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Status and Plans for JET under EFDA

Status and Plans for JET under EFDA. Michael Watkins Head of Programme EFDA Close Support Unit On behalf of all contributors to EFDA-JET Workprogramme 14 June 2004, IEA LTA ExCom19, Jaeri, Japan. JET 2003 performance: year of records. Highest magnetic field operation during EFDA 4.0 T

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Status and Plans for JET under EFDA

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  1. Status and Plans for JET under EFDA Michael Watkins Head of Programme EFDA Close Support Unit On behalf of all contributors to EFDA-JET Workprogramme 14 June 2004, IEA LTA ExCom19, Jaeri, Japan

  2. JET 2003 performance: year of records • Highest magnetic field operation during EFDA 4.0 T • Highest plasma current during EFDA 4.0 MA • Highest Deuterium NBI power ever 22.7 MW • Highest yearly 2.45 MeV neutron yield ever 4.5x10+19 (25% more than in 1997) • Most demanding JET operation ever 3717 pulses/yr (20% more than in 1997) (sustained breakd.) • 3rd operation in Tritium (after 1991 and 1997)

  3. Water leak from LHCD into torus Arc in ohmic heating circuit Reliability over last 10 years Total hours lost per weekNo trend visible 131 S/T days planned (197 plasma operation days), 128 achieved

  4. JET under EFDA: a facility used collectively in preparing for ITER Participation of European Physicists in JET 2000-2004 Experimental Campaigns About 300 European scientists and collaborators from USA, Japan, Russian Federation, China are involved actively on JET experiments

  5. C3 C2 C8 C10-C14 C1 C9 C7b C5 C6 C7a C4 Scientists involved in EFDA-JET 2000-4 2003: Associations:~58ppy for Campaigns (including C7b); similar level for Support International Collaboration:~3.2ppy on-site + off-site participation US (27p/1.8ppy) RF (12p/1ppy) Japan (4p/0.1ppy) China (1p/0.3ppy)

  6. Shutdown 2004-2005 • Shutdown started: 6 March 2004 • Planning revised to take account of repair of water leak on NB system on Octant 8 and present delivery schedules for key components • Expect pump-down: end February 2005 Experimental programme schedule 2005 (Proposal) • Campaigns C15, C17 and C18 - Mid-July to mid-November 2005 (78 S/T days planned, including 10 days contingency) Status of JET Workprogramme 2004/5

  7. 2. Critical issues for ITER 1. Bring new systems to full performance(divertor, diagnostics, LH launcher) (potentially impacting detailed design of ITER components, e.g. first wall, heating & current drive systems, diagnostics…) • Design tolerable ELMs • Commissioning of the MkII HD divertor • Characterise ELM behaviour and edge pedestal in ELMy H-mode • Characterise disruptions • Commissioning of new/upgraded diagnostics and systems • Measure tritium retention and migration • High-level commissioning of theLH system to full power • Establish level of off-axis current with off-axis NBI and/or MC-ICRH) and quantify degree of rotation achieved with low momentum input • Exploit fully the LH system • Quantify physics governing rotational stabilisation of RWMs • Control core MHD (fishbones) typical of hybrid regimes Strong focus in 2005 on preparing ITER detailed design and ITER exploitation

  8. Elmy H-modes Triangularity d Mark II HD divertor • Divertor being modified during 2004 shutdown • ITER-like high triangularity ~0.5at Ip ~ 4 MA • 40MW for 10s • Increased flexibility of plasma configurations for advanced modes studies

