Accessibility and Reproducibility of Stable High-qmin Steady-State Scenarios by q-profile+βN Model Predictive Control
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
San Jose, CA, USA, October 31 - November 4, 2016
Abstract |
The capability of combined q-profile and βN control to enable access to and repeatability of steady-state scenarios for qmin>1.4 discharges has been assessed in DIII-D experiments. To steer the plasma to the de- sired state, model predictive control (MPC) of both the q-profile and βN numerically solves successive optimization problems in real time over a receding time horizon by exploiting efficient quadratic programming techniques. A key advantage of this control approach is that it allows for explicit incorporation of state/input constraints to prevent the controller from driving the plasma outside of stability/performance limits and obtain, as closely as possible, steady state conditions. The enabler of this feedback-control approach is a control-oriented model capturing the dominant physics of the q-profile and βN responses to the available actuators. Experiments suggest that control-oriented model-based scenario planning in combination with MPC can play a crucial role in exploring stability limits of scenarios of interest.