178 results on '"COPPER oxide superconductors"'
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2. Feasibility of large-current capacity YBCO conductors with on-demand transposition.
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Yanagi, Nagato, Mito, Toshiyuki, Noguchi, Hiroki, Terazaki, Yoshiro, Tamura, Hitoshi, Iwakuma, Masataka, Aoki, Yuji, Izumi, Teruo, and Shiohara, Yuh
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FEASIBILITY studies ,ELECTRIC capacity ,COPPER oxide superconductors ,ELECTRIC coils ,ELECTRIC power distribution ,MAGNETIC fields ,CRITICAL currents ,ELECTRIC resistance - Abstract
Abstract: We propose a new idea for fabricating a large-current capacity YBCO conductor having a Roebel-type transposition formed by joining tapes. If the joule heating generated by joints is smaller than other heat sources, such as AC losses, this type of conductor may work as a quasi-superconductor. We note that the Roebel-type transposition can be included on demand in coil windings, not over the whole conductor length but rather locally, such as at terminals and coil edges to secure uniform current distribution among tapes. We fabricated a 1.2 m-long conductor sample based on this idea using 20 YBCO tapes. The Roebel-assembled tapes having joints with a 600-mm pitch length for meandering were imbedded in a copper jacket and soldered. The sample was tested in liquid nitrogen under the self magnetic field and the critical current was measured. The joint resistance was evaluated and compared with the expected value. [Copyright &y& Elsevier] more...
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- 2012
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3. Anew layout of HTS tapes and their critical currents for DC power cables.
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Sun, Jian, HirofumiWatanabe, Hamabe, Makoto, ToshioKawahara, Iiyoshi, Atsuo, and Yamaguchi, Satarou
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HIGH temperature superconductivity ,CRITICAL currents ,ELECTRIC cables ,DIRECT currents ,MONOMOLECULAR films ,COPPER oxide superconductors - Abstract
Abstract: Weinvestigated thegapeects on the critical current of the middle tape in the paralleled arrangements of three straight BSCCO tapes with monolayer, 2-layer and 3-layer structures to improve the cable superconducting performance by the tape arrangement. The critical current of the BSCCO tape increases with the decreasing of thegap for the monolayer structure, increases by 11% for the 2-layer and decreases by 15% for the 3-layer structure. Anew layout of HTS tapes for the DC power cable is presented. The critical current of the BSCCO tape in a cable with a new layout may increase by 10%. [Copyright &y& Elsevier] more...
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- 2012
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4. Enhancement of in-field critical current density by irradiation of MeV-energy ions in YBCO films prepared by fluorine-free metal-organic deposition.
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Matsui, H., Ogiso, H., Yamasaki, H., Sohma, M., Yamaguchi, I., Kumagai, T., and Manabe, T.
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CRITICAL currents ,IRRADIATION ,COPPER oxide superconductors ,ELECTRIC properties of thin films ,METAL organic chemical vapor deposition ,HIGH temperature superconductivity - Abstract
Abstract: We performed irradiation of epitaxial YBa2Cu3O7 films grown on CeO2-buffered SrTiO3 substrates by fluorine-free metal organic deposition with 3-MeV Fe2+ ions to study their effects on critical current density (Jc). We observed an increase of in-field Jc by up to 70%, which did not show a significant field-angle dependence. Since the ion energy used in this study is two orders of magnitude lower than those in majority of the previous works with a similar concept, our results indicate that the enhancement of Jc by ion irradiation in high-temperature superconducting films has wider processing window than previously recognized. [Copyright &y& Elsevier] more...
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- 2012
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5. Recent R&D progress on DI-BSCCO wires with high critical current properties.
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Kagiyama, Tomohiro, Kobayashi, Shin-ichi, Yamazaki, Kouhei, Kikuchi, Masashi, Yamade, Satoru, Nakashima, Takayoshi, Hayashi, Kazuhiko, Sato, Ken-ichi, Shimoyama, Jun-ichi, and Kitaguchi, Hitoshi
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COPPER oxide superconductors ,ELECTRIC wire ,CRITICAL currents ,BISMUTH compounds ,SINTERING ,MICROSTRUCTURE ,LAMINATED materials ,HIGH temperature superconductors - Abstract
Abstract: Sumitomo Electric has been developing the silver-sheathed Bi2223 multi-filamentary wires since the discovery of Bi-based superconductors. DI-BSCCO is the superconducting wire with high and uniform critical current properties produced using the controlled-overpressure (CT-OP) sintering technique. The present commercial DI-BSCCO can provide the uniform high critical current, Ic, up to 180 A with length over 2000 m, and recently over 200 A with length over 1000 m were produced successfully, resulting from the improvement and control of the microstructure in Bi2223 multi-filaments. The short trial wires of several meters have exhibited the highest Ic over 240 A at 77K in self-field (corresponding to 580 A per 1cm-width). Besides, the optimization of carrier density after CT-OP have led to further enhancement of Ic, reached 250 A at 77K in self-field. All the derivative products also have uniform critical current properties over entire length even after lamination with the reinforcing metals. The performances of DI-BSCCO can meet the growing needs for various applications of high temperature superconductor like high in-field applications, such as magnets and motors. The recent progress in transport properties of commercial DI-BSCCO and R&D short trial wires is shown. [Copyright &y& Elsevier] more...
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- 2012
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6. Variation of applied field angular dependence of critical current density in YBCO thin films against deposition temperature and composition.
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Matsunami, T., Ichino, Y., Yoshida, Y., Ichinose, A., and Matsumoto, K.
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COPPER oxide superconductors ,CRITICAL currents ,ELECTRIC properties of thin films ,TEMPERATURE effect ,FLUX pinning ,MAGNETIC flux ,DISTRIBUTION (Probability theory) ,STOICHIOMETRY - Abstract
Abstract: For the magnetic flux pinning in YBa2Cu3Oy (YBCO) thin films, artificial pinning centers (APC) like BaZrO3 and BaSnO3 nanorods act effectively when magnetic fields are applied parallel to the c-axis of the YBCO thin films. However, it is necessary that APC exist into a three dimentional shape and random distribution in order to enhance Jc against all angle range of applied magnetic fields. In this study, we reported YBCO thin films with low anisotropy of Jc against the magnetic field applied angle. As a result, using off-stoichiometric target composition of Y: Ba: Cu = 1: 2: 3.4 and high substrate temperatures, the YBCO thin films which were prepared by pulsed laser deposition method at more than 890°C showed low anisotropic Jc, since the films included pinning centers acting against wide angle range of applied field. [Copyright &y& Elsevier] more...
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- 2012
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7. Fabrication and critical current properties in Nd:YAG-PLD REBa2Cu3Oy (RE=Y and Er) thin films.
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Horii, Shigeru, Fujita, Natsuto, Ogura, Yuta, Maeda, Toshihiko, and Haruta, Masakazu
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MICROFABRICATION ,CRITICAL currents ,ND-YAG lasers ,COPPER oxide superconductors ,ELECTRIC properties of thin films ,PULSED laser deposition ,SUBSTRATES (Materials science) ,TEMPERATURE effect - Abstract
Abstract: We report optimization of substrate temperature (Ts) regions for achievement of the bi-axially oriented growth without the a-axis oriented domains, critical current properties and crystallinities in REBa2Cu3Oy (RE123) films (RE= Y and Er) grown by pulsed laser deposition using a Nd:YAG laser. Appropriate Ts regions for achieving both high critical temperature and self-field critical current density in Y123 and Er123 films were found to be similar. In the case of Y123, infield critical current densities and inplane lattice parameters for the Y123 films grown in a lower Ts region were slightly changed compared with those for the films grown at a higher Ts region. Our findings in the present study give us fundamental information to understand intrinsic effects of introduction of nanorods in the RE123 films containing nanorods. [Copyright &y& Elsevier] more...
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- 2012
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8. High-material yield fabrication of YBCO coated conductors by Nd:YAG-PLD system.
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Ono, I., Ichino, Y., Yoshida, Y., Yoshizumi, M., Izumi, T., and Shiohara, Y.
