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EU Plasma-Wall Interaction TF – Meeting 27.10.-29-10-2008 - Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik.

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Presentation on theme: "EU Plasma-Wall Interaction TF – Meeting 27.10.-29-10-2008 - Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik."— Presentation transcript:

1 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Report of the Special Expert Working Group on Chemical Erosion and (carbon) Transport S. Brezinsek TF-E Institut für Energieforschung- Plasmaphysik, Forschungszentrum Jülich, EURATOM Association, Trilateral Euregio Cluster, D Jülich, Germany with major contributions from SEWG members from the following associations … CU, CNR … group meeting in JET in July 2008 (joint with SEWG Fuel Retention and Fuel Removal)

2 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Clarification of Chemical Erosion under ITER Divertor Relevant Conditions PWI-08-TA-05/CEA/BS/01 Determination of chemical erosion yield in Tore Supra, including gaps and redeposited layers. PWI-08-TA-05/CEA/PS/01 Upgrade of spectroscopy diagnostic for chemical erosion characterization PWI-08-TA-05/CEA/BS/02 Molecular dynamic simulations of graphite surfaces PWI-08-TA-05/CIEMAT/BS/01 Erosion of doped graphites and re-deposited layers PWI-08-TA-05/CU/BS/01 Modelling the interaction of plasma with wall material (Be or W) with impurities (Be, B, O) and/or seeding gases (Ne, N2, Ar) PWI-08-TA-05/CY/BS/01 PWI-08-TA-05/CY/PS/01 Molecular dynamics (CPMD) simulations of carbon erosion PWI-08-TA-05/FOM/BS/01 High ion flux exposure in pilot-PSI and PSI-II under ITER divertor plasma condition. Impact of seeding gases on erosion PWI-08-TA-05/FZJ/BS/02 PWI-08-TA-05/FZJ/PS/02 Impact of ELMs on chemical erosion in the JET divertor High ion flux exposure of graphite/ CFC in TEXTOR, pilot-PSI and PSI-II under ITER-relevant conditions PWI-08-TA-05/FZJ/BS/03 PWI-08-TA-05/FZJ/PS/03 ERO modelling of erosion and material transport in tokamaks and linear devices PWI-08-TA-05/IPP/BS/01 PWI-08-TA-05/IPP/PS/01 Joint MD/DFT simulation of carbon erosion PWI-08-TA-05/OAW/BS/01 MD simulations of carbon erosion PWI-08-TA-05/UKAEA/BS/01 Narrow-band spectroscopic 2D imaging of carbon erosion during ELMs in MAST TASK AGREEMENT: WP08-PWI-05

3 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Erosion, Transport and Deposition of First Wall Impurities PWI-08-TA-06/CEA/BS/01 Carbon balance in TS : evaluation of sources and sinks, including gaps PWI-08-TA-06/CEA/PS/01 Modelling of C erosion /rede-position and fuel retention in TS PWI-08-TA-06/CEA/BS/02 Monitoring of carbon deposited layers (IR, ellipsometry, thermal properties) PWI-08-TA-06/CIEMAT/BS/01 Injection of hydrocarbons by molecular beam techniques PWI-08-TA-06/CNR/BS/01 13CH4 tracer injection in TEXTOR. Post-mortem tile analysis,spectroscopic analysis, local erosion/ deposition. PWI-08-TA-06/FOM/BS/01 Modelling of erosion and re-deposition of graphite exposed to ITER relevant fluxes in Pilot-PSI with ERO PWI-08-TA-06/FZJ/BS/01 13CH4 tracer injection in JET and AUG. Post-mortem tile analysis PWI-08-TA-06/FZJ/BS/02 Development of material tracers TMB and SiH4. PWI-08-TA-06/FZJ/BS/03 Characterisation erosion / re-deposition of graphite PFCs at TEXTOR and marker probes at JET PWI-08-TA-06/FZJ/BS/04 Development and testing of spectroscopic tools for the observation of carbon and beryllium and of QMBs for erosion/deposition measurements in TEXTOR and JET PWI-08-TA-06/FZJ/BS/05 Modelling of erosion / re-deposition of graphite PFCs at TEXTOR and marker probes at JET. ERO code modelling of gap deposition. Coupling of the ERO code to molecular dynamics simulation codes and study of the formation of mixed-materials in ITER. Local erosion/ deposition (ERO) and plasma transport (EDGE2D, DIVIMP) modelling. PWI-08-TA-06/FZJ/PS/05 ERO modelling of redeposition in gaps (TEXTOR,JET) 13CH4 tracer injection in JET and AUG / Characterisation of graphite PFCs at TEXTOR and marker probes at JET TASK AGREEMENT: WP08-PWI-06

