Observations of the effect of lower hybrid waves on ELM behaviour in EAST
Observations of the effect of lower hybrid waves on ELM behaviour in EAST
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低混合波对 EAST 中 ELM 行为影响的观测
DOI：
10.1088/0029-5515/55/3/033012
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发表时间：
2015-03
期刊：
影响因子：
3.3
通讯作者：
Gong, X. Z.
中科院分区：
文献类型：
--
作者：
Zhao, N.;Liu, S. C.;Kong, D. F.;Gong, X. Z.
在EAST 2012年的实验活动中，通过调制以离子回旋共振加热为主的高限制模(H模)等离子体中的低杂波输入功率，首次开展了低杂波对边缘局域模(ELM)影响的专门实验。在相当大的等离子体电流或边缘安全系数范围内，施加低杂波可以有效地缓解自然ELM(ELM频率增加，而其强度急剧下降)。通过扫描低杂波注入功率在目标等离子体中的调制频率(FM)，我们得出结论：在低调制频率(Fm<；100 Hz)下，可以重现幅度明显较大、频率较低的大ELM。对边缘极紫外辐射信号演化的分析进一步表明，基座区域的等离子体波动对低杂波注入功率的快速调制(FM⩾100 Hz)响应不明显。这被认为是低杂波对大榆树的缓解效应的FM依赖性的机制。此外，还估算了低杂波输入功率PLHW的临界阈值，超过这个临界值可以得到外加低杂波对ELM行为的影响。最后，朗缪尔探测器的测量表明，在ELM碰撞之前，通常观察到的自由能集中到窄带准相干前兆中的情况并不是这样，而是在ELM消失阶段随着LHW的应用而持续发展的宽带湍流可能有助于避免ELM碰撞。这些结果为现有的实验提供了新的见解，也为下一步更深入地探索和改进这一新的有吸引力的方法以有效控制ELM诱导的非常大的瞬时热和粒子通量提供了一些基础和参考。
Dedicated experiments focusing on the influence of lower hybrid waves (LHWs) on edge-localized modes (ELMs) were first performed during the 2012 experimental campaign of EAST, via modulating the input power of LHWs in the high-confinement-mode (H-mode) plasma mainly sustained by ion cyclotron resonant heating. Natural ELMs are effectively mitigated (ELM frequency increases, while its intensity decreases dramatically) as the LHW is applied, observed over a fairly wide range of plasma current or edge safety factor. By scanning the modulation frequency (fm) of LHW injected power in a target plasma dominated by the so-called small ELMs, we conclude that large ELMs with markedly larger amplitudes and lower frequencies are reproduced at low modulation frequencies (fm < 100 Hz). Analysis of the evolution of edge extreme ultraviolet radiation signals further indicates that plasma fluctuations at the pedestal region indistinctively respond to rapid modulation (fm ⩾ 100 Hz) of LHW injected power. This is proposed as the mechanism responsible for the observed fm dependence of the mitigation effect induced by LHWs on large ELMs. In addition, a critical threshold of LHW input power PLHW is estimated as , beyond which the impact of applied LHWs on ELM behaviours can be achieved. Finally, Langmuir probe measurements suggest that, rather than the concentration of free energy into a narrowband quasi-coherent precursor commonly observed growing until the ELM crash, the continuous development of broadband turbulence during the ELM-absent phase with the application of LHWs might contribute to the avoidance of ELM crashes. These results present new insights into existing experiments, and also provide some foundations and references for the next-step research about exploring in more depth and improving this new attractive method to effectively control the ELM-induced very large transient heat and particle flux.
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影响因子：
1.6
作者：
M. Jakubowski;T. Evans;M. Fenstermacher;C. Lasnier;O. Schmitz;R. Wolf;L. Baylor;J. Boedo;K. Burrell;H. Frerichs;J. Degrassie;P. Gohil;S. Mordijck;R. Moyer;A. Leonard;D. Reiter;U. Samm;M. Schaffer;T. Osborne;E. Unterberg;J. Watkins
通讯作者：
M. Jakubowski;T. Evans;M. Fenstermacher;C. Lasnier;O. Schmitz;R. Wolf;L. Baylor;J. Boedo;K. Burrell;H. Frerichs;J. Degrassie;P. Gohil;S. Mordijck;R. Moyer;A. Leonard;D. Reiter;U. Samm;M. Schaffer;T. Osborne;E. Unterberg;J. Watkins
影响因子：
3.3
作者：
G. Mckee;Z. Yan;C. Holland;R. Buttery;T. Evans;R. Moyer;S. Mordijck;R. Nazikian;T. Rhodes;O. Schmitz;M. Wade
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G. Mckee;Z. Yan;C. Holland;R. Buttery;T. Evans;R. Moyer;S. Mordijck;R. Nazikian;T. Rhodes;O. Schmitz;M. Wade
影响因子：
2.2
作者：
M. Greenwald
通讯作者：
M. Greenwald
影响因子：
2.2
作者：
Huiqian Wang;Gang Xu;Houyang Y Guo;B. Wan;L. Wang;Rende Chen;S. Ding;N. Yan;X. Gong;Shaocheng Liu;L. Shao;Longwei Chen;Wei Zhang;Y. Liang;G. Hu;Y. Liu;Yingying Li;N. Zhao
通讯作者：
Huiqian Wang;Gang Xu;Houyang Y Guo;B. Wan;L. Wang;Rende Chen;S. Ding;N. Yan;X. Gong;Shaocheng Liu;L. Shao;Longwei Chen;Wei Zhang;Y. Liang;G. Hu;Y. Liu;Yingying Li;N. Zhao
影响因子：
1.6
作者：
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通讯作者：
T. Evans;R. Roeder;J. Carter;B. I. Rapoport