Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 1

Max-Planck-Institut für Plasmaphysik

D retention and release behaviour of Be/C/W mixed materials

K. Sugiyama, K. Krieger, J. Roth

Max-Planck-Institut für Plasmaphysik, EURATOM Association

A. Anghel, C. Porosnicu, C.P. Lungu

National Institute for Laser, Plasma and Radiation Physics of Romania, Association EURATOM-MEdC

M.J. Baldwin, R.P. Doerner

Center for Energy Research, University of California at San Diego

(WP10-PWI-01-02-03/IPP/PS, WP10-PWI-01-02-02/MEdC/PS)

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 2

Outline

Introduction

Experimental procedure

Results

Summary and Outlook

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 3

Introduction

Wall materials in ITER

• 690 m2 Be: first wall and start-up limiter modules

• 140 m2 W: divertor dome / baffle region• 55 m2 CFC: divertor strike point areas

Material mixture Tritium retention in mixed materials

Be

W

CFC

Wall baking for tritium removal in ITER

• 240 ºC: Main chamber• 350 ºC: Divertor region

Experimental approach in this task

• Preparation of ITER relevant (Be-related) mixed material samples

• Investigation of D retention and release behaviour of mixed materials

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 4

Outline

Introduction

Experimental procedure

Results

Summary and Outlook

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 5

Sample preparation

Experimental procedure

Be12W fabrication by annealing of W film on Be substrate sample at 1073K, 10 hours

Be2C fabrication by annealing of C film on Be substrate sample at 773K, 3 hours

WC fabrication by annealing of W film on graphite substrate sample at 1373K, 4 hours

• Compounds fabrication by thermal treatment of Be-W / Be-C / W-C system

• Be-W / Be-C simultaneously deposited layers

Upgrade of TVA setup for the simultaneous deposition

Depositions were successfully done with varying Be/W and Be/C ratios

Be-related depositions were prepared by Thermionic Vacuum Arc (TVA) deposition method in MEdC

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 6

Sample preparation

Experimental procedure

Be12W fabrication by annealing of W film on Be substrate sample at 1073K, 10 hours

Be2C fabrication by annealing of C film on Be substrate sample at 773K, 3 hours

WC fabrication by annealing of W film on graphite substrate sample at 1373K, 4 hours

• Compounds fabrication by thermal treatment of Be-W / Be-C / W-C system

• Be-W / Be-C simultaneously deposited layers

D implantation to prepared layers

• 200 eV D ions implantation in the High Current Ion Source in IPP-Garching

• Flux ~ 1019 D/m2, Fluences up to ~1023 D/m2

Post mortem analysis for the prepared samples

• D release behaviour analysis by Thermal Desorption Spectroscopy (TDS)

• Quantitative analysis by Nuclear Reaction Analysis using D(3He, p)4He reaction

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 7

Outline

Introduction

Experimental procedure

Results

Be-related compounds layer

W-C compound (WC) layer

Be-W simultaneously deposited layer

Be-C simultaneously deposited layer

Summary and Outlook

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 9

1012

1013

1014

1015

300 400 500 600 700 800 900

0 100 200 300 400 500 600

Des

orpt

ion

flux

[D2/c

m2 /s

]

Temperature [K]

Temperature [C]

1012

1013

1014

1015

300 400 500 600 700 800 900

0 100 200 300 400 500 600

Des

orpt

ion

flux

[D2/c

m2 /s

]

Temperature [K]

Temperature [C]

Be2C: Additional desorption stage in the high temperature range (> 400 ºC)

Be2C

Be

D desorption from Be-related compoundsD implantation to Be-related compound layers

Be: Primary desorption peak at 150-200 ºC

D fluence ~ 1023 D/m2 @ RT

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 10

1012

1013

1014

1015

0

100

200

300

400

500

600

700

800

0 1000 2000 3000 4000

Des

orpt

ion

flux

[D2/c

m2 /s

]T

em

perature [C

]

Time [s]

D release during the temperature hold at 350 ºC

Be2C

Be

The desorption flux drops down when the temperature reaches the plateau at 350 ºC.

3.125exp~

t

The desorption flux reaches almost background level during the 20 min. hold. 5-10 % of retained D additionally released during the temperature hold at 350 ºC.