4 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ PWI-08-TA-06/IPP/BS/02 Reflection properties of hydrocarbon radicals for ITER-like divertor conditions /Deposition of hydrocarbons in ITER-like conditions and their interaction with hydrogenic species PWI-08-TA-06/IPP/PS/01 13CH4 tracer experiments,erosion-redeposition studies, reflection properties PWI-08-TA-06/IPP.CR/BS/01 Reactive interaction of mol.ions with surfaces. Reflection properties of hydrocarbon radical for ITER-like divertor conditions PWI-08-TA-06/IPPLM/BS/01 Characterization of erosion/re-deposition of graphite PFCs at TEXTOR: SEM, EPMA, XRD, AES, XPS etc PWI-08-TA-06/MHEST/PS/01 Characterisation of erosion / re-deposition of graphite PFCs at TEXTOR (collab FZJ) Improvement of the NRA ion beam PWI-08-TA-06/MHEST/BS/01 Characterisation of erosion / re-deposition of graphite PFCs at TEXTOR and marker probes at JET PWI-08-TA-06/ÖAW/BS/01 Reactive interaction of molecular ions (fragmentation, sticking) with Surfaces /Reflection properties of hydrocarbon radicals for ITER-like divertor conditions PWI-08-TA-06/ÖAW/BS/02 Determination of sticking coefficients for impact of small (deuterated) hydrocarbon and other molecular ions on ITER relevant surfaces by using a sensitive Quartz Crystal Microbalance technique PWI-08-TA-06/TEKES/BS/01 Analysis of the long-term erosion/deposition marker samples PWI-08-TA-06/TEKES/PS/01 Analysis of the long-term erosion/deposition marker samples, work on hot cells PWI-08-TA-06/TEKES/BS/02 PWI-08-TA-06/TEKES/PS/02 Local erosion/ deposition (ERO) and plasma transport (EDGE2D, DIVIMP) modelling PWI-08-TA-06/VR/BS/01 Extension of spectroscopic and QMB diagnostics for the JET ILW project Characterisation of graphite PFCs at TEXTOR PWI-08-TA-06/VR/PS/01 Tracer experiments. Development of tracer techniques: C-13, TMB, SH4 TASK AGREEMENT: WP08-PWI-06

5 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Motivation - ITER Beryllium Tungsten ITER Lifetime issues Erosion, transport, and deposition of divertor/first wall material (Be/C) Qualification of W as PFM Mixed material systems (Be, C, W) Control of transient heat loads Safety issues Retention of tritium via co-deposition Methods to release the trapped tritium Dust formation Research goal: minimisation of risks and optimisation of ITER availability! All topics are related to each other! Graphite

6 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Material Migration in Tokamaks with low-Z PFCs Present view: Erosion and deposition is a question of flux balance Main chamber is the dominant erosion source of C (Be) caused by ion and neutral bombardment Material is transport to the inner divertor due to flows Multiple step process (C) and transport to remote areas Outer divertor: erosion or deposition zone This SEWG deals primarily with: Measurement and modelling of chemical erosion C and Be migration/transport in fusion devices (measurement and modelling) Deposition and sticking of (hydro)carbons Balance of erosion and deposition in fusion devices Erosion and deposition diagnostics

