Measurements of Initial Relative Permeability of Ferromagnetic Material in Low Magnetic Fields Using a YBCO Superconductor at 77.4K (特集「センシング--システムからデバイスまで」) Measurements of Initial Relative Permeability of Ferromagnetic Material in Low Magnetic Fields Using a YBCO Superconductor at 77.4 K

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A measuring system for determining the initial relative permeability (μ<i><sub>si</sub></i>) of ferromagnetic materials at the boiling point of liquid nitrogen (77.4K) is developed by using a YBCO superconductor as the standard sample. The μ<i><sub>si</sub></i> is measured in low magnetic fields (over 10<sup>-6</sup>T to 10<sup>-4</sup>T) below the lower critical field (μ<sub>0</sub><i>H<sub>c1</sub></i>, 5.0×10<sup>-4</sup>T) of YBCO superconductor. The values of μ<i><sub>si</sub></i> for the typical ferromagnetic materials such as the ferrite, 78-permalloy, soft iron, and electromagnetic stainless steel were 10.70, 10.77, 10.75, and 10.85, at a frequency of 60Hz, respectively. The μ<i><sub>si</sub></i> of a ferrite was constant over the frequency range from 10Hz to 20kHz at both temperatures of 77.4K and 300K. The μ<i><sup>si</sup></i>'s of typical ferromagnetic materials without a ferrite were constant for frequency values up to 100Hz and then decreased as the frequency ranged from 100Hz to 20kHz. It was shown that the frequency dependence of μ<i><sub>si</sub></i> at 77.4K was more remarkable than that at 300K. The μ<i><sub>si</sub></i>'s of typical ferromagnetic materials were also found to be independent of the magnetic field at both 77.4K and 300K over the range from 10<sup>-6</sup>T to 10<sup>-4</sup>T. The accuracy of μ<i><sub>si</sub></i> due to thermal expansions of the rod samples and the differential coil was about 0.1%.

収録刊行物

  • 計測自動制御学会論文集  

    計測自動制御学会論文集 33(7), 563-569, 1997-07-31 

    The Society of Instrument and Control Engineers

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各種コード

  • NII論文ID(NAID)
    10002490879
  • NII書誌ID(NCID)
    AN00072392
  • 本文言語コード
    ENG
  • 資料種別
    ART
  • ISSN
    04534654
  • NDL 記事登録ID
    4256679
  • NDL 雑誌分類
    ZM11(科学技術--科学技術一般--制御工学)
  • NDL 請求記号
    Z14-482
  • データ提供元
    CJP書誌  NDL  J-STAGE 
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