Fusion Science and Technology / Volume 11 / Number 2 / March 1987 / Pages 311-316
Technical Paper / Plasma Engineering / dx.doi.org/10.13182/FST87-A25011
In the case of a tokamak, plasma current and plasma equilibrium cannot be controlled independently of each other because the controlled systems involved are coupled. For a practical solution to the coupling problem, so-called decoupling controllers are suggested. To reduce the problem appreciably, a tokamak operation with controlled input currents rather than voltages is assumed. A decoupling controllers design procedure, based on a simple model of the coupled systems, is described, and a method is developed to identify unknown model parameters by evaluating measured time curves of the tokamak currents. Decoupling controllers are designed and successfully incorporated into the feedback loops of the Tokamak Experiment for Technically Oriented Research (TEXTOR) tokamak. Furthermore, the modeling and identification methods are also implemented for the Joint European Torus and the Axially Symmetric Divertor Experiment tokamak yielding results quite similar to those with TEXTOR so that just as useful decoupling controllers could be designed. These results encourage equipping the control systems oftokamaks other than TEXTOR with decoupling controllers and controlled current sources.