Three-dimensional inhomogeneity of electron-temperature-gradient turbulence in the edge of tokamak plasmas

JET Contributors

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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 ∼40%-through multiscale interactions.

Original languageEnglish (US)
Article number086045
JournalNuclear Fusion
Volume62
Issue number8
DOIs
StatePublished - Aug 2022

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Keywords

  • electron-temperature-gradient instability
  • magnetic geometry
  • multiscale turbulence
  • pedestal turbulence
  • plasma turbulence
  • tokamaks
  • topography of turbulence

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