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Max-Planck-Institut für Plasmaphysik

Max-Planck-Institut für Plasmaphysik. Deuterium inventory in the full tungsten divertor of ASDEX Upgrade K. Sugiyama , M. Mayer, V. Rohde, R. Neu, A. Wiltner, Th. Dürbeck, S. Lindig, T. Höschen, M. Balden, H. W. Müller and ASDEX Upgrade team. Outer divertor target tiles. VPS-W-coated

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Max-Planck-Institut für Plasmaphysik

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  1. Max-Planck-Institut für Plasmaphysik Deuterium inventory in the full tungsten divertor of ASDEX Upgrade K. Sugiyama, M. Mayer, V. Rohde, R. Neu, A. Wiltner, Th. Dürbeck, S. Lindig, T. Höschen, M. Balden, H. W. Müller and ASDEX Upgrade team

  2. Outer divertor target tiles VPS-W-coated (200 mm) graphite Langmuir probes (polycrystalline bulk W) W divertor in 2007 campaign • W-coated divertor • 3 ~ 4 µm PVD-W (except the outer target) • 200 µm VPS-W (outer target) • Langmuir probes (PCW) in outer divertor • Total discharge time: 2620 s • No Boronization • No H discharges in the end of campaign

  3. Post-mortem analysis • 3He+ Nuclear Reaction Analysis (NRA) • 2.5 MeV: amount of D (depth info. ~ 3 µm in W), over the whole divertor region • 0.69 - 4.0 MeV energy scan: D depth profiling up to ~ 6 µm, some specific points • Secondary Ion Mass Spectrometer (SIMS) • Qualitative D depth profiling: available for beyond 6 µm depth • Thermal Desorption Spectroscopy (TDS) • Determination of the amount of D (including bulk)

  4. 6A 3B 6B 3A 5 2 4 1 9A 9D 10 9B 9C Poloidal D distribution • 2.5 MeV 3He+ NRA (depth info. ~ 3 µm): scanning along the poloidal direction 6A 6B 5 4 9A 9B 9C 9D 10 1 2 3A 3B • D distribution is similar to the C distribution on the divertor surface.

  5. Deposition Graphite substrate PVD-W layer S = 0.507 m Deuterium inventory in the inner divertor • D depth profiling byNRA3He+ energy scanning method (0.69 ~ 4.0 MeV : depth info. ~ 6 µm) Graphite substrate PVD-W layer S = 0.052 m 0 1 2 3 4 5 6 Depth [mm]

  6. M=3 (HD) M=4 (D2) M=3 (HD) M=4 (D2) Deuterium inventory in the inner divertor • TDS result (D in bulk) 0.2 0.15 S = 0.022 – 0.042 m 0.1 0.05 0 0.6 0.5 0.4 S = 0.436 – 0.456 m 0.3 0.2 0.1 0 • PVD-W (3 ~ 4 mm) coated tile: Good agreement with NRA data • D inventory in inner divertor is dominated by the codeposition with carbon.

  7. D, NRA (< 3 mm) D, NRA (< 6 mm) VPS-W layer S = 1.151 m S = 1.082 m Deuterium inventory in the outer divertor • D depth profiling byNRA3He+ energy scanning method (0.69 ~ 4.0 MeV : depth info. ~ 6 µm) PVD-W layer Graphite substrate S = 1.604 m

  8. 0.2 S = 1.670 – 1.690 m M=3 (HD) M=4 (D2) M=3 (HD) M=4 (D2) 0.15 0.1 0.05 0 1.2 S = 1.107 – 1.127 m 1.0 (VPS-W) 0.8 0.6 0.4 0.2 0 Deuterium inventory in the outer divertor • TDS result (D in bulk) • VPS-W (200 mm) coated tile: the amount of D is higher than NRA data by a factor of ~ 3.

  9. D in Langmuir Probes (NRA) • 3He+ NRA 0.69 ~ 4.0 MeV energy scan: depth info. ~ 6 µm • The amount of D in < 6 mm depth was about one order of magnitude less than that of VPS-W layer.

  10. Plasma-exposed surface 20 mm • Langmuir probe (Polycrystalline bulk W): The amount of retained D was 2 order of magnitude higher than NRA data. ￫ Nonnegligible D accumulation in the bulk D in Langmuir Probes (TDS) • TDS result (D in bulk) D concentration [%] Depth [mm]

  11. Comparison with lab-experiments AUG Langmuir probes (PCW): TDS AUG outer target tiles (200mm VPS-W): TDS 200eV D ￫ VPS-W (R.T.) 100% retention 200eV D ￫ PCW (R.T.) VPS-W: A.V. Golubeva et al., AIP Conf. Proc. 837 (2006) 12 PCW: O. Ogorodnikova et al., J. Appl.Phys. 103 (2008) 034902

  12. Concluding remarks • D inventory in full-W divertor ￭ Distribution (~ 3 um in depth) on the W divertor was similar to the C distribution. ￭ D inventory in the inner divertor was dominated by codeposition with C -> D retention in the inner divertor decreased by factor of 5 - 10 compared to full carbon AUG due to the decrease of codeposition with C (& B in this campaign) ￭ D accumulation in VPS-W D inventory in the outer divertor • D retention in the near surface layer of VPS-W layer was higher than that of polycrystalline W (Langmuir probe) by factor of 10 ~ 20. • D accumulation in the bulk: ￭ PVD-W (3 ~ 4 mm) coated tile: good agreement with NRA data (~ 6 mm) ￫ No significant D accumulation in the bulk (graphite substrate) ￭ VPS-W (200 mm) coated tile: higher than NRA data (~ 6 mm) by a factor of ~ 3 ￭ PCW (20 mm) Langmuir probe: higher than NRA data (~ 6 mm) by a factor of ~ 200 ￫ Nonnegligible D accumulation in the bulk

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