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V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
EU Task Force Plasma Wall Interaction
SEWG material mixing, report on 2008 activities
V. Philipps on behalf of all SEWG members
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Beryllium
Tungsten
Carbon
1. Binary systems
Be impact on W (compound formation, enhanced erosion of W ↓)
C impact on W (embrittlement of W ↓)
Be impact on C (reduction of C chemical erosion ↑)
W impact on C
2. Ternary systems
Be/ C / O
W/ C/ O (Be)
new compounds?, influence of oxygen
role of seeded impurities
3. Modelling, ITER extrapolations
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Year Associate(s) Baseline Support (ppy)
Priority Support (ppy)
remarks
2008 PWI-08-TA-08/FZJ/PS/00Task Coordinator : V. Philipps
FZJ 3/12
PWI-08-TA-08/CEA/BS/01Molecular dynamic simulations of mixed materials
CEA 6/12
PWI-08-TA-08/FZJ/BS/01ERO-modelling of PISCES-B results. Coupling of ERO with SDTrimSP
FZJ 5/12 Report (SEWG meeting)
PWI-08-TA-08/FZJ/PS/01ERO-modelling of mixed materials (ITER application)
FZJ 2/12 Report (SEWG meeting)
PWI-08-TA-08/FZJ/BS/02Analysis of mixed W-C layer formation in gaps of ITER like castellated W targets
FZJ 3/12 Report (SEWG meeting)
PWI-08-TA-08/IPP/BS/01Binary and ternary systems (Be, C, O, W), kinetic simulation of material mixing
IPP 36/12 Report (SEWG meetin)
PWI-08-TA-08/IPP/PS/01Joint investigation of fuel retention in Be-C/W layers
6/12
PWI-08-TA-08/IPP/BS/02Dual beam experiment D+C on W
IPP 10/12 Report (SEWG meeting)
PWI-08-TA-08/IPPLM/BS/01Post mortem analysis of mixed layers formation: TEM, FIB, SEM, EPMA, XRD, AES etc
IPPLM 4.5/12 Report
Workprogramme 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
PWI-08-TA-08/IPPLM/BS/01Post mortem analysis of mixed layers formation: TEM, FIB, SEM, EPMA, XRD, AES etc
IPPLM 4.5/12
PWI-08-TA-08/IST/BS/01Characterization of samples
IST/ISN 2/12 No samples delivered
PWI-08-TA-08/MEDC/BS/01Preparation of mixed Be-C&W layers and analysis of retention
MEdC 12/12 Report (SEWG meeting)
PWI-08-TA-08/SCK/BS/01Refurbishment of the plasmatron VISION I
SCK-CEN 3/12 Report (SEWG meeting)
PWI-08-TA-08/TEKES/BS/01MD modelling of mixed layers (W, Be),
TEKES 18/12 Report (SEWG meeting)
PWI-08-TA-08/VR/BS/01Post mortem analysis mixed layer formation
VR 5/12 Report (SEWG meeting)
PWI-08-TA-08/VR/PS/01Post mortem analysis mixed layer formation on PFC in TEXTOR and other EU devices
VR 2.4/12 Report (SEWG meeting)
Total 104.5/12 13.4/12
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Vessel Walls 1. High flux case 1x1024/s (Tokamak experience)2. Low flux case 1x 1023/s ( B2-Eirene estimate)
2% Be erosioncase 1:50% dep. in main chamber
37.5% dep. in inner divertor15.5% dep. in outer divertor
case 2:75% dep. in inner divertor25% dep. in outer divertor
ITPA DIV SOL: New empirical scalings combined with modelling
(EU contribution: J. Roth (coordinator), A. Kallenbach, A. Kirschner, O. Ogorodnikova, V. Philipps, K. Schmid, G. Wright )
Impurity fluxes and distribution in ITER
Divertor: Fluxes from B2_EIRENE (equilibrium 1084): total divertor flux 3x1024/sImpurity flux distribution from Divimp ( K. Schmid)Divertor erosion deposition: ERO code with Divimp distribution, matched to the total impurity fluxes
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
4.0 4.5 5.0 5.5 6.0 6.5
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
Z(m
)
R(m)
1.000E-8
1.000E-7
1.000E-6
1.000E-5
1.000E-4
1.000E-3
0.01000
0.1000
Be-Flux fraction in EQ
Further work underway, e.g on Be distribution
K. Schmid, EU PWI TF meeting 2007
SEWG mixed material group should assume a reasonable wide range of impurity fluxes and distributions
