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