Weak effect of ion cyclotron acceleration on rapidly chirping beam-driven instabilities in the National Spherical Torus Experiment
Weak effect of ion cyclotron acceleration on rapidly chirping beam-driven instabilities in the National Spherical Torus Experiment
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DOI：
10.1088/0741-3335/48/9/006
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发表时间：
2006-09
影响因子：
2.2
通讯作者：
W. Heidbrink;E. Ruskov;E. Fredrickson;N. Gorelenkov;S. Medley;H. Berk;R. Harvey
中科院分区：
文献类型：
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作者：
W. Heidbrink;E. Ruskov;E. Fredrickson;N. Gorelenkov;S. Medley;H. Berk;R. Harvey
对国家球形环实验中的快离子分布函数进行了修正，使总注入功率保持在1.2MW。不同能量和切线半径的氘束注入氦L模等离子体，产生丰富的不稳定性，包括压缩阿尔文本征模，环形诱导阿尔文本征模（TAE），50-100 kHz快速频率扫描或啁啾的不稳定性，以及强的低频（10-20 kHz）鱼骨。该实验的动机是由一个理论，属性的频率啁啾形成的孔和团块在相空间。在理论上，增加驱动不稳定性的快离子的有效碰撞频率可以抑制频率啁啾。在实验中，高功率（1.3MW）高谐波快波（HHFW）加热加速快离子，试图改变非线性动力学。稳态频率TAE模式在HHFW加热过程中减少，但几乎没有证据表明频率啁啾被抑制。
The fast-ion distribution function in the National Spherical Torus Experiment is modified from shot to shot while keeping the total injected power at ∼2 MW. Deuterium beams of different energy and tangency radius are injected into helium L-mode plasmas, producing a rich set of instabilities, including compressional Alfvén eigenmodes, toroidicity-induced Alfvén eigenmodes (TAE), 50–100 kHz instabilities with rapid frequency sweeps or chirps, and strong, low frequency (10–20 kHz) fishbones. The experiment was motivated by a theory that attributes frequency chirping to the formation of holes and clumps in phase-space. In the theory, increasing the effective collision frequency of the fast ions that drive the instability can suppress frequency chirping. In the experiment, high-power (≲3 MW) high harmonic fast wave (HHFW) heating accelerates the fast ions in an attempt to alter the nonlinear dynamics. Steady-frequency TAE modes diminish during the HHFW heating but there is little evidence that frequency chirping is suppressed.