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Depth-profiling and thermal desorption of hydrogen isotopes for plasma facing carbon tiles in JT-60U
(Long term hydrogen retention)
T. Tanabe, Kyushu University
☆Depth profiles in redeposited layers and eroded area Depth profiles of T in divertor tiles of JET and JT-60U Depth profiles and TDS of hydrogen isotopes (H, D and T) Importance of Isotopic exchange and tile temperature
☆Deep penetration into the bulk
Penetration thorough open pores of CFC and graphite Thermal diffusion Absorption at and/or permeation to the backside of tiles.
9th ITPA meeting on SOL/divertor physics, Garching, May 7-10, 2007
GasGraphite(Solid)Liquid
Determined by
○ : IR
● : NMR
▲ :EELS
A:C-H film ever produced
Hydrogen solubility
(very small)
T. Tanabe et al., Journal of Nuclear Materials 313–316 (2003) 478–490
RT
Hydrogen solubility
Hydrocarbons are unstable above 800K
Kee
pin
g n
earl
y th
e sa
me
leve
l
Above ~800K
Isotope exchange becomes easier
H2 and H0
Hydrogen retention and depth profile under H+ and H2 exposure
All grains are under the same static pressure
Below ~700K
No diffusion into bulk or particles
0
100
200
300P
SL
in
ten
sity [P
SL
/m
m2 ]
10
100
1000
104
105
106
0 5 10 15 20 25 30 35 40
Cyl_3Cyl_4Cyl4_BN4Cyl_7Cyl_8Cyl_9
Trit
ium
p
er d
isk
[k
Bq
]
Depth [mm]
BN4
BN7
Tritium activity is mostly on the plasma facing surface
JET tile : Cross section of cored hole in divertor base tile :BN4
Surface
Probably due to temperature difference
Backs side of BN7
Stripes corresponding the woven structure of 2-D CFC
PSL intensity [PSL/mm2]
020406080100
120
Absroption of low energy (gaseous) tritium
Cf. No stripes were observed on the front surfaceT. Tanabe et al., Journal of Nuclear Materials 313–316 (2003) 478–490
0
10
20
30
40
50
010203040
50PSL intensity [PSL/mm2]
50
40
30
20
10
0
PS
L in
tens
ity
[PS
L/m
m2 ]
inside
Outside
Tritium depth profile : observed by cross-sectional view of dome top tile in JT-60U divertor
SIMSH retention within <2.1m
~ 4.3 x 1016(/cm2)H/C at surface ~3.5 %
0
1
2
0 0.5 1 1.5 2 2.5Depth (m)
D/C
(%)
NRA_DM2_D/C(%)
0
1
2
3
4
5
0 0.5 1 1.5 2 2.5Depth (m)
H/C
(%)
Estimated H/C(%)
0
1
2
3
4
5
0 0.5 1 1.5 2 2.5Depth (m)
(H+D
)/C
(%)
Estimated (H+D)/C(%)
0
0
( H+D)/12C
H/12C
D/12C
Thin deposits on outer dome wing
NRA:D retention within 2.1m
~ 8.0 x 1016(/cm2) D/C ~ 2%(max)
Y. Oya, Y. Hirohata, et al., J. Nucl. Mater. 313-316 (2003) 209
NRA + SIMS (H+D)/C
(<2.1m) ~ 1.2 x 1017(/cm2)
(H+D)/C (<0.5m)
(H+D)/C ~ 2.5%-
11-
depth1.7mT. Hayashi et al. J. Nucl. Mater
400 600 800 1000 1200 温度 (K)
0
0.5
1
1.5
2
2.5H
2
HD
D2
400 600 800 1000 1200 温度 (K)
(1019
mol
ecul
es・m
-2・s
-1)
気体
放出
率
Inner BafflePlate Divertor
Inner Dome OuterDivertor
Outer BafflePlate
DM3,5,6,7,9
Inboard Outboard
Thermo-Couple
Inner BafflePlate Divertor
Inner Dome OuterDivertor
Outer BafflePlate
DM3,5,6,7,9
InboardInboard OutboardOutboard
Thermo-Couple
H2
HDD
2
400 600 800 1000 1200 温度 (K)
Redeposits on ID3
1000K
Eroded area OD1
1400K
0
2
4
6
8
10
12
14
BP11 BP1 ID1 ID2 ID3 DM3 DM5 DM6 DM7 DM9 OD1 OD3 BP3Removal
ID3BulkOD1Bulk
H2
HDD2
C1 group
C2,3 group
放
出気
体量
(1022
ato
ms/
m2 )
試料名
0
0.2
0.4
0.6
0.8
1
1.2
D/H
Redeposits on DM9
800K
Temperature/K
TDS measurementsD
es
orp
tio
n
rate
/ 1
019
m
ole
cu
les・
m-
2 ・s
-1
To
tal
rete
nti
on
/ 1
022
ato
ms
・m
-2
Sample positionBulk retention
Temperature reduces D/H
D/H << 5.1 (ratio of discharges numbers of DD/HH)
→ Replacement of D by H
0
2
4
6
8
10
0 2 4 6 8 10
BPIDDMODBulk
D蓄
積量
(10
22 a
tom
s・m
-2)
H蓄積量 (1022 atoms・m-2)D
ret
entio
n
D/H ~ 1.6DM 800K
D/H ~ 0.47ID 1000K
H retention
Redeposited layers on ID… Deposited at higher temp(1000K). Low D/H DM…Deposited at lower temp.(800K) High D/H (Less exchange)
1.40 × 1021 atoms·m-2·m-1
0
5
10
15
0 20 40 60 80
HDH+D
Thickness (m)H a
nd D
ret
etni
on(1
022at
oms ・
m-2
)
1.40 × 1021 atoms·m-2·m-1
0
5
10
15
0 20 40 60 80
HDH+D
Thickness (m)H a
nd D
ret
etni
on(1
022at
oms ・
m-2
)
0
5
10
15
0 20 40 60 80
HDH+D
Thickness (m)H a
nd D
ret
etni
on(1
022at
oms ・
m-2
)
Homogeneous distribution with (H+D)/C = 0.031Indicating Isotope exchange even in deep region owing to high temp.
On the Inner Divertor 1000K
Kee
pin
g n
earl
y th
e sa
me
leve
l
Above ~800K
Isotope exchange becomes easier
Bulk retention given by H2 and H0
H2 and H0
Below ~700K
No diffusion into bulk or particles
Redeposited process with hydrogen incorporation
Substrate
Starting DD discharge
Temperature
Temperature
Low High
Low
Formation of redeposited layers
Higher heat load
Lower heat load
Addition of HH discharges
After DDdischyarge
HD mixing in the layers
HD mixing near boundary only
Hydrogen retention at eroded area
Starting DD discharges
Temperature High
Eroded area with high heat load (OD)
Addition of HH discharges
Termination of DD discharges
Substrate
No depositionHigh energy implantation
Hydrogen retention and depth profile
under exposure of energetic H+ and H2 neutrals
All grains are under the same static pressure
773K
973K
623K 623~673K
Base temp.573K
Innerdivertor
Outerdivertor
Baffle platesDome
Surface temperature increase DD discharges >> HH discharges Because NBI power of HH discharges ~ ½ of that of DD discharge
Depth profiles of JT-60U divertor tilesDepth profiles of JT-60U divertor tilesTile temperature monitored by TCs installed in the tiles
Maximum Surface temperatures estimated by a finite element modeling
K.Masaki, et.al., J.Nucl.Mater., 313-316 (2003) 514
Inner divertor tile, ~1000 K
Dome unit tile~800 K
Outer divertor tile ~1400 K