Experimental investigation of the effect of plasma turbulence on microwave propagation.

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K14688
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 14020:Nuclear fusion-related
• Research Institution: National Institute for Fusion Science
• Principal Investigator: Yanai Ryoma 核融合科学研究所, 研究部, 助教 (40824743)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: マイクロ波 / プラズマ乱流 / 電子サイクロトロン共鳴加熱

Outline of Final Research Achievements

The influences of density fluctuations caused by the plasma turbulence in the Large Helical Device (LHD) on microwaves were investigated focusing on a 77 GHz microwave, which is used for electron cyclotron resonance heating in the LHD. No clear effect on the microwave from the density fluctuations was observed in the LHD experiments. The results of electromagnetic field analysis based on the experimental data from the LHD also revealed that the fluctuations had little effect due to their small magnitude, which was less than 1%. However, the simulation results of the electromagnetic field analysis indicated that the microwave beam was scattered as the fluctuation level increased and could affect the shape of the Gaussian beam.

Free Research Field

核融合プラズマ

Academic Significance and Societal Importance of the Research Achievements

プラズマ中を伝播する77 GHzのマイクロ波が、乱流によって駆動される密度揺動で受ける影響について検証した結果、大型ヘリカル装置で計測されたイオンスケールの密度揺動での影響はほとんどないことが電磁界解析によりわかった。しかしながら、より大きな密度揺動の存在下では、77 GHzのマイクロ波が影響を受ける可能性を示す結果が得られた。また、イオンスケールより大きな空間スケールの密度揺動の方が、77 GHzのマイクロ波に与える影響が大きい可能性があることが明らかになった。