1988 Fiscal Year Final Research Report Summary
Research on collapse of double layers and turbulent-heating phenomena
| Project/Area Number |
60420050
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
プラズマ理工学
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| Research Institution | Nagoya University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
INUZUKA Hiroshi Nagoya University, 工学部, 助手 (80176411)
NAGATSU Masaaki Nagoya University, 工学部, 講師 (20155948)
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| Project Period (FY) |
1985 – 1988
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| Keywords | Double Layer / Turbulent Heating / Mirror Machine / Laser Scattering / Plasma Heating / Electron Hole / Computer Simulation / Plasma Transport / オーロラ |
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| Research Abstract |
1. Temporal evolution of electron temperature T. was measured during the period from formation to collapse of double layers (DL) produced in a linear turbulent-heating device, by making use of Ruby laser Thomson scattering. An electron hole was observed berofe the formation of DL. An increase in T. was also observed concomitant with decay of the electron hole,which, in turn, resulted in excitation of ion acoustic waves leading to formation of DL.
2. Parameters which may have effect on the life time of DL were examined. It was found that the life time of DL depends strongly on the distance between two electrodes and partial pressure of neutral particles but less on materials used and size of the wall.
3. Computer simulation were carried out with boundary conditions close to the experimental ones. Qualitatively good agreement was obtained between experimental and simulation results for the formation process of DLs.
4. Based on the experimental and simulation results decribed above, a theortical model was proposed to understand physical process leading to collapse of DL in the linear turbulent=heating device. The model takes into account the inbalance of plasma densities in the anode and cathode sides seen from the DL, which may be brought forth by "the ion transport" through the DL. The pressure inbalance so produced pushes the DL toward the anode. Then the DL vanishes when it reaches the anode.
5. Additional experiments and simulations were carried out under the condition appropriate to verify the proposed model, and reasonable results were obtained.
6. The physical picture obtained in the present research as to the collapse of DL is related to change in internal structure of DL, as opposed to conventional mechanism due to external cicuit, and may be applied to other DLs such as those in aurora.
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