1. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 1 EU-PWI Task Force & EFDA Plasma Edge Technology Programme Alberto Loarte, Joachim Roth, Emmanuelle Tsitrone

2. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 2 Outline 1.Background to EFDA Plasma Edge Technology Programme and Integration with EU-PWI Task Force 2. Description of Existing Tasks & Status Details to be found in http://efdasql.ipp.mpg.de/efdatpphttp://efdasql.ipp.mpg.de/efdatpp 3. Tasks Launched in 2006 Programme 4. Discussions of Priorities for 2007 Programme (new EFDA)

3. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 3 Background Need of fundamental Understanding of PWI Processes Well defined Laboratory Experiments Specific Modelling and Extrapolation to ITER Contributions from Associations without voluntary Physics Programme Financial Volume (2005): 1.3 M(20% sub.) 5.1.a, 475 k(40% sub.) 5.1b (Financial Volume (2006): 3.4 M(20% sub.) 5.1.a, 285 k(40% sub.) 5.1b) EU Task Force aims to better integrate Technology and Physics Aspects of the EFDA Plasma Edge Technology Programme

4. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 4 Integration with EU-PWI TF Topics (I) Tasks in 2002/2003/2004/2005 1. Erosion behaviour Chemical Erosion of C by D/Be, TW2-TPP-ERDEP () (EU-US) Sputtering of W and Be, TW3-TPP-ERTUBE () SEWG Chemical Erosion of C, TW4-TPP-ERCAR () SEWG C/W/Be mixed-material formation, TW5-TPP-CARWBER (EU-US) 2. Material transport and re-deposition Flake Formation from Deposits, TW2-TVM-CFC2 () Scavenger Technique, TW3-TPP-SCAVOP () SEWG C x H y Formation and Re-deposition in ITER Geometries TW4-TPP-TRIDEP () Erosion/deposition metal wall + C divertor TW5-TPP-TILCAR () Midplane and Divertor W macro-brush studies in ASDEX-Upgrade () UT4-TUNAUG & UT5-MBWAUG () Already reported at previous meetings () Reported this year

5. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 5 Integration with EU-PWI TF Topics (II) 3. Fuel recycling, retention and removal (2 SEWGs) Optimisation of He-O Glow for C-H removal, TW5-TPP-HEGLO () T removal by non-O 2 oxidative methods, TW4-TPP-TRIREMA-B () Characterisation of Oxidised PFCs, TW5-TPP-TILCAR () 4. Off-normal heat loads (SEWG) Modelling of Disruptions and ELMs, TW3-TPP-DISELM () Validation of ELM Damage Modelling, TW3-MATDAM () (EU-RF) ELM-Disruption exposed Target Characterisation, TW4-TARCAR () (EU-RF) W and CFC damage and plasma evolution in ITER, TW5-TPP-ITERTRAN () Modelling of Be damage under Disruptions/ELMs, TW5-TPP-BEDAM (EU-RF)

6. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 6 Integration with EU-PWI TF Topics (III) 5. Edge modelling, erosion and deposition modelling Improvements to ERO Code and ITER Modelling, TW3-TPP-ERMOD () MD Modelling of Erosion Processes, TW4-TPP-CARWMOD () W Erosion and Edge Plasma Contamination in ITER, TW5-TPP-TUNMOD () 6. Edge and SOL physics Improvements to B2-Eirene for ITER Modelling, TW3-TPP-NEUTMOD () Modelling of n-n and n- effects in ITER divertor, TW5-TPP-ITERNEUT () 7. Task force relevant diagnostics Speckle Interferometry for Erosion, TW0-T438/01 () Laser Ablation Techniques for Film Deposition, TW3-TPP-ERDIAG ()

7. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 7 Description of Tasks and Status (I) ERTUBE : Exposure of W macro-brush elements to plasmas & fuel retention in TEXTOR and FTU W & Mo macrobrush limiters have been exposed to TEXTOR plasmas in the far SOL (deposition studies) and at separatrix for power load studies W macrobrush is effective in preventing melt layer loss caused by j therm X B forces D deposition inside brush correlated with C deposition with typical decay lengths of ~ 2 mm

8. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 8 Description of Tasks and Status (II) ERTUBE : Exposure of W macro-brush elements to plasmas & fuel retention in TEXTOR and FTU W macrobrush probes have been exposed to C-free plasmas in FTU limiter Surface contamination by C during macrobrush manufacturing most likely cause of larger than expected retention D retention determined by outgassing and typically ~10 -4 of the incident flux (low but ~ 10 times larger than expected)

9. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 9 Description of Tasks and Status (III) TW4-UT4-TUNAUG & TW5-UT5-MBWAUG : Exposure of W macro-brush element in the SOL and divertor in AUG

10. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 10 Description of Tasks and Status (IV) ERCAR : Characterisation of thermal response of Carbon PFCs exposed to plasmas and of CFC under repetitive laser loads AUG samples have been characterised Samples from erosion dominated areas maintain unexposed properties Samples from deposition dominated areas covered by low conductivity layers Exposure of NB31 to 1000 under threshold laser loads does not cause deterioration of thermal properties nor observable surface damage

11. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 11 Description of Tasks and Status (V) TILCAR : Characterisation of erosion/redeposition in divertor tokamaks Marker coating on 3 divertor and 4 limiter tiles produced for AUG 2006 campaign (C- 2 m, W-3 m on Re interlayer) Size of 13 C deposition depends on substrate (12% on C, 6% on W) 12 % of injected 13 C Divertor 11% of injected 13 C Inner wall Analysis of long term erosion/deposition in AUG carried out In 2004 13 CH 4 (1.4 10 22 ) was puffed at outer midplane in 5 SN Type l ELMy H-modes in H Measurements provide basis for understanding of erosion/deposition balance in divertor tokamaks

12. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 12 Description of Tasks and Status (VI) UT4-TUNAUG/UT5-TUNAUG : Development and testing of W coatings for AUG W coated (200 m) tiles installed at ICRH protection limiter in 2004/2005 Thermal cycling and tests in ASDEX Upgrade still outstanding Delay caused by wrong interlayer (Cr vs.Re) used in first coating series (Plansee) Coatings delaminated (wrong C surface treatment) & W melted under power load but only minor restrictions to plasma operations New W coatings with high and low porosity developed (180-210 m) and screen-tested in GLADIS facility to 23.5 MWm -2 16.2 MW/m² 6.5 MW/m² 10.8 MW/m² 4.2 MW/m² 23.5 MW/m² density 95% bulk W 90% bulk W pulse length (s) T surf (°C)

13. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 13 Description of Tasks and Status (VII) TRIDEP : C x H y formation and deposition in remote areas (PSI-2) Deposition experiments in Ar show larger rates than state-of-the-art ERO modelling CH emission shows unexpected local patterns at higher (influenced by V bias ) Experiments to quantify H erosion of C-H re-deposits carried out CH emission n e = 2.0 10 17 m -3 CH emission n e = 2.5 10 18 m -3

14. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 14 Description of Tasks and Status (VIII) HEGLO : Removal of hydrocarbons by He/O 2 plasmas in TEXTOR and ASDEX Upgrade + TILCAR : Characterisation of TEXTOR He/O 2 exposed components HeO GDC applied to TEXTOR C removal rate of 2.0 10 19 C/s weakly dependent on He concentration (30-100%) Recovery : weekend D 2 GDC + Boronisation ICRH HeO discharges Most C released after ICRH pulse, with 1:10 duty cycle similar rates to HeO GDC antenna pressure + pumping limits removal Recovery : overnight D 2 GDC TechniqueC removal rate Oxygen venting 2.5·10 18 C/s for 0.3mbar, T wall =620K Glow discharge conditioning 2-3·10 19 C/s ICRF conditioning 1.8·10 19 C/s for 1:10 duty cycle for pump out Integral TEXTOR carbon redeposition rate 2.7·10 20 C/s

15. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 15 Description of Tasks and Status (IX) HEGLO : Removal of hydrocarbons by He/O 2 plasmas in TEXTOR and ASDEX Upgrade + TILCAR : Characterisation of TEXTOR He/O 2 exposed components Laboratory prepared a:C-D layers and in-situ boronised layers (a:B-D-C layers) were exposed to HeO GDC (removal rate > 10 14 C cm -2 s -1 = 0.1 m/h) for a:C-D layers D removal rates from a:B-D-C layers are a factor of ~ 10 lower than from a:C-D layers

16. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 16 Description of Tasks and Status (X) HEGLO : Removal of hydrocarbons by He/O 2 plasmas in TEXTOR and ASDEX Upgrade + TILCAR : Characterisation of TEXTOR He/O 2 exposed components HeO GDC on a:C-H layers & AUG layers : D removal from real films ~ 10 times lower than for lab films = 10 13 C cm -2 s -1 = 0.01 m/h. No removal of deposits in ~ 3 mm gaps Oxidation of W reversible by exposure to H Tests in AUG consistent with lab tests but arcing problems due to B layers on W (C removal rate of 6.0 10 18 C/s) after before HeO GDC laboratory tests with real AUG tiles HeO GDC in AUG showing arc traces

17. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 17 Description of Tasks and Status (XI) TRIREMA : O 3 oxidation of hydrocarbon deposits in ITER-relevant conditions Oxidation in ozone achieves rates within the ITER requirements (1 mh -1 ) and operating temperature (T < 250 o C) for fusion application graphites Rates of 0.5 mh -1 achieved for TEXTOR flakes Main problem is that oxidation rates of flakes and substrate are similar ~ 1 mh -1

18. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 18 Description of Tasks and Status (XII) 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

19. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 19 Description of Tasks and Status (XIII) MATDAM : Validation of ELM Damage Modelling Experiments carried out in TRINITI plasma guns CFC and W targets exposed to 100 pulses at 0.5, 1.0, 1.5 MJ/m 2 t = 500 s (two higher levels beyond melting of W and sublimation of C) Analysis of target damage on-going (completed for 0.5 & 1.0 MJ/m 2 ) TARCAR

20. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 20 Description of Tasks and Status (XIV) MATDAM : Validation of ELM Damage Modelling CFC Damage is driven by preferential erosion of material above PAN fibres (fibre-matrix detachment) overheating an brittle destruction of material W macrobrush damage threshold melting of castellations edges + layer displacement

21. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 21 Description of Tasks and Status (XV) TARCAR : Characterisation of ELM-disruption damage modelling Analysis of CFC & W targets exposed to 100 small ELM ITER-like pulses in TRINITI plasma guns CFC enhanced erosion of PAN fibres & fibre detachment already at 0.6 MJm -2 W macrobrush shows edge melting and significant surface cracking at 0.8 MJm -2 ) Before exposure Crack formation at edges of bundles PAN fibre erosion ~ 1.0 MJ/m 2 Plasma stream Before exposure ~ 0.9 MJ/m 2 Edge W melting + displacement Cracking of W surface

22. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 22 = 3 o Description of Tasks and Status (XVI) ITERTRAN : Improved concepts for reduction of W and CFC damage + plasma evolution in ITER after ELMs Optimisation of macrobrush geometry shows that minimum damage by melting and displacement is obtained with ~ 0.5 (gap shadowing effective area) Modification of CFC structure to avoid PAN fibres parallel to surface decreases erosion damage (increases threshold energy for damage) by ~ 5 for 45 o t = 0.5 ms E ELM max = 0.5 MJm -2 t = 0.1 ms

23. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 23 Description of Tasks and Status (XVII) ITERTRAN : Improved concepts for reduction of W and CFC damage + plasma evolution in ITER after ELMs Transient evolution of plasma discharge after ELMs in ITER refined : modelling ELMs by an increase of anomalous transport of factor ~ 10 Even for E ELM max < 1 MJm -2 t ~ 300 s significant carbon production and expansion along the field with n ped C ~ 5 10 20 m -3 after 2 ms P rad modelling in progress n C after t ~ 500 s n C after t ~ 1.5 ms

24. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 24 Description of Tasks and Status (XVIII) TUNMOD : W erosion and edge plasma contamination in ITER W concentrations remain under 2 10 -5 for any coverage level by W in ITER and high density operation (weakly influenced by seeding, D anomalous & parallel flows) W concentrations during the limiter phase can reach very large values > 1 % unless T e,limiter < 50 eV without impurity seeding (W self-sputtering runaway) Low n e,sep High n e,sep e n Ar /n e ~ 0.1 % Z eff ~ 1.3 e n W /n e ~ 1% (no self-sputtering) n W /n e ~ 10% (with self-sputtering)

25. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 25 Description of Tasks and Status (XIX) ITERNEUT : Modelling of n-n and n- effects in ITER divertor Nonlinear effects (n-n & n- ) and improved D 2 kinetics introduced in B2-EIRENE Opacity increases plasma density but total divertor source remains constant (larger recombination) different divertor dynamics but same divertor pressure Main impact on the ITER divertor caused by n-n and D 2 + D + collisions (larger P DT for same peak divertor power load) S ion excited > S ion conventional n D = 5 10 20 m -3 R-target recycling VR-volume recombination I: ionization (total) I ph : photo-induced ionization

26. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 26 New Tasks in 2006 (I) 1.Material erosion and transport Erosion/Deposition in divertor tokamaks, TW6-TPP-CARTIL Material erosion and transport in ITER-like conditions, TW6-TPP-ERDEP Hydrocarbon sticking properties, TW6-TPP-CNDMSTICK 2. Fuel retention and removal Fuel removal from macro-brush structures, TW6-TPP-GAPOX Fuel retention in mixed-materials, TW6-TPP-RETMIX Fuel retention in ITER metallic PFCs, TW6-TPP-RETMET 3. Transient heat loads and control Experiments on W & CFC under-threshold damage, TW6-TPP-REPELM Modelling of PFC damage and plasma evolution in ITER, TW6-TPP-DAMTRAN Analysis of Be-coated/Be-clad PFCs exposed to plasma guns, TW6-TPP-ANABE Coating by Be of W/CFC PFCs, TW6-TPP-BECOAT

27. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 27 4. PWI and ITER modelling Modelling of mixed-materials formation, TW6-TPP-BETUNCMOD Modelling of erosion/redeposition balance in ITER, TW6-TPP-ERITERA-B 3-D modelling of SOL transport in ITER, TW6-TPP-SOLITER Modelling of ITER far SOL plasma (for ICRF coupling), TW6-TPHI-ICFCOUPL 5. Dust production and removal Evaluation of dust generation mechanisms in tokamaks, TW6-TPP-DUSTGEN 6. Task force relevant diagnostics Tests of dust measurement techniques in tokamaks, TW6-TPP-DUSTMEAS New Tasks in 2006 (II)

28. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 28 Money matters : History and Facts Budget allocated for TPP area of EFDA Technology programme roughly constant since 2003 Real allocated budget increases with time (by a factor of 3-4 in 2006 !!!) Increase of requested/allocated budget reflects interest of EFDA management on PWI issues + the good work of EU-PWI Task Force!!

29. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 29 Some ideas for 2007 Mixed Materials Studies development of techniques for T removal from mixed materials In-situ & spatially resolved diagnostic for erosion/redeposition measurements Diagnostics for in-situ T retention measurement Techniques for dust removal in tokamaks More ideas ? EFDA-PISCES-B collaboration

30. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 30 EFDA-PISCES-B collaboration EFDA-PISCES-B collaboration research topics in 2007 Studies of CD 4 seeding in Be containing plasmas impacting on a C and W target in steady state and under pulsed loads Studies of Be layers on W targets under steady and pulsed loads Studies of He/Ne/Ar interaction with C and W targets with Be-seeded plasmas Studies of redeposition in the witness plate (D content, changes in reflectivity of mirrors ?, etc.) during these experiments EFDA will provide long term (~ 1 year) scientist to participate in experiments (mission expenses covered by Euratom mobility) : Young dynamic and enthusiastic experimental physicist (post-doc) Knowledge of surface analysis and/or spectroscopic techniques To become Be worker (non-smoker & no beard) CV to be sent to A. Loarte by 31-12-2006 Selection by 30-1-2007 Start date in PISCES-B by spring 2007 (one month test period possible)

31. Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 31 Conclusions EFDA TPP Technology Programme is well integrated with EU-PWI Research Programme and producing ITER-relevant results As recognised by EFDA and ITER management Two major EFDA Collaborations with US (PISCES-B) and RF (TRINITI) on-going New large collaboration approved with RF (Kurchatov +TRINITI) on Be damage under ITER transient loads EU staff to collaborate in-situ in the experiments (Euratom Mobility) + EU industry to provide targets (+ Be coated targets by MEdC) + destructive analysis of targets to be done in EU labs Many Associations involved : CEA, CIEMAT, ENEA-Frascati, ENEA- CNR Milano, FOM, FZJ, FZK, IPP, IPP.CR, IST, MEdC, MHST, ÖAW, TEKES and VR