Mainz 2022 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 19: Poster II
P 19.16: Poster
Donnerstag, 31. März 2022, 16:00–17:30, P
Experimental helium exhaust studies in the full-W ASDEX Upgrade — •Antonello Zito1,2, Athina Kappatou1, Marco Wischmeier1, Volker Rohde1, Edward Hinson3, Oliver Schmitz3, Marco Cavedon4,1, Rachael McDermott1, Ralph Dux1, Michael Griener1, Arne Kallenbach1, Ulrich Stroth1,2, and the ASDEX Upgrade team1 — 1Max-Planck-Institut für Plasmaphysik, Garching, Germany — 2Physik-Department E28, Technische Universität München, Garching, Germany — 3University of Wisconsin-Madison, USA — 4Dipartimento di Fisica G. Occhialini, Università di Milano-Bicocca, Milano, Italy
An efficient removal of helium ash by active pumping in future fusion devices is mandatory, in order to avoid fuel dilution and not degrade confinement properties. Helium exhaust in reactor-relevant edge and divertor scenarios has been experimentally investigated at the ASDEX Upgrade tokamak. A small amount of helium was injected during otherwise steady-state deuterium plasma discharges, and the time evolution of the resulting helium content was measured in the plasma and in the exhaust gas. The dynamics of the helium decay following the injection was characterized in several different scenarios and interpreted by means of simple analytic models. In attached H-modes plasmas, the helium pumping efficiency was found to greatly improve with increasing divertor neutral pressures. This was shown to be mainly driven by a more efficient divertor retention of helium at higher pressures. On the other hand, an exhaust degradation was qualitatively observed with the divertor entering a detached regime in L-mode.