Presentation on theme: "D retention and release behaviour of Be/C/W mixed materials"— Presentation transcript:
1 D retention and release behaviour of Be/C/W mixed materials Max-Planck-Institut für PlasmaphysikD retention and release behaviour of Be/C/W mixed materials(WP10-PWI /IPP/PS, WP10-PWI /MEdC/PS)K. Sugiyama, K. Krieger, J. RothMax-Planck-Institut für Plasmaphysik, EURATOM AssociationA. Anghel, C. Porosnicu, C.P. LunguNational Institute for Laser, Plasma and Radiation Physics of Romania,Association EURATOM-MEdCM.J. Baldwin, R.P. DoernerCenter for Energy Research, University of California at San Diego
2 Outline Introduction Experimental procedure Results Summary and Outlook
3 Introduction Be W CFC Wall materials in ITER 690 m2 Be: first wall and start-up limiter modules140 m2 W: divertor dome / baffle region55 m2 CFC: divertor strike point areasBeWCFCMaterial mixtureTritium retention in mixed materialsExperimental approach in this taskPreparation of ITER relevant (Be-related) mixed material samplesInvestigation of D retention and release behaviour of mixed materialsWall baking for tritium removal in ITER240 ºC: Main chamber350 ºC: Divertor region
4 Outline Introduction Experimental procedure Results Summary and Outlook
5 Experimental procedure Sample preparationBe12W fabrication by annealing of W film on Be substrate sample at 1073K, 10 hoursBe2C fabrication by annealing of C film on Be substrate sample at 773K, 3 hoursWC fabrication by annealing of W film on graphite substrate sample at 1373K, 4 hoursCompounds fabrication by thermal treatment of Be-W / Be-C / W-C systemBe-W / Be-C simultaneously deposited layersBe-related depositions were prepared by Thermionic Vacuum Arc (TVA) deposition method in MEdCUpgrade of TVA setup for the simultaneous depositionDepositions were successfully done with varying Be/W and Be/C ratios
6 Experimental procedure Sample preparationBe12W fabrication by annealing of W film on Be substrate sample at 1073K, 10 hoursBe2C fabrication by annealing of C film on Be substrate sample at 773K, 3 hoursWC fabrication by annealing of W film on graphite substrate sample at 1373K, 4 hoursCompounds fabrication by thermal treatment of Be-W / Be-C / W-C systemBe-W / Be-C simultaneously deposited layersD implantation to prepared layers200 eV D ions implantation in the High Current Ion Source in IPP-GarchingFlux ~ 1019 D/m2, Fluences up to ~1023 D/m2Post mortem analysis for the prepared samplesD release behaviour analysis by Thermal Desorption Spectroscopy (TDS)Quantitative analysis by Nuclear Reaction Analysis using D(3He, p)4He reaction
7 Outline Introduction Experimental procedure Results Be-related compounds layerW-C compound (WC) layerBe-W simultaneously deposited layerBe-C simultaneously deposited layerSummary and Outlook
8 Typical desorption from pure materials Typical D desorption spectra from pure materialsBeFluence ~ 1023 D/m2D implantation to each material200 eV D implantation in the High Current Ion Source in IPP-GarchingFlux ~ 1019 D/m2Implantation temperature: RTW (ITER-grade)Fluence ~ 1023 D/m2Desorption flux [1014 D2/cm2/s]CFC (NB31)Be: Sharp desorption peak at CW: Primary desorption at CCFC: Broad desorption feature above 400 CFluence ~ 1024 D/m2
9 D desorption from Be-related compounds D implantation to Be-related compound layersBe2C: Additional desorption stage in the high temperature range (> 400 ºC)Be2CD fluence ~ 1023 RTBeBe: Primary desorption peak at ºC
10 D release during the temperature hold at 350 ºC BeBe2CThe desorption flux drops down when the temperature reaches the plateau at 350 ºC.The desorption flux reaches almost background level during the 20 min. hold.5-10 % of retained D additionally released during the temperature hold at 350 ºC.
