2019 Fiscal Year Final Research Report

Observation of fine structure in magnetized plasma

Research Project

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Project/Area Number	15H02335
Research Category	Grant-in-Aid for Scientific Research (A)
Allocation Type	Single-year Grants
Section	一般
Research Field	Nuclear fusion studies
Research Institution	Kyushu University
Principal Investigator	Inagaki Shigeru 九州大学, 応用力学研究所, 教授 (60300729)
Co-Investigator(Kenkyū-buntansha)	荒川弘之島根大学, 学術研究院理工学系, 准教授 (00615106) 徳沢季彦核融合科学研究所, ヘリカル研究部, 准教授 (90311208) 山田琢磨九州大学, 基幹教育院, 准教授 (90437773)
Project Period (FY)	2015-04-01 – 2020-03-31
Keywords	プラズマ / 乱流 / 自己組織化 / 核融合
Outline of Final Research Achievements	A goal of this research is to establish a new picture of turbulence in magnetized plasma where spatial structure of plasma is not smooth but is corrugated by meso-scale bump and hole structures. In order to observe such corrugated structures, an offset frequency sweeping microwave comb reflectometry has been developed. A fixed frequency microwave comb has also used together and spatial resolution of 1 mm and temporal resolution of 1 micro second have been achieved by this new system. The system was applied to PANTA plasma diagnostics. Experimental observations show 1) bump and hole structures are formed intermittently and the radial propagation of them is ballistic and travel distance is several times longer than ion sound gyro-radius, 2) propagation of turbulence front accompanied with the propagation of the ump and hole structure and the self-organized criticality is identified. These results support a picture of plasma turbulence where multi-scale structures interact each others.
Free Research Field	プラズマ科学
Academic Significance and Societal Importance of the Research Achievements	本研究により、self-organized criticality等のプラズマ輸送の非局所性を説明できるモデルが大きく進展する。更に、惑星流体や海洋科学でも、海水の温度や濃度が階段状に分布する事が知られており、プラズマ乱流による凸凹空間構造の形成の研究は一般的な流体における構造形成に理解をもたらすという学術的意義がある。また、本研究はマイクロ波コム技術を開発している点にも特色がある。マイクロ波リモートセンシング技術は大気海洋観測から車載レーダ、医療診断にまで応用されており、その技術の新たな応用例の提示は高度な文明社会を構築に寄与する意義がある。