Measurements of magnetic field induced by screening currents in YBCO solenoid coils

Uglietti, D.; Yanagisawa, Yoshinori; Maeda, Hideaki; Toko, Kiyoshi

doi:10.1088/0953-2048/23/11/115002

Cited by 39 publications

(24 citation statements)

References 17 publications

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“…The field temporal stability in a small coil of the same aspect ratio as that of a nominal-size NMR coil was measured; the small coil was found to have a temporal drift of 10 ppm h −1 , clearly much greater than that for a typical NMR operation [159]. One technique proposed recently to shim SFC-induced field impurity is a set of persistent-mode shim coils prepared from RE123 [160].…”

Section: Field Qualitymentioning

confidence: 99%

Progresses and challenges in the development of high-field solenoidal magnets based on RE123 coated conductors

Senatore

Alessandrini

Lucarelli

et al. 2014

Supercond. Sci. Technol.

255

136

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Recent progresses in the second generation REBa 2 Cu 3 O 7 − x (RE123) coated conductor (CC) have paved a way for the development of superconducting solenoids capable of generating fields well above 23.5 T, i.e. the limit of NbTi−Nb 3 Sn-based magnets. However, the RE123 magnet still poses several fundamental and engineering challenges. In this work we review the state-ofthe-art of conductor and magnet technologies. The goal is to illustrate a close synergetic relationship between evolution of high-field magnets and advancement in superconductor technology. The paper is organized in three parts: (1) the basics of RE123 CC fabrication technique, including latest developments to improve conductor performance and production throughput; (2) critical issues and innovative design concepts for the RE123-based magnet; and (3) an overview of noteworthy ongoing magnet projects.

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Section: Field Qualitymentioning

confidence: 99%

Progresses and challenges in the development of high-field solenoidal magnets based on RE123 coated conductors

Senatore

Alessandrini

Lucarelli

et al. 2014

Supercond. Sci. Technol.

255

136

View full text Add to dashboard Cite

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“…The combination of these magnetic fields causes inhomogeneity in the current flowing across the tape, and therefore, the magnetic field at the center of the magnet tends to be nonuniform. [4][5][6][7] Herein, we discuss the realization of a highly uniform magnetic field at the center of a superconducting magnet wound with tape-shaped HTS wires. Figure 1 shows the basic configuration of the magnet system proposed in this paper.…”

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confidence: 99%

A simple method to eliminate shielding currents for magnetization perpendicular to superconducting tapes wound into coils

Komori¹,

Funaki²

2011

Supercond. Sci. Technol.

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Application of an external AC magnetic field parallel to superconducting tapes helps in eliminating the magnetization caused by the shielding current induced in the flat faces of the tapes. This method helps in realizing a magnet system with high-temperature superconducting tapes for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) applications. The effectiveness of the proposed method is validated by numerical calculations carried out using the finite-element method and experiments performed using a commercially available superconducting tape. The field uniformity expected for practical applications is estimated to be less than 1 ppm.Superconducting magnets used in magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) require a highly uniform magnetic field at their center.Hence, a multifilamentary superconducting wire with a circular or rectangular cross section composed of low-temperature superconductors such as NbTi or Nb 3 Sn is wound around the magnets. These materials are usually cooled by liquid helium, which has a boiling temperature of 4.2 K at atmospheric pressure. However, because of the rapidly increasing demand for liquid helium and its limited availability, the cost of this coolant has been increasing steadily. To realize a helium-free superconducting magnet system, 1)it would be necessary to use liquid hydrogen or nitrogen, whose boiling temperatures are about 20 K and 77 K, respectively, as a coolant, or carry out conduction cooling with the help of a cryocooler. Recently, a superconducting magnet with a nominal field of 0.5 T has been wound with a MgB 2 wire and installed in a private clinic for use in MRI. 2)Nevertheless, designing a very high normal field (several tesla or several tens of tesla) magnet using the MgB 2 wire for MRI and NMR applications is very difficult because the critical current density decreases drastically when the magnetic field is on the order of a few tesla.3) High-temperature superconductor (HTS) wires such as first-generation *

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“…If such a tape-shaped wire is used as windings for a superconducting magnet and this magnet is energized, one turn in the windings is exposed not only to a self-magnetic field due to a transport current flowing in itself but also to an external magnetic field generated by currents in the other turns. It has been well known that the combination of these magnetic fields yields the inhomogeneity of current across the tape width, and therefore the magnetic field in the central part of the magnet has very low uniformity [4]- [7]. In this study, simple and powerful methods to reduce the magnetization in the windings composed of HTS tapes are proposed comprehensively although a series of preliminary discussions has already been made by the present authors [8].…”

Section: Introductionmentioning

confidence: 95%

Reduction of Magnetization in Windings Composed of HTS Tapes

Komori

Funaki

2012

IEEE Trans. Appl. Supercond.

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Methods to reduce the magnetization in windings composed of high temperature superconductor (HTS) tapes are presented on the basis of the abnormal transverse-field effect. The toroidal arrangement as well as the coaxial arrangement of additional coils wound with non-magnetic wires such as copper wires is effective to uniformize the distribution of sheet current in the HTS tapes constituting the windings carrying a direct transport current when the non-magnetic coils are energized with an alternating transport current for a short time. By using a layer-wound coil fabricated with a commercially available coated conductor and a pair of copper coils with the coaxial arrangement, the influences of reducing the magnetization in the windings on the central magnetic fields of the HTS coil are studied in detail experimentally.Index Terms-Abnormal transverse-field effect, high temperature superconducting tape, perpendicular magnetization, shielding current.

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Measurements of magnetic field induced by screening currents in YBCO solenoid coils

Cited by 39 publications

References 17 publications

Progresses and challenges in the development of high-field solenoidal magnets based on RE123 coated conductors

Progresses and challenges in the development of high-field solenoidal magnets based on RE123 coated conductors

A simple method to eliminate shielding currents for magnetization perpendicular to superconducting tapes wound into coils

Reduction of Magnetization in Windings Composed of HTS Tapes

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