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ASIPP

HT-7 & EAST. ASIPP. 面对等离子体材料的研究现状与趋式以及我们今后工作的主要考虑 陈俊凌 , 李建刚 2005/6/1. HT-7 & EAST. ASIPP. Materials Issues in Fusion: Extreme Conditions. High thermal loads. Physico-chemical attack. Intense Irradiation, e.g. high n fluence. Complex mechanical loads. HT-7 & EAST. ASIPP.

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ASIPP

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  1. HT-7 & EAST ASIPP 面对等离子体材料的研究现状与趋式以及我们今后工作的主要考虑 陈俊凌, 李建刚 2005/6/1

  2. HT-7 & EAST ASIPP Materials Issues in Fusion: Extreme Conditions High thermal loads Physico-chemical attack Intense Irradiation, e.g. high n fluence Complex mechanical loads

  3. HT-7 & EAST ASIPP • 最高表面温度一般出现在边缘的角点，如点1位置； • PFM和热沉连接由于热膨胀系数的不同引起的应力，其最大值一般出现在角点2的位置；同时2点的位置也是连接界面间温度的最高点； • 3点是冷却水管最高热通量出现点，有可能出现超过Critical heat flux所允值。 1 CFC or W 2 3 CuCr Zr copper alloy Fig. 1. Divertor heat sink and terminology

  4. HT-7 & EAST ELMs and disruptions Lifetime and T- retention ASIPP From JET to ITER Challenge to Technology and Plasma Wall Interactions

  5. HT-7 & EAST ASIPP Fusion devices, parameters JET (fusion power 16 MW, 2 s) ITER (fusion power 500 MW, 400 s) Reactor (DEMO) (fusion power 2000 MW, stationary) ITER power reactor relative size 1 1...1.2 fusion power (MW) 500 2000 power to He-ions (MW) 100 400 total thermal power (MW) 2600 electric power (MW) 1000 efficiency (%) 38 neutron damage (dpa) 5 150 in 5y

  6. HT-7 & EAST ASIPP Material choice compromise various requirements Impurity release versus plasma poisoning Wall lifetime Tritium retention Neutron material damage Melt layer loss CFC on high heat flux areas Particle erosion W on baffle & dome T co-deposition With C No Carbon as PFC? Low activation materials & neutron degradation Low Z (Be or C) (High Z, AUG)?

  7. HT-7 & EAST ASIPP ITER parameter and wall materials Present material choice is the result of long experiences in fusion research 700m2 Be first wall Low Z Oxygen getter 100m2 Tungsten no erosion by low energy particles 50 m2 CFC（NS31) No melting in transient heat losses ITER Main plasma Te 8 KeV Dens 1020/m3 E 3.5 sec Volume 850m3 PFus 500MW P 100MW Paux 50 MW Divertor Plasma Optimised for Power & Particle exhaust

  8. HT-7 & EAST ASIPP Wall lifetime under steady state plasma bobardment First wall Erosion (peak, order of magnitude) derived from ITER calculations: low Z materials: 3.5 mm/burn year; iron: 1 mm/burn year; tungsten: 0.1 mm/burn year but: in_depth assessment needed; seed impurity ion erosion may be critical

  9. HT-7 & EAST ASIPP T-retention How to approach the T- retention problem Understanding of T-retention in present devices Develop T-removal technique Develop full metal scenario Development of control schemes to reduce or mitigate the T-retention (in particular T-tailoring and geometry Lab work and proof in tokamaks Plasma compatibility Power exhaust Melt layer erosion by transient heat loss

  10. HT-7 & EAST Work in plasma simulators + Dedicated lab experiments + Tokamak research • Fuel Removal • Isotope exchange on PFC side • Thermal desorption on PFC side • Oxygen venting remote areas? • Scavenger techniques ?? • and Fuel Control • Temperature tailoring • Carbon traps • Divertor geometry … Needs detailed understanding of the involved physics ASIPP T-removal Control of fuel retention and fuel removal will be essential in any wall material scenario and needs more attention in present research (with and without C walls)

