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Interaction between electromagnetic field and pellet with shape transition due to nonisotropic ablation pressure

Research Project

Project/Area Number 15560719
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Nuclear fusion studies
Research InstitutionNational Institute for Fusion Science

Principal Investigator

ISHIZAKI Ryuichi  National Institute for Fusion Science, Theory and Simulation Research Center, Research Associate, 理論シミュレーション研究センター, 助手 (60301727)

Project Period (FY) 2003 – 2006
Project Status Completed (Fiscal Year 2006)
Budget Amount *help
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2006: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2005: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2004: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Keywordspellet / ablation / MHD / tire tube force / drift / plasmoid / CIP / LHD / 燃料供給 / ExBドリフト / 湾曲ドリフト / 衝撃波
Research Abstract

When a plasmoid with 1000 times density of the bulk plasma is heated by the electron heat flux, the ablation pressure reaches more than 100 times of the bulk plasma and subsequently makes the drift motion to the lower field side. The direction of the curvature vector is almost the major radius direction because a magnetic field faces to almost toroidal direction in tokamak. Then, the plasmoid with an extremely large pressure perturbation drifts due to a tire tube force induced by the difference between the inside circumference and the outside one of that perturbation. 1/R force induced by the magnetic field also makes such a drift motion. When an analytic model by integration of the force balance equation was constructed and was compared with simulation results, we have a very good agreement between the model and simulation results. On the other hand, when the pressure perturbation is very small, it is found that it has just an oscillation with no drift motion. When the perturbation is … More small, the linear theory is applicable to it. The linear theory predicts that the perturbation has just oscillation in stable equilibrium plasmas. Thus, small perturbation dose not have the drift motion. When a perturbation is large, the force balance is not satisfied any more and the linear theory can not be applicable. In other words, a large perturbation violating the linear theory is one essence of the drift motion. When more details are investigated about the drift motion, it is found that the top and bottom portions of the plasmoid drift to the higher field side, although the center of it drifts to the lower field side. The magnetic perturbation at the center of the plasmoid becomes negative due to diamagnetic current induced by the pressure perturbation. In other words, the magnetic field is removed from the center by the extremely large pressure perturbation.
Since that magnetic field removed is compressed at the edge of the plasmoid, the magnetic pressure perturbation becomes positive there. In such a case, the acceleration of the plasmoid becomes negative according to the analytic model described above, namely the edge of the plasmoid drifts to the higher field side.
When the initial plasmoids are located inside and outside of the torus in two characteristic poloidal cross sections in LHD plasma, it is found that the center of the plasmoids drift to the lower field side in all cases. In addition, it becomes clear that the portions with positive velocity and negative velocity in the major radius direction are alternately located along the flux surface. This fact is also verified in straight helical plasmas. Then, that fact may be induced by the helicity. Such an alternate location is most conspicuous when the plasmoid is located inside of the torus on the vertical elongated poloidal cross section, namely the highest field side. The physical meaning will be clarified in the future work. Less

Report

(5 results)
  • 2006 Annual Research Report   Final Research Report Summary
  • 2005 Annual Research Report
  • 2004 Annual Research Report
  • 2003 Annual Research Report
  • Research Products

    (4 results)

All 2006 2004

All Journal Article (4 results)

  • [Journal Article] MHD simulation on ablation cloud in tokamak and heliotron2006

    • Author(s)
      Ryuichi Ishizaki
    • Journal Title

      IAEA-CN-149/TH/P3-6

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] Motion of the ablation cloud in torus plasmas2006

    • Author(s)
      Ryuichi Ishizaki
    • Journal Title

      Journal of Plasma Physics 72

      Pages: 1159-1162

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] MHD simulation on ablation cloud in tokamak and heliotron2006

    • Author(s)
      Ryuichi Ishizaki
    • Journal Title

      IAEA-CN-149/TH/P

      Pages: 3-6

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Two-dimensional simulation of pellet ablation with atomic processes2004

    • Author(s)
      R.Ishizaki et al.
    • Journal Title

      Physics of Plasmas 11/8

      Pages: 4064-4064

    • Related Report
      2004 Annual Research Report

URL: 

Published: 2003-04-01   Modified: 2016-04-21  

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