Electron temperature gradient driven transport model for tokamak plasmas

A new model for electron temperature gradient (ETG) modes is developed as a component of the multi-mode anomalous transport module [Rafiq et al., Phys Plasmas 20, 032506 (2013)] to predict a time-dependent electron temperature profile in conventional and low aspect ratio tokamaks. This model is base...

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Bibliographic Details
Published in:Physics of plasmas 2022-09, Vol.29 (9)
Main Authors: Rafiq, T., Wilson, C., Luo, L., Weiland, J., Schuster, E., Pankin, A. Y., Guttenfelder, W., Kaye, S.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Density gradients
Diffusivity
Electron energy
electron thermal transport
ETG
Low aspect ratio
NSTX
Plasma physics
Plasma pressure
Plasmas (physics)
quasilinear
Safety factors
Spherical tokamak
Temperature dependence
Temperature profiles
Thermal diffusivity
Tokamak devices
turbulence
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Summary:A new model for electron temperature gradient (ETG) modes is developed as a component of the multi-mode anomalous transport module [Rafiq et al., Phys Plasmas 20, 032506 (2013)] to predict a time-dependent electron temperature profile in conventional and low aspect ratio tokamaks. This model is based on two-fluid equations that govern the dynamics of low-frequency short- and long-wavelength electromagnetic toroidal ETG driven drift modes. A low collisionality NSTX discharge is used to scan the plasma parameter dependence on the ETG real frequency, growth rate, and electron thermal diffusivity. Electron thermal transport is discovered in the deep core region where modes are more electromagnetic in nature. Several previously reported gyrokinetic trends are reproduced, including the dependencies of density gradients, magnetic shear, β and gradient of β ( β ′ ), collisionality, safety factor, and toroidicity, where β is the ratio of the plasma pressure to the magnetic pressure. The electron heat diffusivity associated with the ETG mode is discovered to be on a scale consistent with the experimental diffusivity determined by power balance analysis.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0104672