eu plasma-wall interaction tf – meeting 27.10.-29-10-2008 - frascati sewg erosion & transport...
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EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Report of the Special Expert Working Groupon Chemical Erosion and (carbon) Transport
S. Brezinsek
TF-E
Institut für Energieforschung- Plasmaphysik, Forschungszentrum Jülich, EURATOM Association, Trilateral Euregio Cluster, D-52425 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)
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Clarification of Chemical Erosion under ITER Divertor Relevant Conditions
PWI-08-TA-05/CEA/BS/01Determination of chemical erosion yield in Tore Supra, including gaps and redeposited layers.PWI-08-TA-05/CEA/PS/01Upgrade of spectroscopy diagnostic for chemical erosion characterizationPWI-08-TA-05/CEA/BS/02Molecular dynamic simulations of graphite surfacesPWI-08-TA-05/CIEMAT/BS/01Erosion of doped graphites and re-deposited layersPWI-08-TA-05/CU/BS/01Modelling 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/01PWI-08-TA-05/CY/PS/01Molecular dynamics (CPMD) simulations of carbon erosionPWI-08-TA-05/FOM/BS/01High 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/02PWI-08-TA-05/FZJ/PS/02Impact of ELMs on chemical erosion in the JET divertor High ion flux exposure of graphite/ CFC in TEXTOR, pilot-PSI andPSI-II under ITER-relevant conditionsPWI-08-TA-05/FZJ/BS/03PWI-08-TA-05/FZJ/PS/03ERO modelling of erosion and material transport in tokamaks and linear devicesPWI-08-TA-05/IPP/BS/01PWI-08-TA-05/IPP/PS/01Joint MD/DFT simulation of carbon erosionPWI-08-TA-05/OAW/BS/01MD simulations of carbon erosionPWI-08-TA-05/UKAEA/BS/01Narrow-band spectroscopic 2D imaging of carbon erosion during ELMs in MAST
TASK AGREEMENT: WP08-PWI-05
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Erosion, Transport and Deposition of First Wall Impurities
PWI-08-TA-06/CEA/BS/01Carbon balance in TS : evaluation of sources and sinks, including gapsPWI-08-TA-06/CEA/PS/01Modelling of C erosion /rede-position and fuel retention in TSPWI-08-TA-06/CEA/BS/02Monitoring of carbon deposited layers (IR, ellipsometry, thermal properties)PWI-08-TA-06/CIEMAT/BS/01Injection of hydrocarbons by molecular beam techniquesPWI-08-TA-06/CNR/BS/0113CH4 tracer injection in TEXTOR. Post-mortem tile analysis,spectroscopic analysis, local erosion/ deposition.PWI-08-TA-06/FOM/BS/01Modelling of erosion and re-deposition of graphite exposed to ITER relevant fluxes in Pilot-PSI with EROPWI-08-TA-06/FZJ/BS/0113CH4 tracer injection in JET and AUG. Post-mortem tile analysisPWI-08-TA-06/FZJ/BS/02Development of material tracers TMB and SiH4.PWI-08-TA-06/FZJ/BS/03Characterisation erosion / re-deposition of graphite PFCs at TEXTOR and marker probes at JETPWI-08-TA-06/FZJ/BS/04Development and testing of spectroscopic tools for the observation of carbon and beryllium and of QMBs for erosion/deposition measurements in TEXTOR and JETPWI-08-TA-06/FZJ/BS/05Modelling 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/05ERO 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
PWI-08-TA-06/IPP/BS/02Reflection properties of hydrocarbon radicals for ITER-like divertor conditions /Deposition of hydrocarbons in ITER-like conditions and their interaction with hydrogenic speciesPWI-08-TA-06/IPP/PS/0113CH4 tracer experiments,erosion-redeposition studies, reflection propertiesPWI-08-TA-06/IPP.CR/BS/01Reactive interaction of mol.ions with surfaces. Reflection properties of hydrocarbon radical for ITER-like divertor conditionsPWI-08-TA-06/IPPLM/BS/01Characterization of erosion/re-deposition of graphite PFCs at TEXTOR: SEM, EPMA, XRD, AES, XPS etcPWI-08-TA-06/MHEST/PS/01Characterisation of erosion / re-deposition of graphite PFCs at TEXTOR (collab FZJ) Improvement of the NRA ion beamPWI-08-TA-06/MHEST/BS/01Characterisation of erosion / re-deposition of graphite PFCs at TEXTOR and marker probes at JETPWI-08-TA-06/ÖAW/BS/01Reactive interaction of molecular ions (fragmentation, sticking) with Surfaces /Reflection properties of hydrocarbon radicals for ITER-like divertor conditionsPWI-08-TA-06/ÖAW/BS/02Determination of sticking coefficients for impact of small (deuterated) hydrocarbon and other molecular ions on ITER relevantsurfaces by using a sensitive Quartz Crystal Microbalance techniquePWI-08-TA-06/TEKES/BS/01Analysis of the long-term erosion/deposition marker samplesPWI-08-TA-06/TEKES/PS/01Analysis of the long-term erosion/deposition marker samples, work on hot cellsPWI-08-TA-06/TEKES/BS/02PWI-08-TA-06/TEKES/PS/02Local erosion/ deposition (ERO) and plasma transport (EDGE2D, DIVIMP) modellingPWI-08-TA-06/VR/BS/01Extension of spectroscopic and QMB diagnostics for the JET ILW project Characterisation of graphite PFCs at TEXTORPWI-08-TA-06/VR/PS/01Tracer experiments. Development of tracer techniques: C-13, TMB, SH4
TASK AGREEMENT: WP08-PWI-06
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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 risksand optimisation of ITER availability!
