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CONTROL OF RFP DYNAMICS WITH HELICAL FIELDS

Research Project

Project/Area Number 10680459
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field プラズマ理工学
Research InstitutionKYOTO INSTITUTE OF TECHNOLOGY

Principal Investigator

MASAMUNE Sadao  FACULTY OF ENGINEERING AND DESIGN, KYOTO INSTITUTE OF TECHNOLOGY, ASSOCIATE PROFESSOR, 工芸学部, 助教授 (00157182)

Co-Investigator(Kenkyū-buntansha) IIDA Motomi  FACULTY OF ENGINEERING AND DESIGN, KYOTO INSTITUTE OF TECHNOLOGY, RESEARCH ASSOCIATE, 工芸学部, 助手 (80211712)
OSHIYAMA Hiroshi  FACULTY OF ENGINEERING AND DESIGN, KYOTO INSTITUTE OF TECHNOLOGY, PROFESSOR, 工芸学部, 教授 (20026016)
Project Period (FY) 1998 – 1999
Project Status Completed (Fiscal Year 1999)
Budget Amount *help
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥2,100,000 (Direct Cost: ¥2,100,000)
Keywordsreversed field pinch / tearing modes / external kink modes / resistive wall modes / rotating helical field / plasma rotation / mode rotation / 抵抗性シェル不安定性 / ヘリカル磁場 / プラズマフロー(流れ) / 磁気島
Research Abstract

Control of the dynamics of reversed field pinches (RFPs) is one of the urgent issues for the improvements of RFP experiments. In RFPs with a resistive wall, both resistive and ideal modes can become unstable in the time scale of field penetration time of the wall. The growth of core resonant tearing modes would result in highly stochastic magnetic field, leading to significant degradation. Theories have predicted that the growth of tearing modes or their saturation amplitudes can be reduced by toroidal rotation of the plasma.
In this research project, first attempts have been made to drive magnetic fluctuation mode and/or plasma rotation using rotating M/N=1/8 resonant helical field, where M (N) is the poloidal (toroidal) mode number of the applied field.
In standard STE-2 (R/α=0.4m/0.1m) discharges with only the vacuum vessel whose time constant TィイD2wィエD2?0.15 ms, the plasma current IィイD2pィエD2 is around 60 kA with discharge duration TィイD2dィエD2 around 0.7 ms. The discharge resistance is … More about 50% higher than with a close-fitting copper shell of 2 ms time constant, and TィイD2dィエD2 shorter by about 30-40%. After attaining the RFP configuration, the magnetic fluctuations grow whose dominant toroidal mode number n appears to be 8, maintaining the structure for the rest of discharge. The m/n=1/8 mode is the tearing mode whose resonant surface is located at r/α〜0.4. The toroidally rotating helical field (RHF) was applied with two pairs of helical coils together with alternating current sources with a phase difference of π/2. The frequency was 10-20kHz, and the toroidal phase velocity of the rotating field was 4-7 km/s. Since we have used LC damping oscillation to obtain the alternating current in the present research project, effective duration of RHF is restricted to not longer than 0.3-0.4ms. The amplitude of the RHF |BィイD2rαィエD2| is defined as an average peak value from the second to the fifth peak values measured inside the vessel. The RHF was applied at t=0.3 ms, with f〜15 kHz and relative amplitude |BィイD2rαィエD2|/BィイD2θαィエD2 of 0.5%, where BィイD2θαィエD2 is the edge poloidal field. The amplitude of magnetic fluctuations is reduced, and, furthermore, the fluctuations rotate toroidally in the direction of the applied RHF for the amplitude level higher than 0.4%. The phase velocity of magnetic fluctuations is slightly lower than that of the RHF. The time evolution of the n=7, 8, 9 mode amplitudes with the RHF of relative amplitude of 0.5% shows that the growth of these mode amplitudes is suppressed transiently for 0.2-0.3 ms, and, moreover, the amplitudes are reduced for the rest of the discharge.
It is the first demonstration in the RFP of the direct interaction between the rotating M=1 helical field with inherent m=1 core resonant tearing modes. Less

Report

(3 results)
  • 1999 Annual Research Report   Final Research Report Summary
  • 1998 Annual Research Report
  • Research Products

    (18 results)

All Other

All Publications (18 results)

  • [Publications] S. Masamune: "Magnetic Island in Helically Perturbed Force-Free Equilibrium"J. Phys. Soc. Jpn.. 67. 2977-2980 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Masamune: "Active Control of RFP Dynamics with External Fields"Proc. IAEA-TCM/RUSFD, IAEA-F1-TC-536-14. 13-18 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Masamune: "Control of RFP Dynamics with External Helical Fields"Fusion Energy 1998 (Proc. 17th IAEA Fusion Energy Conf.). 3. 919-922 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Masamune: "Stability of Resistive Shell Modes in the RFP Surrounded by Helical Current"J. Phys. Soc. Jpn.. 68. 2161-2163 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] 政宗貞男: "RFPにおけるプラズマ制御"プラズマ・核融合学会誌. 75. 1390-1395 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. MASAMUNE et al.: "Magnetic Island in Helically perturbed Force-Free Equilibrium"J. Phys. Soc. Jpn.. 67. 2977-2980 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. MASAMUNE et al.: "Active Control of RFP Dynamics with External Fields"Proc. IEAE-TCM. IAEA-F1-TC-536-14. 13-18 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. MASAMUNE et al.: "Control of RFP Dynamics with External Helical Fields"Fusion Energy 1998 (Proc. IAEA Fusion Energy Conf.). 3. 919-922 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. MASAMUNE et al.: "Stability of Resistive Shell Modes in the RFP Surrounded by Helical Current"J. Phys. Soc. Jpn.. 68. 2161-2163 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. MASAMUNE .: "Plasma Control in Reversed-Field Pinches"J. Plasma and Fusion Res.. 75. 1390-1395 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S.Masamune: "Magnetic Island in Helically Perturbed Force-Free Equilibrium"J.Phys.Soc.Jpn.. 67(7). 2977-2980 (1998)

    • Related Report
      1999 Annual Research Report
  • [Publications] S.Masamune: "Active Control of RFP Dynamics with External Fields"Proc.IAEA-TCM/RUSFD,IAEA-F1-TC-536-14. 13-18 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] S.Masamune: "Control of RFP Dynamics with External Helical Fields"Fusion Energy 1998 (Proc.17th IAEA Fusion Energy Conf.). 3. 919-922 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] S.Masamune: "Stability of Resistive Shell Modes in the RFP Surrounded by Helical Current"J.Phys.Soc.Jpn.. 68(7). 2161-2163 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] 政宗貞男: "RFPにおけるプラズマ制御"プラズマ・核融合学会誌. 75(12). 1390-1395 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] S.Masamune: "Magnetic Island in Helically Perturbed Force-Free Equilibrium" J.Phys.Soc.Jpn.67(9). 2977-2980 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] S.Masamune: "Control of RFP Dynamics with External Helical Fields" Fusion Energy 1998(Proc.17th IAEA Fusion Energy Conf.). (印刷中). (1999)

    • Related Report
      1998 Annual Research Report
  • [Publications] S.Masamune: "Control of RFP Dynamics with External Fields" Proc.IAEA-TCM/Research Using Small Fusion Devices. (印刷中). (1999)

    • Related Report
      1998 Annual Research Report

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Published: 1998-04-01   Modified: 2016-04-21  

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