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MICROFABRICATION ,COPPER oxide superconductors ,ND-YAG lasers ,PULSED laser deposition ,COST analysis ,SUBSTRATES (Materials science) ,CRITICAL currents - Abstract
Abstract: In order to fabricate superconducting coated conductors with lower cost, fabrication processes are required high material yield. We report an improvement of the material yield of YBCO films prepared by inside-plume Nd:YAG pulsed laser deposition method on metal substrates with an architecture of CeO2/LMO/IBAD-MgO/GZO/HastelloyTM. In this study, we shortened a distance from the target to the substrate (dT-S) in order to improve the material yield. Additionally, we have used Nd:YAG laser because initial and running costs are anticipated to be lower than those of excimer laser. As a result, by shorting the dT-S from 40mm to 20mm, the material yield increased on 10 mm×10mm substrates. Additionally, by changing the O2 pressure (PO2) from 40Pa to 400Pa at dT-S = 20mm, the material yield had a local maximal value of 18.6% at PO2=200Pa. On multi-turn (MT) metal substrates, the material yield reached 56.0%. However, the critical current density (Jc) of the YBCO film which was deposited at dT-S = 20mm and PO2=200Pa on the 10 mm×10mm substrate was 1.2 MA/cm2 at the edges and 0.2 MA/cm2 at the center at 77K in self-field, although the YBCO films showed good aligned crystal textures. In order to improve this non-uniformity, we tilted the surface normal of the target 15 degree from a line connecting target and substrate. As a result, we achieved the uniformity in deposition rate. Then, we prepared YBa1.78Cu2.9Oy target to fabricate YBCO films with stoichiometric composition and obtained the uniform-high Jc. [Copyright &y& Elsevier] more...
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- 2012
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9. Improvement of magnetic properties for long YGdBCO coated conductors using TFA-MOD process.
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Kimura, Kazunari, Hironaga, Ryusuke, Koizumi, Tsutomu, Nakamura, Tatsunori, Nakanishi, Tatsuhisa, Aoki, Nobuo, Hasegawa, Takayo, Takahashi, Yasuo, Yoshizumi, Masateru, Izumi, Teruo, and Shiohara, Yuh
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COPPER oxide superconductors ,SURFACE coatings ,FLUX pinning ,METAL organic chemical vapor deposition ,FLUOROACETIC acid ,MICROFABRICATION ,HEAT treatment of metals ,CRITICAL currents - Abstract
Abstract: YxGd(1-x)Ba2Cu3Oy(YGdBCO) coated conductors (CCs) containing artificial pinning centers (APCs) were fabricated by the trifluoroacetate-metalorganic deposition (TFA-MOD) method using a batch heat-treatment process, which have been industrially applied to fabricate long superconducting tapes which have high critical current (Ic) have been successfully manufactured. From the viewpoint of applications, the characteristics in magnetic fields become further important and one solution has been showed by Miura et al. as introduction of APCs such as BaZrO3 (BZO). We applied their technique to our CCs fabrication process. The heat-treatment conditions, specifically total gas pressure, oxygen concentration and crystallization temperature, were optimized for the batch heat-treatment process. A 40 m-long YGdBCO CC in which APCs are introduced was fabricated, and it has Ic value of 320 A/cm-width (critical current density (Jc) value of 2.2 MA/cm2) in self-field and 20 A/cm-width at 3 T in Liq. N2. [Copyright &y& Elsevier] more...
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- 2012
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10. Influences of oxygen content on the carrier concentration and transport properties of Bi-2212 bulks.
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Zhang, Shengnan, Li, Chengshan, Hao, Qinbin, Zhang, Pingxiang, Liu, Haiming, and Yang, Shenghui
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CRITICAL currents ,OXYGEN ,TRANSPORT theory ,BISMUTH compounds ,COPPER oxide superconductors ,SINTERING ,ANNEALING of crystals - Abstract
Abstract: Bi
2.1 Sr1.96 Ca0.95Cu2.0 O8 (Bi-2212) bulks have been obtained with Spark Plasma Sintering (SPS) method, with the precursor powders synthesized by co-precipitation process. Due to the vacuum environment involved in SPS, oxygen loss can be expected during sintering. Therefore, extra annealing processes under oxygen atmosphere were performed to enhance the superconducting properties of the bulks. Seebeck coefficient has been measured after different annealing process, in order to calculate the carrier concentration change with annealing process. The carrier concentration underwent a change from 0.178 to 0.198 per Cu ions after the 34h annealing in oxygen at 773K. The magnetic field dependence of critical current density, Jc, has been measured at 20K on the samples with different annealing time. The critical current density increase from 550 to 5100Acm-2 at zero field after the 34h annealing, and the optimized Jc value can be obtained at the 34h annealing sample over the entire magnetic field range. [Copyright &y& Elsevier] more...- Published
- 2012
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11. Effect of magnetic particle additions on flux pinning in bulk Y-Ba-Cu-O superconductors.
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Tsuchiya, T., Kikuchi, T., Takano, S., Koshizuka, N., and Murakami, M.
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COPPER oxide superconductors ,MAGNETIC materials ,CRITICAL currents ,HIGH temperature superconductors ,FLUX pinning ,COMPARATIVE studies ,FERROMAGNETIC materials ,POWDER metallurgy - Abstract
Abstract: In order to increase the critical current density of high temperature superconductors, it is commonly employed to disperse nonsuperconducting particles as flux pinning centers into the superconductive matrix. For Y-Ba-Cu-O bulk superconductors Y2BaCuO5 (Y211) phase particles are known to be effective pinning centers. It has been proposed that magnetic particles are more efficient pinning centers, since they will have a stronger positive interaction with quantized fluxoids. A combined addition of Y211 and magnetic metal fine powders has been reported to be effective in improving flux pinning performances. Therefore, in this study we aimed at improving the pinning forces of Y-Ba-Cu-O bulk superconductors by introducing the Fe-Al-Si-based alloys that are ferromagnetic. We also studied the effect of the addition of γ-hematite, which is non-magnetic, in order to compare the contribution to the flux pinning enhancement. For comparative study, we measured the trapped field in single-domain bulk superconductors and found that a small addition of Fe-Al-Si based ferromagnetic powders and γ-hematite improved field trapping ability. [Copyright &y& Elsevier] more...
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- 2012
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12. Superconducting properties of Y-Ba-Cu-O bulk with BaSnO3 addition.
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Iwasaki, M., Seki, H., Koshizuka, N., and Murakami, M.
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COPPER oxide superconductors ,SUPERCONDUCTIVITY ,STANNIC oxide ,CRYSTAL texture ,RARE earth metals ,INTERFACES (Physical sciences) ,CRITICAL currents ,DISPERSION (Chemistry) - Abstract
Abstract: Dispersion of non-superconducting phase particles is commonly employed in melt textured REBa2Cu3O7-δ (RE123; RE: rare earth element) bulk superconductors in order to improve the critical current density. It has been clarified that the interfaces of RE2BaCuO5 (RE211) and RE123 matrix contribute to the flux pinning, and therefore, the critical current density can be enhanced due to the refinement of RE211 particles. In recent years additions of RE2Ba4CuMOy (M=Zr, Nb, Ta, Mo, U, Sn, and Re) particles have been investigated in an attempt to improve the pinning performance. While the common particle size is around 1-5μm for the RE211, the size of RE2Ba4CuMOy particles is much finer and typically 50∼300nm, implying that the pinning may be improved with the dispersion of RE2Ba4CuMOy particles. In this study, we have studied the effects of the BaSnO3 addition to Y2BaCuO5 (Y211) powders. It was found that two different compounds of Y2Ba4CuSnOy and Y2BaCuO5 phase particles were co-produced by adding BaSnO3 to Y211. These powders were added to the precursor and subjected to the melt-textured process to grow bulk Y-Ba-Cu-O superconductors of 20mm diameter with the top-seed melt growth process. The finished bulk samples were observed with optical microscopy and subjected to trapped field measurements with Hall sensors. The trapped field measurements showed that BaSnO3 addition was effective in improving the field trapping ability. [Copyright &y& Elsevier] more...
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- 2012
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13. Processing conditions for (Nd, Eu, Gd)-Ba-Cu-O ternary bulk superconductors.
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Kikuchi, T., Wongsatanawarid, A., Homma, Y., K.Suzuki, Koshizuka, N., and Murakami, M.
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COPPER oxide superconductors ,CRITICAL currents ,SUPERCONDUCTORS ,PRESSURE ,MATHEMATICAL optimization ,TEMPERATURE effect - Abstract
Abstract: (Nd, Eu, Gd)-Ba-Cu-O ternary bulk superconductors have high potential for practical applications since they exhibit very high critical current densities and thus high field trapping capabilities. (Nd, Eu, Gd)-Ba-Cu-O superconductors are synthesized in a reduced oxygen atmosphere, which requires a control of oxygen partial pressure and needs a special device for hot seeding. In the present study, for simplicity, we employed Ar gas flow into the furnace to control oxygen partial pressure instead of flowing oxygen-controlled gas. Hence, it was necessary to modify the melt processing conditions to produce a single domain. Through the optimization of seeding temperature and cooling rate, we obtained the processing conditions, in which a single domain bulk (Nd, Eu, Gd)-Ba-Cu-O of 20mm diameter could be synthesized. [Copyright &y& Elsevier] more...
