carbon balance and deuterium inventory from a carbon dominated to a full tungsten asdex upgrade
Post on 31-Dec-2015
25 Views
Preview:
DESCRIPTION
TRANSCRIPT
PSI 2008 Toledo May 2008 © Matej Mayer
Carbon balance and deuterium inventory from a
carbon dominated to a full tungsten ASDEX
UpgradeM. Mayera, V. Rohdea, K. Sugiyamaa, J.L. Chena, X. Gonga,
C. Hopfa, J. Likonenb, S. Lindiga, R. Neua, G. Ramosc,
E. Vainonen-Ahlgrenb, A. Wiltnera, and ASDEX Upgrade Team
a Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching, Germanyb Association EURATOM-TEKES, VTT Processes, Espoo, Finland
c CICATA-Qro, Instituto Politécnico Nacional, Querétaro, México
• Evolution of B, C deposition in the divertor
• Evolution of D inventory in the divertor
• Comparison between plasma-sprayed and bulk W
Plasma-related aspects of all-W machine were covered by R. Dux, I-6
PSI 2008 Toledo May 2008 © Matej Mayer
Motivation
Tritium inventory in ITER dominated by codeposition
with carbon (if carbon is present)
But large uncertainties: Carbon sources and
carbon transport poorly understood
Stepwise replacement of C by W in AUG offers
unique possibility to study C sources
A. Kirschner et al., JNM 363-365 (2007) 91
Be
W
C
PSI 2008 Toledo May 2008 © Matej Mayer
Motivation (2)
Much lower T inventory in all-W machine
is predicted
All-W predictions based solely on
laboratory data
Confirmation in existing tokamaks
required
All-W is probably the only option for
a future DEMO reactor
Data from existing tokamaks required
J. Roth, this conference, R-1
PSI 2008 Toledo May 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
PSI 2008 Toledo May 2008 © Matej Mayer
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]
AUG inner divertor: Deposition of B + C
2002 – 20034940 s
Inner divertor deposition in 3000 s
C 14.6 gB 2.8 g
6A
4
PSI 2008 Toledo May 2008 © Matej Mayer
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]
AUG inner divertor: Deposition of B + C
2004 – 20053150 s
Inner divertor deposition in 3000 s
C 13.8 gB 4.7 g
6A
4
PSI 2008 Toledo May 2008 © Matej Mayer
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]
AUG inner divertor: Deposition of B + C
2005 – 20062950 s
Inner divertor deposition in 3000 s
C 2.2 gB 2.3 g
6A
4
PSI 2008 Toledo May 2008 © Matej Mayer
0 200 400 6000
1
2
3
4
5
6
7
s-coordinate [mm]
C, RBS C, NRA
9A456B6A
Dep
osi
tio
n o
f B
+C
[10
19 a
t./c
m2]
AUG inner divertor: Deposition of B + C
20072620 s
6A
4
Inner divertor deposition in 3000 s
C 1.0 gB 0 g (below detection limit)
PSI 2008 Toledo May 2008 © Matej Mayer
1
10
2002/2003 2004/2005 2005/2006 2007
Inner divertor C
Remote areas C
Dep
osi
tio
n in
300
0 s
[g]
Campaign
AUG divertor: Evolution of B, C deposition
Reduction of C deposition by
factor ~15 from C-dominated
to all-W machine
Largest decrease after coating of
ICRH protection limiters with W
Decrease in C plasma concentration
by factor 2–3R. Pugno, EPS 2008
Available C source at walls > 1000 times
C plasma inventory even in all-W machine
PSI 2008 Toledo May 2008 © Matej Mayer
1
10
2002/2003 2004/2005 2005/2006 2007
Inner divertor C, B
Remote areas C
Dep
osi
tio
n in
300
0 s
[g]
Campaign
AUG divertor: Evolution of B, C deposition
Reduction of C deposition by
factor ~15 from C-dominated
to all-W machine
Largest decrease after coating of
ICRH protection limiters with W
