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Overview of JET results

Overview of JET results. Acknowledgements Staff and management from EFDA Associates involved in the JET workprogramme, in particular the JET Task Force Leaders and the Operator of the facility (UKAEA) European Commission International collaborators: U.S.A. and Japan. JET EFDA Contributors

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Overview of JET results

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  1. Overview of JET results Acknowledgements • Staff and management from EFDA Associates involved in the JET workprogramme, in particular the JET Task Force Leaders and the Operator of the facility (UKAEA) • European Commission • International collaborators: U.S.A. and Japan JET EFDA Contributors presented by J. Pamela J. Pamela Lyon, 14 October 2002

  2. JET divertor configuration 2000-2002 Septum removed by remote handling: Mk-IIGB to Mk-IISRP 2002 onwards Increased triangularity Increased range of ITB plasma configurations Up to April 2001 J. Pamela Lyon, 14 October 2002

  3. Content of the talk • H-mode • ELMs physics / ELM extrapolation to ITER • MHD and kinetic effects on H-mode performance • H-mode performance / consolidation of ITER reference scenario • Advanced Tokamak • AT Physics • AT performance • Real time control • Erosion and co-deposition • Future plans J. Pamela Lyon, 14 October 2002

  4. ELMs: high pedestal density reduces power transients at ITER shaping High d and high npedestal leads to softer and less frequent ELMs (mixed type I - type II) Other “recipes” for access to softer ELMs: - impurity seeding - high Pin/PLH at moderate d (~0.3) J.Ongena, EX/C2-4 A.Loarte, EX/P1-08 J. Pamela Lyon, 14 October 2002

  5. Extended/improved data base for Type I ELMs extrapolation (2 examples) DWELM scales withn*ped Loarte, EX/P1-08 Matthews, EX/D1-1 ELM energy is balanced in/out in JET even ELM energy distribution  optimal for ITER J. Pamela Lyon, 14 October 2002

  6. Type I- ELM revised extrapolation to ITER The improved/extended data baseallows revised predictionsassuming JET data extrapolate to ITER: Tolerable ELMs (C or W) Wmax = 4 to 19 MJ Type I-ELM size predictions WELM = 10 to 20 MJ => hope that Type I ELMs may be tolerable Matthews, EX/D1-1 Loarte EX/P1-08 J. Pamela Lyon, 14 October 2002

  7. MHD and kinetic effects a-particle simulation experiment in ELMy H-mode Multi-MeV acceleration of 120keV 4He beam ions by 3rd harmonic ICRH • evidence from  emission from nuclear reaction 9Be(,n)12C • fast a’s provide up to 80-90% of plasma heating • long sawteeth stabilised by as leading to NTMs Kiptily, NF 42 (2002) Mantsinen et al., PRL 88 (2002) J.M. Noterdaeme, EX/W-1 caveat: these a’s are not isotropic in contrast to DT fusion born a’s J. Pamela Lyon, 14 October 2002

  8. NTM Control sawtooth control by ICRH raises bN NTM onset • Long period sawteeth (due to ICRH) allow NTMs to be destabilised at any BT • used to extend parameter domain towards ITER • typical H-modes in JET are metastable to NTMs (and r* scaling predicts this to be the case in ITER) • Conversely ICRF heating and current drive near q=1 modifies sawteeth and raises bN for 3/2 NTM onset relative to NBI only case Sauter, PRL 2002Hender, EX/S1-2 J. Pamela Lyon, 14 October 2002

  9. ELMy H-mode Consolidation of ITER reference operation Beneficial effect of triangularity Ongena, EX/C2-4 G. Saibene, PPCF 2002 ITER-like plasma shape Higher edge pressure gradient accessible at high d (MHD modelling byG.T.A. Huysmans, EFPW 2001) J. Pamela Lyon, 14 October 2002

  10. HH ELMy H-mode / future work Increased confidence in ITER operation at H~1 and n/nGW>0.85 JET AUG d=0.47 d=0.29 Gruber, NF 41 (2001) Ongena, EX/C2-4 • Further ELMy H-mode studies to be driven by scientific issues : • understanding experimental differences(details of magnetic configuration d, q etc.; ELM behaviour etc.) • identifyingphysics-based scaling parametersfor high density operation • interrelation edge/core/details of plasma configuration/collisionality J. Pamela Lyon, 14 October 2002

  11. Content of the talk • H-mode • ELMs physics / ELM extrapolation to ITER • MHD and kinetic effects on H-mode performance • H-mode performance / consolidation of ITER reference scenario • Advanced Tokamak • AT Physics • AT performance • Real time control • Erosion and co-deposition • Future plans J. Pamela Lyon, 14 October 2002

