1. Deposition in the MKII - Gas Box Divertor Deposition in Septum
M. Rubel, P. Coad, J. Likonen
OUTLINE
General deposition pattern on MKII-GB tiles
Septum
Summary

2. JET Divertors MKII - GB 1 4 3 5 6 7 8 inner outer
Results for MK-IIA presented on PSI-15 1 4 3 5 6 7 8 GB
inner
outer
MKII - GB
Operation time ~ 18 months in both cases
Mark II-A
divertor

3. Beryllium and Deuterium: Comparison MKII-A and GB (shadowed areas on tiles 3 and 4 are not included)
MKII-GB
MKII-A 1 3 4 6 7 8 D Be
Major differences:
D/Be ratio < 1 on MKII-A
D/Be ratio > 1 on MKII-GB
Possible 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).
Shadowing due to geometrical factor
(as in MKI divertor)

4. SEPTUM a
a: three support plates
b: septum (divider) plate b

5. Deposition on the GB tiles
C-end
Central plate
D-end
Thick
deposit
Shadow after the IPP
deposition monitor

6. Deposition on the divider plates
INNER
OUTER

7. Deposition on the septum tiles: Central support plate

8. Deposition on the septum tiles: Central support plateB C

9. Deposition on the divider plates: Inner divertor
“Base”
Top
Base
Central plate
End rib
Dusty

10. Deposition on the divider plates: Outer divertor
End rib
Base
Top
Central plate
“Base”

11. 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 mm ?) only on a side of one plate (C-end).
Little deposition deep inside the Gas Box (thin deposit, d < 10 mm).
Little deposition on the divider plate (thin deposit, d < 10 mm) .
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).