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 11

1012

1013

1014

1015

300 400 500 600 700 800 900

0 100 200 300 400 500 600

Des

orpt

ion

flux

[D2/c

m2 /s

]

Temperature [K]

Temperature [C]

Be2C

Be2C: Additional desorption stage in the high temperature range (> 400 ºC)

1012

1013

1014

1015

300 400 500 600 700 800 900

0 100 200 300 400 500 600

Des

orpt

ion

flux

[D2/c

m2 /s

]

Temperature [K]

Temperature [C]

Be12W

Be12W: The primary desorption peak becomes less intense and broader

Be

D desorption from Be-related compoundsD implantation to Be-related compound layers

Be: Primary desorption peak at 150-200ºC

D fluence ~ 1023 D/m2 @ RT

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 12

300 400 500 600 700 800

0 100 200 300 400 500 600

D r

emai

ning

fra

ctio

n [%

]

Temperature [K]

Temperature [C]

0

20

40

60

80

100350ºC240ºC

Be2C

Be12WBe

D retained fraction in Be-related compounds

Be: ≈ 90 % of initially retained D is released at 350 ºC Compounds: 60-70 % of initially retained D is released at 350 ºC

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 13

1011

1012

1013

1014

300 400 500 600 700 800

0 100 200 300 400 500 600

D2 d

eso

rptio

n flu

x [D

2/cm

2 /s]

Temperature [K]

Temperature [C]

Fluence ~ 1023 D/m2 @ RT

Bulk-W

WC

D release from WC layer

300 400 500 600 700 800

0 100 200 300 400 500 600

Temperature [K]

Temperature [C]

D r

emai

ning

fra

ctio

n [%

]0

20

40

60

80

100

Bulk-W WC

240ºC 350ºC

D release from WC shows primary desorption stage at 400 - 750 K

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 14

1011

1012

1013

1014

1015

300 400 500 600 700 800

0 100 200 300 400 500 600

D2 d

eso

rptio

n flu

x [D

2/cm

2 /s]

Temperature [K]

Temperature [C]

Be

Be12W

Fluence ~ 1023 D/m2 @ RT

D release from Be-W simultaneously deposited layer

Mixing of W in Be slightly changes the D desorption behaviour. The retention amount decreases by increase of W fraction in Be.

300 400 500 600 700 800

0 100 200 300 400 500 600

Temperature [K]

Temperature [C]

D r

emai

ning

fra

ctio

n [%

]0

20

40

60

80

100

W~10 at.%

W~60 at.%

Be12W

Be

240ºC 350ºC

1011

1012

1013

1014

1015

300 400 500 600 700 800

0 100 200 300 400 500 600

D2 d

eso

rptio

n flu

x [D

2/cm

2 /s]

Temperature [K]

Temperature [C]

W~10 at.%

W~60 at.%Bulk-W

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 15

1011

1012

1013

1014

1015

300 400 500 600 700 800

0 100 200 300 400 500 600

Des

orpt

ion

flux

[D2/c

m2 /s

]

Temperature [K]

Temperature [C]

Be

Be2C

1011

1012

1013

1014

1015

300 400 500 600 700 800

0 100 200 300 400 500 600

Des

orpt

ion

flux

[D2/c

m2 /s

]

Temperature [K]

Temperature [C]

C ~ 50 at.%

C ~ 8 at.%

Fluence ~ 1023 D/m2 @ RT

D release from Be-C simultaneously deposited layer

D release behaviour totally changes in the case of C-rich mixed layer sample

300 400 500 600 700 800

0 100 200 300 400 500 600

D r

emai

ning

fra

ctio

n [%

]

Temperature [K]

Temperature [C]

0

20

40

60

80

100

240ºC

Be2CBe

C ~ 8 at.%

350ºC

C ~ 50 at.%

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 16

How will the wall baking work in ITER ?

Best performance will be expected for:・ removal from clean Be deposit・ the removal from Be-hydrogen

codeposition formed at “cool” areas

The efficiency is marginal for:

・ Be-W codeposited layer and compounds・ “ Be-rich” Be-C mixed deposition

Less efficiency for: ・ “ C-rich” (C conc. > 50 at.%) Be-C

mixed deposition・ the hot surface (temperature is >

350ºC during a discharge)

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80

D r

emai

ning

fra

ctio

n at

350

C [

%]

Impurity concentration in Be [%]

W

C

Be12WBe2C

Kazuyoshi Sugiyama, SEWG meeting on Fuel retention, Garching, July 20 2010 17

Summary and Outlook

Outlook: D implantation to mixed material samples at high temperatures

- Temperature dependence of D retention in mixed material samples

Further upgrade of TVA setup for Be-W-C (ternary) simultaneous deposition

What we have done are: Mixed material sample fabrication (collaboration with MEdC)

- TVA setup successfully upgraded for the Be-W / Be-C simultaneous deposition

Investigation of D release from mixed materials for the assessment of T removal operation in ITER (wall baking at 240 ºC / 350 ºC)

Messages: D release behaviour is affected by material mixing

- Influence of C is more significant.

- T removal efficiency of 350 ºC baking decreases by material mix compared to the case of pure Be or W.