUID and transport measurements were done to compare the wire's critical current density behavior with respect to our past results using different boron. View full abstract»

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  • \hbox {MgB}_{2} Hollow Wires and Cables Embedded in a Mg Alloy Matrix

    Publication Year: 2013 , Article#: 6200605
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    The brittleness of the MgB2 wires prevents performing a cable architecture with very small bending radius, similar to NbTi Rutherford cables. Consequently, it is important to reduce the thickness of the superconducting materials in order to increase its bending strain limit. In this context, thin Ni sheathed MgB2 hollow wires, having wall thickness of the order of 20 μm and length of the order of 100 m, have been produced by the Reactive Mg-Liquid Infiltration process (Mg-RLI). The latest hollow monofilament made by Mg-RLI shows very high transport properties, having an engineering critical current density at 4.2 K, 3 T of 730 A/mm2. In this wire the small thickness of the MgB2 corona allows a twisting with pass of the order of a few cm and fulfils the thermal stability criterion for MgB2. We have demonstrated that cables made by such braided or twisted wires may be conveniently reinforced, by embedding the wires in a molten Mg bath, so that the Ni sheath is almost completely dissolved and the wires are clad by an eutectic Mg10%at Ni alloy. This alloyed matrix is structurally well connected to the MgB2 material, with minimal thermal and electrical resistance at the interface. A cable prototype based on this metallic composite has been prepared with 21 mono-core MgB2 wires, twisted around a central hole, which may be useful for cooling purposes. This cable design may be applied as current leads or in short bus-bars, for high current supply. View full abstract»

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  • Synergetic Combination of LIMD With CHPD for the Production of Economical and High Performance \hbox {MgB}_{2} Wires

    Publication Year: 2013 , Article#: 6200704
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    We propose an economical fabrication concept, the localized internal magnesium diffusion (IMD) method. Instead of using a single magnesium (Mg) rod in the center of a metal sheath tube, we use large-sized Mg particles (20-50 mesh) mixed well with cheap 97% crystalline boron powder to fill the metal sheath tube. After a repeated drawing process, the coarse Mg is elongated along the core wire axis of the metal sheath tube. Textured MgB2 grains are then formed during the sintering process. In the localized IMD process, however, there is still a need to improve the overall density. In order to increase the density of the composite, a modified cold high pressure densification (CHPD) technique has been applied before the reaction. It is found that the critical current density (Jc) of the sample made from large-sized Mg with crystalline boron powder and treated by CHPD is increased significantly, so that it is quite comparable with the Jc values of samples made from expensive small magnesium and nanosized amorphous boron powder. At 4.2 K and 8 T, the Jc value of the wire in this work with the cheapest starting materials reaches 10 000 A/cm2 , which is similar to reported values for samples made by the powder-in-tube and IMD processes with expensive nanosized amorphous boron powder. A possible mechanism is proposed, and the microstructure is analyzed to explain this interesting feature. The main goal of this work is to develop a novel and cost-effective fabrication technique by combining the localized IMD process with CHPD and using cheap crystalline boron powder to manufacture MgB2 superconductor wires with electromagnetic performance superior to that of low-temperature Nb-Ti superconductors. View full abstract»

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  • DC Superconducting Cable Using \hbox {MgB}_{2} Wires

    Publication Year: 2013 , Article#: 6200805
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    Tsinghua University, University of Cambridge, and MIT are collaborating to design, construct, and test an MgB2 dc cable for microgrid applications. Two-stage current leads with nitrogen vapor cooled copper and gaseous helium cooled hightemperature superconductor will be used. The two-stage cryostat will be cooled using a single helium fan with a recuperator. The helium gas used to cool the MgB2 to 20-25 K will be cooled with a two-stage GM cryocooler. The cryogenic stability of the cable will be presented. Designs of cryostats are being investigated. Semi-rigid cryostats, with low heat leak, are being designed and will be tested as part of this program. The system will operate up to 1 kV and 1 kA, limited by the present power equipment. However, the MgB2 conductor is being designed for 5 kA, and may be tested at low voltage with upgraded current leads. A 30-m cable will be tested using facilities at Tsinghua University in Beijing. View full abstract»

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  • Recent Advances in Bi-2212 Round Wire Performance for High Field Applications

    Publication Year: 2013 , Article#: 6400104
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (690 KB) |  | HTML iconHTML  

    There has been sustained interest in the development of Bi-2212/Ag round wire because of its unique potential for application in ultra-high-field magnets (>; 25 T). Our development activity with this material has been focused on improving the engineering current density. Filament densification by swaging and isostatic pressing processes have been evaluated, as has further optimization of the melt heat treatment conditions. These improvements lead to an increased mass density of the filament in the final wire, and are essential to reduce filament porosity and obtain high performance over long wire length. Engineering current density values exceeding 480 A/mm2 at 4.2 K, 15 T have been achieved on 1-m-long barrel samples. View full abstract»

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

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