Impact of fast ions on a trapped-electron-mode dominated plasma in a JT-60U hybrid scenario
Impact of fast ions on a trapped-electron-mode dominated plasma in a JT-60U hybrid scenario
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DOI：
10.1088/1741-4326/ab74a1
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发表时间：
2020-03
期刊：
影响因子：
3.3
通讯作者：
S. Mazzi;D. Zarzoso;J. Garcia;T. Görler;A. Siena;Y. Camenen;S. Benkadda;M. Yoshida;N. Hayashi;K. Shinohara
中科院分区：
文献类型：
--
作者：
S. Mazzi;D. Zarzoso;J. Garcia;T. Görler;A. Siena;Y. Camenen;S. Benkadda;M. Yoshida;N. Hayashi;K. Shinohara
对JT-60U等离子体在高磁剪切和低磁剪切力下的线性和非线性回转动力学模拟，分析了快离子对俘获电子模的影响。首次证明了瞬变电子显微镜诱导的湍流输运不受中性束注入产生的陡峭的快离子压强分布的影响。与最近观察到的离子温度梯度(ITG)引起的快离子引起的湍流输运减少不同，瞬变电磁主导的系统在存在显著的快离子群时可以表现出不同的行为。分析了纬向流作为饱和机制的可能作用，表明它们在报告的JT-60U情景中的微弱影响可能导致快离子相对于以ITG为主的放电的不同行为。结果还表明，Alfvénic剪切模在低波数()时失稳。它们被确认为由ITG失稳的漂移Alfvén波，这是AlfvéNic ITG不稳定性的一种形式。深入的数值分析提供了ITG驱动的BAE稳定的物理参数范围。这些结果为量身定做未来的实验方案开辟了新的可能性，以便从快离子减少传输中受益。
The impact of fast ions on a trapped electron mode (TEM) is extensively analysed by linear and nonlinear gyrokinetic simulations for a JT-60U plasma at high and low magnetic shear using the Gene code in local approximation. For the first time, it is shown that TEM-induced turbulent transport may remain unaffected by the steep fast ion pressure profile generated by the neutral beam injection. Unlike recent observations of ion temperature gradient (ITG)-induced turbulent transport reductions due to fast ions, TEM-dominated systems could act differently in the presence of a significant fast ion population. The possible role of zonal flows as a saturation mechanism is analyzed, showing that their weak impact in the reported JT-60U scenario might lead to different behaviour of fast ions with respect to the ITG-dominated discharges. It is also shown that Alfvénic shear modes are destabilized at low wave numbers (). They are identified as drift Alfvén waves destabilized by ITG, which is a form of Alfvénic ITG instabilities. Deep numerical analysis provides the physical parameter range in which ITG-driven BAEs are stabilized. These results open the way to new possibilities of tailoring future experimental scenarios in order to benefit from transport reduction by fast ions.