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1992 Fiscal Year Final Research Report Summary

Experimental investigation of quasi-steady current driving for spheromak plasmas by means of magnetic helicity injection.

Research Project

Project/Area Number 02452135
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 電力工学
Research InstitutionTHE UNIVERSITY OF TOKYO

Principal Investigator

KATSURAI Makoto  Univ.Tokyo, Dept.Electrical Engrn., Professor, 工学部, 教授 (70011103)

Co-Investigator(Kenkyū-buntansha) ITAGAKI Toshifumi  Univ.Tokyo, Dept.Electrical Engrn., Assistant, 工学部, 助手
ONO Yasushi  Univ.Tokyo, Dept.Electrical Engrn., Associate Professor, 工学部, 助教授 (30214191)
Project Period (FY) 1990 – 1992
KeywordsNuclear fusion research / Plasma science / Magnetic confinement / Toroidal confinement / Compact toroids / Spheromak plasmas / Current driving / Magnetic Helicity
Research Abstract

External drive of the plasma current of spheromak plasmas has been performed to demonstrate the feasibility of sustaining their magnetic configurations by the magnetic helicity injection method. The both of the conductive type and the inductive type of the helicity injection have been examined in the Tokyo University spheromak machine TS-3. Under appropriate current driving conditions. the spheromak configuration is maintained three to five times longer than non-driving conditions. A visible light computer tomography system has been developed to observe unstable plasma motions in the pasmas. In this measurement, the time evolutions of two dimensional emission profile of visible light on the mid-plane of plasmas have been observed by a newly developed three-direction ten-channel computer tomography system. This system can reconstruct the emission profile by the Cormack method based on the Fourier-Bessel-Neumann expansions. From reconstructed images, the relaxation is found to be caused by the inverse-cascade phenomena, in which instabilities with higher toroidal mode numbers are excited first, followed by the energy transmission to those with lower mode numbers. Magnetic measurements have also been performed and the flux conversion from poloidal to toroidal associated with the inverse-cascade phenomena is observed. Three dimensional magnetohydrodynamic computer simulations have also been carried out to examine the dynamic behaviors of the spheromak configuration in helicity injection periods. It is found that a magnetic relaxation cycle, consisting of the current peaking phase and the subsequent MHD relaxation phase, plays very important roles in the magnetic flux conversion from poloidal to toroidal. The nonlinear coupling of the current driven MHD instabilities with mode numbers of n=2 and n=3 takes place in the flux conversion. These findings are qualitatively consistent with the tomographic observations of the MHD activities.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] 森田,小野,桂井: "トロイダル電流駆動方式磁気ヘリシティー注入法によるコンパクトトーラスプラズマの長時間配位維持実験" 電気学会誌. (投稿予定).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] N.Amemiya, A.Morita, M.Katsurai: "Experiments of Axial Compression of Flux-Core Spherowak" J.P.S.J.62. 1552-1561 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 森田,早川,桂井: "回転楕円体容器中におけるフラックスコアースフェロマックの平衡配位" 電気学会論文誌A. 112-A. 706- (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y.Ono, M.Katsurai: "Three-Dimensional Numerical Simulation of the Multi-Helicity Magnetohydrodynamic Relaxation Process in Low-q Spheromaks" Nuclear Fusion. 31. 233-244 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] N.Amemiya,A.Hayakawa,M.Katsurai: "Formation of Free-Boundary Flux-Core Spheromaks" J.P.S.J.60. 2632-2644 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 桂井,雨宮,早川: "円筒容器内フラックスコアースフェロマックの平衡解とその特性" 核融合研究. 64. 262-275 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Morita, Y.Ono, M.Katsurai: "Experiments of long pulse operation of compact torus plasmas by means of magnetic helicity injection through toroidal current driving" Trans.I.E.E.Japan. (to be submitted.).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] N.Amemiya, A.Morita, M.Katsurai: "Experiments of axial compression of flux-core spheromak" J.P.S.J.62-5. 1552 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Morita, A.Hayakawa, M.Katsurai: "Equilibrium analysis of flux-core spheromaks in a spheroidal conductive vessel" Trans.I.E.E.Japan. 112A-8. 706 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Y.Ono, M.Katsurai: "Three-dimensional numerical simulation of the multi-helicity magnetohydrodynamic relaxation process in low-q spheromaks" Nuclear Fusion. 31-2. 233 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] N.Amemiya, H.Hayakawa, M.Katsurai: "Formation of free-boundary flux-core spheromaks" J.P.S.J.60-8. 2632 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M.Katsurai, N.Amemiya, A.Hayakawa: "Equilibrium studies on the magnetic configuration of flux-core spheromaks in a finite-length cylindrical vessel" J.Plasma and Fusion Res.64-4. 262 (1990)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-03-16  

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