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JET PFC Analysis, TFFT and the ILW JET J P Coad EURATOM/UKAEA Culham Division, Abingdon, UK Introduction to TFFT and interaction with JET Summary of programme.

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Presentation on theme: "JET PFC Analysis, TFFT and the ILW JET J P Coad EURATOM/UKAEA Culham Division, Abingdon, UK Introduction to TFFT and interaction with JET Summary of programme."— Presentation transcript:

1 JET PFC Analysis, TFFT and the ILW JET J P Coad EURATOM/UKAEA Culham Division, Abingdon, UK Introduction to TFFT and interaction with JET Summary of programme of analysis of JET samples removed in 2004 Plans for JET samples removed in 2007 Update on progress on the JET ITER-like wall

2 JET FT Tritium in Tokamak Tritium processes & Waste management Test Beds Neutronic & safety Plasma Facing Components Engineering AGHS Activation models T spreading Shutdown dose rate calculation Collection of Operating experience Dust conversion factor of dust Fatigue testing W coatings Glow improvements Active IR thermography JET Flakes Characterisation JET Tiles Improvement of gas balance JET WDS system T removal From tiles Micro gas chromatography Material transport Retention in castellation Microanalysis of cross section detritiation Erosion deposition LIBS Heating of tiles In JET NB test bed AES/XPS T & Be JET tiles Fibres & neutrons

3 JET FT 2008 Tritium in Tokamak Tritium processes & Waste management Test Beds Neutronic & safety Plasma Facing ComponentsEngineering Benchmarking of CAD to MCNP interface Shutdown dose rate prediction: In situ optical Dust measurements Advanced study for detritiation of non-plasma facing metals Be Tiles detritiation Material transport + erosion tungsten erosion in the JET divertor Microanalysis of plasma deposited layers tritium profile in carbon-based plasma- facing components LIBS Installation and commissioning of the plasmatron collection of data (VV & BeHF) characterisation of mirrors Laser lock in Inspection of bolometer

4 Tasks on Fusion Technology and 2008 Plasma Facing Components (10) Test Beds Tritium in Tokamak (2) Tritium process and waste management (4) Engineering (4) Neutronics and Safety (2) 22 new tasks have been launched during WP tasks on going from previous years and 22 tasks launched during the year Presently FT has 37 running tasks For the FT WP new tasks have been approved for a total budget of ~2.4 m More and more papers published and/or presented at conferences

5 Active IR Thermography in metal environment Goal: get rid of reflected flux and measure real surface T Heat pulse = perturbation of T 0 2 measurements and ratio surface T° (Material Emissivity constant!) (CEA, Semerok, Gauthier)

6 LIBS to characterise divertor PFC

7 test of laser detritiation on JET tiles Goal : test in BeHF + assessment of efficiency (CEA, Semerok and UKAEA, Widdowson and Coad)

8 300 microns Laser treated zone CFC substrate Cleaning JET tiles by Laser Ablation total removal of film some damage of the substrate sharp boundary at edge of treated zone

9 Detritiation : inside gap generator Goal : clean & detritiate castellations D=60 mm d= 0.8 mm Power: 130W, Pressure: 69mbar However, pattern not explained

10 Retention in castellations Goal: characterise the retention in Be limiter castellations (VR, Rubel)

11 Cold self-sustained volumetric plasma Volume: 18 litres Target diameter: ~25cm Ion energies: eV Magnetic field: 0.2T Pulse duration: steady state Flux density target: ~ ions/m 2.s Designed for PWI studies Installation for operation in glove box A gas mixture with a certain D/T ratio can be created in a volume by measuring the pressure and the mass flow of D/T coming from volumes containing D and T. Both loops have a separate control system. Brief plasmatron facility description Tominetti S. et al., Vuoto 26 (1997)

12 Plasma chamber Gas, plasma, secondary ions and neutrals analyser Gas inlet CW CW cooling water TC TC temperature control I I I insulation PM PM permanent magnets T T target CC A C cathode A anode UHV 1 UHV1 main pumping UHV 3 UHV3 differential pumping Sedano L. et al., Phys. Stat. Sol. 188 (2001)

13 Task Force E JET JET MkII-SRP Divertor used Key: 1/11 means tile 1, sample 11 Septum Replacement Plate (SRP) Campaign included: 4 weeks reversed field trace tritium experiment 13 C-methane puffing on last day operation with JET wall temperature at 200°C