7 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Motivation - Tasks Where are the species eroded from? How much is eroded? Spatial distribution of the erosion yield … What is the impact of seeding impurities on the erosion process? Synergetic effects with Nitrogen, Argon … What does the plasma do with the eroded hydrocarbons ? Hydrocarbon catabolism and C transport…. What does the plasma do with the eroded Be? Be transport…. Where are the eroded species deposited? Inner divertor, gaps, remote areas …. Amount of deposited particles? Which hydrocarbon films are produced? Hard layers, soft layers, mixed layers …. Which species is re-eroded and how? Chemical sputtering: Methane-, ethane-family … ELM-induced erosion: material clusters …. We have to understand: Erosion Migration Deposition Re-erosion

8 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ ITER Predictions / SEWG Predictions for ITER Data base, A&M data, Material data: HYDKIN, MD, ADAS, TRIM … Code and data base validation: benchmark experiments TEXTOR, AUG, TJ-II, Tore Supra … Plasma background B2-Eirene or EDGE2D Tokamak experiments JET, AUG ERO modelling Laboratory experiments MAJESTIX … Linear experiments pilot-MAGNUM, PSI-II PISCES

9 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Outline Measurement and modelling of chemical erosion C and Be migration/transport in fusion devices (measurement and modelling) Deposition and sticking of (hydro)carbons Balance of erosion and deposition in fusion devices Erosion and deposition diagnostics

10 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Measurement and Modelling of Chemical Erosion Examples: Spectroscopic measurement of chemical erosion und ITER-like detached divertor conditions – FZJ, TF-E Impact of ELMs on chemical erosion in the JET and MAST divertor – FZJ, UKAEA, TF-E High ion flux exposure of different CFC materials in pilot-MAGNUM and PSI-II under ITER-divertor plasma conditions – FOM, IPP, FZJ Understanding of hydrocarbon break-up in He/H plasmas with molecular beams – CIEMAT

11 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Density ramp discharges with transiently detached outer divertor leg: Decrease of intrinisic CD and CII photon flux emission in recombining plasmas: low T e <2 eV and high n e ~2*10 20 m -3 L-mode: Reduction of chemical sputtering at low T e (energetic threshold) JET: Chemical Erosion in Cold Divertor Plasmas Density feedback-controlled discharge with detached outer divertor: Extrinsic carbon source (CD 4 ) observable! Effective D/XB values about 35% higher in detached than in attached plasmas! S. Brezinsek et al. accepted JNM

12 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ ELM-induced Enhanced Erosion in JET Carbon deposition on QMB reflects erosion of divertor target, mainly from ISP position Arrhenius-type equation: ELM energy W ELM [kJ] Physical sputtering (Y=1.5%) Processed exp. data C deposition per ELM [atoms/cm 2 ] ~10x less Thermal decomposition of carbon layers under ELM impact A. Kreter et al. accepted for PFR

13 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ t=0 +33 s+66 s +99 s +132 s +297 s+627 s+1320 s Motivation: characterisation of material transport due to transients Photron camera + optics from the slow filtered camera fitler imaging + speed low spatial resolution 1 cm, 256x256 pixels high time resolution: kHz insufficient time resolution to capture dynamics, but getting closer… LOWER DIVERTOR VIEW CI filter at 910 nm, 5 nm FWHM, 30 kHz, 20 s shutter shot Impurity Production during ELMs in MAST S. Lisgo presented at IAEA 2008 Time resolved measurements of divertor CI, CII and CIII emission during an ELM

14 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Erosion yields at high ion fluxes in pilot-PSI Exposures have been performed in the flux range /m 2 s Calibration of the chemical erosion has been verifies by absolute measurements with CH 4 injection (D/XB ~ 500) Comparison with ERO calculation showed impact of small plasma diameter (~mean free path) at T e <2eV Flux determination is currently being re-examined (~ factor 2) Impact of surface temperature distribution not yet included J. Westerhout et al. ITER domain