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- 2012
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14. Effect of high valency cations on the (BiPb)SrCaCuO compounds.
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Yazici, Duygu and Ozcelik, Bekir
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COPPER oxide superconductors , *VALENCE (Chemistry) , *CURRENT density (Electromagnetism) , *SCANNING electron microscopy , *HYSTERESIS loop , *CRITICAL currents , *X-ray diffraction - Abstract
We have produced the (BiPb)VSrCaCuTiO compounds by a melt-quenching method. For two different sintering times (185 and 192 hours), the effects of vanadium adding and Ti doping on the structure have been investigated by electrical resistance, scanning electron micrographs (SEM), XRD patterns and magnetic hysteresis loop measurements. It has been found that the high- T superconducting phase, (2223), is formed in the samples annealed at 845 C for 185 and 192 h, with concentration x=0.2 and y=0.05. However, with increasing Ti doping the (2223) phase gradually transforms into the (2212) phase. The hysteresis loop areas decrease with increasing Ti concentration and sintering time. Our data have indicated that the critical current, J, decreases with increasing magnetic field. [ABSTRACT FROM AUTHOR] more...
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- 2012
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15. Characteristics of cryocooled racetrack magnet fabricated using REBCO coated conductor
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Daibo, M., Fujita, S., Haraguchi, M., Kikuchi, K., Iijima, Y., and Saitoh, T.
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LOW temperature engineering , *MICROFABRICATION , *COPPER oxide superconductors , *SURFACE coatings , *CRITICAL currents , *ELECTRIC coils - Abstract
Abstract: In the last few years, REBCO coated conductors having a performance greater than a few hundred amperes per cm at 77K have been developed for superconducting applications. Coils that use REBCO coated conductors are expected to have the high operating current (Iop ) against the critical current (Ic ) of the coil. In this paper we report the experimental results of a small cryocooled racetrack magnet (70×150mm in inner diameter, 100×180mm in outer diameter, 27mm in height, 50m (12.5m×4 coils) in total length) fabricated using a REBCO coated conductor, formed by IBAD/PLD method. We measured the critical current of the magnet from 50K to 20K under cryocooled conditions. The critical current was found to be 450A at 20K. The magnetic field of 0.54T was generated at the center of the magnet. We also investigated the stability of the racetrack magnet, at the current of 382.5A, and Iop /Ic ratio of approximately 85%, for 1h at 20K. [Copyright &y& Elsevier] more...
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- 2011
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16. AC over-current test results of YBCO conductor for YBCO power transformer with fault current limiting function
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Tomioka, A., Otonari, T., Ogata, T., Iwakuma, M., Okamoto, H., Hayashi, H., Iijima, Y., Saito, T., Gosho, Y., Tanabe, K., Izumi, T., and Shiohara, Y.
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ALTERNATING currents , *COPPER oxide superconductors , *ELECTRIC transformers , *LIMITER circuits , *ELECTRIC power systems , *CRITICAL currents , *ELECTRIC power production - Abstract
Abstract: We are developing elemental technology for 66kV/6.9kV 20 MVA-class YBCO power transformer. The YBCO transformer is considered to have a possibility to stabilize the power system by improving function of fault current limiting. Current limiting behavior functions over critical current flows. There is a possibility that superconducting characteristic may be damaged due to increase in temperature of YBCO tapes. Therefore, we have taken a measure to combine YBCO tape with CuNi tape or Cu Tape. We manufactured model coils using these conductors and conducted the AC over-current tests. The test current was two to seven times larger than the I c of conductor and it was damped with time from its maximum value according to the generation of conductor resistance. We verified the effectiveness of current limiting characteristics. In these tests, the I c of model coil did not degrade. We consider this conductor to be able to withstand AC over-current with the function of current limiting. [Copyright &y& Elsevier] more...
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- 2011
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17. The short-circuit test results of 6.9kV/2.3kV 400kVA-class YBCO model transformer
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Tomioka, A., Otonari, T., Ogata, T., Iwakuma, M., Okamoto, H., Hayashi, H., Iijima, Y., Saito, T., Gosho, Y., Tanabe, K., Izumi, T., and Shiohara, Y.
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SHORT circuits , *COPPER oxide superconductors , *ELECTRIC transformers , *CRITICAL currents , *DEFORMATIONS (Mechanics) , *ELECTRICAL engineering - Abstract
Abstract: We are developing an elemental technology for 66kV/6.9kV 20MVA-class power transformer with YBCO conductors. The protection of short-circuit technology is one of the elemental technologies for HTS transformer. Since short-circuit current is much higher than critical current of YBCO tape, there is a possibility that superconducting characteristics may be damaged during short-circuit period. We made a conductor to compose the YBCO tape with copper tape. We manufactured 6.9kV/2.3kV 400kVA-class YBCO model transformer using this conductor and performed short-circuit current test. The short-circuit current of primary winding was 346 A which was about six times larger than the rated current. The I–V characteristics of the winding did not change before and after the test. We may consider this conductor withstands short-circuit current. [Copyright &y& Elsevier] more...
- Published
- 2011
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18. Progress of 275kV–3kA YBCO HTS cable
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Yagi, M., Mukoyama, S., Amemiya, N., Ishiyama, A., Wang, X., Aoki, Y., Saito, T., Ohkuma, T., and Maruyama, O.
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COPPER oxide superconductors , *HIGH temperature superconductivity , *ELECTRIC cables , *CRITICAL currents , *MICROFABRICATION , *POLYPROPYLENE , *ELECTRIC discharges , *ELECTRIC insulators & insulation - Abstract
Abstract: A 275kV–3kA high temperature superconducting (HTS) cable has been developed in the Materials & Power Applications of Coated Conductors (M-PACC) project. AC loss reduction of a two-layer HTS conductor was undertaken by removing the edges of YBCO tapes with low critical current density. The HTS conductor using these tapes was fabricated, and low loss of 0.235W/m at 3kArms was achieved. The 275kV–3kA cable was designed, and the 2m model cables were fabricated. This cable had 325mm2 copper stranded former inside the HTS conductor and a 310mm2 copper shield layer on the HTS shield layer for over-current protection. These cables withstood an over-current of 63.0kA for 0.6s, which is the worst situation for 275kV systems. The partial discharge (PD) and V–t characteristics of a liquid nitrogen (LN2)/polypropylene (PP) laminated paper composite insulation system have been integrated into the design of the insulation for the 275kV cable. The results revealed that the PD inception stress (PDIE) did not depend on the insulation thickness, and that lifetime indices of V–t characteristics at PD inception were as high as about 80–100. [Copyright &y& Elsevier] more...
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- 2011
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19. Critical current measurements for design of superconducting DC transmission power cable
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Sun, J., Yamauchi, S., Sugino, M., Watanabe, H., Hamabe, M., Kawahara, T., and Yamaguchi, S.
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CRITICAL currents , *COPPER oxide superconductors , *DIRECT currents , *ELECTRIC power transmission , *ELECTRIC cables , *TEMPERATURE effect , *MAGNETIC flux , *BAND gaps - Abstract
Abstract: In the present experiments three straight high temperature superconducting BSCCO tapes were set parallel to each other on a board and the currents were fed to the tapes. The critical currents of the tape which was set between two tapes were measured with respect to the gap between the tapes. We observed that the critical current increases with decreasing the gap. The calculation of the magnetic flux lines around the tape by finite element method demonstrates the effect on self magnetic field by the adjacent tapes. We could provide some hints on how to arrange the tapes in the power cable for DC power transmission. [Copyright &y& Elsevier] more...
- Published
- 2011
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20. Applied physical characterization of rare-earth based 123 superconductors by means of paraconductivity study
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Mori, N., Yoshida, M., Katoda, S., Ishibashi, T., and Takano, Y.
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RARE earth metals , *SUPERCONDUCTORS , *EVAPORATION (Chemistry) , *COPPER oxide superconductors , *FLUCTUATIONS (Physics) , *TEMPERATURE effect , *CRITICAL currents - Abstract
Abstract: A study of the paraconductivity is adopted to characterize material properties in evaporated YBa2Cu3O7− δ films and melt-textured RBa2Cu3O7− δ superconductors with R=Y, Gd or Sm element, having different values of T c and critical current density or trapped magnetic field. The paraconductivity is analyzed in terms of theoretical expressions for Aslamazov–Larkin, Maki–Thompson and the third terms in which effects of short-wavelength fluctuation are taken into account. The consideration of the momentum cutoff in the fluctuation spectral provides good agreement between theory and experiment in each specimen over the whole temperature range investigated. This allows us to evaluate accurate values for fluctuation parameters, among which the fluctuation amplitude and phase-coherence time could be correlated to critical current density and trapped magnetic field. The results for the paraconductivity analysis are discussed in relevance to parameters for applications. [Copyright &y& Elsevier] more...
