1. RF2011, Newport, RI 1 June 2011 1 Long Pulse Operation with the ITER-Relevant LHCD Antenna in Tore Supra A Ekedahl 1, L Delpech 1, M Goniche 1, D Guilhem 1, J Hillairet 1, M Preynas 1, PK Sharma 2, J Achard 1, YS Bae 3, X Bai 4, C Balorin 1, Y Baranov 5, V Basiuk 1, A Bécoulet 1, J Belo 6, G Berger-By 1, S Brémond 1, C Castaldo 7, S Ceccuzzi 7, R Cesario 7, E Corbel 1, X Courtois 1, J Decker 1, E Delmas 8, BJ Ding 9, X Ding 4, D Douai 1, R Dumont 1, C Goletto 1, JP Gunn 1, P Hertout 1, GT Hoang 1, F Imbeaux 1, KK Kirov 5, X Litaudon 1, P Lotte 1, R Magne 1, J Mailloux 5, D Mazon 1, F Mirizzi 7, P Mollard 1, P Moreau 1, T Oosako 1, V Petrzilka 10, Y Peysson 1, S Poli 1, M Prou 1, F Saint-Laurent 1, F Samaille 1, B Saoutic 1 1) CEA, IRFM, 13108 Saint Paul-lez-Durance, France. 2) Permanent address: Institute for Plasma Research, Bhat, Gandhinagar, Gujarat, India. 3) National Fusion Research Institute, Daejeon, South Korea. 4) Southwestern Institute of Physics, Chengdu, P R China. 5) Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, OX14 3DB, UK. 6) Associaçao Euratom-IST, Centro de Fusao Nuclear 1049-001 Lisboa, Portugal. 7) Associazione Euratom-ENEA sulla Fusione, CR Frascati, Roma, Italy. 8) Present address: ITER Organization, 13067 Saint Paul-lez-Durance, France. 9) Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, P R China. 10) Association Euratom-IPP.CR, Za Slovankou 3, 182 21 Praha 8, Czech Republic.

2. A. Ekedahl et alRF2011, Newport, RI1 June 2011 2 Outline Introduction and motivation >LHCD system upgrade in Tore Supra >Lower Hybrid Current Drive (LHCD) for ITER >Manufacturing and installation of the new LHCD antenna Experimental results >First commissioning period (Sept 2009 – March 2010) >Long pulse operation with full LHCD system (from Oct 2010) Summary

3. A. Ekedahl et alRF2011, Newport, RI1 June 2011 New LHCD system for CW operation ~ 7 tons! ¼ ITER antenna 700kW/klystron CW Together with the upgrade of the LHCD generator, the new antenna is a key element of the LHCD system upgrade in Tore Supra  Increased LHCD capability to ~10MW / 1000s (3.7GHz) at the generator  Extended domain of long pulse operation for Tore Supra: higher density and plasma current Passive Active Multijunction (PAM) chosen for Tore Supra, since preferred option for ITER PAM 3

4. A. Ekedahl et alRF2011, Newport, RI1 June 2011 Which mission(s) for LHCD in ITER ? Save Volt-seconds from early plasma phase (up to 58Wb)  Extend burn duration (extend burn phase to ~500s) Help accessing and sustaining steady-state scenario  Drive far off-axis current, complementarily to bootstrap current, NBCD and ECCD. Challenges for ITER: Technology for long pulses Coupling of RF waves in ITER GT Hoang et al., Nucl. Fusion (2009) 4 Modelling of ITER LHCD antenna: J Hillairet et al., Poster B-08 Thursday

5. A. Ekedahl et alRF2011, Newport, RI1 June 2011 5 Passive Active Multijunction (PAM) Passive Active Multijunction (PAM): Alternance of active waveguides and passive waveguides Allows cooling channels close to the plasma (heat load, ITER environment) Low reflected power at cut-off density (far distance coupling required in ITER) PAM Concept: Ph Bibet et al., Nucl. Fusion (1995) Tore Supra (TS) LHCD PAM antenna TS PAM design: J Belo, Ph Bibet et al., FED (2005)

