1. ITPA May 2007 © Matej Mayer Carbon Erosion and Transport in ASDEX Upgrade M. Mayer 1, V. Rohde 1, J.L. Chen 1, X. Gong 1, J. Likonen 3, S. Lindig 1, G. Ramos 2, E. Vainonen-Ahlgren 3 and ASDEX Upgrade team 1 Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching, Germany 2 CICATA-Qro, Instituto Politécnico Nacional, Querétaro, México 3 Association EURATOM-TEKES, VTT Processes, Espoo, Finland Outer divertor – Tungsten erosion and local transport – Carbon erosion Inner divertor – Carbon and boron deposition Global carbon transport from 2002 – 2006 Extrapolation to ITER

2. ITPA May 2007 © Matej Mayer Experimental: Marker stripes on divertor tiles Marker stripes – 4 – 8 µm C with Re interlayer – 200 – 500 nm W Thickness of layers before and after exposure determined with ion beam analysis methods Re C C C/Re W C tile Net erosion = N Before - N After Gross erosion = N Before + N Deposited – N After N Before, N After : Amounts before and after exposure N Deposited : Amount deposited on C tile B, C W 1 2 1’ 3 prompt redeposition Net erosion  1’ - 3 Gross erosion  1’

3. ITPA May 2007 © Matej Mayer Erosion of C in 2004 – 2005 6A 6B 5 4 9A 9B 9C 1 low 1 up 2 3A 3B W C 10 Delamination of marker Comparable erosion pattern to W (except tile 10 + sharp deposition close to strike point) C-erosion 6-10 times larger than W-erosion

4. ITPA May 2007 © Matej Mayer Total erosion of C in 2004 – 2005 Delamination of marker Total C erosion on strike point obtained from C erosion pattern = W pattern C-erosion/W-erosion = 8 Tile 1 2.6 g 100.2 g Total2.8 g Divertor erosion from spectroscopy: 1 g Kallenbach PSI 2006 Uncertainties Factor 1.5 for surface analysis Factor 2 (– 3?) for spectroscopy  Agreement within error bars Additional sinks Below roof baffle, pumped out, …  C-source > C visible by spectroscopy

5. ITPA May 2007 © Matej Mayer W coverage in AUG 2002 – 2006 Step by step replacement of C offers unique possibility to identify C sources 2002 – 2003 2004 – 20052005 – 2006

6. ITPA May 2007 © Matej Mayer Deposition in inner divertor 2002 – 2003 4800 s 2004 – 2005 3050 s 2005 – 2006 2900 s 6A 6B 5 4 9C Decrease of C-deposition on divertor tiles by factor 7 from 2004/2005 to 2005/2006 Decrease of C-deposition below roof baffle by factor 10 from 2004/2005 to 2005/2006  Outboard limiters are main carbon source

7. ITPA May 2007 © Matej Mayer Total carbon balance 2002 – 20032004 – 20052005 – 2006 Outer divertorErosion C [g]-2.8 Inner divertorDeposition C [g]14.814.32.2 Deposition B [g]2.95.92.4 Deposition on tiles 5, 6 measured in all 3 campaigns  Extrapolate to total inner divertor using 2002/2003 data (factor 2.2) Erosion in outer divertor measured in 2004/2005  Assume identical in 2005/2006 Normalized to 3000 s

8. ITPA May 2007 © Matej Mayer Contribution of carbon ICRH limiters W C 2005-2006 Full carbon limiters used before 2005 Small carbon influx from horizontal part of limiters  Only small contribution of remaining carbon on limiters in 2005/2006 T. Pütterich 2003 V. Bobkov

9. ITPA May 2007 © Matej Mayer Carbon transport 2004 – 20052005 – 2006 3 g 20% 11 g 80% 14 g 3 g 100% 2 g Assumption: Small influx of residual carbon in main chamber

10. ITPA May 2007 © Matej Mayer Extrapolation to ITER ASDEX Upgrade: 1×10 26 ions to outer divertor in 2004/2005  Carbon erosion: 2.8 g ITER: 6×10 26 ions to outer divertor per discharge  Carbon erosion: 18 g Transport to outer divertor, resulting in 0.2% C in incident flux (D+T)/C = 0.1  0.2 g T per discharge, allows 5000 discharges  CFC at strike points is marginally acceptable from T codeposition Notes: 1. AUG at RT to 300°C, ITER at > 1000°C  Small contribution of chemical erosion in both cases 2. Larger ELM size in ITER not taken into account (ELM mitigation) 3. Beryllium from main chamber not taken into account!