Bochum 2015 – scientific programme
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P: Fachverband Plasmaphysik
P 16: Poster Session - Helmholtz Graduate School for Plasma Physics
P 16.10: Poster
Tuesday, March 3, 2015, 16:30–18:30, Foyer Audimax
Change of the SOL power width with the toroidal B-field direction in ASDEX Upgrade — •Michael Faitsch, Thomas Eich, Bernhard Sieglin, Hong-Juan Sun, Albrecht Herrmann, and The Asdex Upgrade team — Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, D-85748 Garching, Germany
The change of the scrape-off layer power width in dependence on the toroidal magnetic field direction has been investigated in L-mode discharges in upper single null (USN) configuration in ASDEX Upgrade. The heat flux onto the outer and inner divertor plates was measured using a fast 2D infrared camera. The heat flux distribution is described by an exponential power fall-off length λq and a diffusive broadening in the divertor region S. The parameters, S and λq, for the inner and outer divertor target are compared for both toroidal magnetic field directions. For the divertor broadening S no dependence on the toroidal magnetic field direction is observed. The comparison between the near scrape-off layer electron temperature fall-off length λTe and the power fall-off length λq are in agreement with the 2-point model. Therefore it is concluded that electron conduction is the main contribution for the scrape-off layer parallel transport in this discharges. The ratio between inner, λqinner, and outer, λqouter, power fall-off length λq is dependent on the toroidal magnetic field direction. The numerical values are λqinner/λqouter = 0.44 for favourable B × ∇ B ion drift direction and λqinner/λqouter = 0.85 for non-favourable drift direction. The different ratios are explained assuming vertical drifts, which are dependent on the toroidal magnetic field direction.