  12. Advanced Tokamak reliable tuning of shear reversal by LHCD providing easy access to ITBs Hawkes PRL 87 (2001) Challis PPCF 44 (2002) Litaudon, EX/C3-4 J. Pamela Lyon, 14 October 2002

  13. Advanced Tokamak Current Hole observation and modelling • 20-40 cm wide core region has j(r)=0 (error bars ± 10-20 kA) • Modelling: Although off-axis co-LHCD is sufficient to drive negative current near axis, repetitive m=1, n=0 modes would ‘clamp’ current to zero • Hawkes, PRL 87 (2001), Huysmans, PRL 87 (2001), Stratton, PPCF 44 (2002) • Miura EX/C3-1Ra, Stratton EX/C3-1Rb J. Pamela Lyon, 14 October 2002

  14. Advanced Scenarios link between rational q surfaces and ITBs • Transport barriers appear/develop when qmin crosses rational q surfaces • The time when qmin crosses rational surfaces is confirmed by the excitation of Alfven cascades Garbet TH/2-1 Joffrin EX/P1-13 J. Pamela Lyon, 14 October 2002

  15. Advanced Scenarios Alfvén cascades as signature of q(r) evolution Borba, NF 42 (2002) 4 5 Alfvén Cascades observed in ITB plasmas (c.f. JT60-U) and modelled Indication of q(r) evolution from TAE antennas: diagnostic for qmin evolution in ITB plasmas (use of TAE antennas demonstrated for monotonic q profiles) 5 5 4 3 5 5 4 3 n=2 n=2 Jaun, CT/P-06, Breizman TH/4-3, Zonca TH/4-4 J. Pamela Lyon, 14 October 2002

  16. Active control #53697 Ip[MA] PLHCD[MW] MW PICRH PNBI Reference 1016 neutron/s s/Lte (x10-2) Reference Vs [V] Advanced Scenarios Feasibility Demonstration of Pressure Profile Real Time Control • Real time feedback loop on • neutron rate controlled by NB • Te-profilecontrolled by ICRH Mazon, PPCF 44 (2002) Litaudon, EX/C3-4 Joffrin EX/P1-13 J. Pamela Lyon, 14 October 2002

  17. Advanced Scenarios Current Profile Real Time Control • Real-time control of plasma current profile • measurement by polarimetry • acting on LHCD Litaudon, EX/C3-4 J. Pamela Lyon, 14 October 2002

  18. A.T. Summary “Long pulse ITB” “high performance ITB” ITER-AT [JET #53521 t=10s] [JET#51976 t=6.8s] Q=5 H H (IPB98y-2) 1 1.9 >1.5 H ITER 89 L-P 2.1 3.3 N 1.7 2.4 >3.0 nel/nGreenwald 0.5 0.35 0.6-1 INon-Inductive/Ip90% 55% 100% Iboot/Ip50% 40% >60% q955.5 4.9 4.5 Prad/Ptot23% 15% 75%  /E. 27 2 >100 Edge type III ELMs type III ELMs soft ELMs => progress … but still significant efforts needed: higher density / long pulse high performance / impurity control / simultaneous pressure and current profile control J. Pamela Lyon, 14 October 2002

  19. Content of the talk • H-mode • ELMs physics / ELM extrapolation to ITER • MHD and kinetic effects on H-mode performance • H-mode performance / consolidation of ITER reference scenario • Advanced Tokamak • AT Physics • AT performance • Real time control • Erosion and co-deposition • Future plans J. Pamela Lyon, 14 October 2002

  20. Erosion / Deposition Tile Analysis (MkII-GB divertor) Analysis of tiles removed during Shutdown 2001: • clear deposition in inner divertor (co-deposited layers) • almost no depositionin outer divertor • Deposited material is mostly from main chamber erosion => Confirm results from tile analysis with the more open MkII-A divertor J. Pamela Lyon, 14 October 2002

  21. Erosion / Depositionshot by shot deposition measurement with Quartz Microbalance Quartz monitor 0.1 m 80 shots louvre Measured deposition rate much lower than concluded from Deuterium-Tritium experiments in 1997 : possible reasons - strike point position (identified to be very important ) - lower density plasmas with larger ELMS in 1997 - reduced operating T: V-vessel from 300 to 200ºC tiles from 200 to 100ºC (effect tbc) - QMB at 100ºC while divertor louvres are water cooled V.Philipps, EX/P5-08 J. Pamela Lyon, 14 October 2002

