ASIPP
EAST
H2 level on EAST with full
carbon walls
J.S Hu, J.G Li and EAST vacuum group
[email protected]
Institute of Plasma Physics, Chinese Academy of Sciences,
Hefei, Anhui 230031, China
Sept. 15-18, 11th ITPA-SOL/DIV meeting, Nagasaki, Japan
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Outline
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Introduction
Pump down
Plasma operation
summary
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Main parameters of EAST
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Plasma major radius
Plasma minor radius
Vessel height
Vacuum volume
Plasma volume
Carbon walls
Pumps
– 4 turbo pumps
– 10 outer Cryopumps
– New inner Cryopump
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1.86m
0.45m
2.6m
~ 40m3
~ 13m3
~60m2
~12m3s-1
~130m3s-1 for H2 (Nominal)
~110m3s-1 for H2
New carbon Plasma facing components
– First wall, Divertor, Movable limiters and antennas guard limiters
– Hot N2 baking/Actively water cooling
– 60m2 carbon walls
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Wall cleanings/conditionings
– GDC cleaning
– ICRF cleaning
– Boronization
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Reliable Plasma Operation
DN, SN, Ip = 0.6 MA, Bt = 2-3.5 T, t > 20s, k=1.6-1.96, D= 0.3-0.6
k = 1.96, D=0.3
k = 1.8, D=0.5
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Normal target plasma
HT-7
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Pump down
•H2 base pressure depended on PFCs Temp. and He-GDC procedures;
•During 112.5hr. He-GDC(0.5Pa, 3A, different wall Temp.), H2 removal was
about 5.85x1023.
•H2 release rate was about few 1015/m2.s before start plasma
operation(Temp.~50oC);
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During plasma experiment
•Base release rate of H2 was ~1015/m2.s;
•H2 base pressure depended on Plasma operation and wall conditionings;
•H2 removal was ~1.1x1023 by 2778min. He-ICRF(5x10-3Pa, 20kW, ~50oC );
•H2 removal was ~0.8x1023 by 780min. D2-ICRF(5x10-3Pa, 20kW, ~50oC ).
•After boronization, its need a few days to recovery H2.
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H2 pressure during plasma discharges
•After plasma discharges, H2 pressure depended on plasma
parameters, such as heating power, duration, density, et.al.
and also depended on wall statues, specially on
boronization.
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H2,D2 Release/removal rate
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Ha evolutions during plasma operation
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H2/(H2+D2) in release gases
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EAST
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H2/(H2+D2), H2 and D2 removal
Before 1st
boronization(Jul.7)
After
boronization(Aug.6)
18 days after 2nd
boronization(Aug.5)
Without
LHCD
20－30KA
~130ms
Max.LHCD(500kW)
Longest Pulse:
250kA/>20s
400kA/>10s
Max.LHCD(500kW)
100-300kA
~6s
Shots number
25
93
97
Time (min.) (Include
interval of discharges)
243
740
890
Plasma parameters
Average H2/(H2+D2)
5%
82%
H2 removal/m2.shot(1018)
0.4
20
6.5
D2 removal/m2.shot(1018)
7
4.5
6.6
50%
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Summary
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During plasma discharges, H2 release depended on plasma parameters,
wall statues and pumps.
Boronization(C2B10H12) strongly influenced on H2 release.
H2/(H2+D2) was in a large range of 5% to 90%, depended on plasma
parameters.
– Before boronization ~5%
– After Boronization near to 90%
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H2 release without plasma discharge
– Release rate at ~50oC were about few 1015/ m2.s
– During 200oC baking ~3x1017/m2.s
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H2 release during wall conditionings depended on gas load on walls.
– He-GDC, He-ICRF and D2-ICRF ~1016-18/m2.s
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During plasma discharges, H2 release rates were about 1018-20/m2.shot.
– Before boronization ~4x 1017/m2.shot(10ms-1s, without LHCD)
– After Boronization ~2x1019/m2.shot(6s-20s, Max.LHCD 500kW)
– 18days after Boronization ~6.5x1018/m2.shot(~6s, Max.LHCD 500kW)
• ~1018/m2.s
• Water and CxHy should be considered.