  11. HT-7 & EAST ASIPP W-coated PFCs W-coated graphite tiles in ASDEX Upgrade (2003/2004) Campaign 2002/2003 d = 1 mm A = 14.6 m central column upper PSL inner divertor baffle Campaign 2003/2004 additionally: d = 3.5 mm A = 7.2 (10.2) m upper divertor outer divertor baffle) protection limiter (Sec 8/9)

  12. HT-7 & EAST ASIPP European Power Plant Concept Studies Main Chamber First Wall: Tungsten Very low erosion yield,high threshold energy Component lifetimeconsiderations PPCS

  13. HT-7 & EAST ASIPP Evaluate the performance of different materials for divertor/FW • FWM: < 1MW/m2, technically ready • High-field side: SiC coating on the doped graphite, bolted heat sink; • Low-field side: W coating on the FS • Divertor: 4-6MW/m2 (8-12MW/m2) • SiC/B4C coating on the high performance doped graphite ( inner leg), C brazed to Cu heat sink. • W coating (0.5mm) on the high performance graphite(out leg), C brazed to Cu heat sink. • W coating (1-2mm) on the Cu heat sink. • W coating (mm) on low radioactive steal (CLAN, similar with H82), high Tw operation for T inventory.

  14. HT-7 & EAST ASIPP Manufacturing Route of PFC

  15. HT-7 & EAST ASIPP CBM表面上的W涂层成为研究热点 Progressive formation of tungsten carbide Ch. Linsmeier et al.: XPS investigations of carbon layers on tungsten

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  17. HT-7 & EAST ASIPP 钨作为PFM的主要优点: • Relatively high strength, highest melting point and low vapor pressure; • ‘Promote deposition’ of high Z atoms; • Higher threshold energy of sputtering and low sputtering yield; • Quite favorable thermal mechanical properties (even >100W/m.K at 15000C); • Higher reflection coefficient for heat deposition;

  18. HT-7 & EAST ASIPP Steady state HHF-PFCs Qabs = 43MW/m2, 10-15s, 2 cycles Qabs = 27MW/m2, 10s, 1500 cycles

  19. HT-7 & EAST ASIPP Shortcomings: Poor ductile (DBTT 1500～4000C), heavy mass, re-crystallization (11500C) ( properties dependent on metallurgical treatment-method of production, machining condition, grain size, temperature of history and impurities.) Bulk tungsten • Pure -W( sintering technique ,electron beam or arc); • PW(W-5Re; W-1%La2O3, W-Cu, W-Cu, W-Cu-Ni, W-Fe-Ni etc.). W-coating methods • PVD • CVD • IPS • VPS

  20. HT-7 & EAST ASIPP Large mismatch of CTE between W and substrate The primary difficulty is cooling the substrate to reduce stresses caused by thermal distortion In essence, the thicker the coating, the larger the T through the thickness which increases the strains between the hot tungsten surface and the cooled copper substrate and can result in and can lead to cracking in the tungsten coating either during the spraying process, during cooling, or during the actual operation of the component. A secondary consideration is that the longer it takes to cool the tungsten during plasma spraying, the larger and more columnar the grain structure, which results in a higher DBTT than would be achieved with a finer grain size. 316LN EUROFER Fig. 2. Tungsten has low CTE (coefficient of thermal expansion) J.W. Davis, J. N. Mater. 233-237(1996) 604-608

  21. HT-7 & EAST ASIPP • Thermally sprayed coatings formed by the deposition of molten or partially molten particles, propelled onto a substrate where they impact, are flattened and quenched to the substrate temperature within a very short time (few ms), and agglomerate to form a thin layer. RS are expected within the sprayed deposit as a consequence of the release of thermal and kinetic energies. • Residual stresses: • Deposition stress; • Thermal stress; • Temperature gradient stress. Fig. 5. Schematic diagram of thermal spray process The shear stress and peeling stress occur near free ends of the coated components…… delaminate the coatings from the free ends; The in-plane normal stress in the interior region …….may result in the coating layer cracking, spalling, or buckling…

