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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. Operation time ~ 18 months in both cases. 1. 8. inner. outer. 3. 7. 5. 4. GB. 6. MKII - GB. Mark II-A
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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
Operation time ~ 18 months in both cases 1 8 inner outer 3 7 5 4 GB 6 MKII - GB Mark II-A divertor Results for MK-IIA presented on PSI-15 JET Divertors
Beryllium and Deuterium: Comparison MKII-A and GB(shadowed areas on tiles 3 and 4 are not included) MKII-GB 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). Possible reason: Shadowing due to geometrical factor (as in MKI divertor) 1 6 4 3 D Be D Be 8 7 MKII-A
SEPTUM a a: three support plates b: septum (divider) plate b
Deposition on the GB tiles Central plate C-end D-end Thick deposit Shadow after the IPP deposition monitor
INNER Deposition on the divider plates OUTER
D A Deposition on the septum tiles:Central support plate
C B Deposition on the septum tiles:Central support plate
Top INNER Central plate End rib “Base” Base Dusty Deposition on the divider plates: Inner divertor
Deposition on the divider plates: Outer divertor OUTER End rib Base Top Central plate “Base”
Deposition on the septum tilesSummary 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).