Highlights 2015

Experimental investigations and numerical modeling of divertor detachment in H-Mode Plasmas in ASDEX Upgrade

In future fusion power plants high power fluxes pose a threat to the wall materials, especially in the divertor. It is thought that detachment of the plasma from the divertor target is necessary to avoid excessive heat loads to and material erosion of the divertor target plates.

Strong detachment has been demonstrated for the first time in the all-tungsten ASDEX Upgrade tokamak in fusion-relevant H-mode plasmas. The deliberate seeding of nitrogen provokes additional line radiation that cools the divertor plasma and provides access to detachment. The observed radiation distribution exhibits a strong concentration above the X-point (s. figure), which indicates low temperatures and significant plasma parameter variations on closed field lines.

The detached plasma has been successfully modeled with the SOLPS-code. Assuming an increased plasma transport perpendicular to the magnetic field lines, most experimental measurements could be reproduced.

With this work Felix Reimold obtained his PhD degree on 08.01.2015 at the TU München.

Reimold et al., Nuclear Fusion 55 3 (2015) 033004
Reimold et al., Journal of Nuclear Materials Submitted (2015)