Measurement of In-Field E-J Characteristics in Multi-Filamentary Bi-2223 Tapes at Ultra-Low Electric-Field Down to around 10^-13 V/m

Zeyu Wu, Takanobu Kiss, Shan Tian, Souki Kishikawa, Kohei Higashikawa, Yoshinori Yanagisawa, Jun ichi Shimoyama

研究成果: ジャーナルへの寄稿学術誌査読

抄録

We have developed a method to investigate in-field electric-field v.s. current-density (E-J) characteristics at ultra low electric field criterion around 10-13 V/m in a multi filamentary Bi-2223 tape at 5 K based on scanning Hall probe microscopy (SHPM). Bi-2223 is widely used in high field applications, e.g. a 30.5 T NMR magnet system is currently being developed in Japan. Ultra-low electric field is induced in such magnets operating in persistent current mode with extremely steady field. Namely, E-J characteristics need to be clarified around that criterion. E-J characteristics can be estimated from decay of magnetization in the whole sample, assuming the uniformity of J. But for multi filamentary Bi-2223 tape, magnetization current path should be clarified. In this study, we measured local magnetic field profile as a function of time for Bi-2223 tapes using SHPM. Additionally, we carried out flux annealing measurements to realize ultra-low electric field induced in the tape. As a result, two main messages we obtained. Experimental field profile or sheet current density obtained from the inverted Biot-Savart law indicated that filaments remain coupled up to high field, and even at ultra-low E criterion. Moreover, local E-J characteristics around 10-13 V/m are obtained at 5 K and 4.5 T of perpendicular magnetic field, which is comparable perpendicular field component in a Bi-2223 insert coil in the high field NMR magnet system. Ic properties at 10-12 V/m decrease to nearly 50%, in comparison to the transport Ic properties at 10-4 V/m.

本文言語英語
ジャーナルIEEE Transactions on Applied Superconductivity
DOI
出版ステータス印刷中 - 2022

!!!All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学
  • 電子工学および電気工学

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