SMuK 2021 – scientific programme

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P: Fachverband Plasmaphysik

P 17: Poster II

P 17.17: Poster

Friday, September 3, 2021, 14:00–16:00, P

Transport coefficients at W7-X based on target heat loads — •David Bold, Felix Reimold, Holger Niemann, Yu Gau, Marcin Jakubowski, and the W7-X team — Max-Planck-Institut für Plasmaphysik, Greifswald, Germany

In the current study the divertor heat load distribution of Wendelstein 7-X (W7-X) has been analysed based on heatfluxes reconstructed from infrared temperature measurements. Due to the inherent 3D nature of the scrape-off layer (SOL) of W7-X, also the heatflux pattern is 2D on the target in nature, unlike in Tokamaks, where a 1D representation is regularly used.

At low densities most of the heatflux is deposited on the low-iota target, as expected from modelling. A narrow strike line, overlayed by a broad feature is observed. The narrow strike line is of the range of 2 to 4 cm, while the broad feature is around 10 to 20 cm wide for an attached case with low radiated power. Additionally to studying the strike line width, also the toroidal distribution on the target is studied. It is observed that in the experiment a significant amount of the power is deposited at the far end of the low-iota target, while with increasing density the power is more evenly distributed on the low-iota target.

The analysis of the experimental data is compared to EMC3-EIRENE simulations, where the diffusion coefficients are varied in order to match the experimental results. It is observed that a simple, constant diffusion coefficient is not sufficient to reproduce the experimental measurements. The impact of spatially varying diffusion coefficients is studied.