Sachiko Suzuki1, Akira Yoshikawa1, Hirotada Ishikawa1, Yohei Kikuchi1,

Yuji Inagaki1, Naoko Ashikawa2, Akio Sagara2, Naoaki Yoshida3,

Yasuhisa Oya1 and Kenji Okuno1

1 Radioscience Research Laboratory, Faculty of Science, Shizuoka University, Japan2 National Institute for Fusion Science, Japan

3 Institute of Applied Mechanics, Kyushu University, Japan

Hydrogen isotope behavior in C+ and D2

+ simultaneous implanted tungsten

Combination usage of tungsten (W) and carbon fiber composite (CFC)

Sputtering by direct contact of plasma

Forming of re-deposition layer (WxCy)

Elucidation of chemical behavior of hydrogen isotopes implanted into C/W mixed materialsElucidation of chemical behavior of hydrogen isotopes implanted into C/W mixed materials

BackgroundBackground

Fig. 1 D2 TDS spectrum in WC

Previous studyPrevious study[1][1]

Peak 1 at 400 K400 K Peak 2 at 490 K 490 K Peak 3 at 600 K600 K Carbon vacancy Peak 4 at 930 K 930 K C-D bond

Trapping sites of deuterium

Interstitial sites

300 500 700 900 11000.0

0.5

1.0

1.5

Des

orpt

ion

rate

/ 10

18 D

2 m-2

s-1

Temperature / K

Peak 1 Peak 2 Peak 3 Peak 4

[1] H. Kimura, et al., Fusion Eng. Des. 81 (2006) 295-299.

Objective Objective

Elucidation of hydrogen isotope behavior in C+ and D2

+ simultaneous implanted tungstenElucidation of hydrogen isotope behavior in C+ and D2

+ simultaneous implanted tungsten

D2+ gun

Ion implantation chamber

Sample insert port

Fig. 2 The simultaneous C+ and D2+ implantation system

C+ gun

ApparatusApparatus

TDS chamber

Ion source gas: CO2E×B mass separation filter

0 100 200 300 400 500 600 7000.0

1.0

2.0

3.0

Ions

D (3 keV D2

+)

C (10 keV C+)

Depth / Ang.

Fig. 3 SRIM calculation results for implantation depth

Energy: 0.5 - 10 keV C+

Flux: 2.0×1017 - 2.0×1018 C+ m-2 s-1

Energy: 0.5 - 3 keV D2

+

Flux: 2.0×1017

– 2.0×1018

D2+ m-2 s-1

SamplesSamples

W (under stress-relieved conditions )

purchased from A.L.M.T. Corp.

Density: 19.3 g/cm3

Size: 10 mmФ0.5 mm

Prepared and polished

Implantation conditions Energy: 3.0 keV D2

+, 10 keV C+

Flux: 1.0 × 1018 ions m-2 s-1

Fluence: 1.0 × 1022 ions m-2

Imp. temp.: R.T.

Heating rate: 0.5 K s-1

Heating temp.: R.T. – 1173 K

C+, D2+

implantations

TDS

XPS

X-ray source: Al K

Implantation procedures Only D2

+ imp. C+ and D2

+ simultaneous imp. D2

+ imp. after C+ imp.

XPS

Experimental procedure 1Experimental procedure 1

Heating temp.: 1173 K Time: 10 min

Preheating

C+ imp.D2

+ imp. and C+ imp.D2+ imp.

Implantation proceduresImplantation procedures

Only D2+ imp. C+ and D2

+ simultaneous imp. C+ and D2+ sequential imp.

D2+ imp.

D2+ gun C+ gun

Implantation conditions Energy: 3.0 keV D2

+, 10 keV C+

Flux: 1.0 × 1018 ions m-2 s-1

Fluence: 1.0 × 1022 ions m-2

Imp. temp.: R.T.

Heating rate: 0.5 K s-1

Heating temp.: R.T. – 1173 K

C+, D2+

implantations

TDS

XPS

X-ray source: Al K

Implantation procedures Only D2

+ imp. C+ and D2

+ simultaneous imp. D2

+ imp. after C+ imp.

XPS

Experimental procedure 1Experimental procedure 1

Heating temp.: 1173 K Time: 10 min

Preheating

Implantation conditions Energy: 3.0 keV D2

+, 10 keV C+

Flux: 1.0 × 1018 D2+ m-2 s-1

Flux: 2.0 × 1017 - 2.0 × 1018 C+ m-2 s-1

Flux ratio of C+/D+: 0.2 -2.00.2 -2.0Fluence: 1.0 × 1022 D2

+ m-2

Fluence: 2.0 × 1021 - 2.0 × 1022 C+ m-2

Imp. temp.: R.T.

