Robust Control of the Safety Factor Profile and Stored Energy Evolutions in High Performance Burning Plasma Scenarios in the ITER Tokamak
J.E. Barton, K. Besseghir, J. Lister and E. Schuster
52nd IEEE Conference on Decision and Control
Florence, Italy, December 10-13, 2013
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Abstract
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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_infinity
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.
