Report on experimental proposals submitted to TF1 ‘RFP performance: high current operation and

1. Report on experimental proposals submitted to TF1 ‘RFP performance: high current operation and advanced scenarios’ R. Lorenzini and F. Milani Consorzio RFX, Euratom-ENEA Association, Padova, Italy

2. ... we expect that the achievement of a baseline 2 MA plasma, ready for full exploitation of confinement, will be the subject of both the 2009 and 2010 experimental campaigns. Why TF1? ... during 2009 the work on the High Current operation will proceed along two synergistic main projects: Project 1: optimization of the 1.5 MA scenario Project 2: initial explorationof the current regime between 1.5 and 2 MA Report ‘Guidelines and strategy for the preparation of the 2009 experimental programme’P. Martin and M.E. Puiatti

3. Part 1: a bit of statistics ...

4. General info and remarks about proposals • Number of Proposals submitted to TF1: 24 • Number of Days required: 111 • Number of Effective Days: 64 • In this talk we present a simple statistical analysis of only these proposals: hence the results we present could be not valid if many proposals requiring high current were not been addressed to TF1 but only to other TFs (we do not know yet ...) • A description of the proposals will be also presented: this description will be brief because many (almost all) proposals have already been described by other TFLs

5. What does ‘High Current’ mean for proponents? • almost all the proposals are at I ≥ 1 MA (except 1, I < 0.4 MA) • the level of current is specified with I ≥ 1 proposal with a current scan 1 proposal with current not specified

6. Investigation of the equilibrium: request on F • Typical request on F : Not specified NSP (hence shallow, since in 2008 we operated essentially at F shallow ?) • Only few experimental days are requested to explore equilibria different from F shallow.

7. Request on density: • Typical request regarding the density : Not specified(NSP) • maybe because we feel we aren’t able to control it?

8. Which is the preferred item of research for TF1? • The preferred item of research at high current (as one could guess) is QSH, better if SHAx • Many aspects of QSH are of interest: magnetic topology, transport and so on... • QSH is favourite at shallow reversal:this is the reason why (maybe) there is not much interest in exploring different equilibria.

9. What about advanced scenarios? • Only 25% of the experimental time is dedicated to explore advanced scenarios (OPCD, PPCD, OFCD) • 75% of the time is dedicated to study standard plasma • This is a comprehensible attitude resulting from the experience of the past year. Standard plasma behaves better than OPCD plasma

10. QSH: spontaneous vs stimulated • QSH is the favourite item: most of proposals regard spontaneous QSH • This is a comprehensible attitude resulting from the experience of the past year. Standard plasma is so efficient in producing QSH that it seems useless to stimulate it by means of an external action. • Anyway we should not stop trying...

11. High overlapping with the other TFs • Proposals submitted only to TF1: 4 on 2423 Days on 111 ( ~20%) • TF1 shares proposals with all the other TFs. • This is an obvious consequence of the fact that ‘high current’ is a plasma regime to study MHD, transport ...

12. Part 2: going deeper...

13. P1: 2, 11, 13, 15, 31, 32, 34, 53, 55, 56, 66, 69, 70, 73, 81, 82, 96, 117, 127 P2: 2, 11, 13, 15, 31, 32, 34, 41, 42, 43, 53, 55, 56, 66, 69, 70, 73, 81, 82, 96, 117, 127 52 24 proposals, 23 at high current

14. 4 proposals addressed only to TF1 • 41) Lorenzini et al. ’Dependence of the plasma properties on the equilibrium’, 1< I < 2MA • 42) Lorenzini et al. ’QSH characterisation at 2 MA’ • 96) Bolzonella et al. ’High Current Oscillating Field Current Drive on RFX’, I > 1.3 MA till the maximum reachable in sustained and non sustained discharges, polarimeter • 127) K. McCollam at al. ‘High-Plasma-Current, Low-Frequency OFCD on RFX’, I > 1.3 MA up to the maximum reachable in sustained and non-sustained discharges, polarimeter, long pulses

15. 11 Proposals are shared with TF2 (MHD): part 1 Effect of the QSH on edge properties: • 2) Carraro et al. ‘Influence of QSH dominant mode on particle influxes (QSH-SHAx)’ • 56) Spolaore at al. ’Edge particle flux monitoring in high current discharges’ Advanced Scenarios: • 34) Terranova et al. ‘OPCD evolution and scan in global plasma parameters’ • 43) Lorenzini et al. ‘OPCD in low density condition’ Magnetic field topology investigation by means of two ‘new’ diagnostics: impurity pellet injector and the polarimeter: • 53) Terranova et al. ‘Internal magnetic field structure investigation by means of pellet injection’ • 31 e 32) Auriemma et al. ‘q profile measurement in SHAx/MH high current regimes’

16. 11 Proposals are shared with TF2 (MHD) : part 2 QSH control and investigation: • 70) Zuin et al. ‘m=0 knocks for QSH sustainment’ • 73) Zuin et al. ‘QSH study through F scan at high current’ Comparison between other machines and RFX-mod 117) Masamune et al. ’Comparative study of neoclassical effect in RFX-mod and RELAX by using the equilibrium reconstruction code (RELAXFit)’ Scalings • 55) Spolaore et al. ‘Plasma current parameter scaling on CMC discharges’

17. 8 Proposals shared with TF3 (transport) Impurity transport • 11) Carraro et al. ‘Evaluation of medium mass impurity transport parameters in RFX-mod in QSH and MH regimes’ • 13) Carraro et al. ‘Evaluation of heavy impurity transport parameters in RFX-mod in QSH and MH regimes’ QSH investigation • 15) Valisa et al. ‘Highly radiating regimes and QSH’ Advanced scenarios • 59) Spolaore et al. ‘Edge plasma monitor of QSH states induced by OPCD operations and not null reference on the dominant mode’ (low current: I <0.4 MA) Momentum transport • 66) Vianello et al. ’Shafranov shift scan at high current for flow asymmetry investigation’. Energy transport by means of a brand new diagnostic! • 69) Zuin et al. ‘Ion temperature measurements in helical plasmas by means ofNPAdiagnostics’

18. 3 Proposals shared with TF4 (Optimization) QSH investigation: • 81) Cavazzana et al., ‘QSH and SHAx at High Density’,Efficient F control to avoid loss of reversal • 82) Cavazzana et al., ‘Extreme F ~ 0- RFP’,Development of an F control system capable of maintaining a precise equilibrium avoiding loss of reversal in different plasma condition. From Project 1 to Project 2: • 52) All TFLs ‘The 1.8 and 2 MA discharges’ ...

19. Special requirements of 52 (see also talk of L. Zanotto) Critical: • ensure correct operation of PVAT and of equilibrium control system to avoid unexpected full poloidal protection. • need to transiently exceed the maximum nominal PVAT current (6.25 kA), to 6.5 kA for ~ 50ms. Recommended: • correction systematic error at 120 deg (MHD controller) • correction of error field during startup (MHD controller) • plasma shape (horizontal equilibrium controller • use of GDC H2 preload and Pellet injector • best would be to carry out experiments not far from Boronization • efficient F control in order to avoid loss of reversal during the discharge Control of field errors Control of density Control of equilibrium