Optimal Control Theory Applied to Fusion Plasma Thermal Stabilization

Optimal control theory is applied to determine feedback control for thermal stability of a driven, subingnition tokamak controlled by fuel injection and additional heating. It was found that the simplifications of the plasma burn dynamics and the control figure of merit required for the synthesis of optimal feedback laws were valid.Control laws were determined which allowed thermal stability in plasmas subject to 10% offset in temperature. The minimum ignition margin (defined as the difference between ignition temperature and the subignition operating point) was found to be 0.95 keV, corresponding to steady state heating requirements of less than 2% of fusion power.