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Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct 17-19 2005 1 Max-Planck-Institut für Plasmaphysik compiled by Arne Kallenbach (IPP - EU-PWI.

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Presentation on theme: "Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct 17-19 2005 1 Max-Planck-Institut für Plasmaphysik compiled by Arne Kallenbach (IPP - EU-PWI."— Presentation transcript:

1 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Max-Planck-Institut für Plasmaphysik compiled by Arne Kallenbach (IPP - EU-PWI contact person) presented by Joachim Roth

2 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Erosion behaviour and impurity location in tokamaks Material transport and re-deposition Fuel recycling, retention and removal Transient heat loads Edge modelling, erosion and deposition modelling Edge and SOL physics Task force relevant diagnostics IPP- Garching Belin Greifswald Chemical erosion in ASDEX Up and beam experiments. D/XB calibration. Determination of main chamber sources. W experiment in ASDEX Up C sources and sinks. C material transport by tracer injection. C deposition in remote areas. W transport in the SOL. Sticking parameters of hydrocarbons. C erosion and re-deposition in PSI-2 simulator. Gas balance in ASDEX Up. Fuel retention in CFC Mixed layers in lab. experiments. Removal of carbon films by active species in lab. experiments. ELM power deposition characteristi cs Disruption power deposition. Disruption mitigation techniques. W erosion and transport modelling with DIVIMP. Edge modelling with B2.5 SOL transport and parallel flow measurement Main chamber wall plasma interaction. Development of Quartz microbalance technique. Topics proposed by IPP Garching, Oct 2001 Chemical Erosion: S. Brezinsek Gas balance: T. Loarer Transient heat loads: A. Loarte High-Z: R. Neu SOLPS modelling of edge and divertor profiles (D. Coster, A. Chankin) Flow measurements for D and C (H.W. Müller, R. Pugno)

3 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct /1996 W-divertor: W is feasible in divertor tokamak main chamber is strong source of C 1999/2000 W-tiles in main chamber: no impact on plasma performance 2001/2003 W centr. col. (start-up lim.): start-up possible, strong reduction of W inventory after x-point formation, erosion mainly by ions 2003/2005 W divertor, LFS limiter: confirmation of '96 divertor results, erosion at LFS limiter dominated by fast ions (NBI) and accelerated ions (ICRH) guard/ ICRH limiter aux. limiter hor. plate lower PSL roof baffle 2006/2007 (planned) W-coating starting with campaign 2003/ / /2006 Milestones of W programme / Schematic view of W PFCs

4 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct ASDEX Upgrade in December % W covered first wall still divertor and wall sources of C impurities frequent boronisation

5 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Deuterium and Carbon deposition in tile gaps Karl Krieger

6 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Tritium growth rates in gaps AUG measurement and ITER extrapolationKarl Krieger

7 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Temperature dependence of a-C:D layer deposition Matej Mayer Si sample Heater Electrical connection Temperature dependence of layer deposition determined with heated long term samples Layer deposition depends strongly on sample temperature Probably due to re-erosion by atomic hydrogen

8 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Glow Discharge Removal of Hydrocarbon Co-Deposits Ch. Hopf Only 10 % O 2 concentration needed in GDC to obtain highest achievable rates. Use of He/O 2 mixture plasmas Stability of glow discharge Less sputtering compared to pure O 2 discharge or heavier noble gas admixtures Good experience with He GDCs Oxidation of W in O 2 plasma saturates and is reversible in an H 2 discharge

9 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Parameters: 10 % He Glow discharge ~ 300 V Ion flux ~ cm -2 s -1 Average erosion rate of carbon co-deposits on AUG tiles: 1.1 ± 1.0 × cm -2 s -1 or ~ 100 hours for 1 micrometer before after after before Glow Discharge Removal of Hydrocarbon Co-Deposits V. Rohde O 2 /He glow in discharge test chamber O 2 /He glow discharge in ASDEX Upgrade 49 h total O 2 /He glow time 600 V, 5.4A 98% He + 2% O 2 Mass spectroscopy T exhaust increased by factor of ~30 compared to pure He (R. Neu) 50 a-C:H marker films for erosion analysis Arcs developed on tiles coated with B oxide layers.

10 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct a-C:H erosion probes: poloidal scan Christian Hopf sectors 6, 7, 8 C removed No C removed Effective erosion on first wall and in large ports No erosion in shielded places, such as tile gaps, behind first wall, and in deep in the divertor anode

11 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct arc traces lower PSL Anodes: Outer Divertor 50 a-C:H erosion probes: toroidal scan Christian Hopf

12 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Films after 2004/2005 campaign are no hydrocarbon films Surface modifications on ASDEX Upgrade tiles Christian Hopf

13 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Removal of carbon co-deposits from wall surfaces in He/O 2 GDC plasmas works 20 g C removed (mass spectroscopy) Glow discharge cleaning works on plasma-facing surfaces does not work in shielded areas and tile gaps There were almost no carbon films in AUG after 2004/2005 campaign mainly oxidised B layers Insulating layers lead to arcing and suppress GDC Conclusion for He/O 2 GDC Christian Hopf

14 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct Be diffuses fast through Be/W alloy and forms alloy at the interface Be 12 W phase starts forming at the interface W on Be transforms completely to Be 12 W upon annealing at 1070 K Material mixing: W on Be W Depth Profiles and Reaction KineticsKarl Ertl

15 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct XPS clearly shows new Be-W alloy phase Different from Be 2 W identified previously From composition: Be 12 W Melting temperature <1750°C BeO Be Be 12 W W Material mixing: W on Be Chemical phase identificationCh. Linsmeier

16 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct (A. Wiltner, Ch. Linsmeier, JNM 337–339 (2005) 951) Surface alloying: monolayer at 300 K, limited to first nm Excess Be disappears above 770 K, no bulk diffusion, sublimation Phase identification as Be 2 W Material mixing: Be on W Mixed layer formationAlmut Wiltner

17 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct XPS confirms beryllides Be 2 W (A. Wiltner et al. J. Nucl. Mater. (2005)) IBA results in Be/cm 2 (1 ML) at 1050°C Be-seeded D plasma bias 75 V typical fluences: 1x10 22 D/cm 2 1x10 19 Be/cm 2 Material mixing: Be on W Be-seeded plasma in PISCESR. Doerner, M. Baldwin

18 Report IPP Garching EU Task Force PWI Meeting, Cadarache Oct W-beryllide phases form in the interaction of W with Be, and bear the potential of a major malfunction: at 1070 K W-beryllide phases can form which melt below 1700 K For W on Be this phase has clearly been identified as Be 12 W through ion beam and XPS analysis. However, under typical ITER conditions (0.1% Be in incident D flux ) only a thin Be 2 W layer will form, excess Be will sputter/reflect/evaporate and deposit elsewhere Studies using higher Be plasma concentrations ( up to 1% ) are underway in PISCES-B Conclusion for Be/W interaction


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