Agung Chris Setiadi

Implementation of model predictive control for resistive wall mode stabilization on EXTRAP T2R

A model predictive control (MPC) method for stabilization of the resistive wall mode (RWM) in the EXTRAP T2R reversed-field pinch is presented. The system identification technique is used to obtain ...

A method for the estimate of the wall diffusion for non-axisymmetric fields using rotating external fields

A new method for the estimate of the wall diffusion time of non-axisymmetric fields is developed. The method based on rotating external fields and on the measurement of the wall frequency response is developed and tested in EXTRAP T2R. The method allows the experimental estimate of the wall diffusion time for each Fourier harmonic and the estimate of the wall diffusion toroidal asymmetries. The method intrinsically considers the effects of three-dimensional structures and of the shell gaps. Far from the gaps, experimental results are in good agreement with the diffusion time estimated with a simple cylindrical model that assumes a homogeneous wall. The method is also applied with non-standard configurations of the coil array, in order to mimic tokamak-relevant settings with a partial wall coverage and active coils of large toroidal extent. The comparison with the full coverage results shows good agreement if the effects of the relevant sidebands are considered.

Improved model predictive control of resistive wall modes by error field estimator in EXTRAP T2R

Many implementations of a model-based approach for toroidal plasma have shown better control performance compared to the conventional type of feedback controller. One prerequisite of model-based co ...

Design and operation of fast model predictive controller for stabilization of magnetohydrodynamic modes in a fusion device

Magnetic confinement fusion (MCF) devices suffer from magnetohydrodynamic (MHD) instabilities. A particular unstable mode, known as the resistive wall mode (RWM), is treated in this work. The RWM perturbs the plasma globally and can degrade the confinement or even terminate the plasma if not stabilized. This paper presents a control design approach to stabilize the RWM in the reversed-field pinch (RFP). The approach consists of: closed-loop system identification of the RFP, design of a fast model predictive controller and experimental validation of the controller. Experimental results shows that the proposed controller manages to stabilize the RWM in plasma.