Safety Factor Profile Control in Tokamaks via Feedback Linearization
A. Pajares and E. Schuster
55th IEEE Conference on Decision and Control
Las Vegas, Nevada, USA, December 12-14, 2016
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Abstract
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The tokamak is a torus-shaped machine in which a reactant plasma is confined using magnetic
fields for the purpose of generating energy from nuclear fusion reactions. In order to be
commercially competitive, a tokamak needs to operate for long periods of time at
high-performance operating points. Those high-performance scenarios are characterized by a
steady-state, stable plasma operation, which is closely related to a property of the plasma
that is known as the safety factor, q. Therefore, control of the q profile is one of the
crucial aspects to the success of tokamaks. Significant research has been carried out to
find control algorithms for the q profile in tokamaks. Most of that previous work makes use
of approximate lineariza- tion and linear control techniques. In the present work, we propose
a nonlinear model-based controller for the regulation of the q profile using feedback
linearization. This nonlinear control approach may be applicable to a greater range of
operating conditions, and may be able to reject larger perturbations than previous linear
controllers. Moreover, this control design combines the advantages of both nonlinear and
linear control techniques, because the nonlinear model is exactly linearized by making use
of an appropriate input transformation. The effectiveness of the controller is demonstrated
via a simulation study in which the controller is tested in a DIII-D scenario.
