Hannover 2016 – scientific programme
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P: Fachverband Plasmaphysik
P 13: Plasma Wall Interactions
P 13.1: Invited Talk
Wednesday, March 2, 2016, 11:00–11:30, b302
Power exhaust by impurity seeding in fusion reactors — •Matthias Bernert1, Felix Reimold2, Arne Kallenbach1, Bruce Lipschultz3, Ralph Dux1, Marco Wischmeier1, the ASDEX Upgrade team1, and the EUROfusion MST1 Team4 — 1Max-Planck-Institut für Plasmaphysik, Garching, Germany — 2Forschungszentrum Jülich GmbH, IEK, Jülich, Germany — 3University of York, York Plasma Institute, Heslington, York, United Kingdom — 4See http://www.euro-fusionscipub.org/mst1
Power exhaust is one of the big challenges for future fusion reactors. The power load at the divertor targets, the primary plasma-wall interaction zone, would exceed material limits and, thus, must be reduced. Therefore, 90% of the exhaust power needs to be dissipated and the divertor is anticipated to be in the detached regime, where the interaction of the plasma with the wall is significantly reduced. Radiation is the dominant dissipation process and is increased by impurity seeding. The radiation distribution can be tailored by using different seed impurities (N for radiation outside, Ne and Ar for radiation at the edge of and Kr for radiation inside the confined region). The tailoring of the radiation profile is required in order to maximize the radiated power and at the same time minimize the impact on the energy confinement.
Recent experiments with intense impurity seeding at the ASDEX Upgrade tokamak demonstrate operation at highest heat fluxes and detached divertor targets at radiated power fractions of up to 90%. In these scenarios the radiation originates predominantly from the confined region and leads to an unexpectedly small confinement reduction.