Study of chirping toroidicity-induced Alfvén eigenmodes in the National Spherical Torus Experiment
Study of chirping toroidicity-induced Alfvén eigenmodes in the National Spherical Torus Experiment
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DOI：
10.1088/0029-5515/52/9/094001
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发表时间：
2012-09
期刊：
影响因子：
3.3
通讯作者：
M. Podestà;R. Bell;A. Bortolon;N. Crocker;D. Darrow;A. Diallo;E. Fredrickson;Guoyong Fu;
中科院分区：
文献类型：
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作者：
M. Podestà;R. Bell;A. Bortolon;N. Crocker;D. Darrow;A. Diallo;E. Fredrickson;Guoyong Fu;
在国家球面环面实验(NSTX(Ono M.et al 2000 Nucl.))上，在中性束注入期间，啁啾环面诱导的Alfvén本征模(TAE)不稳定。核聚变40 557))，其速度高达阿尔芬速度的五倍。TEA表现出重复的幅度猝发和频率向下啁啾。更大的爆发，即所谓的TAE雪崩，最终被观测到，并与在∼1毫秒内损失高达30%的快离子有关。通过磁头线圈和多通道反射仪系统表征了TES的频率、幅度和径向结构。这些模式具有宽广的径向结构，似乎不受频率和幅度变化的影响。然而，较大的模式幅值确实通过有利于不同模式之间的耦合来影响模式的动力学。此外，这种耦合涉及类扭结模式，因此会降低热等离子体的约束。尽管TAE动力学具有非线性区域的特征，但测量的性质与理想MHD程序NOVA的解是合理一致的。
Chirping toroidicity-induced Alfvén eigenmodes (TAEs) are destabilized during neutral beam injection on the National Spherical Torus Experiment (NSTX (Ono M. et al 2000 Nucl. Fusion 40 557)) by super-Alfvénic ions with velocities up to five times larger than the Alfvén velocity. TAEs exhibit repeated bursts in amplitude and down-chirps in frequency. Larger bursts, so-called TAE avalanches, are eventually observed and correlate with a loss of fast ions up to 30% over ∼1 ms. Frequency, amplitude and radial structure of TAEs are characterized via magnetic pickup coils and a multi-channel reflectometer system. The modes have a broad radial structure, which appears to be unaffected by the large frequency and amplitude variations. However, the large mode amplitude does impact the modes' dynamics by favouring the coupling among different modes. In addition, the coupling involves kink-like modes and can therefore degrade the thermal plasma confinement. In spite of the non-linear regime characterizing the TAE dynamics, the measured properties are found to be in reasonable agreement with solutions from the ideal MHD code NOVA.