  9. Fourteen Diagnostics Enhancements Projects under construction, to be operational in 2005 Significant upgrade of the scientific capability of JET Testing of ITER diagnostic technologies • Halo sensors and magnetics (ENEA-RFX/Create) / ITER relevant technology • High Resolution Thomson Scattering (ENEA-RFX)(US collaboration) • CXRS core (UKAEA)(US collaboration) • Microwave access (IST,CNR-Milano, FOM, IPP) / ITER relevanttechnology • Vertical bolometer camera (IPP) • Tritium retention studies diagnostics (UKAEA, TEKES, FZJ, IPP, VR) / ITER relevant technology • Edge Current Profile (UKAEA, VR, CEA, IST)(US collaboration) • IR camera viewing system (CEA, ENEA) / ITER relevant technology • TAE antennae / high n modes (CRPP)(US collaboration) • Magnetic Proton Recoil (VR, CNR-Milano, IST) • Neutron Time Of Flight TOFOR (VR, CNR-Milano, IST) • Lost alphas (IPP)(US collaboration) • Fast Digitizers (IST, UKAEA)(US collaboration) • Disruption mitigation (FZJ, UKAEA) + Collaborations with Russian Federation on Neutron Diagnostics and Neutral Particle Analysers

  10. New TAE antennas Measure the damping rate of AE’s with high toroidal mode numbers 4 compact solenoid like antennae, at 2 toroidal locations

  11. Shot 60835: Magnetics Alfvén cascades Shot 60835: Interferometer • Quiet period around qmin=3 • due to low density of low n rationals • related to reduced transport and ITB formation ? Alfvén cascades Unprecedented resolution : up to m=16 harmonics observed Burning Plasma Diagnostics: evolution of Alfvén cascades using interferometry Much higher resolution compared to magnetic diagnostics Many new modes observed (deuterium plasma)

  12. Test of LH system modified for improved coupling • Previous improvements to system • increased power of LH • increased reliability 58668, Ip as shown/3 T • New improvements to system • Modify gas pipe for localised puffing • Use D2 rather than CD4 10 cm gap Tests of improved system • 2.5 MW coupled with 9.5 cm gap during Type-I ELMs (with CD4 at12x1021 el/s) • 3 MW coupled with 10.5 cm gap, with D2at 8x1021 el/s • Higher electron density in SOL with D2 • Similar plasma performance (neutron yield, b, loop voltage, li) LH coupling maintained • LH coupled with 10 cm plasma-antenna gap ITER-relevant LH coupling achieved on JET

  13. ITER-like Ion Cyclotron Resonance Heating (ICRH) Antenna under construction • Demonstrate High Power Density ICRH coupling in ITER-relevant Plasmas and Heating Scenarios • ITER relevant Power density 8MW/m2 • Resilient to ELMs • ~ 7 MW additional power • Installation end 2005 Operation Spring 2006 • Also tests with High Power Prototype under International Agreement with US

  14. 2. Critical issues for ITER 1. Bring new systems to full performance(divertor, diagnostics, LH launcher) (potentially impacting detailed design of ITER components, e.g. first wall, heating & current drive systems, diagnostics…) • Design tolerable ELMs • Commissioning of the MkII HD divertor • Characterise ELM behaviour and edge pedestal in ELMy H-mode • Characterise disruptions • Commissioning of new/upgraded diagnostics and systems • Measure tritium retention and migration • High-level commissioning of theLH system to full power • Establish level of off-axis current with off-axis NBI and/or MC-ICRH) and quantify degree of rotation achieved with low momentum input • Exploit fully the LH system • Quantify physics governing rotational stabilisation of RWMs • Control core MHD (fishbones) typical of hybrid regimes Strong focus in 2005 on preparing ITER detailed design and ITER exploitation

  15. Prad Before ELM After ELM 30MW PNBI(19MW) 9MJ  5-10 MJ in ITER Wdia = 1MJ 3MA DOC-L fuelling scan 8MJ Touter 2500C 1500C 59 60 Time (s) Divertor ablation by ITER relevant ELMs • Stored energy: W  R4 • Radiation increases non-linearly with ELM size JET enhancements will allow better diagnosis of physics beyond ELM ablation limits Philipps, Matthews