5-6 boronizations/campaign from 2002-2006
B-deposition almost constant
No boronization in 2007, extensive cleaning
B-deposition below detection limit of 0.1 g
PSI 2008 Toledo May 2008 © Matej Mayer
Carbon transport in AUG
2005 – 2006
3 g20%
11 g80%
14 g3 g
100%2 g
2004 – 2005
• Small influx of residual carbon in main chamber• Identical outer divertor erosion in both campaigns, M. Mayer et al., PS T128 (2007) 106
Assumptions:
Spectroscopy: 1 g A. Kallenbach et al., JNM 363-365 (2007) 60
PSI 2008 Toledo May 2008 © Matej Mayer
Carbon sources in all-W machine
100 µm
Residual C deposition in all-W machine:
1 g in 3000 s
• Electrical arc’s can remove W coating and
release C from tile
0.05 g C from inner baffle A. Herrmann, this conference, O-5
• Erosion in not fully coated tile gaps and
back sides of tiles
• Residual carbon layers from previous campaigns
(probably small due to extensive cleaning)
• C impurities in W coatings
• Photo-desorption of CO, CO2 from walls V. Philipps et al., J. Nucl. Mater. 200 (1993) 355
SE
BSE
PSI 2008 Toledo May 2008 © Matej Mayer
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
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
4940 s
2620 s
PSI 2008 Toledo May 2008 © Matej Mayer
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
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
PSI 2008 Toledo May 2008 © Matej Mayer
1000 1100 1200 1300 1400 1500 1600 17000.0
0.1
0.2
0.3
0
100
200
300
400
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
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
PSI 2008 Toledo May 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
PSI 2008 Toledo May 2008 © Matej Mayer
0 5 10 15
0.01
0.1
1
SIMS NRA
Depth [µm]
Co
nce
ntr
atio
n o
f D
[at
%]
1100 12000.0
0.1
0.2
0.3
0.4
0.5 VPS-W, NRA < 3 µm VPS-W, TDS Bulk W, NRA < 7 µm Bulk W, TDS
s-coordinate [mm]
Am
ou
nt
of
D [
1019
at.
/cm
2 ]
VPS-W versus polycrystalline W in outer divertor
• VPS-W and bulk W trap about the same total amount of D
• Bulk W shows deep diffusion (~ mm) at low D concentrations (< 100 ppm)
K. Sugiyama et al., Hydrogen Workshop Salamanca
Bulk W
Langmuir probes
VPS-W
20 mm
Background level
PSI 2008 Toledo May 2008 © Matej Mayer
10-1 100 101 102 103 104 10510-4
10-3
10-2
10-1
100
101
poly-WVPS-W
AUG, all-W (poly)
AUG, all-W (VPS)
Deu
teri
um
inve
nto
ry [
g]
Discharge time [s]
AUG, C-dominated
Extrapolation to higher fluences / longer discharge times
• Good agreement between laboratory measurements and AUG data
• Slower increase of D-inventory in W than in C for longer discharge times
W even more beneficial for long pulse machines
VPS-W: A.V. Golubeva et al., AIP Conf. Proc. 837 (2006) 12poly-W: O. Ogorodnikova et al., J. Appl.Phys. 103 (2008) 034902
D-inventory in AUG divertor
PSI 2008 Toledo May 2008 © Matej Mayer
Conclusions
• Decrease of divertor C deposition by factor ~15 from C-dominated to all-W machine, normalized to 3000 s
• Decrease of trapped D in divertor by factor 5 – 10 from C-dominated to all-W machine
• Boronizations result in high D-inventory due to co-deposition with B Decrease of D-inventory only visible in unboronized machine
• D-inventory in C-dominated machine determined by co-deposition in inner divertor + remote areas
• D-inventory in all-W machine determined by deep diffusion into W at outer strike point
top related