Experimental Results and SOLPS-Modeling of H-Mode Detachment in full-tungsten ASDEX Upgrade

Detached divertor operation in H-Mode is essential for future fusion reactors to be able to handle the occuring power fluxes into the divertor and to avoid major material erosion of the divertor targets. Complete detachment is characterized by a substantial reduction of plasma pressure along a fieldline from midplane to target across the whole Scrape-Off Layer.

Complete detachment has only been observed at the inner target in the boronized full-tungsten wall tokamak ASDEX Upgrade so far. Recently, stable H-Mode operation with a completely detached plasma at both divertor targets has been achieved by significant nitrogen seeding. The pressure loss along the field line exceeded a factor of ten and the power flux was effectively reduced to negligible levels at both targets simultaneously. Tungsten sputtering at the targets is strongly reduced during detached plasma operation.

This contribution will highlight the experimental results and show the accessible operational space for nitrogen induced detachment in H-Mode. Accompanying SOLPS-modeling of the detachment process will be presented.