München 2019 – wissenschaftliches Programm
P 18.52: Poster
Donnerstag, 21. März 2019, 16:30–18:30, Foyer Audimax
Plasma Terminating Events in Large Stellarators — •Daniel Maier1, Andreas Dinklage1,2, Jürgen Baldzuhn2, Rainer Burhenn2, Rene Bussiahn2, Birger Buttenschön2, Phillip Hacker2, Matthias Hirsch2, Udo Höfel2, Thomas Wegner2, and Daihong Zhang2 for the The Wendelstein 7-X Team collaboration — 1Universität Greifswald, 17489 Greifswald, Germany — 2Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany
The sudden termination of fusion plasmas may result in high power loads on plasma facing components. In terms of operational limits, we investigate the amount of fuelling pellets or impurities that a plasma can sustain without termination. Here, also the possibility of plasma recovery for close to marginal termination is an object of investigation.
For a quantitative assessment of mechanisms and timescales of termination, this study focuses on experiments with substantial release of plasma energy due to fuelling pellets or injected impurities. Depending on the material and its amount, plasma termination or recovery is observed. Time scales for the rate of plasma cooling were calculated from waveforms of electron cyclotron emission. The times are found to be in general around 15 to 30 percent of the characteristic energy confinement times. A stronger rate of cooling is typically found in the plasma centre.
The observed time scales and the potential of plasma recovery at marginal limits of injected impurities indicate the beneficial impact of vacuum confinement of stellarator magnetic configuration.