Nonlinear Robust Safety Factor Profile Control in Tokamaks via Feedback Linearization and Nonlinear Damping Techniques
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.