  16. ITER operating diagram for Q=10/Ip=17MA AN=0;AT=2.15;Ar=0.12% ITER equivalent of JET pulse 59029 • Equivalent discharge on ITER would sustain ~350 MW of fusion power Comparison of JET nitrogen-seeded ELMy H-mode discharge with ITER Q=10/17MA scenario Near-integrated ITER Type-III ELMy H-mode demonstrated with N2 seeding (Q=10/17MA) ITER Q=10/17MA JET #59029 I 17MA 2.5MA p B 5.3T 2.0T t H 0.75 0.73 98 f 1.0 1.05 GDL b 1.5 1.7 N q 2.6 2.6 95 T / T 1.1 1.2 i e d 0.5 0.44 f 0.75 0.8 rad Z 1.7 2.2 eff £ D 0.7% W / W 1% ELM tot • Most parameters closely matched in 2.5MA/2T nitrogen seeded discharge (Zeff. somewhat higher)

  17. Type II ELMs on Asdex-U at high n, high d or quasi-double null n*,ped(neo) Type I ELMs on JET or at best mixed type I-type II ELMs d=0.45 2.5MA/2.7T q95 = 3.8 nped/nGW Mild ELM regimes:Is collisionality a key parameter? Key parameters for edge phenomena are Te,ped, ne,ped and n*ped • Attempts to obtain pure Type II ELM on JET yet unsuccessful : • lower pedestal collisionality n*ped when approaching that of ITER ? • role of shear (q95) ?

  18. n*, r* range / all other tokamaks Approaching ITER Physics parametersELMy H-mode International Data Base(ITER reference operation mode) n* collisionality r* normalised Larmor radius bN normalised pressure are the three key parameters of tokamak physics n* and r* normalised to ITER

  19. Mach Probe Erosion? tile analysis QMB Net Erosion, physicaland chemical Limited Physical Erosion and Deposition Deposition Chemical Erosion Impurity migration and SOL flow

  20. Tritium retention / material migration 5 New QMBs will allow study of: • Carbon migration into remote areas - in inner / outer ducts and SRP • Temperature dependence Heated and cooled QMBs • Be deposition by evaporation and erosion by CX sputtering  Link to gas balance measurements  Some dedicated sessions required due to “history effect” Important for predicting carbon and beryllium migration in ITER and associated tritium retention

  21. H-L disruption: Thermal energy ~3 MJ + Magnetic energy ~17 MJ  Disruption Divertor energy ~1 MJ + Radiated energy ~13 MJ - 6MJ missing but not all energy is accounted for  Disruption power load accounting • JET divertor power loadings look favourable for ITER ITB high b disruption: Thermal energy ~4.7 MJ + Magnetic energy ~6.7 MJ  Disruption Divertor energy ~0.7 MJ + Radiated energy ~6.7 MJ - 4MJ missing New IR and bolometry will resolveenergy accounting

  22. Plasma response to applied field increases with increasing bN/li Example of error field amplification RWM model in agreement with observations Comparison of JET data with MARS model 59223 1MA/1.2T MARS model Isad (A) bN Plasma response Br (10-5T) With-wall limit (not reached) Time (s) • Trend in data consistent with trend in model (spread attributed to measurement error) • MARS model is a kinetic damping model with no free parameters • Result allows prediction of rotational stabilisation thresholds on ITER

  23. 4. Specific physics issues of direct relevance to ITER(exploiting unique features of JET) 3. Preparation of ITER operating scenarios • Extend ELMy H-mode operation at high triangularity to high current • Determine transport physics implications for ITER • Explore new burning plasma physics • Extend scaling of ELMy H-mode confinement at low d to lowest r*, ne* and highest b • Develop a robust steady-state non-inductive scenario with acceptable edge / confinement making full use of real-time control • Demonstrate portability, fuelling and b limits of the hybrid scenario Strong focus in 2005 on preparing ITER detailed design and ITER exploitation

  24. JET data until end 1999 JET data 2000-2004 Beneficial effect of increasing plasma triangularity observed in 1998-99 ITER operating range Exploited in 2000-2004: High H-factors (H~1) with simultaneous high densities n/nGW ~1 Triangularity Plasma Performance ITER plasma scenario for Q=10 operation Progress in ELMy H-Mode performance Quality of confinement Plasma density