15 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Preliminary Flux Dependence Analysis Pilot-PSI T e and E ion normalised

16 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Injection of hydrocarbons in TJ-II by molecuar beams SOL Methane and ethene break-up in hydrogen and helium plasmas P. Tabares et al. PSI 2008 The set-up for He beam diagnostic was used to inject methane and ethene in He and H ECRH plasmas The emission profiles of H and CH (A-X) were recorded Ratios of H /CH emission are evaluated by relative calibration 3H per CH are emitted from methane break-up (He plasmas) Penetration of H from methane much larger than from H 2 in He plasmas Same penetration for CH from methane/ethene Common precursor

17 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Carbon Migration/Transport in Fusion Devices Milestones 13 CH 4 tracer injection in JET. Post-mortem tile analysis, spectroscopic analysis, local erosion/ deposition (ERO ) and plasma transport (EDGE2D) modelling - TF-E, UKAEA, VR, TEKES, FZJ 13 CH 4 tracer injection in AUG. Post-mortem tile analysis, spectroscopic analysis, local erosion/ deposition (ERO) and plasma transport (DIVIMP) modelling – IPP, TEKES 13 CH 4 tracer and hydrocarbon injection modelling (ERO) in TEXTOR – FZJ

18 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ JET: 13 C deposition in the Centre of the MKII-GB divertor

19 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ JET: 13 C Deposition in the MKII-SRP Divertor M. Rubel et al.

20 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Measured deposition (AUG divertor) Shape of deposition (ERO) Local Erosion/deposition Modelling of 13 CH 4 Injection in AUG with the ERO code M. Airilia et al. presented at PSI 2008 Extensive modelling of the 2003 AUG divertor puffing experiment was carried out Shape of deposition reasonably well reproduced Locally deposited amount significantly smaller than in experiment (shadowing) The deviation of deposition tail from B direction due to E x B drift can be reproduced by applying a uniform E-field Results suggest that the injection might have a local perturbation in plasma Exact gemoetry with shadowing effects not yet applied

21 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Plasma Transport (EDGE2D, DIVIMP) Modelling (AUG) L. Aho-Mantila et al. L-mode plasma for the 2007 AUG methane injection experiment was modelled with SOLPS A realistic plasma background for the local injection was obtained A DIVIMP model for the global carbon transport was set up using an OSM background plasma Outer divertor target plate 13 C deposition pattern

22 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Next: Check for influence of local injection on local plasma parameters (cooling and increase of n e ) coupling of ERO with fluid model from M. Tokar´ Modelling of CH 4 Injection at TEXTOR Example: hydrocarbon injection through gas inlet – higher hydrocarbons C 2 D 4 injection: radial penetration of C 2 and CII light: EXP vs. ERO Injected species D/XB CD A-X band D/XB C 2 d-a band EXPEROEXPERO CD C2D4C2D C2D6C2D Effective D/XB values: EXP vs. ERO Good agreement of observed and modelled profiles Modelled and observed D/XB agree well for C 2, but differ for CD by a factor of ~2 R. Ding et al. submitted to ppcf

23 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Deposition and Sticking of Hydrocarbons Examples Deposition and re-erosion of hydrocarbons in castellated structures – FZJ, VR, SFA,TF-E, VR, UKAEA Reactive interaction of molecular ions (fragmentation, sticking) with surfaces – ÖAW, CR-IPP Erosion and deposition in remote areas and the impact of N 2 – IPP, CIEMAT

24 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Carbon Deposition in Be Limiter Tile Gaps in JET M. Rubel et al.

