Gyrokinetic flux-driven simulations in mixed TEM/ITG regime using a delta-f PIC scheme with evolving background

In the context of global gyrokinetic simulations of turbulence using a particle-in-cell framework, verifying the delta-f assumption with a fixed background distribution becomes challenging when determining quasi-steady state profiles corresponding to given sources over long time scales, where plasma...

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Bibliographic Details
Published in:Physics of plasmas 2024-11, Vol.31 (11)
Main Authors: Murugappan, M., Villard, L., Brunner, S., Di Giannatale, G., McMillan, B. F., Bottino, A.
Format: Article
Language:English
Subjects:
Adaptive sampling
Background noise
Noise levels
Quasi-steady states
Temperature dependence
Temperature profiles
Time dependence
Turbulence
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Summary:In the context of global gyrokinetic simulations of turbulence using a particle-in-cell framework, verifying the delta-f assumption with a fixed background distribution becomes challenging when determining quasi-steady state profiles corresponding to given sources over long time scales, where plasma profiles can evolve significantly. The advantage of low relative sampling noise afforded by the delta-f scheme is shown to be retained by considering the background as a time-evolving Maxwellian with time-dependent density and temperature profiles. Implementation of this adaptive scheme to simulate electrostatic collisionless flux-driven turbulence in tokamak plasmas show small and nonincreasing sampling noise levels, which would otherwise increase indefinitely with a stationary background scheme. The adaptive scheme furthermore allows one to reach numerically converged results of quasi-steady state with much lower marker numbers.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0233727