Design and Implementation of an Output Regulation Controller for the JET Tokamak

This paper describes the design and the experimental validation of a multivariable current and shape controller for the Joint European Torus (JET) tokamak. Using this new controller, physicists have been able to carry out experiments where accurate control of the plasma boundary is needed. From a control point of view, the problem has been formulated as an output regulation problem for a linear time-invariant (LTI) plant whose controllable outputs are more than the control inputs. For the case of constant references, we propose a control scheme that minimizes a quadratic cost function. This cost function weights the tracking error at steady state. Our methodology is based on the singular value decomposition of the static gain matrix of the plant. In the controller design, we can also take into account the steady-state control effort. The proposed controller has been implemented and tested on the plant; some experimental results are included in this paper. The activity that has been carried out and that is described in this paper is relevant in the perspective of the new experimental reactor ITER.