6. A. Ekedahl et alRF2011, Newport, RI1 June 2011 Manufacturing of the PAM blocks Assembly of the 17 plates with brazing material to constitute one of the two PAM blocks. The two PAM blocks are then joined together by electron beam welding. Brazing material (Cu-Sil) 40 µm 7 days in oven (850  C). Use of pressurized bellows  Patented by CEA D Guilhem et al., FED (2011) 6 0.6m

7. A. Ekedahl et alRF2011, Newport, RI1 June 2011 Installation of the Tore Supra PAM antenna Insertion in Tore Supra, August 2009 7 tons, millimeter precision! E Delmas et al., 7

8. A. Ekedahl et alRF2011, Newport, RI1 June 2011 8 1)At low power, characterise the reflection coefficient behaviour. Validate the ALOHA coupling code. 2)Assess coupling during edge perturbations, mimicking ELM behaviour. 3)Achieve ITER-relevant power density, i.e. 25MW/m 2 at f = 3.7GHz (equivalent to 33MW/m 2 at f = 5GHz). 4)Full non-inductive discharges (V Loop = 0) with PAM. Goals of the PAM commissioning in Tore Supra First test of a PAM carried out FTU, 8GHz, short pulses (<1s): V Pericoli et al., Nucl. Fusion (2005) Participation of 15 collaborators from 7 countries: IST Lisbon; IPP-CR Prague; CCFE Culham; ENEA Frascati; IPR India; SWIP China; ASIPP China; NFRI South Korea; ALOHA code: J Hillairet et al., Nucl. Fusion (2010)  Fast and smooth commissioning period of PAM

9. A. Ekedahl et alRF2011, Newport, RI1 June 2011 9 Low reflected power level with PAM Lower reflected power compared to Full Active Multijunction (FAM) at larger plasma-launcher gap: follows design specification & linear theory PAM FAM (1 st gen.) FAM (2 nd gen.) FAM First generation (No longer in use on TS) Second generation (3.5MW coupled power so far) PAM

10. A. Ekedahl et alRF2011, Newport, RI1 June 2011 10 Coupling agrees with linear theory Computed RC with ALOHA vs density, for different gradients Low reflection coefficient (RC< 2%) near cut-off density  Low power (~200kW) for comparison to linear theory M Preynas et al., Nucl. Fusion (2011), Poster B-06 Thursday ALOHA n e (10 17 m -3 ) Average RC (%) n co = 1.7*10 17 m -3 at f = 3.7GHz

11. A. Ekedahl et alRF2011, Newport, RI1 June 2011 Coupling during edge pertubations demonstrated Supersonic Molecular Beam Injection (SMBI) to mimic ELMs Reflection coefficient behaves according to modelling. At least intermediate power (1.5MW) can be maintained during SMBI. LH power deposition shape does not change during edge perturbations PK Sharma et al., 37 th EPS (2010) 11 Hard X Ray profile, 60-80 keV

12. A. Ekedahl et alRF2011, Newport, RI1 June 2011 12 ITER-relevant power density for 78s 2.75MW (25MW/m 2 ) coupled with PAM for 78 seconds Low RC ( 10cm) Efficient cooling: Waveguides and side protections below 270  C E LHCD = 220MJ IR surveillance A Ekedahl et al., Nucl. Fusion (2010)

13. A. Ekedahl et alRF2011, Newport, RI1 June 2011 Full CD regime (PAM alone) for 50s Double feedback loops to maintain I P constant and V Loop =0 CD efficiency with PAM:  LHCD ~ 0.75x10 19 A/W/m 2 Similar to Full Active Multijunction antennas (GJ-discharges) Hard X Ray profile, 60-80 keV 0.51MA, B T = 2.7T) 13 HXR profile (LH deposition profile) peaked at r/a ~ 0.25 A Ekedahl et al., Nucl. Fusion (2010)

14. A. Ekedahl et alRF2011, Newport, RI1 June 2011 14  n // spectrum from ALOHA code (using measured values of power, phase and edge density) Ray-tracing modelling of full current drive discharge n // spectrum (ALOHA)  Ray tracing code, C3PO, using 36 rays (6 n // -values x 6 waveguide rows) Y Peysson and J Decker. Report EUR- CEA-FC-1739, Euratom-CEA (2008)

