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

Autor(es)

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]

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: Physics of Plasmas; v. 24, n. 12 DEC 2017.
• Citações Web of Science: 13

Resumo

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)

• Processo FAPESP: 14/03289-4 - Teoria quase-linear da interação de partículas energéticas com automodos de Alfvén induzidos por toroidicidade
• Beneficiário: Vinícius Njaim Duarte
• Linha de fomento: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 12/22830-2 - Modos acústicos geodésicos e contínuo de Alfvén em colunas de plasma com rotação
• Beneficiário: Vinícius Njaim Duarte
• Linha de fomento: Bolsas no Brasil - Doutorado