Plasma shape control for the JET tokamak: an optimal output regulation approach

The eXtreme Shape Controller, designed and implemented on the JET tokamak, was described. The controller regulates the plasma shape as specified in terms of plasma-wall distances and maintains this plasma shape in the presence of significant variations of critical plasma parameters, namely the poloidal beta, the internal inductance, and the plasma current. The design procedure is based on the SVD of the plant output matrix. This procedure accounts for specifications on the accuracy of the controller variables as well as the maximum allowable control effort. The new controller has been fully commissioned on the JET tokamak, is in regular operation, and is delivering the expected performance.