Power loads in the scrape-off layer of Wendelstein 7-X

The advanced stellarator Wendelstein 7-X has a five-fold symmetry and started its first campaign (OP1.1) with a limiter configuration in 2015. Five uncooled graphite limiter were placed periodically on the inboard side of the plasma vessel. This campaign was followed by a divertor campaign (OP1.2a) in 2017. The limiters were replaced by ten symmetrically positioned upper and lower uncooled divertors. Infrared camera systems were used in both campaigns to observe the surface temperature of the plasma facing components. From the measured evolution of the surface temperature the heat flux is evaluated with the THEODOR code. We measured heat fluxes up to 7-8 MW/m² on the limiter and up to 10 MW/m² on the divertor. The Double fall-off length was measured at the limiter with the narrow scrape-off layer(SOL) being of order of 8 mm and far SOL of order of 2 cm. The width of the SOL shows a clear scaling with connection length. In the divertor campaign the heat flux pattern varies strongly with the magnetic configuration. Depending on the configuration the local measured strike line width is in the range from around 1 cm to around 3 cm.