Overview of future Plasma Wall Interaction (PWI) work

Transcription

1 1 Overview of future Plasma Wall Interaction (PWI) work J. Likonen VTT,, Finland Contributions from: M. Groth (Aalto), A. Hakola (VTT), K. Nordlund (UH) The Annual Finnish Fusion Seminar Annual Fusion Seminar

2 2 Outline Future PWI work at JET AUG DIFFER Edge modelling Molecular dynamics Summary

3 3 Overview of PWI research at Tekes Experimental: studying erosion, deposition and transport of materials analysis of tiles from JET and ASDEX Upgrade using SIMS and LIBS (VTT, UT) determining erosion and deposition patterns of divertor and limiter tiles investigating the retention of the plasma fuel (deuterium, tritium) long-term erosion and deposition studies of W-coated tiles investigation of transport of tracers ( 13 C) exposure of samples at DIFFER using Pilot-PSI production of marker layers for these purposes (DIARC Technology Inc) Modelling: modelling of PWI phenomena using ERO, EDGE2D, DIVIMP codes (Aalto, VTT) modelling of PWI chemistry using MD simulations (UH)

4 4 Overview of PWI research at Tekes Coordination: JET: two Deputies (TF-E2 and FT) during the ITER-like Wall campaigns ( ) EFDA TF-PWI: project leader for ITER Physics IPH-A01-3 (Influence of mixed surface layers on fuel retention and release)

5 5 JET and ASDEX Upgrade JET 2.5 m AUG 1m Solid Be W-coated CFC Bulk W LBSRP 4 6 JET carbon machine (CFC), Be regularly evaporated ITER-like wall 2010 : W divertor and Be wall in the main chamber 6A 6B 5 9B-1 4 9C 9A 4B 9B A 3B ASDEX Upgrade (AUG) full-w machine since

6 This image cannot currently be displayed. Plasma facing Components: Erosion/Deposition (Global trends) Dump plate: deposition OPL: Erosion near midplane IWGL: erosion deposition divertor: deposition (inboard) erosion (outboard) P Coad PFMC /5/2011

7 7 Future work programme for JET Reference scenario: Full exploitation of the ITER-like wall, leading to 100% tritium and DT operation in 2017 Alternative scenario: Full exploitation of the ITER-like wall, leading to a shutdown starting in 2016 to install one or two major upgrades. Restart of operations is planned in 2017 with deuterium operation for a period of ~1 year (2018) to commission the newly installed systems, followed by 100% tritium and DT operation in Reference scenario: D H D He H T, DT Alternative scenario: D H D D He 2017 Install RMP, ECRH, DT prep H T, DT D D Safe state, samples and calibration 2018 Safe state, sam pl es and calibration 2020 Shutdowns D campaigns H, He campaigns DT campaigns Restart

8 8 Future work programme for AUG Roadmap: The metal wall in AUG means that it has presently an unique role in several Work Packages expected to play an important role during Horizon Finland: Continuation of erosion, migration and deposition studies at AUG including edge modelling Solid tungsten divertor (DIV III): will be installed during the present shutdown for the outer strike-point region (tile 1) Two toroidal rows of ferritic steel (P92) tiles for the heatshield region during the present shutdown New divertor manipulator (DIM-II): capability to move samples up to the size of two tiles 1 close to the plasma 6A 6B 5 9B C 9A 1 4B 9B A 3B

9 9 DIFFER collaboration (Netherlands) Roadmap: Magnum-PSI has an important role in testing of non-irradiated high heat flux and PFC components (especially steady state and transients) Finland: exposing tungsten coatings to different plasmas in Magnum-PSI (He content will be varied as well as the temperature of the sample, also ELM-like pulses will be realized during the exposure); thorough analysis of the samples afterwards effect of dopants in W on erosion (yttrium?); retention of deuterium and/or helium in the samples; how about the effect of surface roughness on erosion? in situ LIBS measurements: determining thickness and composition of samples immediately after the plasma pulses, without breaking the vacuum gross vs. net erosion: gross erosion spectroscopically during the plasma shots all in collaboration with University of Tartu

10 10 Other experimental future PWI activities Arc cleaning technique (A. Hakola) Plasma device in Jülich (Germany): Beryllium compatible linear plasma device being developed FZJ Erosion/deposition and fuel retention studies WEST (CEA, France): An upgrade of the Tore Supra tokamak equipped with a tungsten divertor representative of ITER technology Fuel retention in tungsten Start operations in 2015 Wendelstein 7-X (Greifswald, Germany) Operations will start in 2015 Investigation of PWI phenomena in stellarator JT-60SA (Japan) First plasma expected in 2019 JT-60SA is similar in size to JET Hydrogen isotopes retention in all-metal device (post mortem analyses, lab experiments, modelling) Erosion and damage of metallic plasma facing components

11 Interpretation of experimental results from existing devices using range of edge codes Aalto University edge group is strongly engaged in simulating state of SOL plasma and impurity migration for ASDEX Upgrade and JET effort is going to continue in forthcoming years (next important focus = PSI 2014) Role of impurity radiation in heat flux reduction and divertor detachment in JET (More) complete description of divertor detachment, e.g., momentum losses, role of molecules and molecular ions SOL flows and their impact on divertor asymmetries and material migration Impurity penetration / transport / migration in trace-impurity injection experiments; 2-D versus 3-D transport and deposition W erosion and transport in the SOL M. Groth Aalto University contributions toward edge modelling for existing fusion facilities, ITER, and DEMO 11

12 PSI studies at Univ. of Helsinki Explain the formation mechanism of W fuzz and suggest ways to mitigate the effects ( ). Obtain comprehensive understanding of Be and Be-W mixed system as plasma-facing materials, in particular understanding material mixing effects and effects of Becontaining molecules on the fusion plasma ( ) Obtain predictive capability in describing response of W as divertor material to D, T and He bombardment. Both with respect to sputtering and other plasma-affecting properties and change in mechanical properties (also including neutron effects) [A. Lasa, S. K. Tähtinen and K. Nordlund (2013) submitted] Kai Nordlund, University of Helsinki 12

13 13 Summary TEKES has participated very actively in JET and AUG PWI studies (both experimental and modelling) since 2001 VTT and Univ. of Tartu have actively participated in plasma surface interaction studies at DIFFER since 2010 Several future experimental PWI activities foreseen (DIFFER, FZJ, WEST, Wendelstein, JT-60SA) Edge group at Aalto University is strongly engaged in simulating state of SOL plasma and impurity migration for ASDEX Upgrade and JET effort is going to continue in forthcoming years Investigation of chemistry of plasma-wall interactions will continue Very good collaboration between VTT, Aalto, UH and UT Tekes has become very strong partner Euratom-