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Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 1
Outline:
1. Introduction
2. Experimental procedure
3. Result
4. Summary
Kazuyoshi Sugiyama
First results from the RETMIX task
Max-Planck-Institut für Plasmaphysik
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 2
Present material choice in ITER Be (First wall) Low-Z, Oxygen-getter,
No chemical sputtering
W (Divertor-throat) High melting point, Less erosion
CFC (Divertor-target) Low-Z,
No melting in transient heat load Plasma-wall interaction (erosion, migr
ation and deposition) → material mixture
Fuel retention in mixed materials
Task: EFDA-TWS IPP-RETMIX (Characterization of fuel Retention in ITER relevant Mixed materials)
Introduction
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 3
1. Hydrogen retention in binary layer-substrate systems Combinations of layer-substrate are:
*Substrates: CFC (NB31), Graphite (EK98), W (JET-ILW project grade (Plansee))
Be (99.4 at.% purity bulk Be (Goodfellow Co.Ltd.))
Thin (~ 200 nm) layer deposition by PVD process
C, W layers by magnetron sputter deposition (IPP Garching)
Be layer by Thermionic Vacuum Arc (TVA) deposition (MEdC Bucharest)
Deposition temperature: R.T. and 450 °C
Deposited LayerSubstrate
R.T. / 450 °C
Sample preparation (1/2)
Layer Be W Be C W CSubstrate CFC/Graphite W Be
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 4
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000
W on EK98 (1373K anealed)
WC
Ato
mic
con
cent
rati
on
Depth [nm]
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000
W on EK98 (1373K anealed)
WC
Ato
mic
con
cent
rati
on
Depth [nm]
WC
W2C
W/C C
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000
W on EK98 (1373K anealed)
WC
Ato
mic
con
cent
rati
on
Depth [nm]
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000
W on EK98 (1373K anealed)
WC
Ato
mic
con
cent
rati
on
Depth [nm]
WC
W2C
W/C C
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000
W on EK98 (1373K anealed)
WC
Ato
mic
con
cent
rati
on
Depth [nm]
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000
W on EK98 (1373K anealed)
WC
Ato
mic
con
cent
rati
on
Depth [nm]
WC
W2C
W/C C
Sample preparation (2/2)2. Hydrogen retention in “mixed” layer
Tungsten Carbide / Beryllide
W / C annealed at 1370 K -> Tungsten Carbide on Graphite W / Be annealed at 1000K -> Be12W on Be
Deposited Layer
Substrate Substrate
“Mixed” layer
0.01
0.1
1
0 500 1000 1500 2000 2500
W c
once
ntra
tion
Depth [um]
W/Be after annealing
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 5
200eVD+
Dep
osite
d/M
ixed
La
yer
Sub
stra
te
D+ irradiation at IPP High Current Ion Source (flux: ~ 3.0 x 1019 [/m2s])
600 eV D3+ -> 200 eV / D (irradiated at R.T.)
D+ irradiation and evaluation of D retention
D implantation & evaluation of D retention
Total amount of D retention is determined by Nuclear Reaction Analysis.
Using 3He+ -> D (3He, p) 4He resonant nuclear reaction
0
20
40
60
80
0 1000 2000 3000 4000
Diff
eren
tial C
ross
sec
tion
[mb
/sr]
3He Energy [keV]
D (3He, p) 4He, θ = 135°
1
10
100
1000
0 500 1000 1500 2000
Channel
Prot
on C
ount
s
Proton peak from D (3He, p) 4He reaction
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 6
Substrate R.T. 450°C R.T. 450°C R.T. 450°C
Graphite O.K. O.K. O.K. O.K.
CFC O.K. O.K. O.K. O.K.
W O.K. O.K. O.K. O.K.
Be O.K. O.K. O.K. x
C W BeLayer
Layer stability
→ Likely caused by thermal expansion mismatch.
(W: ~ 4 x10-6 K-1, Be: 11.5~16.5 x10-6 K-1 (20~500 ºC))
→ Potential issue: hazardous dust formation!
Layers were generally stable.
W layer deposited on Be at higher temperature (~ 450 C) blew up.
Sample evaluation
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 7
NO significant dependency on deposition temperature and substrate material.
200eV D+ -> Pyro. Graphite(Alimov, Roth)
Result obtained by NRA using 800keV 3He+
Low mobility of D in C
→ Most of D in C layer
D retention in C layer became saturated at ~ 7 ×1020 D/m2
Saturation level is higher than that in pyrolytic graphite by a factor of 2.5 (probably due to poor graphitization of the C layer).
