Nonlinear Robust Safety Factor Profile Control in Tokamaks via Feedback Linearization and Nonlinear Damping Techniques
A. Pajares and E. Schuster
Proceedings of the 2018 IEEE Conference on Control Technology and Applications (CCTA)
Copenhagen, Denmark, August 21-24, 2018
Abstract
|
|
Tokamaks are toroidal devices in which a plasma is confined by means
of helical magnetic fields with the purpose of obtaining energy from
nuclear fusion reactions. The safety factor, q, is a magnitude that
measures the pitch of the helical magnetic field lines in a tokamak.
Active control of the q profile is needed due to its close relationship
with plasma performance (steady-state operation) and magneto-hydrodynamic
stability. However, the responses of some plasma magnitudes, such as
the electron temperature profile, are difficult to model and introduce
a high level of uncertainty in the model used for q-profile control design.
Control algorithms that are robust against such model uncertainties must
be developed in order to ensure successful q-profile regulation. In this
work, a nonlinear, robust q-profile controller is designed using feedback
linearization and nonlinear damping techniques. The controller makes use
of plasma current modulation, neutral beam injection, electron-cyclotron
heating & current drive, and electron density modulation as actuation
methods. A simulation study is carried out for a DIII-D scenario to test
the controller’s performance under the presence of electron temperature
uncertainties.