Berlin 2014 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 30: Plasma Wall Interactions

P 30.8: Vortrag

Freitag, 21. März 2014, 16:00–16:15, SPA HS202

Turbulence evaluation at PSI-2 by fast visible imaging — •Michael Hubeny, Michael Reinhart, Alexander Huber, and Bernhard Unterberg — Institute for Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH, EURATOM Association, Germany

Turbulent transport in the plasma edge poses a critical challenge for fusion reactors due to the high heat and particle fluxes on plasma facing components. Various chemical and physical processes lead to a deterioration of the surface morphology as well as the inner structure of wall materials. These processes depend strongly on the temperature and density of particles in their onset-threshold region. The turbulent, intermittent structures found in the edge of toroidal machines are also present in linear plasma devices, which running steady state, makes them ideal for studying properties of turbulence.

A fast CMOS camera with a typical time resolution of several 100.000 fps can resolve short turbulent events (blobs) in the linear plasma device PSI-2. Movies of the plasma were taken perpendicular from a side port and axial through the hollow plasma source.

Properties of the intermittent transport are evaluated by conditional averaging and other statistical methods to investigate the dependence of turbulence on discharge parameters and working gases. Intermittent transport events show a strong correlation to the global plasma rotation, thus they might be triggered by an m=1 instability, which appears as a 4 and 8 kHz Fourier component. The profile of the skewness supports the presence of blobs just outside of the density maximum.