Heating rate: 0.5 K s-1

Heating temp.: R.T. – 1173 K

C+, D2+

implantations

TDS

XPS

X-ray source: Al KXPS

Experimental procedure 2Experimental procedure 2

Heating temp.: 1173 K Time: 10 min

Preheating

CC++ and D and D22++ simultaneous imp. simultaneous imp.

Implantation proceduresThe flux dependence of CThe flux dependence of C++

Results and Discussion (1)Results and Discussion (1)

Fig. 4 XPS spectra of C-1s with various implantation procedures

C-W bond ・・・ 282.7 eV [1] C-C bond ・・・ 284.6 eV [2]

[1] H. Kimura, et al., Fus. Eng. Des. 81 (2006) 295-299.

[2] C. D. Wagner, et al. Handbook of X-ray photoelectron spectroscopy, Rerking- Elmer Corp., Physical Electronics, Division.

Fig. 5 Peak areas of C-C and C-W bonds with various implantation procedures

The decrease of C-C bond by D2+ imp. on C+-D2

+ sequential imp.

The sputtering of carbon by D2+ imp.

The area of C-C bondSimultaneous imp. Simultaneous imp. ＞ ＞ Sequential imp.Sequential imp.

Aggregation of carbon on surface after C+-D2+ simultaneous imp.

C-W bondC-C bond

295 290 285 280 2752.0

2.5

3.0

3.5 Only C+ imp. Sequential imp. Simultaneous imp.

Inte

nsit

y / a

rb.u

nit

Binding energy / eV1 2 3

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

SimultaneousOnly C+

Peak

are

a / a

rb.u

nit

C-C bond C-W bond

SequentialImplantation procedures

Fig. 6 XPS spectra of W-4f with various implantation procedures

[3] J. Kovac, et al., Vacuum 82 (2008) 150-153.

C+-D2+ simultaneous imp. ・・・ The positive peak shift of about 0.4 eV

Only C+ imp. ・・・ The positive peak shift of about 0.9 eV

C+-D2+ simultaneous implantation→C-W bond

Only C+ implantation → carbon rich tungsten carbide (WCx)

Main chemical states

Results and Discussion (2)Results and Discussion (2)W ： 31.5 eV [3]

38 36 34 32 300.0

1.0

2.0

3.0

4.0

Inte

nsit

y / a

rb.u

nit

Binding energy / eV

Simultaneous imp. Sequential imp.

Only C+ imp.

Only D2

+ imp.

After preheating

The higher desorption peak at around 800K800K ・・・ C-D bondC-D bondThe least total deuterium retention in Simultaneous imp.

[4] T. Suda, et al., Fus. Eng. Des. 82 (2007) 1762-1766.

In C+-D2+ simultaneous implantation

deuterium was hardly trapped at higher temperature.

Results and Discussion (3)Results and Discussion (3)

Fig. 7 TDS spectra with various implantation procedures

Fig. 8 Total D retention with various implantation procedures

400 600 800 1000 12000.0

0.5

1.0

1.5

2.0

2.5

3.0

D

esor

ptio

n ra

te /

1017

D2 m

-2 s

-1 Only D2

+ imp.

Sequential imp. Simultaneous imp.

Temperature / K

600-1100 K

400 K

0.0

1.0

2.0

3.0

4.0

Des

orpt

ion

rate

/ 10

18 D

2 m-2 s

-1

HOPG[4]

1 2 34.0

5.0

6.0

7.0

8.0

Simultaneous imp.Sequential imp.

D retention

D r

eten

tion

/ 10

19 D

2 m-2

Implantation proceduresOnly D

2

+ imp

The large desorption peak at around 400 K 400 K → Interstitial of WInterstitial of W

300 400 500 600 700 800 900 1000 11000.0

0.5

1.0

1.5

2.0

2.5

3.0

C+/D+=0.2

C+/D+=1

C+/D+=2

Des

orp

tion

rat

e / 1

017 D

m-2

s-1

Temperature / K

Results and Discussion (4)Results and Discussion (4)The flux dependence of CThe flux dependence of C++

Fig. 9 TDS spectra for the simultaneous implanted W with various C+/D+ flux ratio

Fig. 10 Total peak area of C-1s as a function of C+/D+ flux ratio

C+/D+ ＝ 0.2 : The large desorption peak at around 800 K 800 K → C-D bondC-D bond Carbon concentration was decreased as the C+/D+ ratio increased

The enhancement of carbon re-emission in high C+/D+ ratio The low re-emission of carbon leads high retention of D trapped by carbon.

