WP10-PWI (02)/TEKES/BS(PS) Characterization of retention mechanisms in AUG Monitoring meeting of the EFDA PWI SEWG on Gas Balance and Fuel Retention, July, 2010 Antti Hakola VTT Technical Research Centre of Finland Collaborators: S. Koivuranta, J. Likonen: VTT T. Haikola, J. Kolehmainen, S. Tervakangas: DIARC-Technology Inc. K. Krieger, M. Mayer, R. Neu, V. Rohde, K. Sugiyama: IPP-Garching

20/07/ What was proposed? analyze a set of marker tiles, exposed to AUG plasma during the 2009 experimental campaign, and study retention of deuterium in them Secondary Ion Mass Spectrometry (SIMS) analyses at VTT in Finland Nuclear Reaction Analyses (NRA) at IPP-Garching produce new marker tiles for erosion, deposition, and retention studies in AUG

20/07/ Marker tiles for the 2009 AUG campaign inner and outer strike-point tiles (4, 4B, and 1) two different 3B tiles; one of them magnetically connected to an ICRH source tiles had 15-mm wide uncoated stripes, tiles 1 and 3B also 15-mm wide and 2-5 m thick Ni stripes, and m thick W coating 2 × tile 3B Tile 1 Tile 4B Tile 4 W 1 m W, 1 m W 1.5 m W, 1 m Ni 5 m Ni, 2 m C C C C 15 mm

20/07/ What was done: SIMS and NRA analyses NRA analyses performed in March 2010 at IPP Garching 2.5-MeV 3 He + ions used measurements done at 5-10 mm steps along each marker stripe SIMS analyses done in April-May 2010 at VTT, Finland samples drilled from each tile for analyses 5-keV O 2 + ions used measurement points at mm steps along each marker stripe results converted to quantitative ones with the help of the NRA data Photograph of tile 1 before and after drilling SIMS samples

20/07/ Results (1): SIMS depth profiles of D on W Below inner strike point (deposition zone in the private flux region) Above outer strike point (erosion zone) Sputtering rate approximately nm/s largest retention in < 500-nm thick layer

20/07/ Results (2): D on W Tile 4 Tile 1Tiles 3B

20/07/ Results (3): D on C Tile 4 Tile 1Tiles 3B

20/07/ Results (4): D on Ni Tile 1 Tiles 3B

20/07/ Comparison between different substrates: tile 1 deuterium peaks below the outer strike point in the private flux region and on a thin stripe in the middle of the tile (resulted from an injection experiment) clear differences between the different materials: retention largest in carbon (graphite) Ni stripe complicated: stripe heavily eroded between 1060 and 1160 mm (strike- point region) NRA results in this region not reliable, SIMS results cannot be evaluated at all

20/07/ Comparison between different substrates: tile 4 deuterium peaks below the inner strike point in the border region between tiles 4 and 4B (private flux region) again carbon is responsible for larger D inventories than tungsten; notice that the values are order of magnitude higher than in tile 1 SIMS results do not show as prominent peaks as NRA, particularly in the case of C lack of data points in the critical region but impossible to obtain samples for SIMS analyses in that region.

20/07/ retention largest on graphite and lowest on Ni tile 3B-II (magnetically connected to an ICRH source) shows somewhat larger D inventories than tile 3B-I (no magnetic connection Comparison between different substrates: tiles 3B

20/07/ Evolution of D inventory on W ( ) tile 1: retention decreased by a factor of 2-10 from 2007 to 2009 BUT change from VPS tiles to other coatings tile 4/4B: thicker co-deposited layers below the inner strike point in 2009 than in 2007 or 2008 VPS tiles 2007 & 2008 Marker tile 2009 PVD tile 2007 Marker tiles 2008 & 2009 PVD tile 2007 Marker tiles 2008 & 2009

20/07/ New marker tiles for 2010 AUG campaign Mo 2 m Korund, R a = 5.5 m Glas, R a = 0.75 m Original, R a = 0.38 m Korund, R a = 6.4 m Glas, R a = 3.9 m Original, R a = 2.7 m W 2 m W 3 m Mo 3 m Cr 3 m Al 4 m W + 5% Ta 3 m W 3 m Tile 1: poloidal regions with different surface roughness Tile 1: poloidal stripes for erosion/deposition studies Coating half of these tiles belongs to task WP10-PWI /TEKES/PS

20/07/ Conclusions marker tiles exposed to AUG plasma during the 2009 experimental campaign analyzed using SIMS and NRA retention of deuterium in the tiles has been determined: largest retention in graphite, lowest in nickel deuterium accumulated in deposition-dominated regions of the divertor together with carbon and boron tile 3B with magnetic connection to an ICRH antenna shows more D than the tile 3B without such a connection new marker tiles for erosion, deposition, and retention studies in AUG have been produced