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Recent results from Pisces (EU-Pisces cooperation )
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
EU-Pisces cooperation1. Extended retention scalings of D in Be, W, C
literature survey of retention data of D in C, W, Be combined with PISCES data
2. Influence of Argon on Be-C interaction
3. Development of W-nanostructures
EU-PISCES cooperation
Sample analysis (IPP )Long term visitor (A. Kreter)Ero modelling of Be/C interaction ( FZJ)
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
For Beryllium:
For Tungsten
For Carbon
D/C = 0.0204 E –0.43 (D/C)0 exp(2268/Tc)
293 < Tc < 473 K
473 < Tc < 973 K 15 < E < 100 eVD/C < ? large
293 < Tc < 600 K 15 < E < 62 eVD/Be < 2000
293 < Tc < 600 K 60 < E < 280 eVD/W < 500
Models overlap: 293 - 600K~60 eV ~10s - 1000s flux ratios
D/Be = (5.82 x 10-5)En1.17 0.2 (
D/Be)-0.21 0.1 exp(2273 311/Tc)
D/W = (5.13 x 10-8)* En1.85 0.4 * (
D/W)0.4 0.1 * exp(736 228/Tc)
D/C = 0.0204 E –0.43 (D/C)0 exp(2268/473)
Topic: fuel retention in mixed layers:
retention scalings of D in Be, W, C
R. Dörner, SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Roth PPCF 2008
Retention level Scaling (523K, 20eV, D/X =100)
Scaling (523K, 60eV, D/X =100)
0.6 (D+T)/C 0.4 0.3
0.03 (D+T)/Be 0.05 0.2
0.002 (D+T)/W 0.0003 0.003
x
x
x
(D+T)/W~ 0.002
(D+T)/Be ~ 0.03
(D+T)/C~ 0.6
- Codep with W is small- flux arrival factor is not a large effect- Particle energy arriving at the codepositing layer plays a big role
1. Extended retention scalings of D in Be, W, C
R. Dörner, SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
• Codeposits formed at higher temperature retain less deuterium/tritium
• D accumulation from W codeposition is negligible
• D content of Be and C codepoists can be comparable– D content can be significantly less in Be codeposits
formed at lower incident particle energy locations (i.e. divertor and dome)
R. Dörner, SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Topic: chemical erosion of Be-C mixed system
500
1000
1500
2000
2500
3000
3500
4000
No Be injection0.2% Be ion concentration
Wavelength (nm)
CD band
D gamma Be I
459445431 452438
10-4
10-3
10-2
10-1
100
101
0 100 200 300 400 500 600In
tens
ity [a
.u.]
Time [s]
ID
IBeI/ID
ICD/ID(near)-ICD/ID(far)
20060322
Be/C = 86±1 sec
R. Dörner, SEWG meeting, 9-10.10. 2008
Present data: a small beryllium impurity concentration in the plasma drastically suppresses carbon erosion with a characteristic decay time
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
CD band decay time similar with and without argon
R. Dörner, SEWG meeting, 9-10.10. 2008
Addition of Ar to the plasma does not affect the mitigation of carbon chemical erosion by beryllium
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Topic: surface modifications of W due to high fluence mixed-species (D, He, Be) plasma interactions with W
layers of Be suppresses blister formation (300-700 K )
• At 550 K a blistered surface is prevalent after exposure to D2 plasma.
• A thin layer of Be as little as a few 10’s of nm suppress blister formation and D retention.
R. Dörner , SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Mixing He with D-plasma suppresses also blisters on W surface
and reduces D-retention in W.
Pure D2 plasma (SRWM-3b)
D-fluence ~ 5e25 m-2, D ~ 1.0e22 m-2s-1, Ts ~ 573 K, Ei ~ 60 eV
D2-He mixture plasma (SRWM-4b)
D-fluence ~ 5e25 m-2, D ~ 0.9e22 m-2s-1, Ts ~ 573 K, Ei ~ 50 eV, nHe+/ne ~ 20 %
R. Dörner , SEWG meeting, 9-10.10. 2008
Similar new results by Alimov et al
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Topic: development of surface nanostructures
Nano-morphology develops only above 900 K.