  25. 7 6 N 5 b 4 ITER-89P 2000-2002 2003 3 H Filled symbols tduration/tE  10 2 1 0 • High Performance achieved at high dHigh performance sustained for  10tE at low and high d 0.1 0.2 0.3 0.4 0.5 • High b, high power region accessed Triangularity Progress in performance of the Advanced Tokamak (hybrid and steady-state scenarios) 3.0 2.5 2.0 bN 1.5 1.0 0.5 0 5 10 15 20 25 30 P + P + P [MW] NBI ICRH LHCD

  26. Advanced scenario: first demonstration of Real Time current-profile control with reversed shear 1.8MA / 3.0T HxbN~2 • Close match to reference achieved in 4-5 seconds Three actuators: LH, ICRH, NBI

  27. Safety factor (current)  Normalized temperature gradient (pressure)  Advanced scenarios: profile control of ITB'sSimultaneous current and pressure profile control in real time

  28. 1.5MA/3.4T Ptot=23.5MW Prad/Ptot~50%bp~1.5, H89~1.8, bN~1.8, Vl~0.05V #62293 ELM L-mode edge H-mode ITB q=4 Time [s] ITB at large radius with mild ELM's at high triangularity: obtained with Neon injection

  29. Region accessible after JET ICRH/NBI power upgrade (2005/6) Circles: Triangles: d = 0.2 d = 0.45 q95 ~ 4 AUG data DIII-D data Improved H-mode extended towards ITER Original JET/AUG identity experiment Parameter space accessed with improved H-mode bN • Performance sustained for duration limited by plant (~10 s) • Type I ELMs and no core ITB in ASDEX Upgrade identity experiment • But milder edge ELM’s seen at lower r* and lower bN 3 1.7T/1.4MA 2.5 2 3.1T/2.6MA 1.7T/1.4MA 1.5 3.4T/2.8MA 2.4T/2.0MA 1 ASDEX Upgrade ITER 0.5 JET 0 8 9 1 2 3 4 5 6 7 10 r* (x 10-3)

  30. r* ~ 5.8x10-3bN ~ 2.4-2.5 H89 ~ 2.1 H.bN/q952 = 0.33 JET #62494 20 NBI [MW] 10 LH [MW] ICRH [MW] bN 2 H89 1 1 Ha Neutron/s 0 2 4 6 8 10 12 14 16 18 20 Time [s] Development of JET-ASDEX improved H-mode identity experiments to low r* • 2MA/2.4T,d ~0.2 , q95~3.8 • Low amplitude Type I ELMs • 1.4MA/1.7T, d~0.2, q95~3.9bN~2.8 with no MHD limitation (mild NTM’s) and HxbN~5.9 • Improved H-mode requires further optimisation at • - 2.4T and high d- 3.4T (Type III ELMs at low d and Core ITB)

  31. 4. Specific physics issues of direct relevance to ITER(exploiting unique features of JET) 3. Preparation of ITER operating scenarios • Extend ELMy H-mode operation at high triangularity to high current • Determine transport physics implications for ITER • Explore new burning plasma physics • Extend scaling of ELMy H-mode confinement at low d to lowest r*, ne* and highest b • Develop a robust steady-state non-inductive scenario with acceptable edge / confinement making full use of real-time control • Demonstrate portability, fuelling and b limits of the hybrid scenario Strong focus in 2005 on preparing ITER detailed design and ITER exploitation Balance of programme Headlines 1/2/3/4 (Proposal) - approx. 8/68/39/21 sessions - contingency: 20 sessions Programme to be determined by Call for Proposals

  32. JET data 1.5-2.8 MA/1/5 – 2.3 T Dimensionless Scaling Laws E= tB 1/*b *c gyroBohm scaling E= tB*a b *c Dimensionless form of ITER 98 scaling law BE~*-2.7 -0.9 *0.0 GyroBohm scaling law, e.m.effects, no effect of collisions New results from recentJET experiments Favourable to high b,low n* ITER operations BE~*-2.7 0 *-0.35 Needs to be confirmed by higher power experiments

