Core-localized Alfvénic modes driven by energetic ions in HL-2A NBI plasmas with weak magnetic shears
Core-localized Alfvénic modes driven by energetic ions in HL-2A NBI plasmas with weak magnetic shears
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DOI：
10.1088/0029-5515/56/3/036018
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发表时间：
2016-02
期刊：
影响因子：
3.3
通讯作者：
W. Chen;L.M. Yu;X. Ding;H. Xie;Z. Shi;X. Ji;D. L. Yu;Y.P. Zhang;P. Shi;Y.G. Li;B. Feng;M. Jiang;W. Zhong;J.Y. Cao;X. Song;M. Xu;Y.H. Xu;L.W. Yan;Yi Liu;Q.W. Yang;X. Duan
中科院分区：
文献类型：
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作者：
W. Chen;L.M. Yu;X. Ding;H. Xie;Z. Shi;X. Ji;D. L. Yu;Y.P. Zhang;P. Shi;Y.G. Li;B. Feng;M. Jiang;W. Zhong;J.Y. Cao;X. Song;M. Xu;Y.H. Xu;L.W. Yan;Yi Liu;Q.W. Yang;X. Duan
报道了HL-2A中性束注入等离子体中弱磁剪切下的芯局域（即归一化半径ρ=r/a）Alfvénic模的最新实验结果。在不同的等离子体参数范围内，NBI产生的高能离子驱动多种Alfvénic不稳定性，如环形Alfvén本征模（TAE）、β诱导Alfvén本征模、反向剪切Alfvén本征模（RSAE）和鱼骨状高能粒子模（FSE）。在这里，我们专注于高频RSAE（HFRSAE）和共振动力学气球模式（rKBM）。一组下扫频率相干模（HFRSAE），100。分析表明，这些模式本地化内的高阶阿尔文本征模（AE）间隙的阿尔文连续，其本征频率和本征函数依赖于qmin？> Q-profile。当堆芯等离子体密度大于3.0\times {{10}^{19}}$？> ne0>3.0×1019？> m−3时，等离子体密度/压力分布出现峰值，磁剪切为弱或负值。在这种情况下，一组具有30的多谐波相干模式（rKBM）是热离子的抗磁漂移频率。发现当密度分布突然达到峰值时，HFRSAE可以过渡到rKBM。真空室外的中子监测表明，HFRSAE和rKBM都降低了高能离子的约束。rKBM不稳定性也影响体等离子体性能。
Recent experimental results that are associated with the core-localized (i.e. normalized radius ρ=r/a) Alfvénic modes in HL-2A neutral beam injection (NBI) plasmas with weak magnetic shears are reported. In the different plasma parameter regions, the energetic ions produced by the NBI drive multiple Alfvénic instabilities, such as the toroidal Alfvén eigenmode (TAE), beta-induced Alfvén eigenmode, reversed shear Alfvén eigenmode (RSAE) and fishbone and energetic particle mode (EPM). Here, we focus on the high-frequency RSAE (HFRSAE) and resonant kinetic ballooning mode (rKBM). A group of downward-sweeping frequency coherent modes (HFRSAEs) with 100 . The analysis suggests that these modes localize inside the high-order Alfvén eigenmode (AE) gap of the Alfvénic continuum, and their eigenfrequency and eigenfunction depend on the qmin ?> and q-profile. When the core plasma density is more than 3.0\times {{10}^{19}}$ ?>ne0>3.0×1019 ?> m−3 and the impurity or supersonic molecular beam enters the bulk plasma, the profiles of the plasma density/pressure peak, and the magnetic shear is weak or negative. In this case, a group of multi-harmonic coherent modes (rKBMs) with 30 is the diamagnetic drift frequency of the thermal ion. It is found that the HFRSAEs can transit into the rKBMs when the density profile suddenly peaks. Neutron monitoring outside the vacuum chamber demonstrates that the HFRSAE and rKBM both degrade the confinement of the energetic ions. The rKBM instabilities also affect the bulk plasma performance.