Development of real-time density feedback control on MAST-U in L-mode
Gijs Derks, B. Kool, C.H. Vincent, S. Elmore, S. Henderson, J.T.W. Koenders, J. Lovell, G. McArdle, Bryan R. Parry, R. Scannell, R. Sarwar, K. Verhaegh, M. van Berkel
Abstract
In this paper we report on the development and demonstration of density feedback control for MAST-U. Sinusoidal perturbations are used to measure the frequency response from a deuterium gas valve (actuator) to line-integrated core electron density measured by the interferometer (sensor). In the frequency range relevant for control design, only two system-identification experiments were needed to regress a first-order dynamic model. This control-oriented model informs the offline design of a proportional integral controller with the established loop-shaping controller design method. After offline verification of the controller implementation, control is demonstrated by experimentally tracking a staircase reference for the line-integrated electron density. This paper demonstrates the efficiency of controller design using system-identification and loop-shaping, providing reliable density control for MAST-U.