Article
Design of a 30 T Superconducting Magnet Using a Coated Conductor Insert
Toshiba Corp., Yokohama, Japan
IEEE Transactions on Applied Superconductivity (Impact Factor: 1.2). 07/2009; DOI: 10.1109/TASC.2009.2018271 Source: IEEE Xplore

Article: Lowmagneticfield dependence and anisotropy of the critical current density in coated conductors
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ABSTRACT: Many applications of ReBCOcoated conductors operate at low magnetic fields in the superconductor (below 200 mT). In order to predict the critical current and AC loss in these applications, it is necessary to know the anisotropy and field dependence of the critical current density at low magnetic fields. In this paper, we obtain a formula for the critical current density in a coated conductor as a function of the local magnetic field and its orientation. Afterwards, we apply this formula to predict the critical current of a pancake coil that we constructed. We extract the critical current density of the tape from measurements of the infield critical current at several orientations. Numerical simulations correct the effect of the selffield in the measurements and successfully predict the critical current in the pancake coil. We found that a simple elliptical model is not enough to describe the anisotropy of the critical current density. In conclusion, the analytical fit that we present is useful to predict the critical current of actual coils. Therefore, it may also be useful for other structures made of coated conductor, like powertransmission cables, Roebel cables and resistive fault current limiters.Superconductor Science and Technology 03/2011; 24(6):065007. · 2.76 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Mechanical property of GdBa<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> (GdBCO) coated conductor was investigated at 4.2 K in a magnetic field by two ways, which are the tensile test and the hoop stress test. The tensile stress/strain dependence of critical current ( I <sub>c</sub>) of a 2 mm width conductor was explored at 4.2 K, 18 T. The result provided that I <sub>c</sub> reversible strain limit existed in between 0.43% and 0.46%, corresponding to 907 MPa and 960 MPa in stress, and the elastic constant was 203 GPa. The hoop stress test has been performed at 4.2 K, 11 T. A test coil was fabricated by winding a 5 mm width conductor on a 270 mm diameter GFRP bobbin by 1.5 turns. The maximum value of applied hoop stress, which was deduced from a product of magnetic field, current density and coil radius, was 1322 MPa. Five strain gauges glued on the conductor surface showed almost the same values, which were in a range of 0.64% to 0.67%, indicating the uniform longitudinal deformation. Furthermore, the hoop stressstrain characteristics were linear, suggesting an elastic deformation. The deduced elastic constants were in a range of 196204 GPa. It was confirmed that the GdBCO coated conductor performance was deteriorated irreversibly by 1322 MPa hoop stress, whereas not by 1302 MPa hoop stress.IEEE Transactions on Applied Superconductivity 06/2011; 21(3):30943097. · 1.20 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In a high temperature superconducting magnet consisting of pancake windings, the perpendicular magnetic field considerably reduces the value of the critical current of the outer pancake windings due to anisotropy. An air gap was inserted between each pancake winding in this paper to reduce the decrement of the critical current in each pancake winding. In a low temperature superconducting magnet, the central magnetic field decreases when there is an air gap between the pancake windings. On the other hand, the central magnetic field of a HTS magnet increases when an air gap is provided. The properties of the HTS insert/outsert magnet having an air gap between the pancake windings are examined in this paper. YBCO wire and BSCCO wire were used in the insert and the outsert magnets, respectively. An E  J relation and the evolution strategy were adopted to calculate the optimum critical currents of both magnets. The calculation results showed that there was an optimum air gap which maximized the central magnetic field. The optimum air gap was dependent on the specifications of the HTS magnet.IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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