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 .