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Deposition in the MKII - Gas Box DivertorDeposition in Septum
M. Rubel, P. Coad, J. Likonen
OUTLINE
• General deposition pattern on MKII-GB tiles
• Septum
• Summary
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JET Divertors
Results for MK-IIA presented on PSI-15
1
43 5
67
8
GB
inner outer
MKII - GB
Operation time ~ 18 months in both cases
Mark II-A divertor
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Beryllium and Deuterium: Comparison MKII-A and GB
(shadowed areas on tiles 3 and 4 are not included)
0
5
10
15
20
25
30
D a
nd
Be
(e
18
/cm
2)
Be e18
D e18MKII-GB
0.00
5.00
10.00
15.00
20.00
25.00
30.00
1
DIVERTOR TILE (POLOIDAL DIRECTION)
D a
nd
Be
(e
18
/cm
2)
D (e18)
Be (e18)
1
10987
65
4
2 3
MKII-A
1
3 4 6
7 8
DBe
DBe
Major differences:
D/Be ratio < 1 on MKII-A
D/Be ratio > 1 on MKII-GBPossible reason:Cleaning after DTE-1 to reduce T level.
Significant co-deposition (and fuel inventory) in the shadowed corner of the outer divertor (tile 6).Possible reason:Shadowing due to geometrical factor(as in MKI divertor)
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SEPTUM
a
ba: three support platesb: septum (divider) plate
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Deposition on the GB tiles
C-end
D-end
Central plate
Thickdeposit
Shadow after the IPPdeposition monitor
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Deposition on the divider plates
INNEROUTER
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Deposition on the septum tiles:Central support plate
AD
0
2
4
6
8
10
0 50 100 150 200POLOIDAL POSITION [mm]
D a
nd
Be
[10e
18/c
m2]
Be e18
D e18
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BC
0
5
10
15
20
25
0 50 100 150 200POLOIDAL POSITION [mm]
D a
nd
Be
[10e
18/c
m2]
Be e18
D e18
Deposition on the septum tiles:Central support plate
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Deposition on the divider plates: Inner divertor
0
0.5
1
1.5
2
0 20 40 60 80 100 120"Toroidal" position [mm]
D a
nd
Be
[10e
18/c
m2]
Be e18
D e18
“Bas
e”
Top
Base
Cen
tral plate
En
d rib
Dusty
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0
0.5
1
1.5
2
0 20 40 60 80 100 120"Toroidal" position [mm]
D a
bd
Be
[10e
18/c
m2]
Be e18
D e18
“Bas
e”
Base
Top
Central plate
End rib
Deposition on the divider plates: Outer divertor
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Deposition on the septum tiles Summary
Deposition on the plates is mainly seen in the near-plasma region from the inner divertor side (up to 25 mm from the edge).
Thick deposits (> 50 m ?) only on a side of one plate (C-end).
Little deposition deep inside the Gas Box (thin deposit, d < 10 m).
Little deposition on the divider plate (thin deposit, d < 10 m) .
Small content of beryllium in the Gas Box.
No C-13 (above the background level) found on the plates.
Gas Box plates can not be considered as the major trap for transported and re-deposited material.
The results also indicate that the direct across-divertor transport is negligible (if any).