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Chaotic Phenomena in Unstable System

Research Project

Project/Area Number 08458110
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field プラズマ理工学
Research InstitutionKYUSHU UNIVERSITY

Principal Investigator

KAWAI Yoshinobu  Kyushu University, Interdiscplinary Graduate School of Engineering Sciences, Sciences Professor, 大学院・総合理工学研究科, 教授 (10038565)

Co-Investigator(Kenkyū-buntansha) HATORI Tadatsugu  National Institute for Fusion, Theory and Simulation Center, Professor, 理論・シミュレーションセンター, 教授 (80023729)
UEDA Yoko  Kyushu University, Interdiscplinary Graduate School of Engineering Sciences, Res, 大学院・総合理工学研究科, 助手 (70274529)
Project Period (FY) 1996 – 1997
Project Status Completed (Fiscal Year 1997)
Budget Amount *help
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1997: ¥1,900,000 (Direct Cost: ¥1,900,000)
Keywordsunstable system / drift velocity / period doubling / intermittent chaos / type-1 / corelation dimension / ion acoustic instability / electron beam plasma instability / 電子ブーム・プラズマ不安定性 / プラズマカオス / ダブルプラズマ
Research Abstract

To study chaotic phenomen in unstable systems, we excited two types of instabilities by injecting an electron beam or passing a current into a Double plasma. Then, we adjusted to make the system chaotic by controlling the growth rate of the instabilities. The experiments were performed using a Double-Plasma Device. Argon gas was used and the pressure was ranged from 10^<-4> to 3*10^<-4> Torr. The Plasma parameters were : n_e= (1-5) *10^8cm_<-3> and Te=1eV.Obtained main results were as follows :
[1] Electron beam plasma system :
(1) By injecting an elecron beam whose energy is 10-100eV into the plasma, we excited the electron beam plasma instability whose frequency is around 200MHz.
(2) When the electron beam density was increased, the period doubling appeared. The period-2 and period-3's bifurcation took place, showing that there is a window.
(3) We calcurated the correlation dimension D by the embeding method and found that D=2.5 for period-3 and 3.3 for period-4, respectively.
(4) The max … More imum Lyapunov exponent was positive, suggesting that the system is chaotic.
(5) It is concluded from (3) (4) that the electron beam plasma system is in the chaotic state.
[2] Ion acoustic instability system :
(1) In order to pass a current in the plasma, we installed two grid meshes in the plasma and applied DC potentials to one of the grids. When the current exceeded a certain value, the ion acouistic instability was excited, where the upper cut off frequency was around the ion plasma frequency. The electron drift velocity was measured with the probe and amounted to 40Cs (Cs : ion acoustic velocity).
(2) Above results are understood from the dispersion relation of the current-driven ion acoustic instability.
(3) Observed time series showed that the system becomes intermittent chaos above a threshold. The correlation dimension was non-integer and larger than 2. The maximum Lyapunov exponent was positive, which suggests that the system is in an intemittent chaotic state.
(4) The spectrum took a form of f^<-1>, so that observed intemittency is Type-1. Less

Report

(3 results)
  • 1997 Annual Research Report   Final Research Report Summary
  • 1996 Annual Research Report
  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] N.Hayashi: "Observation of Bifurcation Phenomena in an Electron Beam Plasma System" Physics of Plasmas. 3・12. 4440-4445 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Yoshimura: "Excitation Oharacteristics of Ion Waves in a Negative Ion Plasma" Journal of the Physical Society of Japan. 66・12. 3842-3846 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] K.Taniguchi: "Observation of Type-1 Intermittency Caused by Current-Driven Ion Acoustic Instability" Physics of Plasmas. 5・2 掲載予定. (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] N.Hayashi: "Observation of Bifurcation Phenomena in an Electron Beam Plasma System" Physics of Plasmas. 3, No.12. 4440-4445 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Yoshimura: "Excitation Characteristics of Ion Waves in a Negative Ion Plasma" Journal of the Physical Society of Japan. 66, No.12. 3842-3846 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] K.Taniguchi: "Observation of Type-1 Intermittency Caused by Current-Driven Ion Acoustic Instability" Physics of Plasmas. 5.No.2(to be published). (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Yoshimura: "Excitation Characteristics of Ion waves in a Negative Ion Plasma" Jopurnal of the Physical Society of Japan. 66. 3842-3846 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] K.Taniguchi: "Observation of Type-1 Intermittency Caused by Current-Driven Ion Acoustic Instability" Physics of Plasmas. 5(掲載予定). (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] 吉村信次: "負イオンンプラズマ中のイオン波の分散関係" 九州大学総合理工学研究科報告. 18. 7-10 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] N.Hayashi: "Observation of bifurcation phenomena in an electron beam plasma system" Physics of Plasmas. 3. 4440-4445 (1996)

    • Related Report
      1996 Annual Research Report

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Published: 1997-04-01   Modified: 2016-04-21  

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