L. Zanotto – 10 February 2011 – RFX-mod programme workshop

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 developmento H-mode (from DIIID)o Density limito New states (helical boundaries)o Additional heating (DNBI)

Active control of Tokamak dischargeso Active rotationo Sidebands studieso RWM controlo Control of m=2, n=1 and error fieldso Pellet injection and MHD controlo RFA studies

Comparison between RFX-mod Tokamak and RFP dischargeso Tokamak H-mode vs RFP high edge temperature gradient plasmaso Spontaneous rotation

Flow in Tokamakso Effects of magnetic field perturbation on flow profileo 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 schemeso Reconfigured sensor systemo 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 coilso Imposing m=0, n=7 (n = 14) harmonic to vary the island amplitude and study PWIo High gains for m=0, n<7 @ F<=-0.1o 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 rippleo Imposing stationary m=0, n=12,16, 24o Excluding some toroidal field coils

L. Zanotto – 10 February 2011 – RFX-mod programme workshop

Optimisation

Power supplieso Optimisation of toroidal inverter gainso Voltage control of TFAT converterso Enhancement of toroidal power supply control

Upgrade of the Plasma Current Control Systemo Optimisation of the feedback regulatoro Implementation of automatic plasma current ramp-upo Improve controller awarness of machine operative conditions

Correction of local toroidal field measuremento 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 conceptso Modal Dynamic Decouplero System Identification (T2R proposal)o Independent B and Br feedbacko Feedback on plasma responseo Control of the m=1, n=-7 at the resonance

Active controlo DRE pacingo Different toroidal flux conserving boundarieso Test of a different decoupling matrixo 3D boundary conditions at high plasma currento 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

Shut-down

aprile

commissioning

commissioning

Commissioning GDC

GDC

Restart RFP plasma

Restart TOK plasma

GDC 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.

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.