15. A. Ekedahl et alRF2011, Newport, RI1 June 2011 15 Good agreement with modelling, in this example C3PO/LUKE reproduce well the HXR profile and the driven current. Synthetic diagnostic models well the line integrated HXR emission. Y Peysson and J Decker, PoP (2008) J Decker et al., Poster A-50 Wednesday Although good agreement in this example, robustness in LHCD modelling is still required. Y Peysson et al., Poster A-29 Wednesday I Plasma exp: 510kA I LH LUKE: 508kA I LH Cronos/HXR: 443kA Experiment Modelling Line integrated HXR emissionLH current profile for #45534 D fast = 0.1m 2 /s

16. A. Ekedahl et alRF2011, Newport, RI1 June 2011 16 M Goniche et al., PPCF (2010), Poster A-27 Wednesday LHCD at high density: effect of fuelling method HXR emission decays as n e -3, and even faster above ~ 4*10 19 m -3. Faster decay of HXR-signal is correlated with increase in density fluctuation rate at the antenna. T Oosako et al., Poster A-28 Wednesday ITPA task on LHCD efficiency at high density Gas Pellets Gas I Sat level and fluctuation rate HXR emission (60-80 keV)

17. A. Ekedahl et alRF2011, Newport, RI1 June 2011 Summary of PAM commissioning Number of sessionsNumber of pulses 200914 (+ 2 parasitic)240 201017274 Total31 (+ 2 parasitic)514 Fast and smooth commissioning period 2.7MW coupled after 240 pulses on plasma After 500 pulses: 9.7GJ accumulated injected energy Large fraction of time operated at high power (> 2MW) Accumulated time at given powerAll in good shape after the campaign 17 25MW/m 2

18. A. Ekedahl et alRF2011, Newport, RI1 June 2011 First half of LHCD plant equipped with CW klystrons High power CW klystrons: L Delpech et al., Poster A-26 Wednesday RF control system: G Berger-By et al., Poster A-25 Wednesday Pulses with up to 3MW/43s achieved with Full Active Multi- junction antenna, fed by a set of eight 700 kW/CW klystrons TH2013C: 700kW CW on matched load 18 #46518 P LH = 3MW

19. A. Ekedahl et alRF2011, Newport, RI1 June 2011 19 Long pulse operation with both LHCD antennas Both LHCD antennas together  4.5MW/150s obtained (650MJ injected energy) Opens new operational space (n e, I P ) for long pulse operation Slight increase in density due to non-optimised feedback control PAM, FAM Total P LHCD

20. A. Ekedahl et alRF2011, Newport, RI1 June 2011 20 Summary ITER-relevant LHCD antenna (PAM) now in routine operation in Tore Supra. Very encouraging results for non-inductive current drive in long pulse operation on Tore Supra: Fast commissioning of PAM: 2.7MW reached after 240 pulses on plasma. Far distance coupling: RC ~ 2% at large gap (10cm) Good agreement with ALOHA coupling code Long pulse capability at ITER-relevant power density: so far 25MW/m 2 / 78s. CD capability similar to Full Active Multijunction  Gives good confidence for ITER LHCD design Next: Full CW LHCD system with eight new generation klystrons on PAM antenna.

21. A. Ekedahl et alRF2011, Newport, RI1 June 2011 21 Posters, Wednesday 1/6: A-25: G Berger-By Tore Supra LH transmitter upgrade, RF driver for the power spectrum A-26: L DelpechValidation on plasma of the Tore Supra CW LHCD generator A-27: M GonicheLHCD Experiments at high density on Tore Supra A-28: T Oosako SOL density fluctuations in front of the Tore Supra PAM launcher A-29: Y PeyssonEffect of plasma fluctuations on lower hybrid current drive A-50: J DeckerBremsstrahlung emission modelling and fast electron physics A-52: D DouaiModelling of Ion Cyclotron Wall Conditioning plasmas Posters, Thursday 2/6: B-06: M PreynasCoupling of the ITER-relevant LH antenna in Tore Supra B-08: J HillairetRF modeling of the Lower Hybrid Antenna proposed for ITER B-19: J-M BernardTITAN: a test-bed facility for ICRH antenna and components of ITER B-33: J JacquotSelf-consistent non-linear RF wave propagation B-34: M KubicAttenuation of ICRH-induced potentials in the SOL of Tore Supra IRFM / Tore Supra contributions at this conference