Electric field and turbulence in first global simulations across ASDEX Upgrade edge and scrape-off layer with GRILLIX

ASDEX Upgrade Seminar

  • Datum: 14.09.2020
  • Uhrzeit: 12:20 - 14:00
  • Vortragende(r): Wladimir Zholobenko
  • Ort: Garching
  • Raum: Zoom
  • Gastgeber: IPP
W Zholobenko: Electric field and turbulence in first global simulations across ASDEX Upgrade edge and scrape-off layer with GRILLIX
Abstract:
Turbulence simulations in diverted geometry across the edge and scrape-off layer (SOL) of ASDEX Upgrade are performed with the GRILLIX code. The underlying global (full-f) drift-reduced Braginskii model allows to concurrently study the self-consistent dynamics of the turbulence and the background as well as the evolution of toroidal and zonal flows. Different contributions to the radial electric field are identified. The dominant contribution on closed flux surfaces comes from the ion pressure gradient, due to the diamagnetic drift in the curved magnetic field. Large deviations can be induced, in particular, by the polarization particle flux, leading to zonal flows. The latter are driven by small-scale eddies, but do not exhibit much impact on the overall transport which is driven by ballooning modes at larger scales. The zonal flow drive peaks at the separatrix, where a strong shear layer forms due to the sheath-induced counter-propagating SOL flow, allowing for the formation of a transport barrier. In this context, we also discuss the role of ion viscosity and parallel electron and ion heat conductivities.
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