sachiko suzuki 1, akira yoshikawa 1, hirotada ishikawa 1, yohei kikuchi 1, yuji inagaki 1, naoko...

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