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P: Fachverband Plasmaphysik

P 11: Poster I

P 11.47: Poster

Mittwoch, 22. März 2023, 14:00–15:30, HSZ EG

Power balance analysis and predictive modelling using the codes neotransp and NTSS — •Markus Wappl, Marc Beurskens, Sergey Bozhenkov, Hakan Smith, and Yuri Turkin — Max-Planck-Institute for Plasma Physics, Greifswald, Germany

One effect seriously limiting the plasma performance of the stellarator Wendelstein 7-X is ion temperature clamping, which restricts ion temperatures to about 1.5 keV in a wide range of scenarios. Empirical scaling laws such as ISS04 predict the performance of stellarators. However, no first-principle models offering a physical understanding or a clear explanation for the clamping are available. It has been shown that turbulent flux losses limit the achievable performance of a stellarator. ITG modes are thought to be the dominating turbulent process for ion heat losses and might be the cause for the ion temperature clamping observed at W7-X.

Power balance analysis allows a physics-motivated understanding of plasma performance including ion temperature clamping. Detailed modelling of neoclassical and turbulent heat fluxes is critical for this approach. A novel webtool for the power balance analysis of Wendelstein 7-X plasma discharges is presented. It employs the codes neotransp and NTSS for neoclassical calculation as well as Monte Carlo sampling for reliable error propagation. Predictive modelling of ion temperature profiles is performed in the code NTSS using a dummy density profile and ECR heating deposition profile. Ion temperature clamping is reproduced with simplified model assumptions which indicates that ITG modes might not be the primary reason for clamping.