14 Inner Divertor Analysis SIMS profiles sample 3/8 exposed Inner part (to right of line): similar to film deposited Outer part: (to left of line) High Be + other metals (e.g. Ni) except close to surface Little 13 C at surface Tile 1 Tile 3 Tile 4 Task Force E JET Film deposited also has high Be/C ratio, although operations were at 200°C He-fuelled campaign must be responsible for outer layer from Film structure may be different allowing trapping of large amount of D

15 Tile 3: Deposition layer fills up the holes of the W layer G3B top bottom

16 Micro-analysis cross section Goal: Composition of layers of 100µm thick via micro beam analysis of polished cross sections. (% level of main constituents: C, D, O, Be and SS, spatial resolution of a few μm) D 2 mapping (Tekes, Likonen and Emmoth, VR)

17 Tile 1-5, sputter cleaned

18 Tile 1-5 before and after sputter cleaning Before After

19 Picture from previous divertor campaigns in JET as follows: Erosion at outer divertor wall (tiles 7 and 8) [contrast to inner] ~200 μm deposition on sloping part of tile 6 [same as inner] No significant deposition in shadowed corner [contrast to inner] New data from MkII-SRP campaign from 13 C puffing IR measurements Analysis of tiles Deposition monitors, louvre clips from shadowed area Erosion/deposition at the outer divertor Task Force E JET Tile 8 Tile 7 Tile 6 Shadowed region

20 Deposition at outer divertor Task Force E JET Tile 8 Tile 7 Tile 6 Shadowed region 4 weeks reversed field operation gave deposition at outer divertor (clear from the film effect in the infra-red camera) During methane puffing local re-deposition observed Deposition in outer shadow region [c.f. inner]: Film on Deposition monitor slits ~20 μm [c.f. 90 μm] Deposit inside monitor box 18 μm [c.f.35 μm], or atoms cm -2 [c.f atoms cm -2 ] Film on tile (SIMS) 8 μm [c.f. 80 μm] Film on tile (section) 40 μm [c.f. 120 μm] Louvre clips off-gas 0.49 MBq/day [c.f MBq/day]

21 G7B a 1a

22 W Erosion Outer divertor: SEM images 50 µm Inhomogeneous erosion Full erosion of W in some places (IPP, Majer)

23 13 C-methane puffing experiment in 2004 Task Force E JET 31 similar pulses on last day of operation ELMy H-mode discharges:- B T 1.2T, I P 1.2 MA, ~7.5 MW additional heating Total of molecules 13 C- methane puffed in outer divertor from 48 locations Approximate line of W-stripe is shown as white dashes

24 JET Task Force E Field line plot showing strike points and SOL region for the 13 C- puffing experiment Occasional sweeps of strike- point position for Langmuir probe data Collector probe on reciprocating probe in SOL at top of machine

25 Task Force E JET Tile 1 Tile 3 Tile 4 Tile 8 Tile 7 Tile6 Amounts of 13 C measured on divertor tiles by SIMS and IBA Note: Measurements on one poloidal line have been extrapolated, assuming toroidal symmetry Tile Number 13 C amount 1 2.7% 3 0.5% 4 3.8% SRP ? 6 2.5% %* 8 6.1% Total 26.5% * based on average of two poloidal scans SRP

26 Local deposition of 13 C on G3B 19-23(max) x10 18 atoms/cm x10 18 atoms/cm x10 18 atoms/cm x10 18 atoms/cm x10 18 atoms/cm 2 Total number deposited 13 C in this area is ~215 x10 18 atoms Tungsten stripe 13 C injection 20m m Cores cut for SIMS analysis

27 Modelling of the 13 C puffing for the inner divertor Method EDGE2D follows injected 13 C atom trajectories with NIMBUS EDGE2D ELM model of Kallenbach used (modified for smaller ELMs) effects of sputtered carbon and re-erosion not included impurity transport coefficients in private flux region chosen 10x SOL value SOL flows in main chamber created by external force, classical drifts important in private flux region 3 paths dominate the 13 C migration most of carbon re-deposited on the outer target a few % migrates via the main chamber SOL to the inner target (as also seen on a reciprocating probe at the top of the machine), and accounts also for the deposition on the inner baffle a few % migrates via the private flux region by action of ExB drift to vicinity of inner strike point Task Force E JET

