München 2019 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 18: Postersitzung

P 18.120: Poster

Donnerstag, 21. März 2019, 16:30–18:30, Foyer Audimax

Gaussian Process Tomography for the Soft X-Ray Diagnostic of Wendelstein 7-X — •Jonathan Schilling, Sehyun Kwak, Christian Brandt, Henning Thomsen, and Jakob Svensson — Max-Planck-Institute for Plasma Physics, Greifswald, Germany

Measurements of the soft X-ray emission from a high-temperature plasma provides data on its space-time behaviour and allows detection of magneto-hydrodynamic (MHD) instabilites, MHD mode dynamics and direct estimation of the Shafranov shift due to plasma currents. In combination with other diagnostics, transport dynamics of impurities can be determined. Gaussian Process Tomography is an inference method especially well-suited for the tomographic inversion problem of soft X-ray emission from a high-temperature plasma. It does not impose a parameterization in terms of an emission profile model on the prediction of the measured signals. Thus, no overfitting due to an overly complex model or imposition of artificial constraints due to an over-simplified model occurs. In this contribution, a newly developed Bayesian graphical model for the soft X-ray diagnostic in the Wendelstein 7-X (W7-X) stellarator is presented. It is applied to measurements from the latest operational campaign of W7-X.