Ts = 1120 K, He+= 4–6×1022 m–2s–1, Eion ~ 60 eV
Fluence
R. Dörner , SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
• Observed t1/2 proportionality.
• The thickness of the nano-structured layer, d, agrees well with
<d>=(2Kt)1/2,with,K1120 K = 6.6 0.4 10–16 m2s–1
K1320 K = 2.0 0.5 10–15 m2s–1
• Overall process is consistent with an activation energy of ~0.7 eV.
t1/2 (s1/2)
0 50 100 150
Laye
r th
ickn
ess
, d (
m)
05
Ts=1120 K
Ts=1320 K
Nanostructures are observed on various W materials, also doped W materials
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
In D2−He plasmas : nano-morphology persists, growth rate depends on He+ flux.
Simultaneous Be deposition but with no development of thick Be layer ( Be re-erosion dominates deposition, nano-morphology development is enhanced
A thick Be or C layer inhibits nano-morphology..
Importance for various PWI processes not fully clear but
Liner and dome (T below 900 K).– Minimal Be−W alloy or He induced nano-morphology– Be and/or He may alleviate also W blistering.
at W strike-points (T above 1000 K).
– Be−W alloy and/or He induced nano- morphology can develop !!
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Structure-dependent deuterium retention in beryllium:
comparison between Be (11-20) and Be (poly)C.Linsmeier et al , IPP
PWI-08-TA-08/IPP/BS/01
D ion implantation (1 keV) in single and polycrystalline Be ► thermal desorption spectroscopy
Structural modifications
Structural modifications
Local saturation of available
binding sites
Local saturation of available
binding sites
Trapping in ion induced defects
Trapping in ion induced defects
400 600 800 1000
Fluence
[1015cm-2]144
124
122
92
65
47
Desorp
tion r
ate
[a.u
.]
Temperature [K]
C. Linsmeier, SEWG meeting, 9-10.10. 2008
Topic: T retention in bulk Be
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
[ES = -0.10 eV] Atomic D E0≡ 0
[ΔEAd = 0.87 eV]
Molecular D2
[EBE (1/2 D2) = -2.278 eV]
Surface
Mobile state
[ΔED = 0.29 eV]
E (D-Atom)
Activation energies obtained from modeling of TPD spectra
Tem
per
atur
e [K
]
Desorption rate [a.u.]
ΔE = 1.25 eV 1.33 eV
ΔE = 1.9 eV 2.1 eV
(simple model)
Ion-induced defects
Supersaturatedstates
C. Linsmeier, SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Deuterium retention in beryllium
Binding states & retention mechanisms described in a simple model
Surface recombination not rate-limiting for thermal recycling Vacancy clusters determine highest release temperature
Hydrogen retention in ITER: negligible contribution of "pure" Be wall (< 7 g T by implantation)
C. Linsmeier, SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Tokamak observations
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Formation of mixed W/C layers in the gaps of castellated structures, A. Litnovsky
69,6%
2,3%
36%
2,5%
• Strong W intermixing near the top of the gap (up to 70 at. % of W)
• Strong W-decay with depth ( much shorter as C)
• Influence on possible cleaning ?
