2025-10-22 核融合科学研究所,総合研究大学院大学,京都大学
図１ 異なる二つのサイズの乱流の特性を調べるため、ミリ波散乱計測装置を設置した。青い二つのアンテナはサイズの小さい方の乱流を二方向から同時に観測し、緑色のアンテナは同じ位置でサイズの大きい方の乱流を観測する。
＜関連情報＞
高温プラズマのマルチスケール乱流におけるスケール間非線形相互作用と分岐 Cross-scale nonlinear interaction and bifurcation in multi-scale turbulence of high-temperature plasmas
Tokihiko Tokuzawa,Tatsuhiro Nasu,Daiki Nishimura,Katsumi Ida,Mikirou Yoshinuma,Tatsuya Kobayashi,Kenji Tanaka,Shigeru Inagaki,Akihide Fujisawa,Ichihiro Yamada & Kimitaka Itoh
Communications Physics Published:06 October 2025
DOI:https://doi.org/10.1038/s42005-025-02245-4
Abstract
The structural formation of magnetized high-temperature plasmas, which are ubiquitous in nature, is often controlled by turbulence. Such plasma turbulence is characterized by multiple scales and thus cross-scale nonlinear interactions are key to understanding its dynamics and structural formation. This is also the case for laboratory plasmas, for which multi-scale turbulence data are most abundant. The interactions of components on the meso- and ion-gyroradius (micro)-scales have been extensively studied. Here we report, the experimental discovery of the cross-scale nonlinear interactions between fluctuations at micro-scale and hyper-fine (HF)-scale (whose scale is about an electron gyroradius). Cross-scale bifurcation is found, in which micro-scale turbulence is suppressed, and the amplitude of HF-scale turbulence simultaneously increases. There is also an abrupt change in the isotropy of HF-scale components. We discuss a possible mechanisms in which nonlinear interactions, related to the weakening of the electric field generated by micro-scale turbulence, enhance HF-scale turbulence.
