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A new approach to the modeling and control of tokamak fusion reactors is presented. A nonlinear model is derived using the classical arguments of Hamiltonian mechanics and a low-order linear model is derived from it. The modeling process used here addresses flux and energy conservation issues explicitly and self-consistently. The model is of particular value, because it shows the relationship between the initial modeling assumptions and the resulting predictions. The mechanisms behind the creation of uncontrollable modes in tokamak models are discussed. A normalized coprime factorization H∞ controller is developed for the Tokamak a` Configuration Variable (TCV), CRPP-EPFL, Lausanne, Switzerland, tokamak using the linearized model, which has been extensively verified on the TCV and JT-60U, JAERI, Naka, Japan, tokamaks. Recent theory is applied to reduce the controller order significantly whilst guaranteeing a priori bounds on the robust stability and performance. The controller is shown to track successfully reference signals that dictate the plasma's shape, position and current. The tests used to verify this were carried out on linear and nonlinear models.
Date of Publication: May 2005