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arXiv · 1610.05059

Prediction of Nonlinear Evolution Character of Energetic-Particle-Driven Instabilities

Vinicius Duarte·Herbert Berk·Nikolai Gorelenkov·William Heidbrink·Gerrit Kramer·Raffi Nazikian·David Pace·Mario Podesta·Benjamin Tobias·Michael Van Zeeland
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Abstract

A general criterion is proposed and found to successfully predict the emergence of chirping oscillations of unstable Alfv\'enic eigenmodes in tokamak plasma experiments. The model includes realistic eigenfunction structure, detailed phase-space dependences of the instability drive, stochastic scattering and the Coulomb drag. The stochastic scattering combines the effects of collisional pitch angle scattering and micro-turbulence spatial diffusion. The latter mechanism is essential to accurately identify the transition between the fixed-frequency mode behavior and rapid chirping in tokamaks and to resolve the disparity with respect to chirping observation in spherical and conventional tokamaks.

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Vinicius Duarte, Herbert Berk, Nikolai Gorelenkov, William Heidbrink, Gerrit Kramer, Raffi Nazikian, David Pace, Mario Podesta, Benjamin Tobias, Michael Van Zeeland. 2016-10-17. Prediction of Nonlinear Evolution Character of Energetic-Particle-Driven Instabilities. https://doi.org/10.1088/1741-4326/aa6232

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