SummarySummary

Elucidation of the trapping sites and role of carbon on hydrogen isotope retention in C/W mixed materials

Elucidation of the trapping sites and role of carbon on hydrogen isotope retention in C/W mixed materials

D desorption at higher temperature side in C+-D2+ sequential imp.

→ C-D bond Total D retention Only D2

+ imp. C+-D2

+ sequential imp.

Further studies Further studies

Establishment of the simultaneous CEstablishment of the simultaneous C++ and D and D22

++ implantation system implantation system

＜About 25%

C+-D2+ simultaneous imp.

Elucidation of hydrogen isotope behavior in C+ and D2

+ simultaneous implanted tungsten

The flux dependence of CThe flux dependence of C++

The low reemission of carbon leads high retention of D trapped by carbon.

Thank you for your attention

42 40 38 36 34 32 30 280.0

0.5

1.0

1.5

2.0

Inte

nsi

ty /

arb

. un

it

Binding energy / eV

Imp. Temp. 873 K 773 K 673 K 573 K 423 K 323 K Before

295 290 285 280 2750.0

0.5

1.0

1.5

2.0

2.5

Inte

nsit

y / a

rb. u

nit

Binding energy / eV

Imp. Temp. 873 K 773 K 673 K 573 K 423 K 323 K before

284.6 eV C-C + C-D 31.4 eV W-C

Fig. 11 C-1s and W-4f XPS spectra after D2+ implantation at various implantation temperatures.

282.7 eV C-W

Interstitial site I Interstitial site II

W DC

Dependence of implantation temperature on change of Dependence of implantation temperature on change of chemical state of C and W in WCchemical state of C and W in WC

Peak 1Peak 1: Interstitial site IPeak 2Peak 2: Interstitial site II

300 500 700 900 1100 13000.0

0.5

1.0

1.5

Des

orpt

ion

rate

/ 10

18 D

2 m-2

s-1

Temperature / K

Imp. temp. / K 323 423 573 673 873

Energy : 1 keV D2

+

flux : 1.0 x 1018 D+ m-2 s-1

Fluence : 1.0 x 1020 D+ m-2

Analysis methodsAnalysis methods

• TDS (Thermal Desorption Spectroscopy)• XPS (X-ray Photoelectron Spectroscopy)

D2+ implantation

QMS

Heating

Analyzer

X-ray

XPSTDS

Fig. 6 XPS spectra of W-4f with various implantation procedures

[4] J. Kovac, et al., Vacuum 82 (2008) 150-153.

C+-D2+ simultaneous imp. ・・・ The positive peak shift of about 0.4 eV

Only C+ imp. ・・・ The positive peak shift of about 0.9 eV

W ： 31.5 eV [4]

38 36 34 32 300.0

1.0

2.0

3.0

4.0

Inte

nsit

y / a

rb.u

nit

Binding energy / eV

C+-D2

+ simultaneous imp.

C+-D2

+ sequential imp.

Only C+ imp.

Only D2

+ imp.

After preheating

C+-D2+ simultaneous implantation→C-W bond

Only C+ implantation → carbon rich tungsten carbide (WCx)

Main Chemical states

Results and Discussion (2)Results and Discussion (2)

400 600 800 1000 12000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0 W imp. D

2

+

Simultaneous Sequential

WC imp. D2

+

Temperature/K

Fig. TDS spectra with various implantation procedures

0.0 0.5 1.0 1.5 2.0

1.0

1.5

2.0

2.5

3.0

Ret

enti

on /

1017

D m

-2

C+/D+ / -

Fig. Total retention for the simultaneous implanted W with various C+/D+ ratio

0 100 200 300 400 500 600 7000.0

1.0

2.0

3.0

Ions

D (3 keV D2

+)

C (10 keV C+)

Depth / Ang.

Implantation DepthImplantation Depth

Fig. 2 SRIM calculation results for implantation depth

The implantation depth of 10 keV C+ is almost the same as that of 3 keV D2+

Deuterium ion gun

Ion implantation chamber

Sample insert port

Fig. 1 The simultaneous C+ and D2+ implantation system

(a) Photograph (b) Diagrammatic illustration

Carbon ion gun

ApparatusApparatus

TDS chamber

D2+ ion gun

QMS

Manupilator

Differential pumping system

G.V.

C+ ion gun

TDS chamber

Ion implantation chamber

(a) (b)Ion source gas: CO2

E×B mass separation filter