Nonlinear Adaptive Burn Control in ITER Based on Two-Temperature Response Model
V. Graber, E. Schuster
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Fort Lauderdale, FL, USA, October 21-25, 2019
Abstract
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By using robust burn control approaches, ITER will be the first reactor
capable of confining plasmas with reactivities suitable for energy
production. An adaptive nonlinear control scheme that employs planned
actuators for ITER is synthesized from a 0-D plasma model with uncertain
parameters. Because the temperature of the ions and electrons could
differentiate significantly in ITER, the model considers separate ion
and electron temperature response models. The control scheme relies on
neutral beam injection (NBI) for the bulk of the plasma heating.
Electron and ion cyclotron heating are exploited to independently
regulate the electron and ion temperatures, respectively. The dynamics
of fast NBI beam ions and fusion alpha particles are modeled by
including state-dependent thermalization delays and fractional heating
to the ions and electrons. The dynamics of the pellet injector, used
for density control, is modeled as flight-delayed pellets that are
discretely deposited into the plasma. The model contains uncertainty
in the particle recycling from the walls, confinement properties, and
the heating shared between the ions and electrons. The adaptive control
scheme successfully stabilizes the system despite the various time
delays, actuator dynamics, and model uncertainties.