D+ SubstrateC
D retention in C-coated samples
1020
1021
1022
1020 1021 1022 1023 1024 1025
100% retentionPyrolytic GraphiteC on W (deposited at RT)C on W (deposited at 450C)C on Be (deposited at RT)C on Be (deposited at 450C)
Re
tain
ed
Flu
en
ce [D
/m2]
Incident Fluence [D/m2]
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 8
D+ SubstrateBe
D retention in Be-coated samples
200 eV
Be film
Be saturation quantity at R.T.
Anderl et al.
200 eV
Be film
Be saturation quantity at R.T.
Anderl et al.
Be on CFC → no saturation withinD+ fluence range (< 1024 D/m2)
Increased surface due to roughness and…
D retention in Be layer on graphite / W became saturated at
~ 7 x 1020 D/m2
Similar level with C layer Low mobility of D in Be (?)
→ Most of D in Be layer
1020
1021
1022
1020 1021 1022 1023 1024 1025
100% retentionBe on Graphite (deposited at RT)Be on Graphite (deposited at 450C)Be on CFC (deposited at RT)Be on CFC (deposited at 450C)Be on W (deposited at RT)Be on W (deposited at 450C)
Re
tain
ed
Flu
en
ce [D
/m2]
Incident Fluence [D/m2]
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 9
No saturation in this fluence range
D+ SubstrateW
D retention in W-coated samples
Result obtained by NRA using 800keV 3He+
1019
1020
1021
1022
1019 1020 1021 1022 1023 1024 1025
100% retention200eV D -> PCWW on Graphite (deposited at RT)W on Graphite (deposited at 450C)W on Be (deposited at RT)
Re
tain
ed
Flu
en
ce [D
/m2]
Incident Fluence [D/m2]
200 eV D+ -> PCW (Ogorodnikova,
Mayer)
Deposited at R.T.
Deposited at 450C
Higher fluence region: Less D retention than PCW
D accumulation in the bulk might be limited because the mobility of D in the substrate (C or Be) is lower than that in W.
Lower fluence range:
More D retention than PCW
High temperature deposition led to decreasing of D retention
→ “As deposited” W layer might have more trapping sites.
200 eV D+ -> W on Graphite
0 0.1 0.2 0.3 0.4 0.5
Depth [um]
D c
once
ntra
tion
[at.
%]
5.0 x 1020 D/m2
5.0 x 1021 D/m2
5.0 x 1022 D/m2
5.0 x 1023 D/m2
100
101
102
10-1
10-2
200 eV D+ -> W on Graphite
0 0.1 0.2 0.3 0.4 0.5
Depth [um]
D c
once
ntra
tion
[at.
%]
5.0 x 1020 D/m2
5.0 x 1021 D/m2
5.0 x 1022 D/m2
5.0 x 1023 D/m2
100
101
102
10-1
10-2
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 10
No saturation in this fluence range
D retention in CFC substrate samples
~Φ0.5
200eV D+ -> NB31
Be on CFC
W on CFC
1019
1020
1021
1022
1019 1020 1021 1022 1023 1024 1025
100% retentionCFC (NB31)W on CFC (deposited at RT)W on CFC (deposited at 450C)Be on CFC (deposited at RT)Be on CFC (deposited at 450C)
Re
tain
ed
Flu
en
ce [D
/m2]
Incident Fluence [D/m2]
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 11
Pure CFC surface Be-coated CFC surface
Roughness more than 200 nm
Many pores even after coating -> D might be able to penetrate to CFC bulk
Surface morphology – CFC sample
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 12
Be / W coverage reduces D retention compared to the pure CFC
No saturation in this fluence range
Reflection of D at the surface (W)
Low D concentration at near surface layer (coated layer) (W)
Suppression of the chemical sputtering at the surface (W, Be)
Increased surface due to roughness D could penetrate into the CFC bulk
~Φ0.5
200eV D+ -> NB31
D retention in CFC substrate samples
~Φ0.5
200eV D+ -> NB31
Be on CFC
W on CFC
1019
1020
1021
1022
1019 1020 1021 1022 1023 1024 1025
100% retentionCFC (NB31)W on CFC (deposited at RT)W on CFC (deposited at 450C)Be on CFC (deposited at RT)Be on CFC (deposited at 450C)
Re
tain
ed
Flu
en
ce [D
/m2]
Incident Fluence [D/m2]
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 13
Be film
~Φ0.2
1019
1020
1021
1022
1019 1020 1021 1022 1023 1024 1025
100% retentionBe12W
D r
etain
ed fl
uence
[D
/m2]
Incident Fluence [D/m2]
200 eV D+ -> PCW (Ogorodnikova, Mayer)
Be film
~Φ0.2
1019
1020
1021
1022
1019 1020 1021 1022 1023 1024 1025
100% retentionBe12W
D r
etain
ed fl
uence
[D
/m2]
Incident Fluence [D/m2]
Be film
~Φ0.2
1019
1020
1021
1022
1019 1020 1021 1022 1023 1024 1025
100% retentionBe12W
D r
etain
ed fl
uence
[D
/m2]
Incident Fluence [D/m2]
200 eV D+ -> PCW (Ogorodnikova, Mayer)
D+ BeBe12W
No saturation in this fluence range (< ~1024 D/m2)
D retention increases proportional to ~ Φ0.2.