All topics are related to each other!
Graphite
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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 backgroundB2-Eirene
or EDGE2D
Tokamak experiments JET, AUG
ERO modellingLaboratory experimentsMAJESTIX …
Linear experimentspilot-MAGNUM, PSI-II
PISCES
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Density ramp discharges with transiently detached outer divertor leg:
Decrease of intrinisic CD and CII photon flux emission in
recombining plasmas: low Te<2 eV and high ne~2*1020m-3
L-mode: Reduction of chemical sputtering at low Te (energetic threshold)
JET: Chemical Erosion in Cold Divertor Plasmas
Density feedback-controlled discharge with detached outer divertor:
Extrinsic carbon source (CD4) observable!
Effective D/XB valuesabout 35% higher in detached
than in attached plasmas!
S. Brezinsek et al. accepted JNM
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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 WELM [kJ]
Physical sputtering(Y=1.5%)
)/exp( ELMa WW
Processed exp. data
C d
epo
siti
on
per
EL
M [
ato
ms/
cm2 ]
0 100 200 300 400 50010
13
1014
1016
1015
~10x less
1
3
4
inn
er Q
MB
5
Thermal decomposition of carbon layers under ELM impact
A. Kreter et al.accepted for PFR
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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: 30-60 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 20627
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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Erosion yields at high ion fluxes in pilot-PSI
Exposures have been performed in the flux range 1023-1024 /m2s Calibration of the chemical erosion has been verifies by absolute measurements with CH4 injection (D/XB ~ 500) Comparison with ERO calculation showed impact of small plasma “diameter” (~mean free path) at Te<2eV Flux determination is currently being re-examined (~ factor 2) Impact of surface temperature distribution not yet included
J. Westerhout et al.
ITER domain
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Preliminary Flux Dependence Analysis
Pilot-PSI
Te and Eion normalised
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Injection of hydrocarbons in TJ-II by molecuar beams
SOL SOL
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 plasmasThe emission profiles of H and CH (A-X) were recordedRatios of H/CH emission are evaluated by relative calibration3H per CH are emitted from methane break-up (He plasmas)Penetration of H from methane much larger than from H2 in He plasmasSame penetration for CH from methane/ethene Common precursor
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Carbon Migration/Transport in Fusion Devices
Milestones 13CH4 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 13CH4 tracer injection in AUG. Post-mortem tile analysis,
spectroscopic analysis, local erosion/ deposition (ERO) and plasma transport (DIVIMP) modelling – IPP, TEKES
13CH4 tracer and hydrocarbon injection modelling (ERO) in TEXTOR – FZJ
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
JET: 13C deposition in the Centre of the MKII-GB divertor
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
JET: 13C Deposition in the MKII-SRP Divertor
M. Rubel et al.
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Measured deposition (AUG divertor)
Shape of deposition (ERO)
Local Erosion/deposition Modelling of 13CH4 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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 SOLPSA realistic plasma background for the local injection was obtainedA DIVIMP model for the global carbon transport was set up using an OSM background plasma
Outer divertor target plate
13C deposition pattern
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Next: Check for influence of local injection on local plasma parameters (cooling and increase of ne) ⇒ coupling of ERO with fluid model from M. Tokar´
Modelling of CH4 Injection at TEXTOR
Example: hydrocarbon injection through gas inlet – higher hydrocarbons
C2D4 injection: radial penetration of
C2 and CII light: EXP vs. ERO
Injected species
D/XBCD A-X band
D/XBC2 d-a band
EXP ERO EXP ERO
CD4 36 65 930 -
C2D4 31 80 48 45
C2D6 27 76 65 62
Effective D/XB values: EXP vs. ERO
Good agreement ofobserved and modelled profiles
Modelled and observed D/XB agree well for C2, but differ for CD by a factor of ~2
R. Ding et al. submitted to ppcf
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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 N2 – IPP,
CIEMAT
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Carbon Deposition in Be Limiter Tile Gaps in JET