28 J Strachan modelling for 13 C experiment

29 Conclusions from 2004 samples Deposition at the inner divertor is not sensitive to wall temperature Significant erosion of W-markers has been observed at the outer divertor, of interest to the ITER-like Wall Project at JET. Infra-red temperature measurements clearly show when thin films are forming at the outer divertor Some deposition occurred in shadowed region at outer corner in , but the balance between erosion and deposition in this region requires further exploration 13 C-methane was puffed at the outer divertor in 2004, and preliminary modelling shows reasonable agreement with deposition at inner divertor Task Force E JET

30 10μm 7μm7μm 72μm 44cm 3 67cm 3 99cm 3 105cm 3 233cm 3 17cm 3 464cm 3 26μm 10μm 38μm 33μm 41μm 19cm 3 24cm 3 60g on louvre 18μm300μm32μm

31 Tile analysis programme for tiles removed in the 2007 shutdown Objectives: Distribution of 13 C injected in April 2007 at outer mid-plane Erosion of W-coatings in critical areas for ILW Erosion/deposition behaviour to compare with QMB data Results of rotating collector experiment (inc. Be evaporation) Mirror tests for ITER C-redeposition at load-bearing tile

32 Cross-section of JET

33 JET-HD divertor 2005-

34 Quartz Micro-balance at the inner divertor

35 JET ITER-Like Wall Update on materials, timescales Development of W coatings on CFC Be coatings on inconel Be markers

36 View inside JET

37 Beryllium Coatings on Cast Inconel (I) Evaporated 8 m Be coating on inner wall Inconel cladding Estimated maximum load in JET: 0.5 MW/m 2 in 20 s corresponding to 10 MJ/m 2 Steps in the material qualification process: Optimisation of the deposition process (Nucl. Fuel Plant, Romania). Pre-characterisation of layers: purity, structure, uniformity. High Heat Flux testing (Forschungszentrum Jülich). Characterisation after testing. HHF testing in JUDITH to determine the layer durability limits: 1.Screening test by stepwise increase of power density: 0.4 – 3 MW/m 2. 2.Cyclic test: 50 consecutive loads of 1.0MW/m 2 for 10 s. Message: No damage to layers exposed to the energy load of 19.8 MJ/m m Original surface Tested: 1.8 MW/m 2, 11 s Test: 1.8 MW/m 2, 11 s

38 Beryllium Coatings on Cast Inconel (II) SUMMARY OF RESULTS: High uniformity and purity of coatings (oxygen only in a thin surface layer). Layers survive power loads of 2.55 MW/m 2 in 6.2 s (18.1 MJ/m 2 ) Melting of beryllium observed above 3 MW/m 2. No damage by 50 thermal cycles of 1 MW/m 2 for 10 s each (10 MJ/m 2 pulses). Energy density [MJ/m 2 ] extrapolation, ~11 s pulse on 3.5 mm Inconel case ~ 11 s pulses, thickness 3.3 ~ 3.6 mm 6.2 s pulse, thickness 4 mm ~ 11 s pulses, thickness > 4.0 mm Surface Temperature versus Energy Density Temperature [ o C] Conclusion: The layers meet operational requirements for JET-ILW.

39 PISCES PC-Be data scaled ( ) to Ecksteins value Erosion of Beryllium Coatings on Cast Inconel: Exposure of Be to Deuterium Plasma in PISCES (UCSD) D.Nishijima, J.Hanna, R.Doerner GA & Romanian Be coatings show increased Y Be s at higher E ion compared to Poly Crystalline(PC)-Be.

40 Development of Beryllium Marker Tiles (I) AIM: The assessment of beryllium erosion from the main chamber wall (limiters) Beryllium Tile (3 cm) Nickel interlayer (2-3 m) Be layer (7-9 m) 30 mm 28 mm Be coupon with marker coating. For HHF test coupons are with a hole for a thermocouple. Steps in the R & D process Production of optimised layers by Thermionic Vacuum Arc method High Heat Flux testing Broad characterisation of layers before and after testing. Main Result of HHF test: Layers withstand without damage 4.5 MW m -2 for 10 s.

41 Beryllium Marker Tiles (II) Be test coupon with marker layers Topography of Be coating SIMS depth profiles After HHF test Fresh

42 Remaining Work: Produce and Install Tiles in JET Inner Wall Structure with Location of Marker Tiles

43 Conclusions Analysis of tiles removed in 2004 shutdown almost complete Analysis has started on a new poloidal selection of tiles removed in 2007 Preparations are in hand for the ILW installation in , including solid Be and W tiles, Be coatings on inconel, and marker tiles.

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