1. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 1 EFDA Plasma Edge Technology Programme Monitoring of 2006 Activities Alberto Loarte European Fusion Development Agreement Close Support Unit – Garching

2. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 2 Activities within Plasma Edge Technology Programme Programme supports various types of activities : Well defined laboratory experiments/modelling to identify/model important PWI processes in conditions relevant to ITER Analysis of samples/components exposed to tokamak plasmas (and/or in dedicated experiments) to quantify processes relevant to ITER Modelling/experiments to determine influence of ITER components specifications on their behaviour under plasma exposure (transient loads, influence on T retention and removal, etc.) Development of measurement/removal techniques for PWI-related issues which affect the licensing of ITER (Dust, Tritium) EFDA Plasma Edge Technology Programme is coordinated with EU PWI Task Force (Voluntary Physics Research Programme) TW6-TPP budget = 3364 k (art. 5.1.a), 285 k (art. 5.1.b), 340 k (UT)

3. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 3 Tasks in 2006 (I) Tasks finished/running in 2006 1. Material erosion behaviour and transport in tokamaks TW4-TPP-TRIDEP, Studies of hydrocarbon formation and redeposition in ITER- relevant divertor chamber TW5-TPP-TILCAR, Characterisation of erosion/deposition balance in ITER-relevant divertor tokamaks and of PFCs after hydrocarbon removal by oxidative methods TW5-TPP-CARWBER, Erosion/Deposition studies of the Carbon-Beryllium-Tungsten system in PISCES-B (EU-US collaboration) UT_W_Brush2005_TP, Characterization of Reactor relevant W Plasma Facing Components UT_W_PFC2005_TP, Characterization of Reactor relevant W Coatings TW6-TPP-CARTIL, Characterisation of erosion/redeposition balance in ITER- relevant divertor tokamaks TW6-TPP-ERDEP, Studies of material erosion and redeposition in ITER-relevant divertor target temperatures, plasma impact energies and divertor target geometries TW6-TPP-CNDMSTICK, Determination of reflection properties of hydrocarbon radicals for ITER-like divertor conditions

4. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 4 Tasks in 2006 (II) 2. Fuel retention and removal TW4-TPP-TRIREMA, Study of Oxidizing Agents for Tritium Removal in ITER- compatible Conditions: Ozone TW4-TPP-TRIREMB, Study of Oxidizing Agents for Tritium Removal in ITER- compatible Conditions: Alternatives to Oxygen and Ozone TW5-TPP-HEGLO, Optimisation of oxidising glow discharges for removal of hydrocarbon deposits TW6-TPP-RETMIX, Characterisation of fuel retention in ITER-relevant mixed- materials TW6-TPP-GAPOX, Study of Tritium removal from macrobrush structures by oxidative methods TW6-TPP-RETMET, Determination of fuel retention in metallic materials for ITER UT06_TPP_LASRAD, Characterization of the In-Vessel Components Treated by Laser IPPLM__TPP_UT1, Application of pulsed laser light for the removal of co-deposited deuterium/tritium from in vessel components OEAW_UT06_TPP_Be, Dependence of hydrogen retention in Beryllium on the thickness of the oxidised surface layer and its carbon content

5. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 5 3. Transient heat loads and control TW3-TPP-MATDAM, Characterisation of Material Damage for EU W and CFC ITER Divertor Materials under Repetitive Plasma Energy Fluxes by Modelling and Experimental Validation (EU-RF collaboration) TW4-TPP-TARCAR, Characterisation of W and CFC targets exposed to ITER-relevant Type I ELM and disruption loads in plasma gun facilities (EU-RF collaboration) TW5-TPP-ITERTRAN, Modelling of ITER divertor target damage and plasma contamination following ELMs and disruptions (part. EU-RF collaboration) TW5-TPP-BEDAM, Modelling of Material Damage to Be-clad and Be-coated ITER Plasma Facing Components under Type I ELMs, Disruptions and Mitigated Disruptions and Scoping Studies for its Experimental Validation (EU-RF Be-studies contract) TW6-TPP-REPELM, Material damage for CFC and W under large cycle under-threshold ITER ELM-like loads simulated with an e-beam TW6-TPP-BECOAT, Coating of EU CFC/W targets with Beryllium for exposure to ITER-like transient loads in plasma gun facilities (EU-RF Be-studies contract) TW6-TPP-ANABE, Analysis of Be-coated and Be-clad targets for exposure to ITER-like transient loads in plasma gun facilities (EU-RF Be-studies contract) TW6-TPP-DAMTRAN, Modelling of ITER plasma facing component damage and consequences for plasma evolution following ELMs and disruptions (EU-RF Be studies contract) UT-PWI-2006, Analysis of irradiation effects and thermal shock resistance on tungsten and beryllium for plasma facing components EFDA 05-995, Design and R&D work with Kurchatov Institute Moscow on effects of ELMs and disruptions on Be-coated and Be-clad PFCs for ITER Tasks in 2006 (III)

6. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 6 4. Dust in production in fusion devices and removal TW6-TPP-DUSTGEN, Evaluation of dust generation mechanisms at the ITER SOL and divertor plasma TW6-TPP-DUSTMEAS, Demonstration of diagnostic techniques for time resolved dust measurements in tokamaks 5. Modelling of plasma-wall interaction processes for ITER TW5-TPP-TUNMOD, Modelling of Tungsten Erosion and Edge Plasma Transport in ITER TW5-TPP-ITERNEUT, Modelling of neutral-photon and neutral-neutral effects on ITER edge and divertor plasma conditions TW6-TPP-BETUNCMOD, Molecular dynamics simulations of mixed-material formation at the ITER divertor TW6-TPP-ERITERA, Modelling of Erosion/Redeposition for ITER Limiter Ramp up/down and Reference Scenarios including Macrobrush & Gap Geometries, Temperatures and Surface Composition TW6-TPP-ERITERB, Improvement of Surface Processes Modelling in the ERO Code for Advanced Description of mixed Material Formation in ITER Reference Scenarios TW6-TPP-SOLITER, Self-consistent modelling of plasma-wall interactions and SOL transport with real 3-D PFC geometries for ITER reference scenarios Tasks in 2006 (IV)

7. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 7 TRIREMA : O 3 oxidation of hydrocarbon deposits in ITER-relevant conditions Oxidation in ozone achieves rates near the ITER requirements (0.5-5.0 mh -1 ) and operating temperature (T < 250 o C) for TEXTOR flakes (variability of 3-4 depending on impurity content) Oxidation of base material (EK98) is very large cleaning restricted to few cycles Major results in 2006 (I)

8. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 8 TRIREMB : Removal of fuel with alternative methods and comparison to O 2 Oxidation by O 2 / Nitric Oxide (NO) of Hard Films & TEXTOR flakes (H/D>>1) shows that NO oxidation is slower than O 2 and does not produce H 2 (260 o C @ 2 torr) Isotope interchange on flakes from ASDEX Upgrade activated by H 2 O 2 does not occur Activation of samples with H 2 O 2 + H/D interchange Candidate reaction : NO + H NOH + H NO + H 2 Some production of CO with NO but no enhanced production of H 2 H 2 O 2 treated AUG flakes in H 2 1 bar atmosphere show release of H 2, DH and D 2 at similar temperatures than in TDS H2OH2O H2H2 D2D2 DHO D2OD2O HD TDS T(K) HDD2D2 H2H2 Major results in 2006 (II)

9. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 9 TRIDEP : C x H y formation and deposition in remote areas (PSI-2) Deposition experiments show that H plasmas lead to much larger deposition than Ar/He plasmas and is accompanied by different hydrocarbon production from CH 4 Experiments to quantify H erosion of C-H re-deposits in remote locations carried out Effect of N 2 to avoid deposition demonstrated Major results in 2006 (III) Measured conversion of C 2 H 2 to HCN

10. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 10 MATDAM : Validation of ELM damage modelling by experiments in plasma-guns TARCAR : Characterisation of ELM-disruption damage in experiments in plasma-guns ITERTRAN : Development of material damage models and application to ITER [PEGASUS (for CFC and W), PHEMOBRID (CFC), MEMO-S (W), FOREV] Experiments carried out in TRINITI plasma guns under EU-RF collaboration CFC, W, WLa 2 O 3 targets exposed to 100 pulses at 0.5, 1.0, 1.5 and MJ/m 2 and 5 at 2.5 MJm -2 t = 500 s (experiments almost completed) Analysis of target damage almost complete Major results in 2006 (IV) Plasma flow Target Diagnostic windows Vacuum chamber 60 0

11. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 11 Mechanism of CFC damaged under loads identified by experiments and modelling (PAN fibre erosion): Decrease of threshold for damage but larger protection by vapour shielding at larger energies Fibre orientation can decrease damage Major results in 2006 (V) ELM CFC fibers erosion as a function of surface energy density Modelling of PAN fibre erosion without/with vapour shielding Experiments in Judith (FZJ)

12. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 12 Mechanisms of W damage : Melting and molten layer displacement + droplet formation and ejection (& cracking) modelling of molten layer in macro-brush geometry + criteria for droplet formation developed and crack modelling started Major results in 2006 (VI) W ELM = 1 MJm -2 Pestchanyi

13. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 13 The Rayleigh-Taylor instability is responsible for The flow is stable if the Taylor criterion OK V melt velocity surface tension melt density h melt thickness. the formation of jets at melt layer edges the formation of bridges between brushes and jets at brush edges Metal [din/cm] [cm -3 ] h [ m] Vmax [m/s] commentBulk armour Brush armour W 2.2 10 3 1720-80 200-400 3.5-1.8 1.1-0.8 ELM disruption Splashing possible Splashing No Be 1.2 10 3 1.7520-80 200-400 8.4-4.3 2.8-2 ELM disruption Splashing Splashing possible The Kelvin-Helmholtz instability is responsible for the droplet formation and melt layer losses W armour R droplet ~ 10-15 µm V droplets ~15-17 m/s Velocity of mass losses 50-300 g/(cm 2 s) During 1 ms Splashing thickness up to 150 µm Be armour R droplet ~ 20-25 µm V droplets ~9-11 m/s Velocity of mass losses 50-100 g/(cm 2 s) During 1 ms Splashing thickness up to 500 µm Major results in 2006 (VII) Bazylev

14. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 14 T retention within CFC in ITER-like conditions (T surf = 1070 K, incident ion energy of 30 eV and plasma fluence ~10 27 Dm -2 ) in PISCES-B Retained fuel in CFC amounts is very small & independent of Be (3g in ITER) Transient T surf increases lead to increased Be 2 C and low C erosion but increased D retention (although it remains low) Major results in 2006 (VIII)

15. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – CIEMAT 29-31 – 10 – 2007 15 Conclusions EFDA TPP Technology Programme well coordinated with EU-PWI Research Programme (5 th year of existence) Key PWI R & D issues for ITER being addressed Three major international EURATOM collaborations supported by this area : (Be mixed-materials) with US (UCSD) W/CFC target damage under ELMs & disruptions with RF (TRINITI) Be-clad and Be-coated (W/CFC) PFC damage under ELMs & disruptions with RF (Kurchatov-TRINITI) Reasonable number (15) of associations involved in running tasks in 2006 : CEA, CIEMAT, ENEA-F, ENEA-CNR, FZJ, FZK, FOM, IPP, IPP.CR, IPPLM, IST, MEdC, MHST, ÖAW, SCK-CEN & TEKES Special effort to increase participation from new countries bearing fruit (IPP.CR, IPPLM, MEdC, MHST) EU-PWI TF under the new EFDA and the EU Domestic agency will need to coordinate work to maintain an effective contribution to ITER in this area