G3C: a non magnetic, reflectometry–based plasma boundary reconstruction algorithm for control purposes

The installation of an advanced plasma position reflectometry system, aimed at complement- ing magnetic sensors for plasma position and shape control, is foreseen on the DEMOnstration power plant (DEMO). For such a system, we presented in 2018 the G3C boundary reconstruc- tion algorithm, based on the plasma-wall distance reflectometric measurements and on the val- ues of the plasma and poloidal field coils currents. This work presents the upgrades implemented to the algorithm and its application to both the DEMO baseline and several non-baseline scen- arios. The algorithm is further applied to reconstruct the plasma boundary during a vertical dis- placement event. Results indicate that the method is able to estimate plasma shape parameters and position with a remarkable accuracy, provided that reliable reflectometric measurements—within 1 cm accuracy—are used as input. Furthermore, it shows significant robustness to higher measure- ment errors for what concerns the estimation of most of the plasma shape parameters estimation. Overall, G3C proves to be an accurate, reliable and flexible reflectometry-based boundary recon- struction tool.