PPPL-5372
Feedback control design for non-inductively sustained scenarios in
NSTX-U using TRANSP
Authors: M. Boyer, R. G. Andre, D. A. Gates, S. P.
Gerhardt, J. E. Menard, and F. M. Poli
Abstract: This paper examines a method for real-time control
of non-inductively sustained scenarios in NSTX-U by using TRANSP, a
time-dependent integrated modeling code for prediction and
interpretive analysis of tokamak experimental data, as a simulator.
The actuators considered for control in this work are the six
neutral beam sources and the plasma boundary shape. To understand
the response of the plasma current, stored energy, and central
safety factor to these actuators and to enable systematic design of
control algorithms, simulations were run in which the actuators were
modulated and a linearized dynamic response model was generated. A
multi-variable model-based control scheme that accounts for the
coupling and slow dynamics of the system while mitigating the effect
of actuator limitations was designed and simulated. Simulations show
that modest changes in the outer gap and heating power can improve
the response time of the system, reject perturbations, and track
target values of the controlled values.