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TF2: Active control of RFP and tokamak plasmas Report on experimental proposals

TF2: Active control of RFP and tokamak plasmas Report on experimental proposals. L. Zanotto, P. Piovesan, A. Soppelsa. Main areas covered by proposals. Tokamak scenarios 3D magnetic field effects on flow RWM in RFP m=0 control and understanding Active control of RFP plasmas

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TF2: Active control of RFP and tokamak plasmas Report on experimental proposals

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  1. TF2: Active control of RFP and tokamak plasmasReport on experimental proposals L. Zanotto, P. Piovesan, A. Soppelsa L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  2. Main areas covered by proposals • Tokamak scenarios • 3D magnetic field effects on flow • RWM in RFP • m=0 control and understanding • Active control of RFP plasmas • Optimisation L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  3. Main areas covered by proposals L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  4. Tokamak scenarios • Scenario development • H-mode (from DIIID) • Density limit • New states (helical boundaries) • Additional heating (DNBI) • Active control of Tokamak discharges • Active rotation • Sidebands studies • RWM control • Control of m=2, n=1 and error fields • Pellet injection and MHD control • RFA studies • Comparison between RFX-mod Tokamak and RFP discharges • Tokamak H-mode vs RFP high edge temperature gradient plasmas • Spontaneous rotation • Flow in Tokamaks • Effects of magnetic field perturbation on flow profile • RMP effects on zonal flows and edge L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  5. 3D effects on flow in RFPs • Effect of the 1/-7 flow on the penetration of magnetic field errors • External magnetic perturbation effect on plasma flow (T2R team) •  comparison with T2R results L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  6. Resistive Wall Modes in RFP • Model validation experiments • Expand the benchmark of existing and new numerical models • Test of innovative control schemes • Reconfigured sensor system • Resilience to magnetic noise and disturbances • RWM in high current helical plasmas L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  7. m=0 control and understanding • Control of m=0 by means of saddle coils • Imposing m=0, n=7 (n = 14) harmonic to vary the island amplitude and study PWI • High gains for m=0, n<7 @ F<=-0.1 • Study of the toroidal field ripple by imposing stationary m=0, n=12,16, 24 • Development of new feedback control scheme for low order m=0 harmonics • Can benefit from optimisation experiments on toroidal power supply • Study of toroidal field ripple • Imposing stationary m=0, n=12,16, 24 • Excluding some toroidal field coils L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  8. Optimisation • Power supplies • Optimisation of toroidal inverter gains • Voltage control of TFAT converters • Enhancement of toroidal power supply control • Upgrade of the Plasma Current Control System • Optimisation of the feedback regulator • Implementation of automatic plasma current ramp-up • Improve controller awarness of machine operative conditions • Correction of local toroidal field measurement • Slight misalignment due to mechanical tolerance  pick-up of poloidal field • Can provide a reduction of the heating observed at the same two toroidal position L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  9. Active control of RFP plasmas • Innovative schemes and advanced concepts • Modal Dynamic Decoupler • System Identification (T2R proposal) • Independent B and Br feedback • Feedback on plasma response • Control of the m=1, n=-7 at the resonance • Active control • DRE pacing • Different toroidal flux conserving boundaries • Test of a different decoupling matrix • 3D boundary conditions at high plasma current • Study of plasma-shell proximity effect L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  10. Main constraints to be considered • Many proposals involve Tokamaks • Need to develop a reliable scenario (not an easy task with X-point) • Check feasibility of single null X-point configurations (asap) • Check availability of diagnostics and/or additional heating (DNBI, NBI) • New control hardware and software architecture is being developed (see A. Barbalace’s talk) • Integration and interaction with the experimental programme must be assessed as soon as possible • An experimental proposal clearly stating the plan for integration is needed • Ready this year? • Some proposals require work/modifications to be carried out on the control system and on the power supplies • Collaboration between TF2 and Operation Support will be essential • Availability of proposers external to the laboratory • Various constraints to be considered L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  11. Experimental programme GDC commissioning Restart RFP plasma commissioning Restart TOK plasma Commissioning Test TOK with SN X-point GDC GDC aprile First TF2 experiments will be devoted to tokamak. The aim is only to test present capabilities after a long time without tokamak discharges. Operation Support to check technical feasibility of SN X-point. Shut-down L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  12. TF2 commitments for 2011 • Tokamak operation • Re-establish reliable operation to be able to perform proposals on active control, flow and edge studies • Try to develop the H-mode scenario • Improve tools for control and understanding of m=0 modes • Optimisation toroidal power supply • Implementation of a new m=0 controller • Integration of the new control system architecture • Major issue • Test innovative control and identification concepts • Modal Decoupler and/or others L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  13. Missing • Proposals taking advantage from the new control system • Optimisation and setup of diagnostics • Proposals dealing with plasma shape • Comparison with MST (maybe in TF1?) L. Zanotto – 10 February 2011 – RFX-mod programme workshop

  14. Discussion • Is there any other area not covered by proposals? • Integration of the new control system: we should really identify when we want the new system to be in operation • the availability of the new system may lead to a substantial revision of the proposals ( overall re-optimisation of the control gains is probably necessary) • a clear path to the new system should be established now • Do we have enough tools to develop H-mode in RFX-mod tokamaks? It is not simply a matter of producing a Single-Null X-point in vacuum… Experience is needed directly in the control room. L. Zanotto – 10 February 2011 – RFX-mod programme workshop

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