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- 2011
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21. Enhanced critical current density in YBa2Cu3O7− δ thin film deposited on La0.67Sr0.33MnO3 decorated SrTiO3 substrates
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Jha, Alok K., Khare, Neeraj, and Pinto, R.
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COPPER oxide superconductors , *CRITICAL currents , *ELECTRIC properties of thin films , *LANTHANUM compounds , *TITANATES , *SUBSTRATES (Materials science) , *NANOPARTICLES , *LASER ablation , *FLUX pinning - Abstract
Abstract: Thin films of YBa2Cu3O7− δ (YBCO) have been deposited on undecorated and La0.67Sr0.33MnO3 (LSMO) nanoparticles decorated single crystal SrTiO3 (STO) substrate using laser ablation technique and their flux pinning characteristics have been compared using temperature dependent magnetization studies. Significant improvement in the critical current density of YBCO thin film has been observed even at higher applied magnetic field (∼7T). The improved flux pinning properties of YBCO thin films deposited on LSMO decorated STO substrate has been attributed to the presence of ferromagnetic LSMO nanoparticles at the substrate/film interface which seem to be acting as artificially generated magnetic pinning centres leading to improved flux pinning properties. [Copyright &y& Elsevier] more...
- Published
- 2011
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22. Change in local and overall V–I curves with applied tensile strain in DyBCO-coated conductor
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Toda, A., Arai, T., Shimokawa, Y., Nagano, S., Ochiai, S., Okuda, H., Sugano, M., Osamura, K., and Prusseit, W.
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STRAINS & stresses (Mechanics) , *COPPER oxide superconductors , *SURFACE coatings , *ELECTRIC circuits , *CRITICAL currents , *FRACTURE mechanics , *COPPER plating - Abstract
Abstract: Change in local and overall V–I curves with increasing applied tensile strain in copper-plated DyBCO-coated conductor was studied experimentally and analytically. V–I curves under various applied tensile strains were measured for a sample with a length 4.5cm composed of a series circuit of local sections with a length 1.5cm. By modeling analysis of the experimental results, the V–I curve and critical current of cracked sample were reproduced satisfactorily. Also the change in shunting current with increasing current was revealed, from which variation of n-value with current (and voltage) was revealed. The sample length dependence of critical current and n-value under existence of local crack was discussed. [Copyright &y& Elsevier] more...
- Published
- 2011
- Full Text
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23. Recent R&D progress on DI-BSCCO wires with high critical current properties
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Nakashima, T., Kobayashi, S., Kagiyama, T., Yamazaki, K., Kikuchi, M., Yamade, S., Hayashi, K., Sato, K., Shimoyama, J., Kitaguchi, H., and Kumakura, H.
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COPPER oxide superconductors , *ELECTRIC wire , *CRITICAL currents , *PRESSURE , *SINTERING , *MICROSTRUCTURE , *LAMINATED materials , *HIGH temperature superconductivity - Abstract
Abstract: Sumitomo Electric has been developing the silver-sheathed Bi2223 multi-filamentary wires since the discovery of Bi-based superconductors. DI-BSCCO is the high performance wires produced with the controlled-overpressure (CT-OP) sintering technique. The present commercial DI-BSCCO can provide the uniform high critical current, Ic , up to 180A over 2000m, and recently 200A were succeeded to obtain with the same kind of 1000m-long wires, resulting from the improvement and control of the microstructure in Bi2223 multi-filaments. The short trial wires of several meter have exhibited over 240A as the highest Ic at 77K, self-field (corresponding to 580A per 1cm-width) according with high Tc over 112K. Besides, the optimization of carrier density after CT-OP led to further enhancement of Ic , reaching 250A. All the derivative products have also uniform critical current property over the entire length even after lamination with the reinforcements. The performances of DI-BSCCO can meet the growing needs for various high temperature superconducting applications involving high in-field properties, such as magnets and motors. The recent progress on Ic including in-field properties along with the remarkable findings on the performances of DI-BSCCO will be shown. [Copyright &y& Elsevier] more...
- Published
- 2011
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24. Local and overall critical current and n-value of DyBCO coated conductor under applied tensile strain
- Author
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Nagano, S., Toda, A., Arai, T., Ochiai, S., Okuda, H., Sugano, M., and Prusseit, W.
- Subjects
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CRITICAL currents , *COPPER oxide superconductors , *SURFACE coatings , *STRAINS & stresses (Mechanics) , *STATISTICAL correlation , *TEMPERATURE effect , *SHUNT electric reactors - Abstract
Abstract: Under applied strain/stress, extent of damage varies with location in a sample. Accordingly, overall critical current and n-value of a sample depend on extent of damage of local sections. The present work aimed to reveal the correlation of critical current and n-value of overall sample to those of local sections in DyBCO coated conductor. Critical current and n-value were measured for the voltage probe distances 45 and 15mm, respectively, at 77K in a self magnetic field. Both critical current and n-value beyond irreversible strain (≈0.32%, corresponding to stress 320MPa) decreased significantly with applied strain/stress. The reason for this was accounted for by the increase in crack size, accompanied by increase in shunting current. While the local critical current and n-value were different from section to section due to the difference in extent of damage, the relation of overall critical current and n-value to the local ones was described comprehensively by combining the Fang model with a voltage summation approach. [Copyright &y& Elsevier] more...
- Published
- 2011
- Full Text
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25. Magnetic-field angle dependent critical current densities and flux pinning in commercial YBCO tapes below liquid nitrogen temperatures
- Author
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Lee, Y., Yamasaki, H., and Furuse, M.
- Subjects
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COPPER oxide superconductors , *MAGNETIC fields , *CRITICAL currents , *FLUX pinning , *LIQUID nitrogen , *TEMPERATURE effect , *MICROFABRICATION , *COHERENCE (Physics) - Abstract
Abstract: We investigated the magnetic-field angle dependence of critical current densities (J c) for commercial YBCO and Zr-doped (GdY)BCO tapes fabricated by an MOCVD method at temperatures from 80K down to 20K in fields (μ 0 H) up to 5T. For the YBCO tape it was observed that the flux pinning contribution from random pins smaller than 2ξ(T) (ξ(T) is the Ginzburg–Landau coherence length at temperature T) diminished as T decreased, while they were still important even at 20K. As the temperature went down, the peaks at H||ab were found to be increasingly sharp, which agrees well with the Tachiki–Takahashi intrinsic pinning model. The Zr-doped (GdY)BCO tape showed peaks near H||c as well as H||ab and exhibited improved in-field J c properties, compared with the YBCO tape. [Copyright &y& Elsevier] more...
- Published
- 2011
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26. Influence of crossing angles of columnar defects on vortex glass transition in YBCO thin films
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Sueyoshi, T., Sogo, T., Yonekura, K., Fujiyoshi, T., Mitsugi, F., Ikegami, T., Ishikawa, N., Awaji, S., and Watanabe, K.
- Subjects
- *
POINT defects , *VORTEX motion , *PHASE transitions , *COPPER oxide superconductors , *ELECTRIC properties of thin films , *CRITICAL currents , *FLUX pinning - Abstract
Abstract: To investigate the influence of the crossing angles of columnar defects (CDs) on the in-field properties of the critical current density J c and the scaling parameter m derived from the isothermal current–voltage characteristics near the glass-liquid transition at B||c-axis, YBCO thin films were irradiated using the 200MeV Xe ions at two angles ±θi relative to the c-axis. For the thin films, the obvious effect of the crossing angle of CDs occurred on the vortex glass-liquid transition more than the J c properties. On the glass-liquid transition line, two inflection points induced by the c-axis correlated pinning were confirmed even for the samples of θi =±45°. In the magnetic field dependence of m, the peak or kink appeared near B/Bϕ =1/3 for the smaller crossing angles, whereas that was slightly visible for the samples of θi =±45°. In addition, the values of m for the small crossing angle were larger than those for the parallel CD configuration, while those for the larger crossing angle became smaller. These results suggested that the morphologies of correlated pinning centers strongly affect the dynamics of flux lines even in the disordered system such as thin films. [Copyright &y& Elsevier] more...