M. Rubel et al.
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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, CHn-transfer)
Experimental setup
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Reactive Interaction of Molecular Ions with SurfacesReactive Interaction of Molecular Ions with Surfaces
0 20 40 60 80 1000,0
0,1
0,2
0,3
0,4
0,5
Stic
king
coe
ff. o
f D
Collision Energy (eV)
CD2
+ on
CFC PSW
CD2+ on plasma sprayed tungsten (PSW) and CFC (AUG tiles)very stable beam with D flux of ~1011 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 CD2+: CFC: S ~ 0.1 - 0.4; PSW: S ~ 0.05 - 0.1
W. Schustereder et al. Nucl. Instr. Meth. B
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
C+, H+
to thepumps
pumping duct
JET MKII divertor
experimental setup in PSI-2
adjustableneutra lizerp late
plasm a
hot liner( )sta in less stee l
Si-wafer
N , H ,2 2 CH 4
opticald iagnostic
pumping duct
T=200°C
PSI-2 Experimental Setup: Pumping Duct Measurements
W. Bohmeyer et al.PSI 2008
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
PSI-2: Impact of Nitrogen on Erosion & Deposition Pattern in Remote Areas
220 240 260 280 300 320 340 360tim e (m in)
54
55
56
57
58th
ickn
ess
(nm
)
2 sccm C H4
2 sccm N2
-0 .044 nm /m in
-0.044 nm /m in
2 sccm N2
no injection
Tcoll =330 K
+0.031nm /m in-0.043 nm /m in
Film thickness in the pump duct vs. time:In pure H2 plasma and co-injection of CH4 and / or N2
Collector temperature 330 K.
Pressure 1 Pa
W. Bohmeyer et al.PSI 2008
No synergetic effect of enhanced erosion with H2 and N2
=> volume process not a surface process
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
8000 12000 16000 20000 24000 28000 32000tim e / s
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
film
thic
knes
s / n
m
P lasm aO N
Plasm aO FF
310 K 330 K 350 K
2 sccm CH4
1.4 sccm Ne
collector tem perature :
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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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
4
3
4
3
VT HT
<
Deposition on the QMB in the inner divertor pump duct entrance
S. Brezinsek et al.EPS 2008
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
JET: Inner vs. Outer Divertor Deposition and Erosion
Direct comparison between inner and outer divertor deposition with QMBs
5
8
7
4 6
3
1
HTVT
QMBQMB
SOL 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
72372 72376 7237772371
HT VT
outer divertor QMBinner divertor QMB
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
TS: Measurement of Chemical Erosion on the TPL
CCD
Filters wheel(Dα, C2, C+, CD)
Splitter cube
Optical view
erosion area
erosion area optical fibres validate filtered images
CCD and spectrometer system both calibrated in situ with labsphere
D434.0 nm
CD 430.7 nm
38799C+ 426.7 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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 (CII426nm/Dγ)
[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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
0 1 2 3 4 5 6 7 8 9 10
0.1
1
10 SIMS SEM
La
ye
r th
ick
ne
ss
[m
]
Distance from surface [mm]
0 1 2 3 4 5 6 7 8 9 10
0.1
1
10 SIMS SEM
La
ye
r th
ick
ne
ss
[m
]Distance from surface [mm]
Deposition profile tile 20 toroidal gap (1.5 mm)
Deposition profile tile 20poloidal gap (1.8 mm)
= 0.54 mm
Composition from EPMA, RBS: B : C : O ~ 2 : 1 : 1 Mass density ~1.3 g/cm3
= 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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 (nbottom/nedge~ 20% for RN
D = 0.9)
RNC = 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.
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation EURATOM-FZJ
Summary
Progress in both Task Agreements clearly visibleTasks 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
EU Plasma-Wall Interaction TF – Meeting27.10.-29-10-2008 - Frascati
SEWG Erosion & TransportS. Brezinsek
Institut für Energieforschung –PlasmaphysikAssoziation 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 13CH4, SiH4 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
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