1. A.Soppelsa – 7 February 2011 – RFX-mod programme workshop Session on the active control of MHD Instabilities Hot points A. Soppelsa, A. Barbalace, B. B. de Carvalho, P. Zanca, G. Marchiori, L. Frassinetti (on behaf of E. Olofsson), S. A. Sabbagh

2. A.Soppelsa – 7 February 2011 – RFX-mod programme workshop Upgrade of the real-time control system  Improvements on the total cost of the system, delay and control loop frequency  Alternative implementation from IST collegues: Pros and Cons  What’s the bottleneck? IO or Computations? How this correlates with the proposed pipeline?  MARTe: a new paradigm for implementing real-time algorithms?

3. A.Soppelsa – 7 February 2011 – RFX-mod programme workshop Tearing modes control in RFX-mod  RFX-locking shows impressive reduction of the residual field with 125 us delay.  Derivative signal acquisition will lead to better PD gains optimisation  Debate on m=0 control. Only slightly affected by radial field coils, but too much by the toroidal field coils?  What about the upgrades required to the toroidal coils system?  The modal dynamic decoupler could be required for m=0 control, m=0 n>=7 should be removed from the radial field spectrum  Independent feedback on the radial and toroidal components of the field can be tested.  Can state space modeling be useful with regard of this?  Does a non-zero radial field at the edge help to sustain QSH?

4. A.Soppelsa – 7 February 2011 – RFX-mod programme workshop RWM Experiments in RFX-mod  RFX-mod can be used as an invaluable tool to test RFA using the flexibility of the MHD active control system  Are there RWM triggers in RFX-mod as a Tokamak, out there?  Mode rigidity Experiments or how to control a mode with the minimum number of coils  What about applying the more recent tools of control theory to the RFX-mod RWM? Why?  The effect of 3D structures on the modes eigenvalues can be used to further benchmark the coupling between Electromagnetic and MHD codes

5. A.Soppelsa – 7 February 2011 – RFX-mod programme workshop Closed-loop identification  The method is essential when the open loop identification is not possible because the instabilities would lead to a potential damage of the machine  It allows to diligently obtain empirical eigenmodes and eigenvalue, directly comparable with the theoretical models  What about the physical meaning of the states?  The method can be applied to directly identify MIMO systems reducing the number of shots required for identification  The effect of 3D structures in inherently taken into account  Can this method be used to identify the inverse system?

6. A.Soppelsa – 7 February 2011 – RFX-mod programme workshop State space controllers  The use of different set of sensors in an integrated way is benefical and fits perfectly in the state space control paradigm. This has been highlighted also in the P. Zanca presentation  State space controllers applied to RWM control at NSTX allow to sustain higher normalized Beta and lower l i plasmas  Impressive state space reduction techniques: the useful information for control can be one hundredths of that contained in the original model  What kind of reduction techniques has been employed?  Can a real-time state space observer of the tiles temperature be constructed from electromagnetic measurements?  It could be verified against data coming from CMOS camera