2019 Fiscal Year Research-status Report
Simulation study of the energy channel and the particle radial transport due to the energetic particle driven geodesic acoustic mode
| Project/Area Number |
18K13529
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| Research Institution | National Institute for Fusion Science |
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Principal Investigator |
Wang Hao 核融合科学研究所, ヘリカル研究部, 助教 (30724760)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | energetic particle / EGAM / energy channeling / EGAM channeling / hybrid simulation / energy transfer |
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| Outline of Annual Research Achievements |
In the present research, EGAM channeling is reproduced by simulation with realistic parameters for the first time, and the systematic investigation of EGAM channeling was conducted. In detail, the mechanism of EGAM channeling is clarified, the sideband resonance is dominant during the energy transfer from EGAM to the bulk ions, and the transit frequencies of resonant bulk ions are one-half of the EGAM frequency. In an experiment, the higher NBI power, the lower NBI velocity, the higher number of perpendicular injected particles, and the wilder bulk ion temperature profile is probably applicable strategies for improving observation of EGAM channeling.
The present research is significant because it will be very helpful to improve plasma confinement. The proposed target is achieved.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The EGAM channeling is reproduced by simulation with realistic parameters for the first time, and the mechanism was clarified. Also, the systematic investigation of EGAM channeling was conducted to give experimentalists pieces of advice. These mean the proposed target is achieved.
In addition, two extra investigations are started. Firstly, the simulation of energetic particle driven instabilities in CFQS device was conducted. Preliminary results were obtained, and a kind of GAE-like mode was observed. Secondly, the simulation of energetic particle driven instabilities in W7-X stellarator was started. The realistic equilibria were constructed for on-axis heating cases, and collaboration with W7-X staff was established. These mean the progress is better than expected.
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| Strategy for Future Research Activity |
In the future, three investigations will be made.
The first investigation will be a more precise simulation of EGAM in LHD. At present, the noise in the simulation is large, which causes great difficulties for further detailed analysis. In June 2020, the new supercomputer of NIFS will be put into use. At that time, we will conduct a larger-scale simulation to explore more details during the EGAM activities. A deeper understanding will be provided.
The second and third investigations will be the instabilities in CFQS and W7-X devices. These studies have already been started, and we will continue in the future. However, the proposed research has been finished in March 2020, and the remaining funds are not too much, thus, The research on CFQS and W7-X may not be too detailed.
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| Causes of Carryover |
At present, the noise in the simulation is large, which causes great difficulties for further detailed analysis and better visualizations. Thus, we are planning to make further investigation to obtain more clear results.
In June 2020, the new supercomputer of NIFS will be put into use. At that time, we will conduct a larger-scale simulation on the supercomputer with more simulation particles and grids. More particle details in both phase space and real space during the EGAM activities will be explored, and a deeper understanding of EGAM will be provided.
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