- Published
- 2011
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27. Homoepitaxial growth of MOD-YBCO thick films on evaporated and MOD templates
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Tanabe, D., Yamaguchi, I., Sohma, M., Tsukada, K., Matsui, M., Kumagai, T., and Manabe, T.
- Subjects
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HOMOEPITAXY , *METAL organic chemical vapor deposition , *COPPER oxide superconductors , *THICK films , *EVAPORATION (Chemistry) , *CHEMICAL templates , *CRITICAL currents , *SURFACE coatings , *PYROLYSIS - Abstract
Abstract: We have prepared metal organic deposition (MOD)-YBCO thick films by repeating the coating-pyrolysis-crystallization procedure onto ∼100-nm-thick evaporated and MOD templates. Surface morphology of the template was found to strongly affect the homoepitaxial growth of MOD-YBCO layers on the template; namely, the epitaxial growth of MOD-YBCO on the evaporated template was much easier than that on the MOD template. A 220-nm-thick epitaxial MOD-YBCO film was successfully prepared on the 100-nm-thick evaporated-YBCO template to obtain a 320-nm-thick YBCO film, which exhibited J c =2.44MA/cm2 and I c =78A/cm. The I c value has significantly increased from 37A/cm for the evaporated-template. [Copyright &y& Elsevier] more...
- Published
- 2011
- Full Text
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28. Strongly enhanced flux pining of GdBCO coated conductors with BaSnO3 nanorods by pulsed laser deposition
- Author
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Ko, K.P., Choi, S.M., Kim, Y.C., Lee, J.W., Moon, S.H., Park, C., and Yoo, S.I.
- Subjects
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FLUX pinning , *COPPER oxide superconductors , *SURFACE coatings , *STANNIC oxide , *NANOSTRUCTURED materials , *PULSED laser deposition , *CRITICAL currents , *CRYSTAL texture , *CRYSTAL growth - Abstract
Abstract: We report the effects of BSO addition on the crystallinity, texture, and the field dependency of critical current density (J c) of GdBCO coated conductors (CCs) prepared by pulsed laser deposition (PLD). Undoped and BSO-doped GdBCO films showed only c-axis oriented growth, and the incorporated BSO nanorods exhibited epitaxial relationship with the GdBCO matrix. In comparison with undoped film, BSO-doped GdBCO film exhibited greatly enhanced J c and higher pinning force densities in the entire field region of 0–5T (H//c) at 77 and 65K. The BSO-doped GdBCO film showed the maximum pinning force densities (F p) of 6.5GN/m3 (77K, H//c) and 32.5GN/m3 (65K, H//c), ∼2.8 times higher than those of the undoped sample. Cross-sectional TEM analyses exhibited nano-structured BSO nanorods roughly aligned along the c-axis of the GdBCO film, which are believed effective flux pinning centers responsible for strongly improved critical current densities in magnetic fields. [Copyright &y& Elsevier] more...
- Published
- 2011
- Full Text
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29. Effects of calcium doping on the superconducting properties of top-seeded melt growth processed Y1.5Ba2− x Ca x Cu3O y superconductors
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Park, S.D., Kim, H.J., Park, B.J., Han, Y.H., Jun, B.-H., Lee, J.S., and Kim, C.-J.
- Subjects
- *
SUPERCONDUCTIVITY , *CRYSTAL growth , *CALCIUM , *COPPER oxide superconductors , *INORGANIC synthesis , *POWDER metallurgy , *SURFACES (Technology) , *CRITICAL currents - Abstract
Abstract: The effect of calcium doping on the superconducting properties of top seeded melt growth (TSMG) processed Y1.5Ba2− x Ca x Cu3O y superconductors was studied in terms of calcium content (X ca). YBa2− x Ca x Cu3O7− δ (X ca =0, 0.005, 0.01, 0.02, 0.04, 0.1, 0.3) powders were synthesized by the powder calcination method. YBa2− x Ca x Cu3O7− δ powders were mixed with 0.25mole Y2O3 powder and 1wt.% CeO2 as Y2BaCuO5 (Y211) refiner, and finally made into Y1.5Ba2− x Ca x Cu3O y (Y1.5)+1wt.% CeO2 composition. The single Y123 growth on the top surface was observed up to X ca =0.1, while the multiple Y123 growth was observed at X ca ⩾0.1. The superconducting transition temperature (Tc ) and critical current density (Jc ) of TSMG processed Y1.5 samples were inversely proportional to X ca. The Y211 size increased with increasing X ca due to the enhancement of Y211 coarsening by calcium doping. No Y211 refining effect by CeO2 was observed in the calcium doped samples. The Tc and Jc decrease by calcium doping are likely to be due to the calcium incorporation with the Y123 lattice and formation of coarse Y211 particles. [Copyright &y& Elsevier] more...
- Published
- 2011
- Full Text
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30. Stable barium compounds in YBa2Cu3O y superconductors
- Author
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Kita, R., Suzuki, K., Takeuchi, T., Iwasa, T., Miura, O., Ichino, Y., Yoshimura, T., Yoshida, Y., Yamada, K., Kaneko, K., and Ichinose, A.
- Subjects
- *
COPPER oxide superconductors , *BARIUM compounds , *SINTERING , *TEMPERATURE effect , *CRITICAL currents , *MAGNETIC fields , *X-ray diffraction , *PHYSICAL constants - Abstract
Abstract: The stability of various amounts of Ba3Cu3In4O12 (334) or BaTbO3 (BTO) in a sintered YBa2Cu3O y (YBCO) matrix was examined. Samples with added 334 or BTO exhibited critical temperatures (T c) above 90K for up to 20vol.% addition and improved critical current densities (J c) under a magnetic field. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis indicated that 334 and BTO did not react with the YBCO matrix under the sintering conditions used. The normalized J c under a magnetic field of 1T reached a maximum at 14vol.% of 334 addition and 20vol.% BTO addition. YBCO thin films with added BTO showed a gradual decrease in the T c with increasing BTO content. YBCO films with added 334 showed a constant T c of 87K up to a 334 content of 4vol.%. [Copyright &y& Elsevier] more...
- Published
- 2011
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31. Biotemplated synthesis of superconducting plate-like YBa2Cu3O7−δ using oligosaccharides
- Author
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Hall, Simon R., Wimbush, Stuart C., Shida, Yosuke, and Ogasawara, Wataru
- Subjects
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CHEMICAL templates , *HIGH temperature superconductivity , *STRUCTURAL plates , *COPPER oxide superconductors , *OLIGOSACCHARIDES , *INORGANIC synthesis , *SUPERCONDUCTING quantum interference devices , *CRITICAL currents - Abstract
Abstract: Crystallization of the high temperature superconductor YBa2Cu3O7−δ (Y123) in a plate-like morphology has been achieved through the use of the short-chained oligosaccharides. This is the first time that biotemplates with such a high degree of monodispersity have been used to synthesize superconducting oxides, with control over crystallization being effected through a single molecular species. We find that for all the oligosaccharides used, there is an increasing prevalence of thin, plate-like crystals as the oligosaccharide chain length increases. SQUID magnetometry revealed that there was an increase in critical current density (Jc ) concomitant with an increase in the plateyness of the crystallites. [Copyright &y& Elsevier] more...
- Published
- 2011
- Full Text
- View/download PDF
32. Current Distribution in YBCO Coated Conductors of Toroidal Coil Composed of Multiple Double Pancake Coils.
- Author
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Tsuda, M. and Hamajima, T.
- Subjects
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ELECTRIC coils , *CRITICAL currents , *TOROIDAL magnetic circuits , *COPPER oxide superconductors , *ALTERNATING currents , *SELF-inductance , *MAGNETIC tapes - Abstract
We should prevent non-uniform current distribution due to manufacturing errors of tape size, coil size, and conductor deformation in the toroidal coil composed of multiple YBCO double pancake coils. This is because the non-uniform current distribution causes the increase of AC losses and the decrease of critical current in the YBCO tapes. Therefore, we analytically investigated the relationship between the manufacturing error and the current distribution in the toroidal coils composed of the eight series-connected double pancake coils composed of the transposed conductor with two parallel-connected YBCO tapes and the eight sets of two parallel-connected double pancake coils composed of single YBOC tape conductor connected in series. The parallel-connected multiple double pancake coils composed of single tape conductor is much more effective for preventing the non-uniform current distribution than the double pancake coil composed of the transposed conductor with parallel-connected multiple tapes. The non-uniformity of current distribution can be improved by increasing the length of parallel-connected current path by increasing the number of series-connected double pancake coils in each current path. [ABSTRACT FROM AUTHOR] more...
