Three-Dimensional Inhomogeneity of Electron-Temperature-Gradient Turbulence in the Edge of Tokamak Plasmas

Abstract

Nonlinear multiscale gyrokinetic simulations of a Joint European Torus edge pedestal are used to show that electron-temperature-gradient (ETG) turbulence has a rich three-dimensional structure, varying strongly according to the local magnetic-field configuration. In the plane normal to the magnetic field, the steep pedestal electron temperature gradient gives rise to anisotropic turbulence with a radial (normal) wavelength much shorter than in the binormal direction. In the parallel direction, the location and parallel extent of the turbulence are determined by the variation in the magnetic drifts and finite-Larmor-radius (FLR) effects. The magnetic drift and FLR topographies have a perpendicular-wavelength dependence, which permits turbulence intensity maxima near the flux-surface top and bottom at longer binormal scales, but constrains turbulence to the outboard midplane at shorter electron-gyroradius binormal scales. Our simulations show that long-wavelength ETG turbulence does not transport heat efficiently, and significantly decreases overall ETG transport -- in our case by $\sim$40 \% -- through multiscale interactions.

17 pages, 14 figures

References in corpus (4)

• Reduced models for ETG transport in the pedestal
• Electromagnetic instabilities and plasma turbulence driven by electron-temperature gradient
• A Scale-Separated Approach for Studying Coupled Ion and Electron Scale Turbulence
• A novel approach to radially global gyrokinetic simulation using the flux-tube code $\text{stella}$

Cited by in corpus (4)

• An analytical form of the dispersion function for local linear gyrokinetics in a curved magnetic field
• Advanced surrogate model for electron-scale turbulence in tokamak pedestals
• Suppression of temperature-gradient-driven turbulence by sheared flows in fusion plasmas
• Scale invariance and critical balance in electrostatic drift-kinetic turbulence