Maeyama Shinya, Watanabe Tomo-Hiko, Nakata Motoki, Nunami Masanori, Asahi Yuuichi, Ishizawa Akihiro
Department of Physics, Nagoya University, Nagoya, Japan.
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Japan.
Nat Commun. 2022 Jun 7;13(1):3166. doi: 10.1038/s41467-022-30852-0.
Turbulent transport is a key physics process for confining magnetic fusion plasma. Recent theoretical and experimental studies of existing fusion experimental devices revealed the existence of cross-scale interactions between small (electron)-scale and large (ion)-scale turbulence. Since conventional turbulent transport modelling lacks cross-scale interactions, it should be clarified whether cross-scale interactions are needed to be considered in future experiments on burning plasma, whose high electron temperature is sustained with fusion-born alpha particle heating. Here, we present supercomputer simulations showing that electron-scale turbulence in high electron temperature plasma can affect the turbulent transport of not only electrons but also fuels and ash. Electron-scale turbulence disturbs the trajectories of resonant electrons responsible for ion-scale micro-instability and suppresses large-scale turbulent fluctuations. Simultaneously, ion-scale turbulent eddies also suppress electron-scale turbulence. These results indicate a mutually exclusive nature of turbulence with disparate scales. We demonstrate the possibility of reduced heat flux via cross-scale interactions.
湍流输运是约束磁约束聚变等离子体的关键物理过程。对现有聚变实验装置的近期理论和实验研究揭示了小（电子）尺度和大（离子）尺度湍流之间存在跨尺度相互作用。由于传统的湍流输运模型缺乏跨尺度相互作用，因此需要明确在未来以聚变产生的α粒子加热维持高电子温度的燃烧等离子体实验中是否需要考虑跨尺度相互作用。在此，我们展示了超级计算机模拟结果，表明高电子温度等离子体中的电子尺度湍流不仅会影响电子的湍流输运，还会影响燃料和灰烬的湍流输运。电子尺度湍流扰乱了负责离子尺度微不稳定性的共振电子轨迹，并抑制了大尺度湍流波动。同时，离子尺度湍流涡旋也会抑制电子尺度湍流。这些结果表明了不同尺度湍流的相互排斥特性。我们证明了通过跨尺度相互作用降低热通量的可能性。
