Speaker
Dr
Jan Horacek
(Institute of Plasma Physics)
Description
I’m reviewing a large European team progress in 2003-2018, showing inter-connections between various tokamak SOL turbulence studies. It is based mostly on tokamak TCV reciprocating probe data. Thanks to relatively high data quality we found interesting fractal properties in analogy with a sandpile [Graves’05, Horacek’05, Labit’07]. We cross-checked them with a 2D fluid turbulence plasma model ESEL with transport coefficients based on fundamental principles [Fundamenski’07]. This describes plasma turbulence (split into blobs), driven by fundamental interchange instability through gradients of the magnetic field and plasma pressure. This yielded many interlinked statistical benchmarks [Garcia’06, Pitts’07, Garcia’07] with especially the plasma density spatial profiles and its fluctuations we found described very well by this simple 2D turbulence model also on tokamak ASDEX Upgrade [Horacek’10]. We concluded later [Ondac’15], however, quite bad model description of both the potential and temperature profiles and fluctuations on both ASDEX Upgrade and COMPASS obtained by ball-pen probes [Adamek’10]. Even though we attempted joining ESEL with another 1D model [Havlickova’11], we stopped using ESEL as being too simplistic. Later we continued with a more complex 3D model [Halpern’13, Halpern’16] capable of quantifying the Near-SOL feature studied experimentally using tokamak TCV wall probes [Tsui’17] and IR camera [Nespoli’17] with practical implications towards ITER first wall design [Horacek’15, Kocan’15, Horacek’16] observed on COMPASS and another 10 tokamaks. Using extremely long probe time-series of TCV edge plasma turbulence, we argue that the established paradigm of the "long-range correlations" is false; rather the observed correlations are a pure statistical coincidence of uncorrelated blobs passing by a probe [Garcia’15, Theodorsen’16]. Extremely high TCV statistics allowed scaling of blob velocities [Tsui18] in four established edge plasma regimes.
Primary author
Dr
Jan Horacek
(Institute of Plasma Physics)
