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

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.5007811· OSTI ID:1414903
 [1];  [2];  [3];  [4];  [3];  [3]; ORCiD logo [5]; ORCiD logo [3];  [5]
  1. Univ. of Sao Paulo (Brazil). Inst. of Physics; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies
  3. Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. Univ. of California, Irvine, CA (United States)
  5. General Atomics, San Diego, CA (United States)

Alfvén 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. Furthermore, 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 Alfvén-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 Alfvénic 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. We proposed a criterion that 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.

Research Organization:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
2012/22830-2; 2014/03289-4; AC02-09CH11466; FC02-04ER54698
OSTI ID:
1414903
Alternate ID(s):
OSTI ID: 1413027
Journal Information:
Physics of Plasmas, Vol. 24, Issue 12; ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 19 works
Citation information provided by
Web of Science

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Cited By (14)

Discrepancy between estimated and measured fusion product rates on MAST using TRANSP/NUBEAM journal November 2018
Stochastic effects on phase-space holes and clumps in kinetic systems near marginal stability journal June 2018
Study of the likelihood of Alfvénic mode bifurcation in NSTX and predictions for ITER baseline scenarios journal June 2018
Collisional enhancement of energetic particle Alfvénic resonance width in tokamaks journal March 2019
Energetic-particle-modified global Alfvén eigenmodes journal April 2018
A simple model for perturbative kinetic particle resonances in tokamaks journal April 2019
Verification and application of resonance broadened quasi-linear (RBQ) model with multiple Alfvénic instabilities journal July 2019
Collisional resonance function in discrete-resonance quasilinear plasma systems journal December 2019
Resonance frequency broadening of wave-particle interaction in tokamaks due to Alfvénic eigenmode journal June 2018
NSTX/NSTX-U theory, modeling and analysis results journal June 2019
Resonance broadened quasi-linear (RBQ) model for fast ion distribution relaxation due to Alfvénic eigenmodes journal June 2018
Analytical nonlinear collisional dynamics of near-threshold eigenmodes journal February 2019
Modeling of chirping toroidal Alfvén eigenmodes in NSTX journal September 2019
Study of the likelihood of Alfvénic mode bifurcation in NSTX and predictions for ITER baseline scenarios text January 2018