  33. Plasma Transport and Profile Stiffness • Determine stiffness dependence on plasma parameters using heating modulation. • stiffness seems to depend sensitively on Te/Ti. • clarify the interplay between electron and ion channels. • Investigate the role of s/q. • Uniqueness of JET: • low values of *, • high RF modulated power in H-mode, • E >> fast ions slowing-down, CX acquisition times. ITER relevance: high stiffness implies high temperature pedestal to achieve core temperatures required for ITER

  34. Curvature driven particle pinch in L-mode Particle pinch: experimental results Peaked density in H-mode at low collisionality No core particle source nor Ware pinch, still peaked ne Strong dependence on collisionality Density peaking Current peaking

  35. Tritium transport studies14 MeV D-T neutron tomography provides time and spatial evolution of T distribution in Trace Tritium Experiment Unique data on particle transport

  36. Neutron tomography: Studies of tritium transport Excellent capability to predict D+ and T+ transport confirmed by 14 MeV D-T neutrons tomography (Oct. 2003)

  37. Tritium transport studies (Trace Tritium r* scan) High r* Mid r* Low r* DT Neutrons signal decay tpuff = 514 ms tpuff = 573 ms tpuff = 711 ms Time [s] Time [s] Time [s] The improvement of particle confinement with decreasing r* is in line with Gyro-Bohm scaling

  38. aslowing down directly measured g from Be-a reactions (Ea > 1.7 MeV) g-spectroscopy: detection of fast a-particles First direct measurements of a-particle slowing down(in D-T October 2003 and with a simulation February 2004) • Very powerful technique used to study a slow-down in all plasma configurations foreseen for ITER

  39. g-ray spectrometry (a Be) at tritium blip in trace-tritium experiments 0.8 • Behaviour similar to that in low-current with standard current profiles • current hole plasmas : a particles escape before slowing down 0.7 2-3 MA, 2.25-3.4 T, monotonic q(r) 0.6 2.0 MA/3.2 Tand2.5 MA/3.2 Tcurrent hole discharges 0.5 Decay time of g radiation(s) 0.4 0.3 1.0 MA, 3.2 T, monotonic q(r) 0.2 0.1 TRANSP 0.0 0.0 0.2 0.4 0.6 0.8 1.0 slowing down time on axis (Teo3/2/neo) (s) First direct measurement of Fusion a-particle slowing down with g spectroscopy • Successfully reproduced by Transport Codes

  40. commitment 2000-2004 commitment 2003 JET FT: Making use of JET Facilities and operating experience to develop JET and ITER relevant R&D 55 tasks since 2000 Budget ~10 M€ (3.1M€ WP2003) 2005 JET FT programme will focus on issues of relevance to ITER licensing

  41. Co-deposit Cleaned substrate Controlling tritium in the tokamak • Novel system for removing tritium from first wall materials • Flash-lamp gives >1GW/m2 • Deployed using MASCOT Laboratory tests done JET trials performed

  42. Summary JET Year 2003 • the most busy year of operation in JET’s history together with 1997: a success for the Operation Team • outstanding scientific results, including trace tritium experiments • successful extension of international collaborations with US and Japan to include Russian Federation and People’s Republic of China JET Years 2004-2005 • challenging shutdown • challenging enhancement programme (divertor, diagnostics) • enhanced scientific capability from mid-2005 • reinforced focus on ITER needs in 2005

  43. Conclusions: The Longer Term • JET is significant for preparing ITER operation through extensive programme which integrates all elements of fusion physics • - ITER scenarios- Physics, including burning plasma physics - ITER auxiliaries and first wall material • JET is used in a fully collaborative framework involving all EU Associates and many institutes under international agreement • EFDA could agree to a wider use by ITER parties- UKAEA ready to open up Operator Team (~400 staff: mainly UKAEA + 50 Operator Secondees over past 4 years) to other ITER parties This would fully internationalise both the use and operation of JET and provide an opportunity to establish the ITER operation team in advance

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