- Published
- 2011
- Full Text
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33. Current carrying capability of HTS Roebel cable
- Author
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Thakur, K.P., Jiang, Z., Staines, M.P., Long, N.J., Badcock, R.A., and Raj, Ashish
- Subjects
- *
HIGH temperature superconductors , *NUMERICAL analysis , *SURFACE coatings , *CRITICAL currents , *SELF-consistent field theory , *COMPARATIVE studies , *COPPER oxide superconductors - Abstract
Abstract: We have developed a numerical technique to estimate the current carrying capability of HTS Roebel cable composed from coated conductor strands. The influence of self-field on the critical current density is studied computationally for a Roebel cable using a realistic field and angle dependence behaviour of critical current. The computations are carried out for N/2 (number of strands/strand width in mm), and N/5 Roebel cable for N =2–15. The local current distribution in each strand satisfies the self-consistent criteria J = J c(B(J)) except for a small region where the current density is set to zero to maintain the condition of equal currents in all strands. The variation of critical current with vertical and horizontal separation between the strands is also investigated. Results are compared with the measured values of critical current for some of our cables. The comparison shows an error of up to 10% which we attribute mostly to the model not accounting for the spread in I c values of the constituent strands. [Copyright &y& Elsevier] more...
- Published
- 2011
- Full Text
- View/download PDF
34. Study of higher-order harmonics of complex ac susceptibility in YBa2Cu3O7−δ thin films by the mutual inductive method
- Author
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Pérez, Israel, Sosa, Víctor, and Gamboa, Fidel
- Subjects
- *
ELECTRICAL harmonics , *MAGNETIC susceptibility , *COPPER oxide superconductors , *MUTUAL inductance , *TEMPERATURE effect , *MAGNETIC fields , *NUMERICAL analysis , *INTEGRAL equations , *CRITICAL currents - Abstract
Abstract: We have applied the mutual inductive method to study higher-order harmonics of complex ac susceptibility for YBa2Cu3O7−δ thin films as function of the temperature and the applied magnetic field. The experimental results were compared with analytical and numerical results obtained from the Ishida–Mazaki model and the solution of the integral equation for the current density, respectively. Both models allow us to reproduce the main experimental features, however, as n increases the numerical model shows notable discrepancies. This failure can be attributed to the current–voltage characteristics. Also this investigation yields the activation energy U c and the critical current density J c both at T =0 for two samples. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
35. ENHANCEMENT OF TRANSPORT CRITICAL CURRENT DENSITY IN NANO Cr2O3 ADDED Ag-SHEATHED (Bi1.6Pb0.4)Sr2Ca2Cu3O10 SUPERCONDUCTOR TAPES.
- Author
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KONG, W. and ABD-SHUKOR, R.
- Subjects
- *
TRANSPORT theory , *CRITICAL currents , *ELECTRON distribution , *CHROMIUM compounds , *COPPER oxide superconductors , *MICROFABRICATION , *INTERMEDIATES (Chemistry) , *TEMPERATURE effect , *MAGNETIC fields - Abstract
Ag-sheathed (Bi1.6Pb0.4)Sr2Ca2Cu3O10(Bi-2223) high temperature superconductor tapes with 0.1 wt% nano Cr2O3 were fabricated using the powder-in-tube method. The effects of intermediate rolling and sintering temperature on the transport critical current density (Jc) under self-field and applied magnetic field were studied. The X-ray patterns showed a dominant Bi-2223 phase (~80%). A decrease in Jc in applied magnetic field, parallel or perpendicular to the sample wide surface was observed for all tapes. Intermediate rolling improved the self-field Jc(T=77 K) of the tapes by 25%. Both Jc versus applied field curves and normalized pinning force density Fp/Fpmax versus applied field curves showed that the pinning strength was significantly enhanced with thermo-mechanical treatments. SEM micrographs showed improvements in the grain alignment of tapes with intermediate rolling. Enhancement in Jc was observed in the nano Cr2O3 added tapes. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
36. Study on stability evaluation and quench characteristics of non-stabilizing layer YBCO thin-film wire wound with the radius of curvature for application of SFCLS
- Author
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Du, H.-I., Kim, M.-J., Han, B.-S., and Song, S.-S.
- Subjects
- *
METAL quenching , *LAYER structure (Solids) , *COPPER oxide superconductors , *ELECTRIC properties of thin films , *ELECTRIC wire , *LIMITER circuits , *CRITICAL currents , *TRANSPORT theory - Abstract
Abstract: The YBCO thin-film wire for superconducting fault current limiters shows promise with the following characteristics. (1) It has a high index value that enables a quick phase transition. (2) It has a high current density. (3) It experiences little change in the critical current in high magnetic fields. (4) It has varying quenching phenomena according to its stabilizing layers. Thus, it is being actively studied in many countries for application to power transmission and distribution systems. Based on current research results, this study examined the quenching occurrence trends in the YBCO thin-film wire that has been verified as a superconducting fault current limiter element and that has no stabilizing layers. This was done according to the wire’s radii of curvature and in terms of the increase in its resistance, initial limited current, and quenching occurrence time. Five kinds of spiral-shaped formers were produced with the radii increasing from the minimum radius by 25%, taking into account their changing critical properties due to bending stress. The YBCO thin-film wire without stabilizing layers was wound around these formers. Then an alternating over-current was applied to the current limiting elements that were produced according to the radii of curvature. The resulting trends in resistance enhancement were examined to evaluate the stability of the produced current limiting elements. Finally, the produced current limiting elements’ initial limited current and quenching occurrence time were observed at 90K, 180K, and 250K to evaluate the performance of the current limiting elements. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
37. AC over-current characteristics of YBCO coated conductor with copper stabilizer layer considering insulation layer
- Author
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Du, H.-I., Kim, M.-J., Kim, Y.-J., Lee, D.-H., Han, B.-S., and Song, S.-S.
- Subjects
- *
COPPER oxide superconductors , *ELECTRIC currents , *SURFACE coatings , *ELECTRIC insulators & insulation , *ELECTRIC wire , *CRITICAL currents , *ELECTRIC properties of thin films , *METAL quenching , *ELECTRIC resistance - Abstract
Abstract: Compared with the first-generation BSCCO wire, the YBCO thin-film wire boasts low material costs and high J c and superior magnetic-field properties, among other strengths. Meanwhile, the previous BSCCO wire material for superconducting cables has been researched on considerably with regard to its post-wire quenching characteristics during the application of an alternating over-current. In this regard, the promising YBCO thin-film wire has yet to be further researched on. Moreover, still lacking is research on the YBCO thin-film wire with insulating layers, which is essential in the manufacture of superconducting cables, along with the testing of the application of an alternating over-current to the wire. In this study, YBCO thin-film wires with copper-stabilizing layers were used in testing alternating over-current application according to the presence or absence of insulating layers and to the thickness of such layers, to examine the post-quenching wire resistance increase and quenching trends. The YBCO thin-film wire with copper-stabilizing layers has a critical temperature of 90K and a critical current of 85Arms. Moreover, its current application cycle is 5.5 cycles, and its applied currents are 354, 517, 712, and 915Apeak. These figures enabled the YBCO thin-film wires with copper-stabilizing layers to reach 90, 180, 250, and 300K, respectively, in this study. These temperatures serve as a relative reference to examine the post-quenching wire properties following the application of an alternating over-current. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
38. Conceptual design of 275kV class high-Tc superconducting cable
- Author
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Mukoyama, S., Yagi, M., Fujiwara, N., and Ichikawa, H.
- Subjects
- *
EXPERIMENTAL design , *HIGH temperature superconductors , *ELECTRIC cables , *ELECTRIC lines , *COPPER oxide superconductors , *MAGNETIC fields , *CRITICAL currents - Abstract
Abstract: High-temperature superconducting (HTS) cables are expected to be next generation transmission line because of the compact, lightweight, large capacity, and low loss features. Especially, since the YBa2Cu3O x (YBCO) tape has a high critical current, high magnetic-field property, low AC loss, and low cost, using YBCO tapes for a HTS cable seems to be one of the most promising ways to make the HTS cable attractive. Therefore, YBCO HTS cables have been studied extensively in Japan, the United States, Korea, and many other countries. We now believe that 275kV class HTS cables will be used for future large capacity lines based on the needs of Japanese transmission networks for bulk transmission power in overhead transmission lines or gas insulated transmission lines (GIL). We started to develop the 275kV class HTS cable for the new energy and industrial technology development organization (NEDO) project at 2008, and we have studied the applicability and the environmental and economic advantages of the 275kV cable. This paper will introduce advantages and a conceptual design of the 275kV HTS cable. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
39. Effect of filament twist and high resistive barrier on the properties of Ag-sheathed Bi2223 tape
- Author
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Nakamura, Y., Fujiwara, Y., Nagaoka, A., Machida, T., Inada, R., and Oota, A.