D retention in Be12W
200 eV D+ -> Be12W
0 0.1 0.2 0.3 0.4 0.5 0.6
Depth [um]
10-2
10-1
100
101
102
D c
once
ntra
tion
[at.%
]
5.3 x 1021 D/m2
5.0 x 1020 D/m2
4.7 x 1022 D/m2
4.1 x 1023 D/m2
200 eV D+ -> Be12W
0 0.1 0.2 0.3 0.4 0.5 0.6
Depth [um]
10-2
10-1
100
101
102
D c
once
ntra
tion
[at.%
]
200 eV D+ -> Be12W
0 0.1 0.2 0.3 0.4 0.5 0.6
Depth [um]
10-2
10-1
100
101
102
D c
once
ntra
tion
[at.%
]
5.3 x 1021 D/m2
5.0 x 1020 D/m2
4.7 x 1022 D/m2
4.1 x 1023 D/m2
5.3 x 1021 D/m2
5.0 x 1020 D/m2
4.7 x 1022 D/m2
4.1 x 1023 D/m2
D maximum concentration at near
surface layer reaches saturation
above 5 x1021 D/m2 fluence range.
D distribution expands to deeper regio
n → Higher D mobility in Be12W than t
hat in pure Be ?
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 14
200 eV D+ -> PCW (Ogorodnikova,
Mayer)
200 eV D+ -> Pyro. graphite (Alimov, Roth)
1019
1020
1021
1022
1019 1020 1021 1022 1023 1024 1025
100% retention200eV D -> PCWW carbide on Graphite
Re
tain
ed
Flu
en
ce [D
/m2 ]
Incident Fluence [D/m2]
D+ SubstrateWC / W2C
D retention in Tungsten Carbide
No saturation in this fluence range (< ~1024 D/m2)
Trend of D retention in WC/W2C layer
is closer to that in W compared to the graphite.
200 eV D -> Tungsten Carbide
0 0.1 0.2 0.3 0.4 0.5
Depth [um]
D c
once
ntra
tion
[at.
%]
10-2
10-1
100
101
102
3.5 x 1021 D/m2
4.3 x 1022 D/m2
4.0 x 1023 D/m2
3.5 x 1021 D/m2
4.3 x 1022 D/m2
4.0 x 1023 D/m2
200 eV D -> Tungsten Carbide
0 0.1 0.2 0.3 0.4 0.5
Depth [um]
D c
once
ntra
tion
[at.
%]
10-2
10-1
100
101
102
200 eV D -> Tungsten Carbide
0 0.1 0.2 0.3 0.4 0.5
Depth [um]
D c
once
ntra
tion
[at.
%]
10-2
10-1
100
101
102
3.5 x 1021 D/m2
4.3 x 1022 D/m2
4.0 x 1023 D/m2
3.5 x 1021 D/m2
4.3 x 1022 D/m2
4.0 x 1023 D/m2
3.5 x 1021 D/m2
4.3 x 1022 D/m2
4.0 x 1023 D/m2
3.5 x 1021 D/m2
4.3 x 1022 D/m2
4.0 x 1023 D/m2
D maximum concentration at near surface layer reaches saturation above 4 x1022 D/m2 fluence range.
D distribution expands to deeper region with increasing the incident fluence.
Kazuyoshi Sugiyama, SEWG meeting, Culham, 9 -10 July 2007 15
D retention in binary layer-substrate samples C, Be film show similar trend:
D in W film in high fluence range showed less retention than PCW.
Summary
D retention in mixed layer samples
No saturation was observed in < 1024 D/m2 fluence range. D trapping sites in mixed layer were still unclear. Influence of bulk diffusion in mixed material would be important to understand the
impact of T accumulation in mixed layer.
- D retention properties in Be12W and WC/W2C layers were investigated.
No significant dependency on deposition temperature and substrate material → Low mobility of D in C, Be film → D is retained in C, Be film
The amount of D retention in PVD film is larger than that in well-crystallized surface by a factor of 2 ~ 3.
D accumulation in the bulk was limited by difference of D diffusion properties between W and Be, C.
Thermal expansion mismatch between Be and W is potential issue from the viewpoint of dust formation.
D in CFC substrate samples did not reach saturation in the < 1024 D/m2 fluence range. Amount of D retention decreased by Be, W coating .