Robust control of the safety factor profile and stored energy evolutions in high performance burning plasma scenarios in the ITER tokamak

The next step towards the development of a nuclear fusion tokamak power plant is the ITER project. Integrated closed-loop control of the plasma stored energy and safety factor profile (q-profile) is key to maintaining the plasma in a stable state and maximizing its performance. The q-profile evolution in tokamaks is related to the poloidal magnetic flux profile evolution, which is described by a physics model called the magnetic diffusion equation. A first-principles-driven (FPD), nonlinear, control-oriented model of the poloidal magnetic flux profile evolution is obtained by first combining the magnetic diffusion equation with simplified physics-based models of the noninductive current-drives. Secondly, the electron density, electron temperature, and plasma resistivity profiles are modeled as uncertain parameters by defining ranges in which they are expected to be in typical ITER high performance scenarios. This FPD model is then employed to synthesize an H_∞ feedback algorithm that utilizes ITER´s auxiliary heating/current-drive sources and the total plasma current as actuators to control the q-profile and stored energy in high performance burning plasma scenarios while ensuring the closed-loop system is robust to the uncertainties in the plasma parameters. Finally, the effectiveness of the controller is demonstrated through simulation.