Transcript Slide 1

TF2: Active control of RFP and tokamak plasmas
Report on experimental proposals
L. Zanotto, P. Piovesan, A. Soppelsa
L. Zanotto – 10 February 2011 – RFX-mod programme workshop
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
Main areas covered by proposals
L. Zanotto – 10 February 2011 – RFX-mod programme workshop
Tokamak scenarios
 Scenario development
o H-mode (from DIIID)
o Density limit
o New states (helical boundaries)
o Additional heating (DNBI)
 Active control of Tokamak discharges
o Active rotation
o Sidebands studies
o RWM control
o Control of m=2, n=1 and error fields
o Pellet injection and MHD control
o RFA studies
 Comparison between RFX-mod Tokamak and RFP discharges
o Tokamak H-mode vs RFP high edge temperature gradient plasmas
o Spontaneous rotation
 Flow in Tokamaks
o Effects of magnetic field perturbation on flow profile
o RMP effects on zonal flows and edge
L. Zanotto – 10 February 2011 – RFX-mod programme workshop
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
Resistive Wall Modes in RFP
 Model validation experiments
o Expand the benchmark of existing and new numerical models
 Test of innovative control schemes
o Reconfigured sensor system
o Resilience to magnetic noise and disturbances
 RWM in high current helical plasmas
L. Zanotto – 10 February 2011 – RFX-mod programme workshop
m=0 control and understanding
 Control of m=0 by means of saddle coils
o Imposing m=0, n=7 (n = 14) harmonic to vary the island amplitude and study
PWI
o High gains for m=0, n<7 @ F<=-0.1
o 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
o Can benefit from optimisation experiments on toroidal power supply
 Study of toroidal field ripple
o Imposing stationary m=0, n=12,16, 24
o Excluding some toroidal field coils
L. Zanotto – 10 February 2011 – RFX-mod programme workshop
Optimisation
 Power supplies
o Optimisation of toroidal inverter gains
o Voltage control of TFAT converters
o Enhancement of toroidal power supply control
 Upgrade of the Plasma Current Control System
o Optimisation of the feedback regulator
o Implementation of automatic plasma current ramp-up
o Improve controller awarness of machine operative conditions
 Correction of local toroidal field measurement
o Slight misalignment due to mechanical tolerance  pick-up of poloidal field
o Can provide a reduction of the heating observed at the same two toroidal
position
L. Zanotto – 10 February 2011 – RFX-mod programme workshop
Active control of RFP plasmas
 Innovative schemes and advanced concepts
o Modal Dynamic Decoupler
o System Identification (T2R proposal)
o Independent B and Br feedback
o Feedback on plasma response
o Control of the m=1, n=-7 at the resonance
 Active control
o DRE pacing
o Different toroidal flux conserving boundaries
o Test of a different decoupling matrix
o 3D boundary conditions at high plasma current
o Study of plasma-shell proximity effect
L. Zanotto – 10 February 2011 – RFX-mod programme workshop
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
Experimental programme
GDC
commissioning
Restart RFP plasma
commissioning
Restart TOK plasma
Commissioning GDC GDC
aprile
Test TOK with SN X-point
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
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
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
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