Progress of Yoroi-Coil Structure in Mechanical Strength with High Current Density

Tomonori Watanabe, Shigeo Nagaya, Naoki Hirano, Satoshi Awaji, Hidetoshi Oguro, Atsushi Ishiyama, Masaki Hojo, Masaaki Nishikawa

    Research output: Contribution to journalArticle

    2 Citations (Scopus)

    Abstract

    Yoroi-coil (Y-based oxide superconductor and reinforcing outer integrated coil) structure has been developed to fabricate very strong pancake coils against electromagnetic force. In Yoroi-coil structure, the outer supporting structure is effective to make a mechanically robust coil having a high current density in the case that the hoop stress must exceed the yield strength of a REBCO-coated conductor without this reinforcement. By the experiments and analysis, we pointed out that the remarkably weak delamination stress can cause the delamination of the coated conductor in coils. So that Yoroi-coil structure has advantages to delamination because it could maintain a coil shape with reinforcing materials, without impregnation. Since higher current density is required by various applications, the Yoroi-coil using austenitic stainless steel reinforcing frames and plates, has been verified by the hoop stress test with high current density. Then, high coil current density of 446 A/mm2 was achieved by the Yoroi-coil-structured double pancake (DP) coil, with the total number of the winding turns of 574, at 4.2 K in the back-up magnetic field of 11 T. The inner and outer diameters of the DP coil were 190 and 250.1 mm, respectively. Although the hoop stress evaluated on the assumption of excluding the supporting structure exceeds 1 GPa, Yoroi-coil structure restricted the strain of coil winding ranging 0.2% to 0.3%. The stainless steel reinforcing member well supported a part of electromagnetic force in Yoroi-coil structure, even with high coil current density.

    Original languageEnglish
    Article number7839265
    JournalIEEE Transactions on Applied Superconductivity
    Volume27
    Issue number4
    DOIs
    Publication statusPublished - 2017 Jun 1

    Fingerprint

    Oxide superconductors
    Strength of materials
    high current
    Current density
    coils
    current density
    Delamination
    oxides
    hoops
    Stainless Steel
    Austenitic stainless steel
    Impregnation
    Yield stress
    Reinforcement
    Stainless steel
    reinforcing materials
    Magnetic fields
    conductors
    electromagnetism
    austenitic stainless steels

    Keywords

    • Delamination
    • Electromagnetic force
    • Hoop stress
    • REBCO coated conductor
    • Stainless steel reinforcing

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Electrical and Electronic Engineering

    Cite this

    Progress of Yoroi-Coil Structure in Mechanical Strength with High Current Density. / Watanabe, Tomonori; Nagaya, Shigeo; Hirano, Naoki; Awaji, Satoshi; Oguro, Hidetoshi; Ishiyama, Atsushi; Hojo, Masaki; Nishikawa, Masaaki.

    In: IEEE Transactions on Applied Superconductivity, Vol. 27, No. 4, 7839265, 01.06.2017.

    Research output: Contribution to journalArticle

    Watanabe, Tomonori ; Nagaya, Shigeo ; Hirano, Naoki ; Awaji, Satoshi ; Oguro, Hidetoshi ; Ishiyama, Atsushi ; Hojo, Masaki ; Nishikawa, Masaaki. / Progress of Yoroi-Coil Structure in Mechanical Strength with High Current Density. In: IEEE Transactions on Applied Superconductivity. 2017 ; Vol. 27, No. 4.
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