Magnetic Flux Invasion and Field-Capturing in Pulsed-Field Magnetization for Layered MgB2 Bulk Magnets

Tetsuo Oka; A. Takeda; S. Sasaki; J. Ogawa; S. Fukui; T. Sato; J. Scheiter; W. Häßler; J. Katsuki; A. Miura; K. Yokoyama

doi:10.1109/TASC.2018.2792530

Magnetic Flux Invasion and Field-Capturing in Pulsed-Field Magnetization for Layered MgB₂ Bulk Magnets

Tetsuo Oka, A. Takeda, S. Sasaki, J. Ogawa, S. Fukui, T. Sato, J. Scheiter, W. Häßler, J. Katsuki, A. Miura, K. Yokoyama

Research output: Contribution to journal › Article › peer-review

8 Citations (Scopus)

Abstract

The pulsed-field magnetization experiments have been carried out for the layered MgB₂ bulk magnets to clarify the magnetic flux motion during the activation processes. Since MgB₂ is characterized as homogeneous, lightweight, and inexpensive HTS material in comparison to RE123 compounds (RE = rare earth), the material may have an advantage of possibly uniform magnetic field generation. The values of applied field B_a which begin to reach the sample center were responsible for the total sample thickness, reflecting the shielding effect to suppress the flux invasion. As well, the estimation on the ratios of trapped field B_T over penetration field B_p showed us the reluctant field invasion with increasing sample thickness. The field trapping ratios B_T B_p decreased with increasing applied field due to heat generation. In the region over 1.4 T, the drastic flux flow and sudden flux jumps were often observed, which lowered the field-capturing ability. The arriving time which corresponds to the flux increasing speed showed us that the rapid flux invasions which occur in the low-field ranges resulted in the highest field-capturing. This suggests us the possible promotion of field-capturing without significant heat generation.

Original language	English
Article number	8255574
Journal	IEEE Transactions on Applied Superconductivity
Volume	28
Issue number	4
DOIs	https://doi.org/10.1109/TASC.2018.2792530
Publication status	Published - 2018 Jun
Externally published	Yes

Keywords

Bulk superconductor
heat generation
magnetic flux
magnetization
pulsed field

ASJC Scopus subject areas

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

Access to Document

10.1109/TASC.2018.2792530

Cite this

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title = "Magnetic Flux Invasion and Field-Capturing in Pulsed-Field Magnetization for Layered MgB2 Bulk Magnets",

abstract = "The pulsed-field magnetization experiments have been carried out for the layered MgB2 bulk magnets to clarify the magnetic flux motion during the activation processes. Since MgB2 is characterized as homogeneous, lightweight, and inexpensive HTS material in comparison to RE123 compounds (RE = rare earth), the material may have an advantage of possibly uniform magnetic field generation. The values of applied field Ba which begin to reach the sample center were responsible for the total sample thickness, reflecting the shielding effect to suppress the flux invasion. As well, the estimation on the ratios of trapped field BT over penetration field Bp showed us the reluctant field invasion with increasing sample thickness. The field trapping ratios BT Bp decreased with increasing applied field due to heat generation. In the region over 1.4 T, the drastic flux flow and sudden flux jumps were often observed, which lowered the field-capturing ability. The arriving time which corresponds to the flux increasing speed showed us that the rapid flux invasions which occur in the low-field ranges resulted in the highest field-capturing. This suggests us the possible promotion of field-capturing without significant heat generation.",

keywords = "Bulk superconductor, heat generation, magnetic flux, magnetization, pulsed field",

author = "Tetsuo Oka and A. Takeda and S. Sasaki and J. Ogawa and S. Fukui and T. Sato and J. Scheiter and W. H{\"a}{\ss}ler and J. Katsuki and A. Miura and K. Yokoyama",