25 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Ion Survival Probability ION SURVIVAL PROBABILITY Sa(%) HYDROCARBON IONS ON CARBON INCIDENT ENERGY 3 – 45 eV Z. Hermant et al. neutralization of ions (survival pobability) surface-induced dissociations (energy partitioning) chemical reactions at surfaces (H-atom, CH n -transfer) Experimental setup

26 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Reactive Interaction of Molecular Ions with Surfaces CD 2 + on plasma sprayed tungsten (PSW) and CFC (AUG tiles) very stable beam with D flux of ~10 11 cm -2 s -1 long time exposure (BESTOF) very low incident energy (~ 0 eV), narrow energy distribution (~100 meV FWHM) sticking coefficient of D from CD 2 +: CFC: S ~ ; PSW: S ~ W. Schustereder et al. Nucl. Instr. Meth. B

27 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ C +, H + to the pumps pumping duct JET MKII divertor experimental setup in PSI-2 PSI-2 Experimental Setup: Pumping Duct Measurements W. Bohmeyer et al. PSI 2008

28 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ PSI-2: Impact of Nitrogen on Erosion & Deposition Pattern in Remote Areas Film thickness in the pump duct vs. time: In pure H 2 plasma and co-injection of CH 4 and / or N 2 Collector temperature 330 K. Pressure 1 Pa W. Bohmeyer et al. PSI 2008 No synergetic effect of enhanced erosion with H 2 and N 2 => volume process not a surface process

29 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ No impact of Ne on the erosion and deposition process! PSI-II: Impact of Nitrogen on Erosion & Deposition Pattern in Remote Areas W. Bohmeyer et al. PSI 2008

30 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Balance of Erosion and Deposition in Fusion Devices Examples In-situ layer disintegration in the inner divertor of JET – TF-E, FZJ, UKAEA, FOM Carbon balance in Tore Supra: Carbon sources and sinks - CEA Characterisation and modelling of erosion and re-deposition of graphite PFCs at TEXTOR – FZJ, VR, SFA, IPPLM

31 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Dynamics in Material Migration in the Inner Divertor of JET Strongest deposition observed in the inner divertor pump duct area Post-mortem analysis, spectroscopy and deposition monitors (QMB) used The (step-wise) local migration is mainly determined by Strike-point configuration (line-of-sight transport) History effect (soft layer appearance and destruction) Power to the target (ELM strength) Cleaning discharges in H-mode with strike-point sweeping over the horizontal target led to the strongest deposition in the pump duct area VTHT < Deposition on the QMB in the inner divertor pump duct entrance S. Brezinsek et al. EPS 2008

32 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ JET: Inner vs. Outer Divertor Deposition and Erosion Direct comparison between inner and outer divertor deposition with QMBs HT VT QMB SOL PFR Fuelled ELMy H-mode Similar conditions Outer divertor close to erosion/deposition balance Different surface conditions in inner and outer divertor leg Investigation is ongoing (impact of other configurations, gas injections HT VT outer divertor QMB inner divertor QMB

33 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ TS: Measurement of Chemical Erosion on the TPL CCD Filters wheel (Dα, C2, C+, CD) Splitter cube Optical view erosion area optical fibres validate filtered images CCD and spectrometer system both calibrated in situ with labsphere D nm CD nm C nm wavelength CCD Filters wheel (Dα, C2, C+, CD) Splitter cube 4 fibers linked to a Czerny- Turner spectrometre E. Delchambre et al. PSI 2008

34 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Erosion Yield Measurements in TS CD band observed on TPL since Chemical erosion experiment (Dec 06) (sensitivity 10x lower in this region ! integration time = 3 s) Ychem = CD(431 nm)/Dg [S/XB] Hg = 1000 [S/XB] CD = 65 Erosion experiment: Ychem ~ 2 % = 30% of Ytot (CII 426nm /D γ) [S/XB] Hg = 1000 [S/XB] CII (426nm) = 20 Erosion experiment : Ytot ~ (CII/Da) * ([S/XB]CII/[S/XB]Ha) ~ 6 % However, other line combinations Da and CII at 658 nm suggest lower yield E. Delchambre et al. PSI 2008

