itpa may 2007 © matej mayer carbon erosion and transport in asdex upgrade m. mayer 1, v. rohde 1,...

ITPA May 2007 © Matej Mayer

Carbon Erosion and Transport in ASDEX Upgrade

M. Mayer1, V. Rohde1, J.L. Chen1, X. Gong1, J. Likonen3,

S. Lindig1, G. Ramos2, E. Vainonen-Ahlgren3

and ASDEX Upgrade team

1 Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching, Germany2 CICATA-Qro, Instituto Politécnico Nacional, Querétaro, México

3 Association EURATOM-TEKES, VTT Processes, Espoo, Finland

• Outer divertor – Tungsten erosion and local transport – Carbon erosion

• Inner divertor – Carbon and boron deposition

• Global carbon transport from 2002 – 2006

• Extrapolation to ITER


Experimental: Marker stripes on divertor tiles

• Marker stripes – 4 – 8 µm C with Re interlayer – 200 – 500 nm W

• Thickness of layers before and after exposure determined with ion beam analysis methods

ReC

CC/Re W

C tile Net erosion = NBefore - NAfter

Gross erosion = NBefore + NDeposited – NAfter

NBefore, NAfter: Amounts before and after exposure

NDeposited: Amount deposited on C tileB, C

W1 2

1’

3

prompt redeposition

Net erosion 1’ - 3

Gross erosion 1’


Erosion of C in 2004 – 2005

6A

6B

5

4

9A

9B

9C

1low

1up

2

3A

3B

WC

10

Delamination of marker

• Comparable erosion pattern to W (except tile 10 + sharp deposition close to strike point)

• C-erosion 6-10 times larger than W-erosion


Total erosion of C in 2004 – 2005

Delamination of marker

Total C erosion on strike point obtained from

• C erosion pattern = W pattern

• C-erosion/W-erosion = 8

Tile

1 2.6 g

10 0.2 g

Total 2.8 g

Divertor erosion from spectroscopy: 1 gKallenbach PSI 2006

Uncertainties

• Factor 1.5 for surface analysis

• Factor 2 (– 3?) for spectroscopy

Agreement within error bars

Additional sinks

• Below roof baffle, pumped out, … C-source > C visible by spectroscopy


W coverage in AUG 2002 – 2006

Step by step replacement of C offers unique possibility to identify C sources

2002 – 2003 2004 – 2005 2005 – 2006


Deposition in inner divertor

2002 – 20034800 s

2004 – 20053050 s

2005 – 20062900 s

0 200 400 6000

2

4

6

s-coordinate [mm]

B + C C

9C456B6A

Dep

osi

tio

n o

f B

+C

[10

19 a

t./c

m2]

0 200 400 6000

2

4

6

s-coordinate [mm]

B + C C

9C456B6A

Dep

osi

tio

n o

f B

+C

[10

19 a

t./c

m2]

0 200 400 6000

2

4

6

s-coordinate [mm]

B + C C

9C456B6A

Dep

osi

tio

n o

f B

+C

[10

19 a

t./c

m2]

6A

6B

5

4

9C

• Decrease of C-deposition on divertor tiles by factor 7

from 2004/2005 to 2005/2006

• Decrease of C-deposition below roof baffle by factor 10

from 2004/2005 to 2005/2006

Outboard limiters are main carbon source


Total carbon balance

2002 – 2003 2004 – 2005 2005 – 2006

Outer divertor Erosion C [g] - 2.8 2.8

Inner divertor Deposition C [g] 14.8 14.3 2.2

Deposition B [g] 2.9 5.9 2.4

• Deposition on tiles 5, 6 measured in all 3 campaigns Extrapolate to total inner divertor using 2002/2003 data (factor 2.2)

• Erosion in outer divertor measured in 2004/2005 Assume identical in 2005/2006

• Normalized to 3000 s


Contribution of carbon ICRH limiters

W

C

2005-2006 Full carbon limitersused before 2005

Small carbon influx from horizontal part of limiters

Only small contribution of remaining carbon on limiters in 2005/2006

T. Pütterich 2003V. Bobkov


Carbon transport

2004 – 2005 2005 – 2006

3 g20%

11 g80%

14 g 3 g100%

2 g

Assumption: Small influx of residual carbon in main chamber


Extrapolation to ITER

ASDEX Upgrade: 1×1026 ions to outer divertor in 2004/2005 Carbon erosion: 2.8 g

ITER: 6×1026 ions to outer divertor per discharge Carbon erosion: 18 g

Transport to outer divertor, resulting in 0.2% C in incident flux(D+T)/C = 0.1 0.2 g T per discharge, allows 5000 discharges

CFC at strike points is marginally acceptable from T codeposition

Notes:

1. AUG at RT to 300°C, ITER at > 1000°C Small contribution of chemical erosion in both cases

2. Larger ELM size in ITER not taken into account (ELM mitigation)

3. Beryllium from main chamber not taken into account!

itpa may 2007 © matej mayer carbon erosion and transport in asdex upgrade m. mayer 1, v. rohde 1,...

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