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
ITPA May 2007 © Matej Mayer
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’
ITPA May 2007 © Matej Mayer
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
ITPA May 2007 © Matej Mayer
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
ITPA May 2007 © Matej Mayer
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
ITPA May 2007 © Matej Mayer
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
ITPA May 2007 © Matej Mayer
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
ITPA May 2007 © Matej Mayer
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
ITPA May 2007 © Matej Mayer
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
ITPA May 2007 © Matej Mayer
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!
