Development of plasma magnetic equilibrium control for the MAST upgrade tokamak

Active real-time estimation and control of the magnetic equilibrium is required for the MAST Upgrade (MAST-U) tokamak for exploring extended- and expanded-leg divertor geometries. Assessment of the proposed local expansion method for MAST-U for strike point position estimation has been successfully simulated and modelled on the DIII-D tokamak with a long-legged divertor plasma configuration and has also been tested experimentally on MAST-U. The local expansion method has been further extended for estimating additional magnetic equilibrium parameters (inner gap, X-point and strike point position) and implemented on the MAST-U control system. TokSys closed-loop simulations with the axisymmetric linear and non-linear plasma models, have been performed for the assessment, identification, and verification of the algorithm implementation and controller performance for the various axisymmetric control variables. Demonstration of full magnetic equilibrium control with modified local expansion method is planned for the upcoming MAST-U 2022 experimental campaign.