Fundamental processes of formation of three-dimensional flow in magnetized plasma turbulence

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K18335
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Nuclear fusion studies
• Research Institution: Kyushu University
• Principal Investigator: Sasaki Makoto 九州大学, 応用力学研究所, 助教 (70575919)
• Research Collaborator: Itoh Kimitaka ; Kasuya Naohiro ; Kobayashi Tatsuya
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 閉じ込めプラズマ / プラズマ乱流 / 輸送 / 帯状流 / トロイダル自発回転 / 構造形成 / ダンジェロモード / ドリフト波

Outline of Final Research Achievements

In the series of the study, we clarified important physical mechanisms for the spatial profiles of plasma transport in the presence of strong flows. When the flow becomes strong, the spatial inhomogeneity itself could be a cause of instabilities such as Kelvin-Helmholtz instability and so on. In this study, instabilities that stem from the flow inhomogeneity were considered as well as the drift waves. We elucidated “competition of multiple instabilities”, and “the selection rule of the topology of macroscopic flow”. It was clearly demonstrated that the “turbulence trapping due to flow” is a key to determine the spatial profiles of turbulence. Moreover, we extended the situation to include the energetic particles, and a mechanism was found that the perpendicular flow driven by the energetic particles drives parallel momentum transport to excite the parallel flow.

Free Research Field

プラズマ輸送

Academic Significance and Societal Importance of the Research Achievements

閉じ込めプラズマには自発的に流れを駆動する機構がある一方、エネルギー注入が普遍的に存在し、それに伴う運動量流入があるため通常強い流れが存在する。従来研究で中心的研究対象であったドリフト波に加え、流れが駆動する不安定性が共存する系を調べた。流れや乱流輸送の空間構造を決める重要な物理機構を明らかにし、核融合プラズマに存在する高エネルギー粒子効果を含む系への拡張を行った。さらに、改善閉じ込めプラズマでしばしば観測される突発的輸送について、複数不安定性の競合を考える事で、その前兆振動と思われる不安定性を発見した。本研究によって、強い流れを伴うプラズマについての輸送の空間構造についての理解を進展させた。