Gyrokinetic modelling of anisotropic energetic particle driven instabilities in tokamak plasmas

Energetic particles produced by neutral beams are observed to excite energetic-particle-driven geodesic acoustic modes (EGAMs) in tokamaks. We study the effects of anisotropy of distribution function of the energetic particles on the excitation of such instabilities with ORB5, a gyrokinetic particle...

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Bibliographic Details
Published in:arXiv.org 2022-01
Main Authors: Brando Rettino, Hayward-Schneider, Thomas, Biancalani, Alessandro, Bottino, Alberto, Lauber, Philipp, Chavdarovski, Ilija, Vannini, Francesco, Jenko, Frank
Format: Article
Language:English
Subjects:
Anisotropy
Distribution functions
Energetic particles
Neutral beams
Particle beams
Particle in cell technique
Plasmas (physics)
Stability analysis
Tokamak devices
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Summary:Energetic particles produced by neutral beams are observed to excite energetic-particle-driven geodesic acoustic modes (EGAMs) in tokamaks. We study the effects of anisotropy of distribution function of the energetic particles on the excitation of such instabilities with ORB5, a gyrokinetic particle-in-cell code. Numerical results are shown for linear electrostatic simulations with ORB5. The growth rate is found to be sensitively dependent on the phase-space shape of the distribution function. The behavior of the instability is qualitatively compared to the theoretical analysis of dispersion relations. Realistic neutral beam energetic particle anisotropic distributions are obtained from the heating solver RABBIT and are introduced into ORB5 as input distribution function. Results show a dependence of the growth rate on the injection angle. A qualitative comparison to experimental measurements is presented and few disagreements between them are found, being the growth rate in the simulations much lower than that from experiments. An explanation for the difference is advanced.
ISSN:2331-8422
DOI:10.48550/arxiv.2201.03836