Advanced tokamak operation using the DIII–D plasma control system

The principal focus of experimental operations in the DIII–D tokamak is the advanced tokamak (AT) [Proc. 18th Symp. on Fusion Technol., August, 1994, Karlsruhe, Germany, Elsevier, Amsterdam, 1 (1995) 731] regime, which requires highly integrated and flexible plasma control to achieve. In a high performance AT, accurate regulation of the plasma boundary, internal profiles, pumping, fueling, and heating must be well coordinated with MHD control action to stabilize such instabilities as tearing modes and resistive wall modes. Sophisticated monitors of the operational regime must provide detection of off-normal conditions and trigger appropriate safety responses with acceptable levels of reliability. Many of these capabilities are presently implemented in the DIII–D plasma control system (PCS), and are now in frequent or routine operational use. The present work describes recent development, implementation, and operational experience with AT regime control elements for equilibrium control, MHD suppression, and off-normal event detection and response.