  22. HT-7 & EAST ASIPP Stress induced by temperature profile under full constraint Oncethe temperature profile has been obtained from a forgoing thermal analysis, the thermal stress of the armor tile is determined applying the strain suppression method where full constraint by the heat sink is assumed. 2003/05/15, Max-Planck-Institut für Plasmaphysik, Garching bei München, Germany J.L.Chen, MF

  23. HT-7 & EAST ASIPP Final stress levels The final residual stress levels at the bottom face and top face of the substrate are obtained by adding the contributions represented by (38) (39) (40) Where . For example, the stress as the midpoint of the nth layer is, 2003/05/15, Max-Planck-Institut für Plasmaphysik, Garching bei München, Germany J.L.Chen, MF

  24. HT-7 & EAST ASIPP Motivation W as a plasma facing material: • low erosion rate • heat resistant, lowest vapor pressure of all metals VPS offers an industrial coating of first wall to be loaded up to 1MW/m² Development of 2 mm VPS W coatings on actively cooled steel substrates: DEMO/ power plant: potentially as FW Covering on EUROFER/ F82H (ITER: FW, special divertor comp. made of 316L)

  25. HT-7 & EAST ASIPP Manufacturing Garching-IPP initiated a development program of VPS W layers on cooled steel substrates mixed W/ steel interlayer actively cooled substrates reduction of residual stress Vacuum plasma spraying: • temperature up to 15.000 K • velocity of particles: 500 m/s • no oxidation length: 190 mm PLANSEE AG, 2003: fabrication of 2 mm W-VPS layers - 3 mock-ups made of EUROFER - 3 mock-ups, F82H - 3 mock-ups, 316L samples after heat load tests

  26. HT-7 & EAST ASIPP Characterization Metallographical examination: • measured properties: VPS-W layer Interlayer Substrate • Coating micro structure, homogeneity of thickness, SEM • • D retention • • Residual stress measurements, hardness, Young’s modulus (Univ. Stuttgart)

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  28. HT-7 & EAST ASIPP Thermal loading tests- W on EUROFER Preliminary results of heat flux tests W-VPS on EUROFER, FZJ 10.02.04, comparison of calclulated and measured temp. distribution, 60 s heating Incident heat flux, MW/m²

  29. HT-7 & EAST ASIPP Thermal loading tests- W on 316L Preliminary results of heat flux tests W-VPS on 316L, FZJ 12.02.04, comparison of calclulated and measured temp. distribution, 60 s heating Incident heat flux, MW/m²

  30. HT-7 & EAST thick tungsten layers (up to 23mm) ASIPP Sulzer-Metco low pressure plasma spray facility with F4 torch tranfered arc cleaning B4C deposition on flat samples

  31. HT-7 & EAST ASIPP The ability to study the science of plasma interaction with materials is provided by the DIII-D divertor material evaluation system (DiMES)

  32. HT-7 & EAST ASIPP Schematic view of the test limiter in TEXTOR’ 94 device

  33. HT-7 & EAST ASIPP Simple ITER-like TZM catellated structures have been used in TEXTOR with TZM in erosion and C-depositiondominated area

  34. HT-7 & EAST ASIPP ITER is planned to have tungsten baffles in the first operation phaseand probably a full W wall in its reactor like operation phase Issues to be addressed: • Erosion, deposition and migration in a mixed material device • Behaviour under transient heat loads • Hydrogen retention and material degradation under high H fluxes • W diagnostics (spectroscopy) • Operation must be compatible to W PFCs • Seed impurity scenarios to replace intrinsic C radiation • High performance scenario development along W compliant route • Code simulations for interpretation and extrapolation Þ issues may be investigated in existing fusion devices as well in other laboratories

  35. HT-7 & EAST ASIPP Installation of W divertor possibly during shut down in 2008

  36. HT-7 & EAST ASIPP 谢谢大家！ Thanks for your attention!

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