Speaker
Dr
Peter Manz
(Max-Planck-Institut für Plasmaphysik)
Description
Transport codes such as SOLPS, EDGE2D, EMC3, SOLedge2D and UEDGE are still the main workhorses for scrape-off layer (SOL) investigations.
They are based on a diffusive description of the turbulent transport, where the transport is proportional to the mean gradient.
In particular in the far-SOL or at high densities where a density shoulder is formed the mean gradients are flattened
out and strong events cannot be locally excited. However, in
particular in the far-SOL or at high densities strong fluctuation
levels are observed. It is well known that these strong events
called plasma blobs or filaments are generated in the plasma edge around the separatrix and propagate into the far SOL.
Therefore, the plasma edge as the driving region has to be coupled to the SOL. This makes
SOL transport intrinsically nonlocal.
Usually, filamentary
transport can be included by a convective term in the transport model. This in principle allows for transport across the flat gradient region. It will be shown that such a description faces problems once
the perpendicular transport competes with the parallel transport.
The transport
of fluctuation amplitude is called turbulence spreading.
In magnetically confined plasma physics
turbulence spreading and nonlocal transport has been mainly investigated in the core in the context of zonal flow and pinch physics as well as heat transport phenomena. In the scape-off layer
exhibiting low gradients and high fluctuation amplitudes this
phenomenon has been rarely considered so far.
In the present contribution
it will be shown how nonlocal transport and turbulence spreading
can be quantified and modeled with application to scrape-off-layer plasmas.
Primary author
Dr
Peter Manz
(Max-Planck-Institut für Plasmaphysik)
