Study of interaction between energetic ions and MHD instabilities in a helical plasma

螺旋等离子体中高能离子与 MHD 不稳定性之间相互作用的研究

• 批准号: 12480127
• 负责人: TOI Kazuo
• 金额: $ 5.89万
• 依托单位: National Institute for Fusion Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12480127/
• 关键词: energetic ions; Alfven eigenmodes; helical devices; energetic ion loss; shear Alfven soectrum; core-localized TAEs; helicity induced Alfven eigenmodes (HAEs); Alfven eigenmode spectroscopy; ヘリカルプラズマ; 高速イオン励起; HAE; バースト的モード; 内部輸送障壁; 高速周波数掃引

Characteristics of energetic ion driven MHD modes and their effects on energetic ion transport were studied in neutral-beam-injection (NBI) heated plasmas of the Large Helical Device(LHD). The following new and important results were obtained.(1) Two types of toroidicity-induced Alfven eigenmodes (TAEs) were observed. One is a core-localized TAE(C-TAE) of which TAE gap location is near the plasma center with low magnetic shear. The other is a global TAE of which gap location is in the outer portion of the minor plasma radius. In a few shots, C-TAEs with even and odd parity were simultaneously excited.(2) When the rotational transform at the plasma center exceeds a certain value, the relevant C-TAE has been converted to two global Alfven eigenmodes (GAEs) because the TAE gap is removed. This mode transition from C-TAE to GAE is also observed in a reversed shear configuration of the JT-60U tokamak.(3) In high beta plasmas, high frequency Alfven eigenmodes of which frequency is by eight times higher than the TAE gap frequency were observed. Comparison of the modes with the calculated shear Alfven spectra suggests that the high frequency mode is a helicity-induced Alfven eigenmode (HAE).(4) About 30-50 % of total energetic ions generated by NBI is transiently lost by bursting TAEs with rapid frequency chirping. The bursting TAEs often trigger the formation of internal transport barrier.In the Compact Helical system (CHS) heliotron/torsatron, TAEs were excited by external magnetic perturbations generated by the inserted electrodes into a low density and low temperature plasma without energetic ions. This experiment was carried out as a basic study ofAlfven eigenmodes in a helical plasma.This research project has demonstrated that the Alfven eigenmode spectroscopy using energetic ions and externally applied magnetic perturbations is very useful to study MHD properties of a helical plasma.

在大型螺旋装置（LHD）的中性注入（NBI）加热等离子体中研究了能量离子驱动的MHD模式及其对能量离子转运的影响。 （1）观察到两种类型的环形性肌动物（TAES）。一个是一个核心核心的TAE（C-TAE），其中TAE间隙位置在血浆中心附近，磁性剪切较低。另一个是一个全球TAE，其中缝隙位置位于小血浆半径的外部。在几次镜头中，具有均匀和奇数的C-TAE同时受到激发。（2）当等离子体中心的旋转变换超过一定值时，相关的C-TAE已转换为两个全局的Alfven Eigenmodes（GAES），因为删除了TAE间隙。在JT-60U TOKAMAK的反向剪切构型中也观察到了从C-TAE到GAE的模式过渡。（3）在高β等离子体中，观察到高频的高频Alfven eigenmodes，其频率比TAE间隙频率高八倍。将模式与计算出的剪切Alfven光谱进行比较表明，高频模式是螺旋性诱导的Alfven eigenmode（HAE）。（4）约有NBI产生的总能量离子的30-50％通过快速频率沿着快速频率挤压而瞬时损失。爆发的TAE经常会触发内部传输屏障的形成。在紧凑的螺旋系统（CHS）Heliotron/Torsatron中，TAE受到插入电极产生的外部磁扰动而激发的，将其插入了低密度和低温血浆，而无需富集式离子。该实验是作为螺旋血浆中钙本征模的基本研究进行的。该研究项目表明，使用能量离子的Alfven本征素光谱谱图和外部施加的磁扰动对于研究螺旋血浆的MHD特性非常有用。

项目成果

K.Toi: "Impact of Energetic Ion Driven Global Modes on Toroidal Plasma Confinement"Journal of Plasma and Fusion Research. SERIES 5. 50-56 (2002)

K.Toi：“高能离子驱动全局模式对环形等离子体约束的影响”等离子体与聚变研究杂志。

M.Takechi: "Transition of Toroidal Alfven Eigenmode to Global Alfven Eigenmode in CHS Heliotron/Torsatron"Journal of Plasma and Fusion Research. 78. 1273-1274 (2002)

M.Takechi：“CHS Heliotron/Torsatron 中环形阿尔文本征模式到全局阿尔文本征模式的转变”等离子体与聚变研究杂志。

S.Ohdachi: "High-Speed Tangentially Viewing Soft X-Ray Camera to Study Magnetohydrodynamic Fluctuations in Toroidally Confined Plasma"Reviews of Scientific Instruments. 74. 2136-2143 (2003)

S.Ohdachi：“高速切向观察软 X 射线相机研究环形受限等离子体中的磁流体动力波动”科学仪器评论。

K.Toi: "Energetic ion driven MHD instabilities observed in the heliotron/torsatron devices Compact Helical System and Large Helical Device"Nuclear Fusion. 40・7. 1349-1362 (2000)

K.Toi：“在日射管/扭转管装置紧凑螺旋系统和大型螺旋装置中观察到的高能离子驱动 MHD 不稳定性”核聚变 40・7 (2000)。

M. Takechi: "Transition of Toroidal Alfven Eigenmode to Global Alfven Eigenmode in CHS Heliotron/Torsatron"Jounal of Plasma and Fusion Research. Vol.78. 1273-1274 (2002)

M. Takechi：“CHS Heliotron/Torsatron 中环形阿尔文本征模式到全局阿尔文本征模式的转变”等离子与聚变研究杂志。