Session 3.2: Material – PMI and High Heat Flux Testing R. Neu: Recent PMI Experience in Tokamaks R. Doerner: PMI Issues beyond ITER M. Roedig: High Heat Flux Testing of Different Armor F. Escourbiac: Critical Heat Flux Testing in Support of ITER S. Abdel-Khalik: Experimental Validation of He-Cooled Divertor Thermal Performance

R. Neu: Recent PMI Experience in Tokamaks Flux dependence of chemical erosion is settled and it provides a firm basis for extrapolations Erosion of high-Z materials is mainly caused by low-Z impurities Destructive transients (large ELMs, disruptions) are not easily acceptable in present day machines D-retention by co-deposition with C is quantitatively reproduced in dedicated tokamak experiments D-retention in metals is low (lab experiments, Asdex Upgrade) Dust investigations just started, sources are not well known Conditioning by boronization / Be evaporation are helpful for O-reduction, but not helpful for long pulse operation lab experiments and modelling are indispensible for extrapolations

R. Doerner: PMI Issues beyond ITER Higher efficiency will lead to higher armor temperatures Steady state operation: sufficient time to develop PMI at high temperatures Almost all PMIs are temperature dependent Very few data for DEMO relevant temperatures High temperature work is needed DEMO relevant fluence data is needed

M. Roedig: High Heat Flux Testing of Different Armor PFCs – Thermal Fatigue Technical solutions up to 20 MW/m 2 are available CFC and W monoblocks represent a very robust design solution After n-irradiation: elevated surface temperatures (esp. Carbon) PFMs – Thermal Shock Behavior Tungsten: melting (tile edges) starts at 0.4 MJ/m 2 Deformed tugsten: dense crack pattern for low cycle numbers, cracks gow perpendicular to the surface CFC: brittle destruction – PAN fibers parallel to the surface are heavily eroded After n-irradiation: increased crack formation in W, increased erosion and crack formation in carbon

F. Escourbiac: Critical Heat Flux Testing in Support of ITER CHF increases with twist ratio, tape thickness, water pressure, flow rate CHF decreases with width of tube and inlet temperature On the base of the TONC-75 correlation, a whole set of correlations was developed for heat transfer prediction Predictive tools already used for Tore Supra and W7-X components and are now applied to ITER PFCs

S. Abdel-Khalik: Experimental Validation of He-Cooled Divertor Thermal Performance Approach Test modules which match already the geometry of the proposed designs Tests at prototypical non-dimensional parameters Compare data against CFD model predictions Outcome Validated CFD codes can be used to optimize design and establish limits on manufaturing tolerances Results Code predictions match experimental data  predicted thermal performance data (10 MW/m 2 ) values are reliable Preferable to use simple one-equation turbulance models (Spalart Allmaras)