COMPREHENSIVE FEEDBACK-CONTROL OF A TOKAMAK FUSION-REACTOR

Results for the first simulated comprehensive feedback control study f or a tokamak operating in the fusion regime are presented. A standard Burning Plasma Experiment (BPX) design is the simulated reactor but th e results apply to any tokamak. Feedback gains are derived for specifi c classes of dynamic models and control objectives using model-based o ptimal control. An integrated control approach treats both kinetic and electromagnetic parameters and radial profiles. The control actuators include poloidal field coils, fast-wave and lower-hybrid current driv e and heating sources, and pellet fuel injectors. Results show that th e strongly coupled plasma parameters provide unintended secondary resp onses to controller inputs. In particular, attempts to modify the q-pr ofile greatly affect the temperature and density profiles when the tra nsport model incorporates International Thermonuclear Experimental Rea ctor (ITER) scaling. The hot, highly conductive plasma and poor source penetration in the nominal BPX discharge make the central q-values di fficult to regulate. Fusion events also complicate the control efforts . Further simple plasma circuit models are inadequate to account for a significantly evolving current profile. Proper understanding and use of integrated, model-based feedback control will avoid these pitfalls.