The linearized CREATE-L plasma response model for the control of current, position and shape in tokamaks

Abstract

CREATE-L, a simple and reliable linearized plasma response model for the control of the plasma current, position and shape in tokamaks, is presented. The basic assumption made is that the plasma behaviour is described using three degrees of freedom, related to the total plasma current, internal inductance and poloidal beta. The state variables are the coil and plasma currents; the inputs are the applied voltages, whereas poloidal beta and internal inductance play the role of disturbances. The outputs are field and flux values and some basic plasma parameters. The model is tested against non-linear codes and validated via comparison with experimental results.

Modeling and control of TCV

“…A number of linearized models suitable for control system design have already been developed. In the case of the CREATE-L, we refer the reader to [3]. Comparable studies have been performed on DIII-D 2 [4], [5], and on TCV [6], [7].…”

“…To begin, flux and energy conservation issues are treated explicitly and self-consistently. In [3], for instance, plasma profile parameters are considered as disturbances, which the authors acknowledge is not self-consistent. Previous derivations of the RZIP-type models [so-called as they model plasma radial and vertical position (R, Z) and current (IP)] [6] have also not considered conservation laws in a self-consistent manner.…”

“…Following from [6] and [9], the model presented in this paper considers fully the effects of plasma resistance, showing how to incorporate resistance and mass into the 2 The General Atomics National Fusion Facility, San Diego, CA. 3 International thermonuclear experimental reactor. model from the initial stages, if required.…”

“…The control scheme was based on the CREATE-L model presented in [3]. In [13], a multivariable normalized coprime factor controller is designed using a simple single-filament model of the DIII-D tokamak.…”

Plasma equilibrium response modelling and validation on JT-60U

“…There are many methods of constructing linearised plasma equilibrium models in a form suitable for feedback control design, typified by the CREATE-L deformable plasma response model [1], the DPM deformable plasma response model [2] and the RZIP rigid current displacement model [3]. Until recently there was no way of deciding whether these models are sufficiently accurate.…”