35 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Deposition profile tile 20 toroidal gap (1.5 mm) Deposition profile tile 20 poloidal gap (1.8 mm) = 0.54 mm Composition from EPMA, RBS: B : C : O ~ 2 : 1 : 1 Mass density ~1.3 g/cm 3 = 0.75 mm Larger thickness in toroidal than in poloidal gaps (factor of >~2) Decay length comparable to previous experiments despite larger gap A. Kreter, P.Wienhold et al. TEXTOR: Long-term Deposition in Gaps of the Toroidal Limiter

36 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Profile shape is similar to the experimental one Absolute values are not recovered Deposition at the bottom (not shown here) can be partially recovered (n bottom /n edge ~ 20% for R N D = 0.9) R N C = 0.5 3DGAP code has been developed and simulations started: reflection at inside walls of gap chemical erosion of layers deposited inside gaps elastic collisions with neutral gas inside gaps various particle sources Coupling of 3DGAP code with PIC modelling and ERO (plasma penetration, electrical field, usage of ERO infrastructure, …) in preparation Modelling of Deposition in Gaps First comparison with TEXTOR experiments (castellated test limiter) A. Kirschner et al.

37 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Summary Progress in both Task Agreements clearly visible Tasks cover a wide range of physics and chemistry from basic research to tokamak discharges Main points: benchmark of modelling codes with experiments => code verification machine comparison => general trends basic understanding of sticking coefficients => input for codes experiments under ITER-like conditions

38 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ Outlook 2009 New Task Agreement Erosion, transport and deposition of first wall impurities focuses on the material migration part of the SEWG Objectives for 2009/2010 Global transport investigations using 13 CH 4, SiH 4 tracer and Be-evaporation in divertor tokamaks and associated plasma transport modelling Global transport investigations tokamaks and associated plasma transport modelling Local transport investigations with associated plasma transport modelling Deposition and re-erosion in gaps Measurements and modelling of first wall material erosion under high particle fluxes

39 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ UHV chamber H2H2 CH 3 N 2 (CH 3 ) 2 ellipsometry substrate preparation chamber rf plasma H Wien Filter Ar + 1 keV Ar + 20 eV de- celeration UHV experiment with 2 radical beam sources and one ion beam source A. von Keudell, M. Meier, and T. Schwarz-Selinger: Review of Scientific Instruments 74, (2003). MAJESTIX: Experimental Set-up W. Jacob, Ch. Hopf,

40 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ in contrast to Ne + TRIM (= physical sputtering) cannot describe the results for pure N 2 + yield 1 for E ion > 50 eV threshold between 20 and 50 eV almost no energy dependence in range 50 to 900 eV new model yields excellent description of experimental results: Y tot = Y chem + Y phys (N-on-C model) at high E: physical sputtering as calculated by TRIM.SP at low E: chemical sputtering, i.e., formation of volatile species due to reaction of N (at end of ion range) with C from the layer W. Jacob, C. Hopf, and M. Schlüter: APL 86, (2005). M. Schlüter, C. Hopf, and W. Jacob: submitted to NJP. A New Model for Chemical Sputtering by N 2 +

41 EU Plasma-Wall Interaction TF – Meeting Frascati SEWG Erosion & Transport S. Brezinsek Institut für Energieforschung –Plasmaphysik Assoziation EURATOM-FZJ chemical sputtering for combined bombardment with N 2 + and H 0 yield increases from about 1 at 30 eV to 7 at 900 eV (R = 380) yields higher than predicted by Hopf model (red dash-dotted line) new model yields excellent description of experimental results: Y tot = Y Hopf + Y N-on-C impinging energetic N causes chemical erosion as described by the Hopf model (bond breaking by energetic species and reaction with H) decelerated N at end of ion range reacts with C to form volatile C x N y species – this lead to an additional contribution to chemical sputtering M. Schlüter, C. Hopf, and W. Jacob: submitted to NJP. A New Model for Chemical Sputtering by N H 0


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