C deposition in gaps while surface is erosion dominated
A. Litnovsky , SEWG meeting, 9-10.10. 2008PWI-08-TA-08/FZJ/BS/02
Poloidal gaps
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Low W fraction detected in the deposits: Wfr.max<10 at.%
Large differences of W intermixing in toroidal and poloidal gaps
W mixing in toroidal gaps
D=5.51C= 20.4D/C=2.7
D=0.98C=13.4
D/C=0.73
D=3.29 C=25.3D/C=1.3
Wfr.max 4%
D=10.09C=19.9D/C=5.5
Wfr.max 4%
D=9.68C=44.8
D/C=0.38Wfr.max 10%
D=1.07C=28.2
D/C=2.16Wfr.max 10%
D=3.26 C=39.8
D/C=0.82Wfr.max 5%
D= 15.8C=28.2D/C=5.6
Wfr.max 5%
Bt
Left of field line direction
Right of field line direction
Geometry and plasma impact effect
Under analysis
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Inner divertor: Tiles 1 and 3 analysed with SIMS and RBS so far
heavy deposition
•SIMS depth profiles from inner divertor wall tile 1 and 3
•Deposit: Be/C high (varies as a function of depth)
•Low vessel temperature (200oC)layer D (at
%)Be (at%)
12C
(at%)
13C (at%)
O (at%)
1 3 25 57 3 12
2 3 53 25 19
3 3 22 59 15
4 1 46 44 8
5 6 19 69 6
New data from 2005-2007, MkIIHD JET campaign
J. Likonen , SEWG meeting, 9-10.10. 2008
High Be content in deposited layers on plasma wetted areas
PWI-08-TA-08/VR/BS/01
Mixed Be/C layer formation in JET
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
JG
03
.67
6-1
c
layer D (at%)
Be (at%)
12C
(at%)
13C (at%)
O (at%)
1 18 0.5 57 9 15
2 16 3 68 13
3 15 3 68 13
Previous results: Composition of deposits in the PFR (2001-2004, MkIISRP)
Low Be content in (C) - layers on remote areas
J. Likonen , SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
JET Be toroidal belt limiter
• Operation: 1989 – 1992
• 56 000 s of plasma
• 2000 castellated blocks.
Castellated bulk Beryllium JET limiters VPS-Tungsten Coated Limiters (TEXTOR) ( M. Rubel)
Small amount of deuterium retained in solid Be .
Co-deposition of deuterium with carbon.
More deuterium in areas which were molten.
Bridging of gaps by molten metal.
M. Rubel , SEWG meeting, 9-10.10. 2008
PWI-08-TA-08/VR/PS/01
Post mortem analysis of
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
• No or very little deuterium detected in bulk beryllium . Small amount of co-deposited deuterium with carbon on all surfaces of Be belt limiters.
• CD (castellation) / CD (top surface) ~ 0.4
• Short decay length l ~ 1.5 – 2.0 mm for deuterium and carbon in co-deposits.
• No difference in fuel content and carbon co-deposition between toroidal
• castellated grooves and poloidal gaps between tiles.
• Deuterium is found in the surface layer of BeO.
• Deuterium in areas which were molten.
• Bridging of gaps by molten metal.
M. Rubel , SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
X
• W carbides and borides found
• Deuterium only with carbon
• Amount of D in W: < 5x1014cm-2
Side wall analysis Main phases: Graphite and W carbide: WC• Traces: Tungsten and Tungsten
carbide: W2C
• The same phases found in all analysed
points on both sides of limiter block.
Limiter_A2a - File: Limiter_A_2a.raw - Type: 2Th/Th locked - Start: 20.000 ° - End: 129.999 ° - Step: 0.019 ° - Step time: 486.5 s - Temp.: 25 °C (Room) - Time Started: 23 s - 2-Theta: 20.000 ° - The
Sqr
t (C
ount
s)
10
100
1000
2000
3000
2-Theta - Scale
34 40 50
W2
CW2CW2C W
C
C
C
WC WC
35
45 40
50 55 101
103
102
3x103
2 scale
Inte
ns
ity
[sq
rt
sca
le]
TEXTOR VPS poloidal W limiters
Side wall
M. Rubel , SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Post mortem examinations of divertor strikepoint tiles of ASDEX-U (E. Fortuna et al)
PWI-08-TA-08/IPPLM/BS/01
Material
9 samples from 2 divertor strikepoint tiles:
Tile 1 from the outer strikepoint region, coated with a 200 µm W VPS layer
Tile 2 from the inner strikepoint region, coated with ~4 µm W
• Tiles installed from 4 o 10/07 (All PFCs tungsten coated)• No boronisation performed
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
AES examinations (Microlab 350)Tile 1 (outer divertor)
SEM image of the tile topography and AES spectrum from position 1
Results of point analyses
Position C. at.% W at.% O at.%
P1 32 54 10
P3 39 49 12
P4 35 60 5
1
3
4
W-C intermixing observed
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Surface morphologyTile 2 ( inner divertor)
