TOWARD A DESIGN FOR THE ITER PLASMA SHAPE AND STABILITY CONTROL-SYSTEM

A design strategy for an integrated shaping and stability control algo rithm for ITER is described. This stategy exploits the natural multiva riable nature of the system so that all poloidal field coils are used to simultaneously control all regulated plasma shape and position para meters. A nonrigid, flux-conserving, linearized plasma response model is derived using a variational procedure analogous to the ideal MHD Ex tended Energy Principle. Initial results are presented for the nonrigi d plasma response model approach applied to an example DIII-D equilibr ium. For this example, the nonrigid model is found to yield a higher p assive growth rate than a rigid current-conserving plasma response mod el. Multivariable robust controller design methods are discussed and s hown to be appropriate for the ITER shape control problem.