note = "Funding Information: Manuscript received September 17, 2017; accepted January 7, 2018. Date of publication January 12, 2018; date of current version January 25, 2018. This work was supported by the U.S. Department of Energy under Grant ABC-123456. (Corresponding author: Tetsuo Oka.) T. Oka, A. Takeda, S. Sasaki, J. Ogawa, S. Fukui, and T. Sato are with the Niigata University, Niigata 950-2181, Japan (e-mail: okat@eng.niigata-u.ac.jp). J. Scheiter and W. H{\"a}{\ss}ler are with the IFW Dresden, Dresden 01069, Germany (e-mail: w.haessler@ifw-dresden.de). J. Katsuki, A. Miura, and K. Yokoyama are with the Ashikaga Institute of Technology, Ashikaga 326-8558, Japan (e-mail: k-yokoyama@ashitech.ac.jp). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TASC.2018.2792530 Publisher Copyright: {\textcopyright} 2017 IEEE.",

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T1 - Magnetic Flux Invasion and Field-Capturing in Pulsed-Field Magnetization for Layered MgB2 Bulk Magnets

AU - Oka, Tetsuo

AU - Takeda, A.

AU - Sasaki, S.

AU - Ogawa, J.

AU - Fukui, S.

AU - Sato, T.

AU - Scheiter, J.

AU - Häßler, W.

AU - Katsuki, J.

AU - Miura, A.

AU - Yokoyama, K.

N1 - Funding Information: Manuscript received September 17, 2017; accepted January 7, 2018. Date of publication January 12, 2018; date of current version January 25, 2018. This work was supported by the U.S. Department of Energy under Grant ABC-123456. (Corresponding author: Tetsuo Oka.) T. Oka, A. Takeda, S. Sasaki, J. Ogawa, S. Fukui, and T. Sato are with the Niigata University, Niigata 950-2181, Japan (e-mail: okat@eng.niigata-u.ac.jp). J. Scheiter and W. Häßler are with the IFW Dresden, Dresden 01069, Germany (e-mail: w.haessler@ifw-dresden.de). J. Katsuki, A. Miura, and K. Yokoyama are with the Ashikaga Institute of Technology, Ashikaga 326-8558, Japan (e-mail: k-yokoyama@ashitech.ac.jp). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TASC.2018.2792530 Publisher Copyright: © 2017 IEEE.

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N2 - The pulsed-field magnetization experiments have been carried out for the layered MgB2 bulk magnets to clarify the magnetic flux motion during the activation processes. Since MgB2 is characterized as homogeneous, lightweight, and inexpensive HTS material in comparison to RE123 compounds (RE = rare earth), the material may have an advantage of possibly uniform magnetic field generation. The values of applied field Ba which begin to reach the sample center were responsible for the total sample thickness, reflecting the shielding effect to suppress the flux invasion. As well, the estimation on the ratios of trapped field BT over penetration field Bp showed us the reluctant field invasion with increasing sample thickness. The field trapping ratios BT Bp decreased with increasing applied field due to heat generation. In the region over 1.4 T, the drastic flux flow and sudden flux jumps were often observed, which lowered the field-capturing ability. The arriving time which corresponds to the flux increasing speed showed us that the rapid flux invasions which occur in the low-field ranges resulted in the highest field-capturing. This suggests us the possible promotion of field-capturing without significant heat generation.

AB - The pulsed-field magnetization experiments have been carried out for the layered MgB2 bulk magnets to clarify the magnetic flux motion during the activation processes. Since MgB2 is characterized as homogeneous, lightweight, and inexpensive HTS material in comparison to RE123 compounds (RE = rare earth), the material may have an advantage of possibly uniform magnetic field generation. The values of applied field Ba which begin to reach the sample center were responsible for the total sample thickness, reflecting the shielding effect to suppress the flux invasion. As well, the estimation on the ratios of trapped field BT over penetration field Bp showed us the reluctant field invasion with increasing sample thickness. The field trapping ratios BT Bp decreased with increasing applied field due to heat generation. In the region over 1.4 T, the drastic flux flow and sudden flux jumps were often observed, which lowered the field-capturing ability. The arriving time which corresponds to the flux increasing speed showed us that the rapid flux invasions which occur in the low-field ranges resulted in the highest field-capturing. This suggests us the possible promotion of field-capturing without significant heat generation.

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KW - heat generation

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KW - magnetization

KW - pulsed field

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