A practical method for performing a tokamak equilibrium reconstruction in realtime for arbitrary time varying discharge shapes and current profilesis described.An approximatesolution to the Grad-Shafranov equilibrium relation is found which bestfits the diagnostic measurements.Thus, a solution for the spatial distribution of poloidal flux and toroidalcurrent density is available in real timethat is consistent with plasma force balance,allowing accurate evaluation of parameters such as discharge shape and safetyfactor profile.The equilibrium solutions are produced at a rate sufficient for dischargecontrol.This equilibrium reconstruction algorithm has been implemented on the digitalplasma control system for the DIII-D tokamak.The first application of real time equilibrium reconstruction to dischargeshape control is described.
Toroidal current profile control during low confinement mode plasma discharges in DIII-D via first-principles-driven model-based robust control synthesis