Further development of the microwave demagnetization and magnetization system

• Project/Area Number: 23740340
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Solid earth and planetary physics
• Research Institution: Kochi University
• Principal Investigator: YAMAMOTO YUHJI 高知大学, 自然科学系, 助教 (00452699)
• Project Period (FY): 2011-04-28 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2013: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2012: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000); Fiscal Year 2011: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
• Keywords: 固体地球物理学 / 地球電磁気学 / 磁性 / マイクロ波 / 地球電磁気 / 国際研究者交流 / 中国

Outline of Final Research Achievements

We have developed a demagnetization system using 18 GHz microwaves. Initially the system was planned to be implemented with a 50 W solid state power amplifier (SSPA) but we could only implement a 10 W SSPA due to a limitation of the cost. The system uses a disc-shaped mini rock sample with a diameter of 3 mm and a thickness of 1-2 mm. To control input microwaves and monitor input and diffracted powers, a software was developed using LabView. Final tests revealed that about 60 percent of the initial remanent magnetization of a sample could be demagnetized using the system. It is expected that a complete demagnetization will be possible if the system will be implemented with a 50 W SSPA in future.

Research Products

• [Presentation] Preliminary application of the microwave LTD-DHT Shaw method to old Icelandic samples (2011)
  • Author(s): Yamamoto, Y. and Hill, M.J.
  • Organizer: 2011 International Union of Geodesy and Geophysics (IUGG) General Assembly
  • Place of Presentation: メルボルン, オーストラリア
• [Presentation] アイスランドSudurdalur 地域溶岩から推定される過去400-600 万年前の古地磁気強度 (2011)
  • Author(s): 山本裕二, 畠山唯達
  • Organizer: 日本地球惑星科学連合2011年大会
  • Place of Presentation: 千葉県
• [Presentation] Geomagnetic field intensity inferred from 3-6 Ma lava sequences in Sudurdalur area, Iceland
  • Author(s): Yuhji Yamamoto, Tadahiro Hatakeyama
  • Organizer: American Geophysical Union 2012 Fall Meeting
  • Place of Presentation: サンフランシスコ, アメリカ