Gyrokinetic modelling of the Alfvén mode activity in ASDEX Upgrade with an isotropic slowing-down fast-particle distribution

In the present paper, the evolution of the Alfvén modes is studied in a realistic ASDEX Upgrade equilibrium by analysing the results of simulations with the global, electromagnetic, gyrokinetic particle-in-cell code ORB5. The energetic particles are modelled both via the newly implemented isotropic...

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Bibliographic Details
Published in:arXiv.org 2022-03
Main Authors: Vannini, Francesco, Biancalani, Alessandro, Bottino, Alberto, Hayward-Schneider, Thomas, Lauber, Philipp, Mishchenko, Alexey, Poli, Emanuele, Brando Rettino, Vlad, Gregorio, wang, Xin, ASDEX Upgrade team
Format: Article
Language:English
Subjects:
Distribution functions
Energetic particles
Equivalence
Maxwellian distribution
Particle in cell technique
Online Access:Get full text
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Summary:In the present paper, the evolution of the Alfvén modes is studied in a realistic ASDEX Upgrade equilibrium by analysing the results of simulations with the global, electromagnetic, gyrokinetic particle-in-cell code ORB5. The energetic particles are modelled both via the newly implemented isotropic slowing-down and with Maxwellian distribution functions. The comparison of the numerical results shows that modelling the energetic particles with the equivalent Maxwellian rather than with the slowing-down, does not affect the frequency of the driven Alfvén mode, while its growth rate appears to be underestimated with a quantitative difference as large as almost 30 %. Additionally the choice of the isotropic slowing-down allows a better description of the nonlinear modification of the dominant Alfvén mode frequency, while an equivalent Maxwellian underestimates it. A good comparison with the experimental spectrogram is found.
ISSN:2331-8422
DOI:10.48550/arxiv.2203.01162