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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Theory and observation of the onset of nonlinear structures due to eigenmode destabilization by fast ions in tokamaks

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Duarte, V. N. [1, 2] ; Berk, H. L. [3] ; Gorelenkov, N. N. [2] ; Heidbrink, W. W. [4] ; Kramer, G. J. [2] ; Nazikian, R. [2] ; Pace, D. C. [5] ; Podesta, M. [2] ; Van Zeeland, M. A. [5]
Total Authors: 9
[1] Univ Sao Paulo, Inst Phys, BR-05508090 Sao Paulo, SP - Brazil
[2] Princeton Univ, Princeton Plasma Phys Lab, Princeton, NJ 08543 - USA
[3] Univ Texas Austin, Inst Fus Studies, Austin, TX 78712 - USA
[4] Univ Calif Irvine, Irvine, CA 92697 - USA
[5] Gen Atom, San Diego, CA 92186 - USA
Total Affiliations: 5
Document type: Journal article
Source: Physics of Plasmas; v. 24, n. 12 DEC 2017.
Web of Science Citations: 14

Alfven waves can induce the ejection of fast ions in different forms in tokamaks. In order to develop predictive capabilities to anticipate the nature of fast ion transport, a methodology is proposed to differentiate the likelihood of energetic-particle-driven instabilities to produce frequency chirping or fixed-frequency oscillations. The proposed method employs numerically calculated eigenstructures and multiple resonance surfaces of a given mode in the presence of energetic ion drag and stochasticity (due to collisions and micro-turbulence). Toroidicity-induced, reversed-shear and beta-induced Alfven-acoustic eigenmodes are used as examples. Waves measured in experiments are characterized, and compatibility is found between the proposed criterion predictions and the experimental observation or lack of observation of chirping behavior of Alfvenic modes in different tokamaks. It is found that the stochastic diffusion due to micro-turbulence can be the dominant energetic particle detuning mechanism near the resonances in many plasma experiments, and its strength is the key as to whether chirping solutions are likely to arise. The proposed criterion constitutes a useful predictive tool in assessing whether the nature of the transport for fast ion losses in fusion devices will be dominated by convective or diffusive processes. Published by AIP Publishing. (AU)

FAPESP's process: 14/03289-4 - Quasilinear theory of energetic particles interaction with toroidicity-induced Alfvén eigenmodes
Grantee:Vinícius Njaim Duarte
Support Opportunities: Scholarships abroad - Research Internship - Doctorate
FAPESP's process: 12/22830-2 - Geodesic Acoustic Modes and Alfvén Continuum in Plasma Columns with Rotation
Grantee:Vinícius Njaim Duarte
Support Opportunities: Scholarships in Brazil - Doctorate