  22. Erosion / Deposition Plasma flow in SOL transports carbon to divertor inner target Mach Probe tile analysis QMB Net Erosion, physicaland chemical Limited Physical Erosion and Deposition Deposition Chemical Erosion J. Pamela Lyon, 14 October 2002

  23. Content of the talk • H-mode • ELMs physics / ELM extrapolation to ITER • MHD and kinetic effects on H-mode performance • H-mode performance / consolidation of ITER reference scenario • Advanced Tokamak • AT Physics • AT performance • Real time control • Erosion and co-deposition • Future plans J. Pamela Lyon, 14 October 2002

  24. Experimental Campaigns until February 2004, including a Trace Tritium Campaign 2004 shutdown: new/upgraded diagnostics ICRHITER-like antenna => High Power Density ICRH coupling / ELM-resilience modified divertor (ITER-like d in an extended range of Ip/BT ; increased power handling) Near Term Plans ITER like antenna / Resonant Double Loop Concept from ORNL and CEA J. Pamela Lyon, 14 October 2002

  25. Conclusion • ELMy H-mode • revised Type I ELMs predictions / hope that Type I ELMs be tolerable on ITER • possible paths to alternate / softer ELMy regimes compatible with high HH • progress in NTM physics and control (sawtooth / ICRH) • new tool for alpha particle studies available (4He acceleration by ICRH) • consolidation of ITER operating scenario HH ~1 and n/nG>0.85 at ITER relevant d(~0.5), q95(~3) in relevant Zeff range (1.5-2.0) • Advanced Modes • LHCD provides easy and reliable access to Reversed Shear and control of off-axis current in long pulses • Current Holes observed in R.S. / Transport & MHD models developed • Rational q surfaces play a key role in ITB formation/development • Alfvèn cascades in R.S. plasmas: promising tool for q(r,t) diagnostic • Real Time control of pressure profile demonstrated • Real Time control of current profile demonstrated • JET remains a key asset with unique features in preparation of ITER Operation (ITER scenarios / test of ITER auxiliaries prototypes) J. Pamela Lyon, 14 October 2002

  26. JET papers at this confrence LOARTE "Type I ELM energy and particle losses in JET ELMy H-modes and implications for ITER", EX/P1-08 MATTHEWS .,"Steady state and transient power loads in JET", EX/D1-1 RAPP "Reduction of divertor heat load in JET ELMy H-modes using impurity seeding techniques", EX/P1-09 PARAIL "Integrated Modelling of JET H-mode Plasmas with type-I ELMs", TH/P3-08 KOSLOWSKI "Observation of Pre- and Postcursor Modes of Types I ELMs on JET", EX/P1-14 LITAUDON "Progress towards steady state operation and real time control of ITBs in JET", EX/C3-4 HENDER "Sawtooth, Neo-Classical Tearing Mode and Error Field Studies in JET", EX/S1-2 ONGENA "Towards the realization on JET of an integrated H-Mode scenario for ITER", EX/C2-4 TESTA "Experimental Study of the Stability of Alfven Eigenmodes on JET", EX/P1-17 NOTERDAEME "Heating, current drive and energetic particles studies on JET ...", EX/W-1 MANTICA "Transient Heat Transport Studies in JET Conventional and Advanced Tokamak Plasmas", EX/P1-04 GARBET "Micro-stability and Transport Studies of Internal Barriers in JET", TH/2-1 JOFFRIN "Internal Transport Barrier triggering by rational magnetic flux surfaces", EX/P1-13 DUX "Impurity transport in internal barrier discharges on JET", EX/C3-5Ra PHILIPPS "Recent results on long term fuel retention in JET and TEXTOR and predictions for ITER", EX/P5-08 SUTTROP "Parameter similarity studies in JET, ASDEX Upgrade and ALCATOR C-Mod", EX/P5-07 HIDALGO "Experimental evidence of fluctuations and flows near marginal stability ...", EX/C4-4 STRATTON "Equilibria and Stability of JET Discharges with Zero Core Current Density", EX/C3-1Rb (see talk by Miura, EX/C3-1Ra) CASTALDO "Transport barriers produced in JET discharges by ion Bernstein waves", post-deadline JAUN "Collective modes and Fast Particle Confinement in ITER", CT/P-06 ASAKURA "Studies of ELM heat load, SOL flow and carbon erosion ..." , CT/P-01 BREIZMAN "Alfven Eigenmodes in Shear Reversed Plasmas", TH/4-3 J. Pamela Lyon, 14 October 2002

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