- Subjects
- *
COPPER oxide superconductors , *CRITICAL currents , *SILVER , *ELECTRIC loss in electric power systems , *ELECTRIC resistance , *MICROFABRICATION , *CROSS-sectional method - Abstract
Abstract: Although the introduction of filament twisting with high resistive barrier between the filaments is effective to reduce the AC loss, the J c value of the tape was easily decreased by the filament twisting and insertion of high resistive barrier. This decrease in J c is a problem to achieve low AC loss and high I c tape. In this study, the effects of filament twist and high resistive barrier on the microstructure and J c property were investigated to overcome the J c reduction. The Bi2223 tapes with filament twist or oxide barrier were fabricated by powder-in-tube method. The J c value of twist tape gradually decreased as decreasing the twist pitch, and the degree of J c reduction was small in slim tape compared to wide tape. This reduction would attribute to the small actual cross sectional area of the filament perpendicular to the current direction because the filament has a tilt angle from the tape axis. On the other hand, the conversion ratio of Bi2223 became small as increasing the thickness of SZO barrier layer. Since the SZO barrier has less reactivity with 2223 filament, this suppression of the Bi2223 formation would not be caused by the formation of impurity phase but would be caused by the suppression of gas release from the filaments by oxide barrier. The conversion ratio of Bi2223 increased in the short sample where the gas could be released from the both end of the tape. These results suggest that the gas diffusion from filaments would be important for the formation of Bi2223. Hence, the use of slim tape for decreasing the tilt angle of the filament and keeping the diffusion path of gas from the filaments may improve the J c value of twist and barrier tapes. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
40. Influence of nanoparticles on flux pinning properties in TFA-MOD processed YGdBCO coated conductor
- Author
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Matsutani, F., Takahashi, Y., Kiuchi, M., Otabe, E.S., Matsushita, T., Miura, M., Izumi, T., and Shiohara, Y.
- Subjects
- *
FLUX pinning , *NANOPARTICLES , *METAL organic chemical vapor deposition , *COPPER oxide superconductors , *MAGNETIC fields , *ACETATES , *ZIRCONIUM oxide , *CRITICAL currents , *ANISOTROPY - Abstract
Abstract: The flux pinning properties in a magnetic field of various directions are investigated for trifluoroacetates-metal organic deposition (TFA-MOD) processed Y1−x Gd x Ba2Cu3O y (YGdBCO)-coated conductors with the superconducting layer of 0.5μm thick with artificial BaZrO3 (BZO)-nanoparticles. It is found that the critical current density is enhanced in a wide range of field angle except around the direction parallel to the a − b plane, resulting in low field-angle anistropy. The enhancement of J c in the wide range of field angle is attributed to the isotropic pinning of nanoparticles. The decrease in the critical current density in the field direction parallel to the a − b plane is considered to be caused by limitation of growth of stacking faults by distributed BZO nanoparticles. The observed results were theoretically explained by the flux creep-flow model and the above speculation of the pinning mechanism was confirmed. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
41. Microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the pressing–melting–sintering process
- Author
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Lu, X.Y., Yi, D., Chen, H., Nagata, A., and Sugawara, K.
- Subjects
- *
COPPER oxide superconductors , *MICROFABRICATION , *FUSION (Phase transformation) , *SINTERING , *CRYSTAL texture , *COMPRESSIBILITY , *CRITICAL currents , *HIGH temperature superconductors - Abstract
Abstract: The microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the pressing–melting–sintering process were investigated. Both the partial-melting and compressing have significant influence on the microstructure and the critical current density J c. A high proportion and a low c-axis alignment of Bi-2223 phase exist in the tape with no-melting and no-compressing. The partial-melting process before sintering improves obviously the c-axis alignment, lowers a slight proportion of Bi-2223 phase. The compressing process during melting and sintering enhances the density of the HTS oxide core and heals the cracks. The tape sintered at 835°C after partial-melting at 845°C under compressing, which has fine second phases, strong c-axis grain alignment, very few cracks and dense the HTS oxide core, exhibits the highest J c value. These results indicated that both partial-melting process and compressing process are of real importance to the improvement of J c in Bi-2223 tapes. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
42. Non-destructive evaluation of longitudinal uniformity for twisted Bi2223 tapes using scanning Hall-probe microscopy
- Author
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Inada, R., Makihara, T., Araki, Y., Baba, S., Nakamura, Y., Oota, A., Sakamoto, S., Li, C.S., and Zhang, P.X.
- Subjects
- *
NONDESTRUCTIVE testing , *LONGITUDINAL method , *MAGNETIC tapes , *COPPER oxide superconductors , *SCANNING probe microscopy , *ELECTRIC loss in electric power systems , *TRANSPORT theory , *PERMANENT magnets , *CRITICAL currents - Abstract
Abstract: In general, shorter filament twisting should be required for substantial AC loss reduction of Bi2223 tapes under an AC external field. However, the longitudinal uniformity of both transport property and wire structure of a tightly twisted tape could be easily deteriorated. To qualify the uniformity of twisted tape, simple and non-destructive evaluation techniques should be urgently required. In this study, we non-destructively measured the remanent magnetic field distributions for twisted Bi2223 tapes using scanning Hall-probe microscopy (SHM) with an active area of 50μm×50μm. Twist pitch lengths of the tapes used for the measurements were 10mm and 6mm. After the tape was fixed on the sample holder at 77K and zero fields, the magnetic field in perpendicular to the broader face of the tape was applied by a rectangular permanent magnet moving along a tape length. After removing the field, the distributions of remanent field B rz in perpendicular to tape surface were measured by SHM at a fixed distance of 0.5mm away from a tape surface. For tightly twisted tape with twist pitch length of 6mm, the longitudinal uniformity of B rz and transport critical current I c were degraded remarkably and the local positions at which B rz greatly drops were well corresponding to low I c region. It was also confirmed that the defects in filaments caused by tight twisting strongly affect on the intensity and shape of B rz profiles. The results suggest that SHM has the potential for simple and non-destructive characterization to qualify the longitudinal uniformity of twisted tapes. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
43. J c anisotropy for magnetic field angle in YBCO coated conductor on IBAD-MgO buffered metal tapes
- Author
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Suzuki, H., Yoshida, Y., Ichino, Y., Takai, Y., Awaji, S., Watanabe, K., Yoshizumi, M, Izumi, T., Shiohara, Y., and Kato, T.
- Subjects
- *
CRITICAL currents , *ANISOTROPY , *COPPER oxide superconductors , *MAGNESIUM oxide , *MAGNETIC tapes , *FLUX pinning , *ION bombardment , *SURFACES (Technology) , *THICKNESS measurement - Abstract
Abstract: We found that YBCO films deposited by the controlled process showed improved superconducting properties in magnetic fields, even without any artificial pinning centers such as BaZrO3 and BaSnO3. The YBCO films with a thickness of 450nm were deposited on hastelloy tapes with a textured MgO buffer deposited by IBAD (Ion Beam Assist Deposition) method (IBAD-MgO) by PLD method. In the YBCO films on the IBAD-MgO (IBAD–YBCO), the critical current density of 2.9MA/cm2 at 77K in self-field and the ratio of J c(B//c)/J c(B//a, b) at 1T was almost unity. Furthermore, we found that the J c anisotropy changed with surface morphology on underlying buffer layer and YBCO thickness. This means that some c-axis correlated pinning centers are included in the films. From the cross-sectional TEM images of the IBAD–YBCO, there were not so many defects such as dislocations, Y2O3 inclusions and so on. Thus it is considered that some defects such as oxygen heterogeneity, displacementof a local composition and so on are pinning centers, although such defects can not be detected by a present analytical technique. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
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44. Fracture behavior of coated layer and its influence on critical current of DyBCO coated conductor
- Author
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Arai, T., Shin, J.K., Toda, A., Ochiai, S., Okuda, H., Sugano, M., Osamura, K., and Prusseit, W.
