Elucidation of heat transport process during high-beta/merging spherical tokamak formation

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H01866
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 14010:Fundamental plasma-related
• Research Institution: The University of Tokyo
• Principal Investigator: Tanabe Hiroshi 東京大学, 大学院新領域創成科学研究科, 准教授 (30726013)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: プラズマ・核融合 / プラズマ診断 / 磁気リコネクション / コンピュータトモグラフィ

Outline of Final Research Achievements

We investigated the explosive energy coversion process of magnetic reconnection as in solar flare with our falicity of high-beta/merging-startup spherical tokamak expreimentin the university of Tokyo. We mainly carried out the following two projects: (1) development of 2D imaging measurement of electron and ion acceleration/heating and (2) investigation of electron and ion acceleration/heating during "guide field" reconnection which has perpendicular toroidal component to reconnecting/anti-parallel poloidal magnetic field.
We mainly carried out those two projects and found that electrons are accelerated/heated in the lower potential region, while ion temperature increases at higher potential side. Then, both electrons and ions are affected by collisional relaxation/transport process in the downstream and finally their structure is aligned with the magnetic field lines of closed flux surface of the spherical tokamak plasma after the end of merging.

Free Research Field

プラズマ科学

Academic Significance and Societal Importance of the Research Achievements

本研究で主として取り組んだガイド磁場リコネクション現象は、太陽フレア等の爆発的エネルギー解放現象の基盤物理の理解という理学的側面の他に、工学的には球状トカマクの効率生成・加熱法として近年核融合ベンチャー等で応用が進む、合体法の基盤物理となる物理現象として重要である。応用を意識した時、既に解明済みの加熱スケーリング特性の他、加熱後にどのような構造が形成され、閉じ込め・輸送がどのようになるのかを理解しておくことが重要である。電子・イオンがどこでどのように加速・加熱を受け、輸送されるのか、今回特にシミュレーションで予測されなかった高電位領域のイオン加熱が実験主導で新たに発見されたことは特筆に値する。