1. Member of the Helmholtz Association Institute of Energy Research – Plasma Physics | Association EURATOM – FZJ A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Investigations of fuel accumulation and material transport into gaps of ITER-like castellated structures A. Litnovsky, M. Freisinger, V. Philipps, P. Wienhold, H.-G. Esser, S. Brezinsek, D. Rudakov, S. Allen, T. Dittmar, E. Tsitrone B. Pequourie, TEXTOR, Tore Supra and DIII-D teams Progress reports on the task: WP10-PWI-01-02-02/FZJ/BS

2. Slide 2 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. TDS measurements on Tore Supra tiles: a part of DITS project TORE SUPRA Please see the talk of E. Tsitrone for an overview of entire DITS project

3. Slide 3 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. TDS measurements on DITS samples TORE SUPRA Samples from different areas of TPL: Erosion zone; Zone with thick deposits; Zone with thin deposits. Several samples with flakes; 13 samples measured, 6 samples are to be outgased. In the frame of the DITS project, several graphite samples from Tore Supra toroidal limiter (TPL) delivered to FZJ for the TDS measurements

4. Slide 4 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. TDS facility at FZJ: overview Main parameters: Sample dimensions: maximum 55 mm; Maximum temperature: 1150 o C (oven can go up to 1200 o C); Separate vacuum evacuation of sample chamber; Programmable temperature increase: unlimited time (can be days); Sample weight: samples up to 200 g are OK; Temperature control: thermocouple in the oven (if necessary – may be installed in the sample); Calibration technique: calibration leaks.

5. Slide 5 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. TDS facility at FZJ: main components Sample mounting and transport system Oven

6. Slide 6 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. 1.4E18 7.8E17 1E20 1.85E18 1.34E18 3.06E18 7.13E19 2.03E19 3.87E20 6.61E18 2.54E20 X bulk top flakes to be done Preliminary TDS results: cartography Color legend: 6.3E18 1.39E18 bulk top Thin deposits* Thick deposits* * B. Pequourie, PSI 18 Toledo, Spain, May 2008 + J. Nucl. Mater., 390–391 (2009) 550 Erosion zone* TORE SUPRA Approximate dimensions of samples: 25×25×3 mm Standard samples were supplied by W. Jacob (IPP Garching)

7. Slide 7 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Preliminary first TDS results: trends Erosion zoneThin deposits Thick depositsFuel accumulation in flakes Fuel inventory (absolute): D tops /D bulk ~70; D tops /C~ 0.04-0.6% Almost no D. High temperature Fuel inventory (absolute): D tops /D bulk ~3; D tops /C~ 0.01-0.04% Almost no D Measurements are in progress Fuel inventory (absolute): D flakes /D bulk ~0.1; D flakes /C~ 40-80% Highest fuel inventory so far Lowest temperature No firm results yet TORE SUPRA

8. Slide 8 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Exposure of ITER-like castellated structures in the DIII-D divertor

9. Slide 9 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Exposure on DiMES manipulator at the level of divertor floor; Exposure in PFR; Non-heated sample; Exposure 1 (2008): 8 identical NBI-heated discharges with partially detached plasmas in the divertor; Exposure 2 (2009): 3 days in piggyback mode; Scheme of exposure Castellated DiMES Strong and optimized shaping 0.2 mm 1.0 mm A B Castellation blocks (W) Exposure of castellation in DIII-D divertor View of castellation after exposure

10. Slide 10 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Exposure 2 Strong deposition both on toroidal and poloidal gaps: deposits with thickness of up to 250 nm were detected in the gaps according to SIMS and colorimetry; Carbidization of tungsten at the interface between deposit and substrate (SIMS); Small or negligible metal mixing in the deposit layers both in poloidal and toroidal gaps: results from EPMA and SIMS. Strong asymmetry in the deposition in toroidal gaps: full similarity with TEXTOR results. Exposure of castellation in DIII-D divertor: current results

11. Slide 11 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Fuel removal castellated structures: O-bake experiment in DIII-D

12. Slide 12 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. O-bake experiment in DIII-D: general information Demonstrate an oxygen bake on the DIII-D tokamak and recover high performance plasma operation (with only clean vents) Demonstrate removal from several tiles with a second oxygen bake Goals: O-bake experiments 2010: 2 hours; 20% O + 80% He; 13 mbar; 350 o C; 1 st experiment: 13.04.2010, 2 nd experiment: 27.04.2010 (with castellation) DiMES (castellation at 350 o C) Tile shelf with samples (350 o C->160 o C)

13. Slide 13 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. O-bake experiment in DIII-D: exposure of castellation Tungsten ITER-like castellation was exposed in the DIII-D divertor during 2 nd O-bake exposure Poloidal gaps were coated a-C:D film prior to O-bake; a:-C-D film was pre-characterized via identical witness sample Details: Castellated DiMES sample Pre-coated poloidal gaps First impression: exposure did not change much beforeafter Next steps-analyses in the gaps: EPMA, NRA, SIMS/DEKTAK 4.5*10 17 C/cm 2 (EPMA) ~ 70 nm

14. Slide 14 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Castellated limiter IV for TEXTOR

15. Slide 15 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Castellated limiter IV: castellation at different angles to B field Critical region: the edges must be at the same height and position Features 3 angles: 3 o, 10 o, 20 o Rectangular and moderately shaped geometries of cells Activities 2010: Castellation manufacturing: done; Holder manufacturing: in progress; Thermal simulation of castellation: in progress. Miranda van den Berg, Gregory De Temmerman (TEC, FOM)

16. Slide 16 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Finalizing TDS measurements; Analyses of data and providing an input to DITS. TDS measurements on DITS samples Plans 2010: Investigations of fuel accumulation and material transport into gaps of ITER-like castellated structures WP10-PWI-01-02-02/FZJ/BS Analyses are underway on the castellated samples exposed in Tore Supra and DIII-D tokamaks. The effectiveness of deposit and fuel removal from castellated structures using O-bake technique in DIII-D is being studied.

17. Slide 17 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Finalizing surface analyses of deposits; Analyses of all the data from all gaps; Recommendations on castellation shaping. Comparison of TEXTOR and DIII-D results. Plans 2010 (continued): Finalizing the thermal loads simulation and holder manufacturing; Exposure in TEXTOR. Castellated limiter IV (TEXTOR) Analyses of deposits and fuel distribution in the gaps; Assessment of the O-bake effectiveness in DIII-D. O-bake experiment in DIII-D Castellation exposures in DIII-D

18. Slide 18 of 18 A. Litnovsky et al., Progress report on the task WP10-PWI-01-02-02/FZJ/BS, EU TF PWI SEWG on fuel retention, Garching, July 19-20, 2010. Thank you