deposit
disclosed tungsten coating
Compact, glassy-like layer of deposit
Stratified character of deposit layer
50 m 25 m
5 m 10 m
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Laboratory experiments
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Topic: W - C interaction
chemical and physical sputtering processes under simultaneous C-D irradiation of W (H. T. Lee, K. Krieger et al)
H. T. Lee, K. Krieger SEWG meeting, 9-10.10. 2008PWI-08-TA-08/IPP/BS/02
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
0.0 0.1 0.2 0.3 0.4 0.5 0.60.0
0.2
0.4
0.6
EXP. TRIDYN25% : 16% : 13% : 7% :
Imp
lan
ted
C (1
022 m
-2)
W Sputtered (1022 m-2)
Continuous W Erosion
C layer growth
6keV C + 3keV D W
Transition point : 9%<fc<10%
Detailed study of C implantation, re-erosion and layer growth depending on exposure parameters & temperature
Comparison with Tridyn modelling
C selfsputtering on W enhanced (deviations at 600C )
Importance of C chemical erosion on W
Decreases from RT towards 500C
H. T. Lee, K. Krieger SEWG meeting, 9-10.10. 2008
PWI-08-TA-08/IPP/BS/02
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Topic: thermal behaviour of multispecies mixed layers
Detailed lab study of the thermal stbility of the ternary Be –C –W system ( C. Linsmeier et al )
F. Kost, C. Linsmeier SEWG meeting, 9-10.10. 2008
PWI-08-TA-08/IPP/BS/01
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Be
Be
C
C
W
W
Be2W + Desorption
Be12W (Be-Diffusion)
W2C and WC(C-Diffusion)
Su
bst
rate
Layer
CurrentExperiments
Be2C (Be-Diffusion)
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
C
Be
W
Be/C/W
C
Be
W
0.88 nm
1.15 nm
2.7 nm
1.6 nm
1
2
excess of C
excess of Be
Heat treatment: RT, 570 K – 1270 K
F. Kost, C. Linsmeier SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
elem.C
excess of C excess of Be
XPS data
F. Kost, C. Linsmeier SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Carbide formation at RT at both interfaces Be2C phase dominating
formation at 770 K dissociation at 1070 K
Be desorbs / dissolves in WC forms tungsten carbides
Remaining Be diffuses to the substrate Be2W formation at T > 670 K Be2W loss at 1070 K
W2C formation at T > 1070 K WC formation at T > 1170 K
F. Kost, C. Linsmeier SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Lab study of the ternary system Be-O-W
(thin Be-Layers on different Tungsten Oxides ( WO2 and WO3-x)
► heating from 300 °C – 1000 °C in steps of 100 °C for 30 min
C. Linsmeier SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
• 673 K, 773 K, 873 K: Decay of BeWO3
• 973 K: Formation of BeWO
• 1073 K, 1173 K, 1273 K: Decay of BeWO4
Be on WO3: Main Reactions
Be on WO2
In contrast to WO3 , tungsten dioxide does not react much with beryllium
WO2 first shows a real reaction at its dissociation temperature of 1273 K
Explained by different structure of WO3 ( more open porosity) compared with WO2
C. Linsmeier SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Topic : modelling of mixed layer formation
Molecular dynamics modelling of mixed layer formation K. Nordlund et al
Potential development for the Be-C-W-H system
Structure change and erosion of WC during high-dose D bombardment
Structure change and erosion in BeC
PWI-08-TA-08/TEKES/BS/01 K. Nordlund, SEWG meeting, 9-10.10. 2008
MD simulations : optimise potentials for special systems
Detailed study of the WC system has been done
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
ERO Modelling of Erosion and Deposition of Mixed Materials: PISCES-B & ITER ( A. Kirschner , D. Borodin)
-10 0 10 20 300
2
4
6
8
10
12
14
16
x 1016
Ch
em
ica
l ero
sio
n [
CH 4/s
]
Time from injection start [s]
1.0e+018 Be/s3.0e+018 Be/s1.0e+019 Be/s3.0e+019 Be/s
Modelling of the chemical erosion of C during Be deposition in Pisces
-10 0 10 20 300
2
4
6
8
10
12
14
16
x 1016
Ch
em
ica
l ero
sio
n [
CH 4/s
]
Time from injection start [s]
1.0e+018 Be/s3.0e+018 Be/s1.0e+019 Be/s3.0e+019 Be/s
no Be-C carbide formation with Be-C carbide formation
A. Kirschner, SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
1. Deviations between simulated and experimental axial Be profiles (Be density & transport) clarified by implementaion of new tools in ERO Pisces simulation.
