1. PSI 2008 Toledo May 2008 © Matej Mayer Carbon balance and deuterium inventory from a carbon dominated to a full tungsten ASDEX Upgrade M. Mayer a, V. Rohde a, K. Sugiyama a, J.L. Chen a, X. Gong a, C. Hopf a, J. Likonen b, S. Lindig a, R. Neu a, G. Ramos c, E. Vainonen-Ahlgren b, A. Wiltner a, and ASDEX Upgrade Team a Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching, Germany b Association EURATOM-TEKES, VTT Processes, Espoo, Finland c CICATA-Qro, Instituto Politécnico Nacional, Querétaro, México Evolution of B, C deposition in the divertor Evolution of D inventory in the divertor Comparison between plasma-sprayed and bulk W Plasma-related aspects of all-W machine were covered by R. Dux, I-6

2. PSI 2008 Toledo May 2008 © Matej Mayer Motivation Tritium inventory in ITER dominated by codeposition with carbon (if carbon is present) But large uncertainties: Carbon sources and carbon transport poorly understood  Stepwise replacement of C by W in AUG offers unique possibility to study C sources A. Kirschner et al., JNM 363-365 (2007) 91 Be W C

3. PSI 2008 Toledo May 2008 © Matej Mayer Motivation (2) Much lower T inventory in all-W machine is predicted All-W predictions based solely on laboratory data  Confirmation in existing tokamaks required All-W is probably the only option for a future DEMO reactor  Data from existing tokamaks required J. Roth, this conference, R-1

4. PSI 2008 Toledo May 2008 © Matej Mayer W coverage in AUG 2002 – 2007 Step by step replacement of C tiles by W coated tiles 3 – 4 µm W-PVD on most tiles 200 µm plasma-sprayed W at outer strike point

5. PSI 2008 Toledo May 2008 © Matej Mayer AUG inner divertor: Deposition of B + C 2002 – 2003 4940 s Inner divertor deposition in 3000 s C14.6 g B 2.8 g 6A 4

6. PSI 2008 Toledo May 2008 © Matej Mayer AUG inner divertor: Deposition of B + C 2004 – 2005 3150 s Inner divertor deposition in 3000 s C13.8 g B 4.7 g 6A 4

7. PSI 2008 Toledo May 2008 © Matej Mayer AUG inner divertor: Deposition of B + C 2005 – 2006 2950 s Inner divertor deposition in 3000 s C2.2 g B 2.3 g 6A 4

8. PSI 2008 Toledo May 2008 © Matej Mayer AUG inner divertor: Deposition of B + C 2007 2620 s 6A 4 Inner divertor deposition in 3000 s C1.0 g B  0 g (below detection limit)

9. PSI 2008 Toledo May 2008 © Matej Mayer AUG divertor: Evolution of B, C deposition Reduction of C deposition by factor ~15 from C-dominated to all-W machine  Largest decrease after coating of ICRH protection limiters with W Decrease in C plasma concentration by factor 2 – 3 R. Pugno, EPS 2008  Available C source at walls > 1000 times C plasma inventory even in all-W machine

10. PSI 2008 Toledo May 2008 © Matej Mayer AUG divertor: Evolution of B, C deposition Reduction of C deposition by factor ~15 from C-dominated to all-W machine  Largest decrease after coating of ICRH protection limiters with W 5-6 boronizations/campaign from 2002-2006  B-deposition almost constant No boronization in 2007, extensive cleaning  B-deposition below detection limit of 0.1 g

11. PSI 2008 Toledo May 2008 © Matej Mayer Carbon transport in AUG 2005 – 2006 3 g 20% 11 g 80% 14 g 3 g 100% 2 g 2004 – 2005 Small influx of residual carbon in main chamber Identical outer divertor erosion in both campaigns, M. Mayer et al., PS T128 (2007) 106 Assumptions: Spectroscopy: 1 g A. Kallenbach et al., JNM 363-365 (2007) 60

12. PSI 2008 Toledo May 2008 © Matej Mayer Carbon sources in all-W machine 100 µm Residual C deposition in all-W machine: 1 g in 3000 s Electrical arc’s can remove W coating and release C from tile 0.05 g C from inner baffle A. Herrmann, this conference, O-5 Erosion in not fully coated tile gaps and back sides of tiles Residual carbon layers from previous campaigns (probably small due to extensive cleaning) C impurities in W coatings Photo-desorption of CO, CO 2 from walls V. Philipps et al., J. Nucl. Mater. 200 (1993) 355 SE BSE

13. PSI 2008 Toledo May 2008 © Matej Mayer Deuterium inventory C-dominated campaign 2002/2003 D on divertor tiles 0.9 – 1.3 g D below roof baffle 0.4 g in 3000 s Full W campaign 2007 D on divertor tiles 0.15 – 0.23 g D below roof baffle 0.03 g in 3000 s 6A 4 9B 1A 3A 4940 s 2620 s

14. PSI 2008 Toledo May 2008 © Matej Mayer Deuterium inventory in inner divertor of all-W machine Correlation between distributions of C and D  D inventory in inner divertor still dominated by C-codeposition 6A 4

15. PSI 2008 Toledo May 2008 © Matej Mayer Deuterium inventory in outer divertor of all-W machine D inventory in outer divertor dominated by trapping in W  Deep diffusion (> 3 µm) observed for VPS layers at outer strike point 3B 1

16. PSI 2008 Toledo May 2008 © Matej Mayer AUG divertor: Evolution of D inventory Carbon dominated machine Total D-inventory dominated by inner divertor and remote areas All-W machine Boronizations result in high D-inventory, co-deposition with B (2005/2006 campaign) D-inventory dominated by trapping in VPS-layers at outer strike point Decrease of total D-inventory by factor 5 – 10 from C-dominated to all-W

17. PSI 2008 Toledo May 2008 © Matej Mayer VPS-W versus polycrystalline W in outer divertor VPS-W and bulk W trap about the same total amount of D Bulk W shows deep diffusion (~ mm) at low D concentrations (< 100 ppm) K. Sugiyama et al., Hydrogen Workshop Salamanca Bulk W Langmuir probes VPS-W 20 mm Background level

18. PSI 2008 Toledo May 2008 © Matej Mayer Extrapolation to higher fluences / longer discharge times Good agreement between laboratory measurements and AUG data Slower increase of D-inventory in W than in C for longer discharge times  W even more beneficial for long pulse machines VPS-W: A.V. Golubeva et al., AIP Conf. Proc. 837 (2006) 12 poly-W: O. Ogorodnikova et al., J. Appl.Phys. 103 (2008) 034902 D-inventory in AUG divertor

19. PSI 2008 Toledo May 2008 © Matej Mayer Conclusions Decrease of divertor C deposition by factor ~15 from C-dominated to all-W machine, normalized to 3000 s Decrease of trapped D in divertor by factor 5 – 10 from C-dominated to all-W machine Boronizations result in high D-inventory due to co-deposition with B  Decrease of D-inventory only visible in unboronized machine D-inventory in C-dominated machine determined by co-deposition in inner divertor + remote areas D-inventory in all-W machine determined by deep diffusion into W at outer strike point