The Coupling Structure Features Between (2,1) NTM and (1,1) Internal Mode in EAST Tokamak

In the discharge of EAST tokamak, it is observed that (2,1) neoclassical tearing mode (NTM) is triggered by mode coupling with a (1,1) internal mode. Using singular value decomposition (SVD) method for soft X-ray emission and for electron cyclotron emission (ECE), the coupling spatial structures and...

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Bibliographic Details
Published in:Plasma science & technology 2015-05, Vol.17 (5), p.358-365, Article 358
Main Authors: Shi, Tonghui, Wan, Baonian, Sun, Youwen, Shen, Biao, Qian, Jinping, Hu, Liqun, Chen, Kaiyun, Liu, Yong
Format: Article
Language:English
Subjects:
Amplitudes
Coupling
Discharge
Emission analysis
Singular value decomposition
Statistical analysis
Tearing
Tokamak devices
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Summary:In the discharge of EAST tokamak, it is observed that (2,1) neoclassical tearing mode (NTM) is triggered by mode coupling with a (1,1) internal mode. Using singular value decomposition (SVD) method for soft X-ray emission and for electron cyclotron emission (ECE), the coupling spatial structures and coupling process between these two modes are analyzed in detail. The results of SVD for ECE reveal that the phase difference between these two modes equals to zero. This is consistent with the perfect coupling condition. Finally, performing statistical analysis of r sub(1/1), xi sub(1/1) and w sub(2/1), we find that r sub(1/1) more accurately represents the coupling strength than xi sub(1/1), and r sub(1/1) is also strongly related to the (2,1) NTM triggering, where r sub(1/1) is the width of (1,1) internal mode, xi sub(1/1) is the perturbed amplitude of (1,1) internal mode, and w sub(2/1) denot es the magnetic island width of (2,1) NTM.
ISSN:1009-0630
DOI:10.1088/1009-0630/17/5/02