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Dommerque R.,Nexans SuperConductors GmbH | Kramer S.,Nexans SuperConductors GmbH | Hobl A.,Nexans SuperConductors GmbH | Bohm R.,Nexans SuperConductors GmbH | And 7 more authors.
Superconductor Science and Technology | Year: 2010

In 2008/09 Nexans SuperConductors GmbH made the step from R&D activities to the production of the first non-publicly funded fault-current limiter units. In close cooperation with two customers, Applied Superconductor Limited (ASL, UK) and Vattenfall (Germany), Nexans was able to design, produce and deliver two resistive superconducting limiter devices. Both devices are designed for the medium voltage grid and were tested at the high voltage and high power lab IPH in Berlin. The superconducting components of both limiters, coils of bulk MCP BSCCO-2212, have been designed and produced by Nexans. © 2010 IOP Publishing Ltd.

Deng S.,Applied Superconductor | Qu T.,Tsinghua University | Lin G.,Tsinghua University | Han Z.,Applied Superconductor
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2014

The preparation of Bi2Sr2CaCu2Ox (Bi-2212) thin film was relatively simple and Bi-2212 thin film showed good properties at low temperature, so great attention was focused on this material and many research groups fabricated high quality Bi-2212 thin films by vacuum or non-vacuum methods. In general, single crystal substrates were widely used for the preparation of Bi-2212 thin films. Different from single crystal substrates, the Ag substrates did not show texture, but factors such as the roughness of silver substrates affected the c-axis texture and critical current density of Bi-2212. Moreover, because of the low surface energy of silver substrates for BSCCO high temperature superconductors, it was stable for the growth of Bi-2212 thin film on silver substrate. Based on acetic acid-ammonia water solution, a method to fabricate Bi-2212 thin film on silver substrate was developed. Critical processes were studied carefully, including the polishing of silver substrates, the preparation of chemical solution, the sintering temperature, and so on. It was found that repeating the spin-coating and pyrolysis processes could eliminate the bubbles produced by one time coating. It was also found that on the Ag substrates and under low oxygen pressure, the sintering temperature for Bi-2212 phase went down. Bi-2212 single phase thin film could be fabricated by heating at 790℃ for 5 h. The smooth surface of Bi-2212 thin film without cracks was shown by scanning electron microscopy (SEM). With the increase of sintering temperature, Bi-2201 phase began to emerge, and its diffraction intensity increased fast with the rise of sintering temperature. A rod phase occurred when the sintering temperature was 850℃. The result of energy dispersive spectroscopy (EDS) showed that this rod phase was a Cu-free phase. ©, 2014, Editorial Office of Chinese Journal of Rare Metals. All right reserved.

Wang C.,CAS Institute of Electrical Engineering | Wang C.,Academy of Armored force Engineering | Chang T.,Academy of Armored force Engineering | Rong M.,Academy of Armored force Engineering | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2011

An optimal design method for high-field MRI magnet is put forward. The design procedure can be divided into two steps. First step is to design a set of coils to achieve the necessary center field, which is called the background field, and it is based on the optimal algorithm of minimum volume consumption by SQP. During the optimization, the safety factor of superconducting wires has been considered. The second step is to design a set of correction coils to achieve the necessary homogeneity, and the magnetic field produced by previous coilsis set as background field, then optimize the homogeneity based on the nonlinear Least Square Method. © 2010 IEEE.

Wang C.,CAS Institute of Electrical Engineering | Wang C.,Academy of Armored force Engineering | Wang Q.,Applied Superconductor | Zhang Q.,CAS Institute of Electrical Engineering
IEEE Transactions on Applied Superconductivity | Year: 2010

A design method of multiple layers superconducting magnet for MRI is introduced. Considering the actual coils layout, the candidate domain is divided into several layers. The current density curves of each layer are solved by Quadratic Programming optimization with Minimum Stored Energy. The seed coils are arranged at the peak positions of current curves. Based on the regularization solution, the current of the seed coils can be solved. According to the coil's current, selecting the current density of the superconducting wires, the original sections for the coils can be obtained. Then a further optimization about the homogeneity based on constrained nonlinear multivariable optimization method is employed to determine the final coils' geometries. The method is especially suitable for short superconducting MRI magnet design. © 2006 IEEE.

Zhang H.,CAS Institute of Electrical Engineering | Wang Q.,Applied Superconductor | Wang H.,Applied Superconductor | Song S.,Applied Superconductor | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2010

Fiber Bragg grating (FBG) sensor for monitoring the electromagnetic strain in a low temperature superconducting (LTS) magnet was studied. Before used to LTS magnet strain sensing, the strain response of the sensor with 1.54-μm wavelength at liquid helium was experimentally studied. It was found that the wavelength shift showed good linearity with longitudinal applied loads and the strain sensitivity is constant at 4.2 K. And then, the hoop strain measurement of a LTS magnet was carried out on the basis of measured results. Furthermore, the finite element method (FEM) was used to simulate the magnet strain. The difference between the experimental and numerical analysis results is very small. © 2006 IEEE.

Applied Superconductor | Date: 2012-07-04

A coil (12, 112, 212) is described, the coil (12, 112, 212) comprising an electrically conducting element (18, 118, 218) defining a plurality of first turns (20, 120, 220) around a first axis (X1, X101, X201), wherein at least two first turns are adapted to carry a current in opposite senses around the first axis (X1, X101, X201); and a respective plurality of second turns (22, 122, 221, 222) around at least one second axis (X2, X102, X202, X203), wherein at least two second turns are adapted to carry a current in opposite senses around a respective second axis (X2, X102, X202, X203); wherein at least two first turns are connected in series via at least one second turn. A superconducting fault current limiter (400) is described, comprising a coil (12, 112, 212) as described above, the conducting element (18, 118, 218) of which comprises a superconducting material.

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