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FRACTURE mechanics , *SURFACE coatings , *CRITICAL currents , *COPPER oxide superconductors , *STRAINS & stresses (Mechanics) , *ELECTROMAGNETISM , *MECHANICAL behavior of materials , *MAGNESIUM oxide - Abstract
Abstract: The coated conductors are attractive due to their high superconducting properties. As the conductors are subjected to mechanical and electromagnetic stresses in preparation and service, the study on the mechanical behavior and its influence on superconducting properties is demanded for application. In the present work, the DyBa2Cu3O7− δ coated conductor with MgO buffer layer deposited on the Hastelloy C-276 substrate by inclined substrate deposition, prepared at THEVA, was used as the sample. The relation of the deformation and fracture behavior to the change of critical current under applied tensile strain was investigated. The experimental result of tensile test and critical current measurement revealed that the change of critical current with increasing applied tensile strain is caused in two stages; micro-cracking of the coated layer in the fist stage and extensive multiple cracking of the coated layer induced by the discontinuous yielding of the substrate in the second stage. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
45. Effect of number of filaments on the critical current density in multifilamentary Bi-2223 tape
- Author
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Ueno, S., Yamashita, S., Kiuchi, M., Otabe, E.S., Matsushita, T., Ayai, N., Kikuchi, M., Hayashi, K., and Sato, K.
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CRITICAL currents , *COPPER oxide superconductors , *SILVER , *PRESSURE , *TEMPERATURE effect , *ANISOTROPY , *SINTERING , *SUPERCONDUCTIVITY - Abstract
Abstract: The critical current property of (Bi-2223) silver-sheathed tape has been remarkably improved by application of ConTrolled Over Pressure (CT-OP) process with adjusting temperature and oxygen partial pressure. For further improvement of the property of Bi-2223 tapes, the effect of number of filaments on the critical current density J c was investigated. It was found that J c was higher and its decrease with increasing magnetic field was weaker in the tape with larger number of filaments. In addition, the irreversibility field B i increased with increasing filament number. The field-angle anisotropy J c(0°)/J c(90°) of the tape with the largest filament number was smallest, where the field-angle was measured from the a–b plane. However, the out-of-plane misorientation angle is fairly small in this tape. Hence, the low field-angle anisotropy in this tape seems to be attributed to improved superconductivity in the block layers in the superconducting region near the interface with silver matrix. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
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46. Effect of fatigue loading on critical current in stainless steel–laminated DI-BSCCO superconducting composite tape
- Author
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Hojo, M., Osawa, K., Adachi, T., Inoue, Y., Osamura, K., Ochiai, S., Ayai, N., and Hayashi, K.
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STEEL fatigue , *MECHANICAL loads , *CRITICAL currents , *LAMINATED materials , *COPPER oxide superconductors , *COMPOSITE materials , *STRAINS & stresses (Mechanics) , *MECHANICAL behavior of materials - Abstract
Abstract: Tensile strain tolerance of the critical current in (Bi,Pb)2Sr2Ca2Cu3O x (Bi2223) composite superconductor is dramatically improved when the tape is laminated with stainless steel. For practical applications, it is important to understand whether this reinforcement by lamination is effective under fatigue loading. In the present study, we carried out fatigue tests in LN2 and measured the critical current at the specific fatigue cycles to clarify the strain tolerance of the critical current in stainless steel–laminated drastically innovative Bi2223 (DI-BSCCO®) tapes. The fatigue tests were carried out using a computer-controlled 10 kN servo-hydraulic fatigue testing machine with a load cell capacity of 2.5kN. Tests under static loading showed that the irreversible stress at which the critical current is reduced by 1% from the original value (tensile stress at Ic/Ic 0 =0.99) was 315MPa when measured at unloading state. The present fatigue tests results indicated that the critical current was maintained at over 98% of the original value at unloading state after stress cycles of 106 when the static irreversible stress was selected as the maximum stress under fatigue loading. Thus, laminated DI-BSCCO tapes showed excellent mechanical properties even under fatigue loading. [ABSTRACT FROM AUTHOR] more...
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- 2010
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47. Recent progress of high performance Ag-sheathed Bi2223 wire
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Osabe, G., Ayai, N., Kikuchi, M., Tatamidani, K., Nakashima, T., Fujikami, J., Kagiyama, T., Yamazaki, K., Yamade, S., Shizuya, E., Kobayashi, S., Hayashi, K., Sato, K., Shimoyama, J., Kitaguchi, H., and Kumakura, H. more...
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PERFORMANCE evaluation , *SILVER , *CRITICAL currents , *COPPER oxide superconductors , *ELECTRIC wire , *TEMPERATURE effect - Abstract
Abstract: Recently, we have updated the highest J c and I c at 77K, self-field, for our R&D short length tapes and I c × L at 77K, self-field, for our kilometer-length manufacturing product. For our short length R&D tapes, we have updated the I c to 236A. The highest J c has reached 663A/mm2. Furthermore, we have broken our own world record performance of I c × L with the production of a 4.2mm wide, 2084m long Bi wire that carries an average current of 176A. This has resulted in a new record—high wire performance of 367kAm. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
48. Relationship between intrinsic surface resistance and critical current density of YBCO thin films with various thickness
- Author
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Nakagawa, K., Nakayama, S., Saito, A., Ono, S., Kai, H., Mukaida, M., Honma, T., and Ohshima, S.
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SURFACES (Technology) , *ELECTRIC resistance , *CRITICAL currents , *COPPER oxide superconductors , *THICKNESS measurement , *PENETRATION mechanics , *PULSED laser deposition , *SUBSTRATES (Materials science) - Abstract
Abstract: We investigated the relationship between the intrinsic surface resistance () and critical current density (J c) of YBa2Cu3Oy (YBCO) film thinner than the penetration depth (λ L). The measured YBCO films were deposited on CeO2-buffered r-cut Al2O3 substrates by the pulsed laser deposition method. The thicknesses of these films were 300, 200, and 100nm, respectively. The means the surface resistance of YBCO film removing the loss by the impedance of the substrates. The effective surface resistance () including the impedance of the substrate and the J c of each YBCO film were measured using the dielectric resonator method at 21.8GHz and the inductive method. We calculated by using phenomenological expressions and the value. The values of each YBCO film were almost the same in the measured temperature region. As a result, we found that was in inverse proportion to the J c of YBCO film thinner than λ L. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
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49. Influence of tensile damage on V–I curve and critical current of DyBCO coated conductor
- Author
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Toda, A., Arai, T., Ochiai, S., Okuda, H., Matsubayashi, H., Sugano, M., Osamura, K., and Prusseit, W.
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DEFORMATIONS (Mechanics) , *CRITICAL currents , *COPPER oxide superconductors , *SURFACE coatings , *STRAINS & stresses (Mechanics) , *ELECTROMAGNETISM , *FRACTURE mechanics - Abstract
Abstract: The coated conductors are subjected to mechanical and electromagnetic stresses in preparation and service. When the stress is high, the coated layer is damaged, resulting in loss of superconducting property. The present work was carried out to reveal the influence of tensile damage on V–I curve, critical current and n-value of DyBa2Cu3O7− δ coated conductor. The changes of the V–I curve, critical current and n-value with increasing applied tensile strain were measured experimentally. The features of the shift of the V–I curve to the lower current range and increase in its curvature, and accordingly the decrease in critical current and n-value, with increasing applied strain, were detected. For analysis of the experimental results, the model of Fang et al, which treats with the voltage generation due to the current shunting under existent crack, was applied. The experimentally observed features were described satisfactorily. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
50. Critical current degradation behaviors of ReBCO coated conductor tapes under pressurized liquid nitrogen
- Author
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Shin, H.S. and Dedicatoria, M.J.
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CRITICAL currents , *COPPER oxide superconductors , *SURFACE coatings , *LIQUID nitrogen , *TRANSPORT theory , *DEFORMATIONS (Mechanics) , *PRESSURE , *STRAINS & stresses (Mechanics) - Abstract
Abstract: In the case of 2G coated conductor (CC) tapes, it has been reported that thin–thick CC tapes with IBAD substrate showed a superior electromechanical property even at smaller bending radius compared with the cases of 1G BSCCO tapes. Considering the application of CC tapes it is significant to evaluate the transport property under operating environment, because CC tapes might experience a change in operating pressure that can affect its current carrying capacity due to temperature variation and deformation. This study was focused on the I c degradation behavior in bent CC tapes under pressurized liquid nitrogen. Differently processed YBCO and SmBCO CC tapes with IBAD substrate are used as samples. The bending strain characteristics at elevated pressure levels were evaluated by using the ρ-shaped sample holder which can induce different bending strain values at pressured state. Depressurization and thermal cycling were performed to check the reversibility of I c in CC tapes. Vacuuming tests were also carried out to investigate the characteristics of I c at different LN2 temperature levels. [ABSTRACT FROM AUTHOR] more...
- Published
- 2010
- Full Text
- View/download PDF
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