SIMS and RBS analysis of the recent 13CH4 experiment

J. Likonen, P. Coad, A. Hakola, D. Hole, M. Rubel, J. Strachan, A. Widdowson

Joint TFE-SEWG meeting on Material Migration and Material Mixing

JET, Culham, 8 July, 2009

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

2

Post-mortem analysis

Experiment in 2004 and 2007

Recent results (SIMS, RBS)

EDGE2D results

Conclusions

OutlineOutline

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

3

TRANSPORT MARKERS and ANALYSIS

Dedicated marker experiments (2001, 2004, 2007)

Gas injection 13CH4

Marker-coated tiles

Distribution on tiles determined by ex-situ analysis:

Accelerator-based Ion Beam Analysis

– Rutherford backscattering spectroscopy

– Nuclear reaction analysis

Secondary Ion Mass Spectrometry

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

4

Probe

1.4x1017 Hf

4.29x1023 13C at

4.5x1021 B at

Main plasma:

Ip=1.2 MA Bt=-1.2T, ne= 7.8x1019m-3

H-mode discharges 32 good shots (63405-

63445) DOC-L configuration

Analysed until now:• collector probe• two sets of divertor tiles• four OPL and IWGL tiles

Tracer injection on the last operation day of C14 (2004)

Tracer injection on the last operation day of C14 (2004)

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

5

Probe

9.3x1022 13C at

Main plasma:

Ip=1.6 MA Bt=-1.6T, ne= 1.1x1020m-3

H-mode discharges 18 good shots (70725-

70750) Puffing through GIM6

Analysed until now:• one set of divertor tiles• 4 OPL and IWGL tiles• collector probe not available

Tracer injection on the last operation day of C19 (2007)

Tracer injection on the last operation day of C19 (2007)

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

6

Tile 1: Steep 13C profiles.

Tiles 3, 4 and 6: Broad 13C profiles with a slow decay.

Tiles 7 and 8: Relatively steep 13C profiles.

SIMS depth profiles of 13C (2007 experiment)SIMS depth profiles of 13C (2007 experiment)

Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1019

1020

1021

1022

1023

8/38/58/88/11

Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1019

1020

1021

1022

4/16/1

Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1020

1021

1022

1023

1/111/81/2

Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1019

1020

1021

1022

3/73/53/33/1 Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1020

1021

1022

1023

7/17/47/77/8

Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1019

1020

1021

1022

1023

8/38/58/88/11

Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1019

1020

1021

1022

4/16/1

Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1020

1021

1022

1023

1/111/81/2

Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1019

1020

1021

1022

3/73/53/33/1 Depth (nm)

1 10 100 1000 10000

13 C

am

ou

nt

(cm-3

)

1020

1021

1022

1023

7/17/47/77/8

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

7

JET13931.TXTSimulatedH BeC O Cr

Channel1 000950900850800750700650600550500450400350300250200150100500

Co

un

ts

1 150

1 100

1 050

1 000

950

900

850

800

750

700

650

600

550

500

450

400

350

300

250

200

150

100

50

0

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

Energy [keV]

Examples of RBS spectra (outer divertor, 2007)Examples of RBS spectra (outer divertor, 2007)

Be

12C

O

13C

SS

D

13C: 9 at.%, 2.6x1017 at/cm2

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

8

JET13915.TXTSimulatedH BeC O Cr

Channel1 000950900850800750700650600550500450400350300250200150100500

Co

un

ts

1 500

1 450

1 400

1 350

1 300

1 250

1 200

1 150

1 100

1 050

1 000

950

900

850

800

750

700

650

600

550

500

450

400

350

300

250

200

150

100

50

0

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

Energy [keV]

Examples of RBS spectra (inner divertor, 2007)Examples of RBS spectra (inner divertor, 2007)

Be

12C

O

13C

SS

No 13C (cannot be determined because of O)

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

9

Examples of RBS spectra (inner divertor, 2007)Examples of RBS spectra (inner divertor, 2007)

layer D (at.%)

Be (at.%)

12C (at.%)

13C (at.%)

O (at.%)

Cr (at.%)

1 3 26 35 33 2

2 5 22 44 28 1

3 2 1 81 15 ? 1

Composition determined with SIMNRA

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

10

13C distribution (2007)13C distribution (2007)

s coordinate (mm)

0 500 1000 1500 2000

13C

/inje

cted

13C

(cm

-2)

10-9

10-8

10-7

10-6

10-5

10-4

SIMSRBS

ISP OSP

s=0

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

11

Comparison of 13C experimentsComparison of 13C experiments

Experiment 2001 2004 2007

Injection Top of the vessel

Outer divertor (between tiles 7 and 8) Outer mid-plane

Tile 13C amount (% of total

input)

13C amount (% of total

input)

13C amount (% of total input)

13C amount (% of total input)

1 21.0 2.7 2.2 6.7

3 24.0 0.5 0.7 1.0

4 0.8 3.8 3.2 2.5

6 0.1 2.5 2.5 2.7

7 0.3 10.9 15.4 4.1

8 <0.1 6.1 0.9 0.8

SRP 1.8

OPL 0.6 1.4

total 46.2 26.5 27.3 19.2

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

12

EDGE2D simulations of 13C transport (C14, 2004)

EDGE2D simulations of 13C transport (C14, 2004)

Figure 2. EDGE2D calculated Carbon densities when all the carbon originates by injection at the red arrow. The green arrows indicate the migration pathways.Figure 2. EDGE2D calculated Carbon densities when all the carbon originates by injection at the red arrow. The green arrows indicate the migration pathways.

Migration Channels

13CH4

OSP

ISP

poloidal distance around divertor (mm)

0 500 1000 1500 2000

13C

dep

osit

ed /

cm2 /

13C

inje

cted

10-8

10-7

10-6

10-5

10-4

SIMS

IBA

SIMS -2nd toroidal locationmodel

13C deposition

J.D. Strachan, J. Likonen, P. Coad, et al., NF 48 (2008) 105002

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

13

EDGE2D simulations of 13C transport (C19, 2007)EDGE2D simulations of 13C transport (C19, 2007)

s coordinate (mm)

0 500 1000 1500 2000

13C

/inje

cted

13C

(cm

-2)

10-9

10-8

10-7

10-6

10-5

10-4

SIMSRBSEDGE2D

ISP OSPEDGE2D:13C migrating through the SOL to the inner divertor deposits above the inner strike point.

Erosion is required in the simulations to explain small amounts of 13C near the inner and outer strike points.

A multi-step recycling model was used at the outer divertor.

Deposits in the private flux region (PRF) originate from the outer target:

•“walking” to the outer strike point and then travelling as neutrals to the PFR •as ions to the inner strike point, where they undergo further erosion to become neutrals and deposit on the PFR.

EDGE2D results still very PRELIMINARY.EDGE2D results not in agreement with SIMS and RBS data especially on tiles 3 and 8.

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

VTT

14

ConclusionsConclusions

18% of the puffed 13C amount found on the divertor tiles with SIMS.

SIMS and RBS results agree well with each other.

Highest amount of 13C on Tile 1.

EDGE2D results still very PRELIMINARY.

EDGE2D results not in agreement with SIMS and RBS data especially on tiles 3 and 8.