sewg fuel retention july 2008 © matej mayer fuel retention in asdex upgrade tungsten coatings m....
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SEWG Fuel Retention July 2008 © Matej Mayer
Fuel retention in ASDEX Upgrade tungsten coatingsM. Mayer, M. Balden, K. Krieger, S. Lindig,
O. Ogorodnikova, V. Rohde,
K. Sugiyama, and ASDEX Upgrade Team
Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching, Germany
• Retention in ASDEX Upgrade from post-mortem studies
• First results on modelling of ASDEX Upgrade retention
• Surface modifications (“blistering”)
SEWG Fuel Retention July 2008 © Matej Mayer
Retention in ASDEX Upgrade
from post-mortem studies
SEWG Fuel Retention July 2008 © Matej Mayer
W coverage in AUG 2002 – 2007
Step by step replacement of C tiles
by W coated tiles
• 3 – 4 µm W-PVD on most tiles
• 200 µm plasma-sprayed W at outer strike point
SEWG Fuel Retention July 2008 © Matej Mayer
0 200 400 600 800 1000 1200 1400 16000.0
0.5
1.0
1.5
2.0
2.5
3.0
NRA < 3.3 µm TDS
3B3A21109D9C9B9A456A
s-coordinate [mm]
Am
ount
of D
[10
19 a
t./cm
2 ]6B
Deuterium inventory
C-dominated campaign 2002/2003
D on divertor tiles 0.9 – 1.3 gD below roof baffle 0.4 gin 3000 s
Full W campaign 2007
D on divertor tiles 0.15 – 0.23 gD below roof baffle 0.03 gin 3000 s
6A
4 9B
1A
3A 4940 s
2620 s
SEWG Fuel Retention July 2008 © Matej Mayer
0 100 200 300 400 5000.0
0.1
0.2
0.3
0
100
200
300
400
D, NRA D, TDS C, NRA
s-coordinate [mm]
Am
ou
nt
[1019
at.
/cm
2 ]
456B
Str
ike
po
int
[s]
6A
Deuterium inventory in inner divertor of all-W machine
Correlation between distributionsof C and D
D inventory in inner divertor
still dominated by C-codeposition
6A
4
SEWG Fuel Retention July 2008 © Matej Mayer
1000 1100 1200 1300 1400 1500 1600 17000.0
0.1
0.2
0.3
0
100
200
300
400
0
2
4
6
8
D, NRA < 3 µm D, TDS C, NRA
s-coordinate [mm]
Am
ou
nt
[1019
at.
/cm
2 ]
3-4 µm PVD
3B3A21
Str
ike
po
int
[s]
10
200 µm VPS
Ion
flu
ence
[10
25 io
ns/
m2 ]
Deuterium inventory in outer divertor of all-W machine
D inventory in outer divertor
dominated by trapping in W
Deep diffusion (> 3 µm) observed for VPS layers at outer strike point
3B
1
SEWG Fuel Retention July 2008 © Matej Mayer
AUG divertor: Evolution of D inventory
Carbon dominated machine
• Total D-inventory dominated by inner divertor
and remote areas
All-W machine
• Boronizations result in high D-inventory,
co-deposition with B (2005/2006 campaign)
• D-inventory dominated by trapping
in VPS-layers at outer strike point
• Decrease of total D-inventory by factor 5 – 10
from C-dominated to all-W
0.1
1
2002/2003 2004/2005 2005/2006 2007
Inner divertor Outer divertor Remote areas Total
D-I
nve
nto
ry in
300
0 s
[g]
Campaign
SEWG Fuel Retention July 2008 © Matej Mayer
First results on modelling of
ASDEX Upgrade retention
SEWG Fuel Retention July 2008 © Matej Mayer
1021 1022 1023 1024 1025 1026
1019
1020
1021
1022
1023
~F0.53
Experimental dataPoly W lab; AUGVPS-W lab; AUGFitPoly W lab + AUGVPS-W lab + AUG
Deu
teri
um
ret
ain
ed [
D/m
2]
Incident fluence [D/m2]
~F0.72
Retention as function of fluence
VPS-W
• Laboratory and AUG data (VPS-W from tile 1) available
Polycrystalline W
• Laboratory and AUG data (Langmuir probes) available
4 µm PVD-W