11 D desorption from Be-related compounds D implantation to Be-related compound layersBe12WBe12W: The primary desorption peak becomes less intense and broaderD fluence ~ 1023 RTBeBe2CBe: Primary desorption peak at ºCBe2C: Additional desorption stage in the high temperature range (> 400 ºC)
12 D retained fraction in Be-related compounds Be2CBe12WBeBe: ≈ 90 % of initially retained D is released at 350 ºCCompounds: % of initially retained D is released at 350 ºC
13 D release from WC layer WC WC Bulk-W Bulk-W Fluence ~ 1023 RTWCBulk-WD release from WC shows primary desorption stage at K
14 D release from Be-W simultaneously deposited layer W~10 at.%W~60 at.%Bulk-WW~10 at.%W~60 at.%Be12WBe240ºC350ºCFluence ~ 1023 RTBeBe12WMixing of W in Be slightly changes the D desorption behaviour.The retention amount decreases by increase of W fraction in Be.
15 D release from Be-C simultaneously deposited layer C ~ 50 at.%C ~ 8 at.%240ºCBe2CBeC ~ 8 at.%350ºCC ~ 50 at.%Fluence ~ 1023 RTBeBe2CD release behaviour totally changes in the case of C-rich mixed layer sample
16 How will the wall baking work in ITER ? Best performance will be expected for:・ removal from clean Be deposit・ the removal from Be-hydrogen codeposition formed at “cool” areasWCBe12WBe2CThe efficiency is marginal for:・ Be-W codeposited layer and compounds・ “Be-rich” Be-C mixed depositionLess efficiency for:・ “C-rich” (C conc. > 50 at.%) Be-C mixed deposition・ the hot surface (temperature is > 350ºC during a discharge)
17 Summary and Outlook What we have done are: Messages: Outlook: Mixed material sample fabrication (collaboration with MEdC)- TVA setup successfully upgraded for the Be-W / Be-C simultaneous depositionInvestigation of D release from mixed materials for the assessment of T removal operation in ITER (wall baking at 240 ºC / 350 ºC)Messages:D release behaviour is affected by material mixing- Influence of C is more significant.- T removal efficiency of 350 ºC baking decreases by material mix compared to the case of pure Be or W.Outlook:D implantation to mixed material samples at high temperatures- Temperature dependence of D retention in mixed material samplesFurther upgrade of TVA setup for Be-W-C (ternary) simultaneous deposition
19 Compound layer formation Compound layer preparationBe-related compounds fabrication by thermal treatment of Be-W / Be-C systemBe2CBe12W fabrication by annealing of W film on Be substrate sample at 1073K, 10 hoursBe2C fabrication by annealing of C film on Be substrate sample at 773K, 3 hoursBe12W
20 Tungsten carbide layer formation W on graphite: annealed at ~1300 K, 4 hrsCh. Linsmeier et al. (2001)M. BaldenW on graphite: W layer is completely changed to WC layer
21 Chemical state: Be-W simultaneously deposited layer Sputter XPS depth profilingSample: Be ~ 80%, W ~20 %Most of Be is metallic and the rest is oxide.Almost no alloy
22 Fluence dependence of D retention Fluence dependence of D retention in Be-related compounds200 eV D RTExpected fluence to the wall after single ITER discharge (400 s)WBe-filmBe-bulkLiterature data:Be-bulk: Anderl et al. (2001)Graphite: Staudenmaier et al. (1979)W: Ogorodnikova et al. (2003)Be2CGraphiteBe12W
23 D retention in mixed material layers Be-C simultaneously deposited layerBe-W simultaneously deposited layer
24 D release from Be-W simultaneously deposited layer W~10 at.%W~60 at.%Bulk-WFluence ~ 1023 RTBe240ºC350ºCBe12WW~60 at.%Bulk-WBe12WW~10 at.%BeMixing of W in Be slightly changes the D desorption behaviour.The retention amount decreases by increase of W fraction in Be.
25 D retention in Be at different implantation temperatures Implantation temperature [K]U. Toronto: A.A. Haasz et al. (1997)SNL/LANL: R.A. Causey et al. (1997)PISCES-B: R.P. Doerner et al. (1997)INEEL: R.A. Anderl et al.(1997)DiMES: W.P. Wampler et al. (1996)Literature dataBe filmBe12WThis studyAmount of D retention in the Be decrease with the implantation temperature, especially, above 200 ºC.
26 Influence of implantation temperature D implantation to Be layers at different temperatures350ºC300ºC150ºCRT240ºCRT150 ºC300 ºCD desorption in the low temperature stage is reasonably reduced by increase of implantation temperature.Obviously no D desorption at temperature below the implantation temperature