Core impurity flow measurements with coherence imaging charge exchange recombination spectroscopy in Wendelstein 7-X

The coherence imaging charge exchange recombination spectroscopy (CICERS) diagnostic employs the coherence imaging spectroscopy technique to obtain two-dimensional (2D) maps of physical quantities derived from charge-exchange radiation in the core region of Wendelstein 7-X plasmas. This work investigates the diagnostic ability to resolve core carbon impurity flow () measurements. The workflow for the diagnostic calibration is addressed and uncertainty estimates are determined from a diagnostic synthetic model. The first 2D core impurity flow measurements with CICERS are presented. Incorporating a geometrical model that accounts for Pfirsch–Schlüter return flows allows for the development of a Bayesian inversion routine to infer radial electric field () and carbon parallel flow () profiles from the diagnostic toroidal view. The resulting profiles are compared with neoclassical predictions and experimental measurements from standard CXRS and Doppler Reflectometry. The overall agreement to data from independent diagnostics demonstrate the validity of the diagnostic measurements.