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P: Fachverband Plasmaphysik
P 1: Magnetic Confinement I/HEPP I
P 1.4: Vortrag
Montag, 26. Februar 2024, 12:20–12:35, ELP 6: HS 3
Creating a power balance database study on turbulence at Wendelstein 7-X — •Markus Wappl, Marc Beurskens, Sergey Bozhenkov, Tamara Andreeva, Sebastian Bannmann, and Håkan Smith — Max Planck Instiute for Plasma Physics, Greifswald, Germany
Power balance analysis is used to compile a comprehensive database of anomalous transport in various plasma scenarios at the stellarator Wendelstein 7-X. The anomalous transport is attributed to turbulence. As a figure of merit, an effective turbulent transport coefficient χeff is defined. The database spans a broad parameter range covering different fueling schemes, heating power values and methods as well as different magnetic configurations of W7-X.
Experiments with neutral beam or hydrogen pellet injection allow to increase the central density and ion temperature while creating steep gradients. The database unveils a characteristic dependence of χeff on the gradient lengths of density and ion temperature, a/Ln and a/LT. This hints at the prevalence of ion temperature gradient (ITG) modes. The critical parameters governing ITG stability, a/Lncr and a/LTcr, are identified from the database. Based on power and density scan experiments, the scaling behaviour of the effective turbulent transport coefficient is explored. χeff positively correlates with electron cyclotron heating power, predominantly in the electron channel of turbulent transport.
The benefits of the turbulence database results in a future extrapolation to a stellarator reactor based on W7-X are discussed.
Keywords: Stellarator; Wendelstein 7-X; Turbulence; ITG; Power balance