• No data (with known fluence/retention) available
Assume same properties as polycrystalline W
4 µm thickness taken into account I4µm = 0.67 x ITotal
SEWG Fuel Retention July 2008 © Matej Mayer
1
3B
2
3A
Incident fluence
Outer divertor
• Ion fluence measured with Langmuir probes on tile 1
Extrapolation to tiles 2, 3A
Fluence on 3B from erosion in 2004/2005
Inner divertor
Assume identical number of ions as outer divertor 4.2 m2, 1022 ions/m2 s
Roof baffle
Assume 3.3 m2, 1021 ions/m2 s
Main chamber
Assume 8 m2, 1021 ions/m2 s and 32 m2, 1019 ions/m2 s
Codeposition with C
• 1.9x1019 C-atoms/s, D/C = 0.41.1 1.2 1.3 1.4 1.5 1.6 1.7
0
1
2
3
4
5
6
7
8
Langmuir-probe data Fit and extrapolation
3B3A2
Ion
flu
ence
[10
25 io
ns/
m2]
s-coordinate [m]
1
SEWG Fuel Retention July 2008 © Matej Mayer
1
3B
2
3A
Modelling: Outer divertor
Good agreement between modeland experimental data, keepingthe uncertainties in mind
1.1 1.2 1.3 1.4 1.5 1.6 1.70
1
2
34 µm PVD
Model TDS NRA < 3.3 µm
3B3A2
D-i
nve
nto
ry [
102
2 D
/m2]
s-coordinate [m]
1
200 µm VPS
SEWG Fuel Retention July 2008 © Matej Mayer
100 1000 10000
1021
1022
1x1023
Model Total Inner divertor Roof baffle Outer divertor Codeposition with C Main chamber
Experimental Inner + roof + outer + main chamber (model) Inner divertor Roof baffle Outer divertorD
-in
ven
tory
[A
tom
s]
Discharge time [s]
Modelling: Full ASDEX Upgrade
• Good agreement for outer divertor
• Model gives too high inventory for inner divertor More realistic fluence data necessary
SEWG Fuel Retention July 2008 © Matej Mayer
Modelling: Work in progress
• Ion fluences for inner divertor K. Krieger, July 2008
• Temperature history of outer divertor for 2007 campaign A. Herrmann, July 2008
• Inventory in 4 µm PVD-W as function of fluence O. Ogorodnikova, October 2008
SEWG Fuel Retention July 2008 © Matej Mayer
Surface modifications (“blistering”)
SEWG Fuel Retention July 2008 © Matej Mayer
= 1026 D/m2, Tirr = 550 K
= 1026 D/m2, Tirr = 583 K
Lab studies, 38 eV D-ions: “Blisters” AUG, Langmuir-probes: “Blisters”
V. Kh. Alimov
SEWG Fuel Retention July 2008 © Matej Mayer
Lab studies, 38 eV D-ions: “Blisters” AUG, Langmuir-probes: “Blisters”
“Blisters” are not hollow!
V. Kh. Alimov
SEWG Fuel Retention July 2008 © Matej Mayer
Lab studies, 38 eV D-ions: “Blisters” AUG, Langmuir-probes: “Blisters”
Often (always?) widened cracks (grain boundaries?) below “blisters”
V. Kh. Alimov
SEWG Fuel Retention July 2008 © Matej Mayer
Tirr = 515 K
Tirr = 567 K
Lab studies, 38 eV D-ions: “Sponge” AUG, Langmuir-probes: “Sponge”
“Sponge”-like structures are observed
V. Kh. Alimov
SEWG Fuel Retention July 2008 © Matej Mayer
Summary
Retention in ASDEX Upgrade:
• Decrease of trapped D in divertor by factor 5 – 10 from C-dominated to all-W machine
• D-inventory in all-W machine determined by deep diffusion into W at outer strike point
Modelling of ASDEX Upgrade data:
• First modelling using experimental laboratory/AUG data and measured AUG fluxes
• Good agreement for outer divertor, further work needed for inner divertor
Surface modifications:
•“Blister”-like structures observed in laboratory studies and AUG polycrystalline W
• No blister cap, not hollow (but often/always cavity/crack observed)
These are no classical blisters! Naming?