A Reference Governor for Plasma-Shape Control in Tokamak
A. Pajares, W.P. Wehner, A.S. Welander, E. Schuster and D.A. Humphreys
IEEE Conference on Control Technology and Application (CCTA)
Bridgetown, Barbados, August 16-18, 2023
|
Abstract
|
|
Tokamaks are torus-shaped devices where a high-
temperature, ionized gas (i.e. a plasma) is confined by means of
helical magnetic fields. The ultimate goal of tokamaks is producing
net electrical energy by means of nuclear-fusion reactions
within the plasma. The shape of the plasma inside the tokamak
is closely related with its confinement characteristics and,
therefore, with the produced fusion power. In order to achieve
and maintain plasma shapes that maximize the fusion yield,
feedback controllers have been successfully developed during
the years. However, machine-protection and plasma-stability
requirements impose hard constraints on the plasma-shape
targets that can be safely achieved by a feedback controller.
In this work, a reference governor is proposed to provide, in
real time, plasma-shape targets that fulfill the aforementioned
safety requirements. The reference governor calculates such
plasma-shape targets in response to changes in the state of
the closed-loop system, as well as disturbances in the plasma
energy and current. The reference-governor design is based
on a dynamical model of the plasma electromagnetic response.
Simulation tests of the reference governor have been carried
out for different plasma scenarios in the DIII-D tokamak to
emulate realistic cases where safety may be compromised.