2. Modelling indicates strongly spontaneous Be-C formation with complete suppression of C chemical erosion of carbidised C.
3. Still differences between modelling and experiment
1. different time scales (faster decay in simulation)
2. complete C erosion mitigation in modellling only in case of high concentrations of Be in plasma
A. Kirschner, SEWG meeting, 9-10.10. 2008
Importance of additional processes
surface roughness effects
inhibition of chemical erosion of a large number of C atoms
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Status of ERO Modelling for ITER: implementation of new T/ Be,C retention scaling for mixed layers
-0.2 0.0 0.2 0.4 0.61E-4
1E-3
0.01
0.1
1
(T+D)/Be (T+D)/C
distance along inner target (m)
(T+
D)/
Be
, (T
+D
)/C
0
1x1015
2x1015
3x1015
4x1015
5x1015
Be deposition C deposition (*10)
Be
, C d
ep
so
ition
(pa
rticle
s/m
m2s
)Example Inner target: resulting (T+D)/Be and (T+D)/C
A. Kirschner, SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
on target remote
beryllium carbon beryllium carbon
(D+T)/Be
=0.1
(D+T)/Be
~fit
(D+T)/C
=0.1
(D+T)/C
~fit
(D+T)/Be
=0.1
(D+T)/C
=1.0
outer 0.9 0.17 0.2 0.27 0.02 0.8
inner 6.0 1.3 0.02 0.1 0.1 0.1
Revised estimated T retention rates
A. Kirschner, SEWG meeting, 9-10.10. 2008
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Gas, plasma, secondary ionsand neutrals analyser
CW
CW
Cooling Water (CW)Isolation
(I)
I
Permanentmagnets(PM)
PM
Cathode
Anode
Target
Ultra High Vacuum (UHV 1)
UHV 2
Thermo-couples(TC)
Inletgas
Cathode
UHV 3 Gas, plasma, secondary ionsand neutrals analyser
CW
CW
Cooling Water (CW)Isolation
(I)
I
Permanentmagnets(PM)
PM
Cathode
Anode
Target
Ultra High Vacuum (UHV 1)
UHV 2
Thermo-couples(TC)
Inletgas
Cathode
UHV 3
Status of the plasmatronVISION I (I. Uytdenhouwen
PWI-08-TA-08/SCK/BS/01
I. Uytdenhouwen SEWG meeting, 9-10.10. 2008
• re-establishment of the vacuum systems June 2008explanation of the working system
Design of a new frame. Plasmatron: removed in parts from the gloveboxes and will be
rebuilt outside. Sensors, valves will be checked and replaced in case of
damage. Vacuum chambers need to be investigated on their status
(electropolished surface, leak tightness, …). Connections (vacuum tubes, cooling, …) will be subject to a
maintenance. Electric circuit diagram and layout control cabinet are ready Assembly new control cabinet has started Development control software has started …
• plasma generation December 2008
For this goal more software control of the valves and pumps is needed
Filaments and targets were purchased and replaced Minor instrumentation should be present and will be set up
soon
Good progress has been made
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Summary
Successful workprogramme executed
Scaling of T retention in deposits
Development of W surface structures
He &Be prevents blistering
Diffusion dominated nanostructure growth
Behaviour of H in solid Be
Dynamics of W-C system ( selfsputtering, chemical erosion)
Be-C chemical erosion behaviour versus modelling
ITER modelling on material mixing and T retention
And …..
To be done:
Including seeded impurities (inert gases, N, ..) in mixing
More close coupling of MD modelling to observations (?)
V.Philipps, SEWG mixed materials, EU PWI meeting Frascati, Oct 2008
Most critical issue (from present view )
Development of W surface structures and/or Be-W compounds in the T range 800-1300K