Unified modeling of both resonant and non-resonant neoclassical transport under non-axisymmetric magnetic perturbations in tokamaks

A numerical model for neoclassical transport under nonaxisymmetric magnetic perturbations in low collisionality plasmas in tokamaks is developed. To take into account bounce-drift resonances and magnetic drift effects, a Fourier decomposition of the drift kinetic equation in new coordinates, rather...

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Bibliographic Details
Published in:Physics of plasmas 2019-07, Vol.26 (7)
Main Authors: Sun, Y., Li, X., He, K., Shaing, K. C.
Format: Article
Language:English
Subjects:
Drift
Kinetic equations
Magnetic resonance
Mathematical analysis
Mathematical models
Model accuracy
Pitch (inclination)
Plasma physics
Plasmas (physics)
Tokamak devices
Transport
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Summary:A numerical model for neoclassical transport under nonaxisymmetric magnetic perturbations in low collisionality plasmas in tokamaks is developed. To take into account bounce-drift resonances and magnetic drift effects, a Fourier decomposition of the drift kinetic equation in new coordinates, rather than bounce average of it, is employed. A pitch angle scattering collisional operator is used to keep accuracy in the nonresonant regimes or resonant plateau regimes with resonant pitch near pitch space boundaries. Full toroidal geometry effects are also included to increase the accuracy in the modeling of neoclassical transport in the resonant regimes. Neoclassical transport in the most important collisionless regimes, including resonant super-banana plateau and bounce-drift resonances regimes, nonresonant 1/ν and ν − ν regimes, and the transitions between them, can be modeled simultaneously in this model by numerically solving the drift kinetic equation. By application to the neoclassical toroidal viscosity modeling in one discharge in the EAST tokamak, it is found that the bounce-drift resonances dominate the contributions near the plasma core where the plasma E → × B → drift frequency is close to the bounce frequency, while the precessional resonance dominates the contribution near the edge pedestal top where the E → × B → drift frequency is close to zero.
ISSN:1070-664X
1089-7674
DOI:10.1063/1.5099376