High performance integrated plasma control in DIII-D

The DIII-D mission to explore the advanced tokamak (AT) regime places significant demands on the DIII-D plasma control system (PCS) [D.A. Humphreys, et al., Fusion Eng. Des. 66–68 (2003) 633], including simultaneous and accurate regulation of plasma shape, stored energy, and density, as well as coordinated suppression of magnetohydrodynamic (MHD) instabilities. The present work describes selected new solutions to key control problems in DIII-D AT operation. These include novel nonrigid, resistive linear plasma response models, nonlinear algorithms for avoidance of current limiting, and improved neoclassical tearing mode control algorithms.