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P: Fachverband Plasmaphysik
P 4: HEPP II
P 4.5: Vortrag
Montag, 20. März 2023, 18:10–18:35, CHE/0091
Characterization and identification of MHD-like fluctuations of core electron temperature transitions in W7-X plasmas — •Juan Fernando Guerrero Arnaiz1,2, Andreas Dinklage1,2, Axel Könies2, Carolin Nührenberg2, Alessandro Zocco2, Matthias Borchardt2, Christian Brandt2, Neha Chaudhary2, Joachim Geiger2, Matthias Hirsch2, Udo Höfel2, Ralf Kleiber2, Kian Rahbarnia2, Sara Vaz Mendez2, Alexei Mishchenko2, Jonathan Schilling2, John Schmitt3, Henning Thomsen2, Marco Zanini2, and W7-X Team2 — 1Universität Greifswald, Greifswald, Germany — 2Max-Planck-Institut für Plasmaphysik, Greifswald, Germany — 3Auburn University, Auburn AL, United States
Previously unexpected spontaneous transitions to higher core-electron temperatures preserving plasma pressure were detected in low-iota configuration W7-X plasmas. Transitions occurred at stationary plasma conditions at fixed heating power and line integrated density but with evolving plasma currents. Here we report on low frequency activity preceding the transitions. To gain insight on the transition mechanism, this activity is characterized. This is done through experimental and numerical modelling, shedding light on the nature of the underlying MHD instability. The rational iota-values and the impact of radial electric fields on the mode activity and the transition to enhanced core electron temperature are examined. As for now, the instability is narrowed down to GAM oscillations and zonal flow activity, both of which were found to potentially exist according to systematic simulations.