| Magnetization Losses in Multiply Connected YBa2Cu3O6+x-Coated Conductors (Postprint) |
Feb 2012 |
13 pages |
| Authors:
G A Levin; P N Barnes; Naoyuki Amemiya; Satoshi Kasai; Keiji Yoda; Zhenan Jiang; A Polyanskii; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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 | We report the results of a magnetization loss study in experimental multifilament, multiply connected coated superconductors exposed to time-varying magnetic field. In these samples, the superconducting layer is divided into parallel stripes segregated by nonsuperconducting grooves. In order to facilitate the current sharing between the stripes and thus increase the reliability of the striated conductors, a sparse network of superconducting bridges is superimposed on the striated film. We find that ... |
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| The Integration of YBCO Coated Conductors into Magnets and Rotating Machinery (Postprint) |
Feb 2012 |
9 pages |
| Authors:
G A Levin; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| The implementation of the second generation high-Tc superconductors in power applications, such as electrical transformers, motors and generators requires superconducting wires that are superior to copper Litz wires at cryogenic temperatures in terms of losses in time-varying magnetic field, as well as in engineering current density. Another problem is to find a way to make practical coils and armatures out of flat tape-like conductors with low bending strain tolerance. We ... |
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| Improving YBCO Coated Conductors for Applications (Postprint) |
Feb 2012 |
10 pages |
| Authors:
P N Barnes; B C Harrison; J W Kell; G A Levin; M D Sumption; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Superconducting power devices made of high temperature superconductors (HTS) can enable megawatt-class power systems which are lighter in weight and smaller in size than their conventional counterparts. The YBCO coated conductor is expected to be the premiere HTS conductor in making these systems. With advances in YBCO deposition techniques and the establishment of reel-toreel processing, new research should address enhancement of the YBCO coated conductor's performance. These improvements in the ... |
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| Coupling Losses and Transverse Resistivity of Multifilament YBCO Coated Superconductors (Postprint) |
Feb 2012 |
6 pages |
| Authors:
M Polak; E Usak; L Jansak; E Demencik; G A Levin; P N Barnes; D Wehler; B Moenter; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| We studied the magnetization losses of four different types of filamentary YBCO coated conductors. A 10 mm wide YBCO coated conductor was subdivided into 20 filaments by laser ablation. We measured the frequency dependence of the total losses in the frequency range 0.1 Hz f 608 Hz. The coupling loss was obtained from the total by subtracting the hysteresis loss. The latter was measured at low frequencies since ... |
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| Time-Resolved Magneto-Optical Imaging of Y1Ba2Cu3O7-delta Thin Films in High-Frequency AC Current Regime (Postprint) |
Feb 2012 |
6 pages |
| Authors:
A Lucarelli; G Luepke; T J Haugan; G A Levin; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| We present a time-resolved magneto-optical (MO) imaging study of high-temperature superconductor (HTS) in a high-frequency alternating current (AC) regime. The evolution of the magnetic flux density distribution in YBa2Cu3O7-delta (YBCO) thin film samples is studied as a function of the phase of the applied AC current. A quantitative analysis of the data shows that the maxima of the AC current density is shifted from the edges further inside the sample, ... |
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| Transport AC Losses in Striated YBCO Coated Conductors (Postprint) |
Feb 2012 |
6 pages |
| Authors:
G A Levin; P N Barnes; M Majoros; B A Glowacki; A M Campbell; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| DC current-voltage characteristics and transport ac losses of striated and non-striated Y1Ba2Cu3O7-delta (YBCO) coated conductors have been measured. Transport ac loss measurements have been performed in frequencies from 40 Hz up to 2 kHz at 77.4 K. Degradation in the critical current of about 40% due to the laser striation process has been found. The striated sample was much more thermally stable than the non-striated one. Transport ac losses were ... |
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| AC Losses in a YBa2Cu3O7-x Coil (Postprint) |
Feb 2012 |
5 pages |
| Authors:
M Polak; E Demencik; L Jansak; E Usak; P Mozola; D Aized; C L Thieme; G A Levin; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| The properties of a small pancake coil made with a 10 mm wide copper-stabilized YBa2Cu3O7-x YBCO-coated conductor were investigated. The radial component of the magnetic field was mapped at the coil edge in both the dc and ac regimes and differs significantly from that calculated assuming a uniform current distribution. The observed hysteresis indicates the strong influence of the ferromagnetic properties of the substrate. The ac losses of the coil ... |
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| Properties of a YBCO Pancake Coil Operating with AC Current at Frequencies up to 1000 Hz (Postprint) |
Feb 2012 |
6 pages |
| Authors:
M Polak; E Demencik; L Jansak; E Usak; P Mozola; C L Thieme; D Aized; G A Levin; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| A small pancake coil was wound using 1.2m long, 10 mm wide YBCO coated superconductor tape with impregnation by epoxy resin. The coil was immersed in liquid nitrogen and tested in several regimes. In the DC regime, we measured the I-V curve, the hysteresis of the magnetic field-current curve at liquid nitrogen temperature and the radial component of the coil field at the coil edges. The critical currents of a ... |
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| Second Generation Superconducting Wires for Power Applications (Postprint) |
Jan 2007 |
31 pages |
| Authors:
G A Levin; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| We review conceptual and experimental explorations of magnetization losses in multifilament, multiply connected coated superconductors exposed to time-varying magnetic field. In these conductors the superconducting layer is divided into parallel stripes segregated by non-superconducting grooves. In order to facilitate the current sharing between the stripes and thus increase their reliability, a sparse network of superconducting interfilament bridges needs to be introduced. We find that the presence of the bridges does ... |
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| Properties of a YBCO Pancake Coil Operating With AC Current at Frequencies up to 1000 Hz (Postprint) |
Jun 2006 |
6 pages |
| Authors:
M Polak; E Demencik; L Jansak; E Usak; P Mozola; C L Thieme; D Aized; G A Levin; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| A small pancake coil was wound using 1.2 m long, 10 mm wide YBCO coated superconductor tape with impregnation by epoxy resin. The coil was immersed in liquid nitrogen and tested in several regimes. In the DC regime, we measured the I-V curve, the hysteresis of the magnetic field-current curve at liquid nitrogen temperature and the radial component of the coil field at the coil edges. The critical currents of ... |
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| Scientific Presentations on Superconductivity from 2002-2005 |
Jan 2006 |
411 pages |
| Authors:
Paul N Barnes; Brandon C Harrison; Timothy Haugan; G A Levin; Srinivas Sathiraju; Raghavan Srinivasan; T A Campbell; J C Tolliver; J M Evans; C V Varanasi; I Maartense; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE/POWER DIVISION/POWER GENERATION BRANCH
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| This program addresses the basic scientific and engineering issues related to the development of the second-generation high-temperature superconducting (HTS) coated conductor for use in magnet and generator coil windings of power applications relevant to the Air Force (AF). Current work focuses on the development of an ac YBCO-coated conductor and enhancement of the current dc coated conductor. The dc coated conductor development is done as part of an overall AF ... |
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