t loarer – tfe meeting – 20 february 2004 1 tore supra association euratom-cea gas balance -...
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T Loarer – TFE meeting – 20 February 2004 1
TORE SUPRA
AssociationEuratom-Cea
Gas Balance - fuel retention in JET
T Loarer, J Bucalossi, D Brennan*, G Matthews*, V Philipps°, P Morgan*, M Stamp* , E Tsitrone
and JET-EFDA Collaborators
Association EURATOM-CEA, DSM-DRFC, CEA Cadarache,
13108 St Paul lez Durance, France
*Euratom-UKAEA Association, Fusion Culham Science Centre,
Abingdon,OX14 3EA, UK.
TORE SUPRA
AssociationEuratom-Cea
T Loarer – TFE meeting – 20 February 2004 2
TORE SUPRA
AssociationEuratom-Cea
Assessment of fuel retention in JET
Aim: perform a gas balance with the maximum accuracy• Divertor Cryopump regeneration just before and just after the session (+
gas analysis)• no NBI (no LHCD) to avoid NBI Box (LHCD) pumping• no disruption• high D2 fuelling rate and maximum pulse rate
Reference pulse # 61751: 2MA/2.43T, 5-6MW ICRH, high density• Gas ~6 Bar.l, with QMB…• dry run with gas puff (to check divertor pumping speed)• 40 pulses at 6 Bar.l/pulse ~ 240 bar.l (reasonable for PCD and GB)
T Loarer – TFE meeting – 20 February 2004 3
TORE SUPRA
AssociationEuratom-Cea
6th February39 consecutive and repetitive discharges# 62887 to 62926 DOC-L and L-modeIp=2MA
BT=2.4T
ICRH =3MW <ne>=3.8 1019m-3
Gas rate~1.5 1022 Ds-1 ~4.3 Bar.l per discharge
Steady state ~ 11s.
T Loarer – TFE meeting – 20 February 2004 4
TORE SUPRA
AssociationEuratom-Cea
Overall gas balance
Total injected : 159.6 Barl (from PPF data) – 170 Barl from (AGHS)
Total recovered : 171.9 Barl (from AGHS – regeneration N°PD-493)
Balance : Excess of 12 Barl. Equilibrium assumed in a first approximation.
The outgasing between pulses is calculated
- Neutral pressure in the vessel (DPF when available): PRES/PEN3
- Resulting pumping speed of the cryopump in the vessel: Scryo_vessel=125m3s-1
Balance during the dry run : Pressure and time constant : very good agreement
For these pulses : outgasing between discharges ~ 15% of the injected flux
Exhausted flux during the pulse adjusted
during the pulse : retention of 15% of the injected flux
T Loarer – TFE meeting – 20 February 2004 5
TORE SUPRA
AssociationEuratom-Cea
Particle fluxes : Gas injection only by - GIM 7 : ~2/3- GIM 8 : ~1/3(top of the machine)
Retention :(puff exh)/ puff ~ 15%
Particle balance for one typical discharge of the series # 62925
T Loarer – TFE meeting – 20 February 2004 6
TORE SUPRA
AssociationEuratom-Cea
Balance
- Injected : 4.48 Bar.l- Pumped :3.81 Bar.l- Wall : 0.67 Bar.l
Outgasing after the pulse : 0.67 Bar.l
Integral particle balance # 62925
If we assume that the pumped flux is consistent for this series What are the consequences for the “old” data ?
T Loarer – TFE meeting – 20 February 2004 7
TORE SUPRA
AssociationEuratom-Cea
Comp. with the ref. pulse 61751(Nov 2003)
Psub_div61751 < Psub_div62925
Scryo61751= Scryo62925
Since Inj61751>Inj62925
Ret # 61751 (35%)> # 62925 (15%)
Difference from plasma geometry ? 5.95 Barl
4.5 Barl
T Loarer – TFE meeting – 20 February 2004 8
TORE SUPRA
AssociationEuratom-Cea
Particle balance for the reference pulse # 61751
-Particle fluxes : Gas injection by - GIM 8 : ~1/2 (top) GIM 10 : ~1/2 (Div Out Ring)
Retention :
30% @ t~58 sec50% @ t~60 sec
T Loarer – TFE meeting – 20 February 2004 9
TORE SUPRA
AssociationEuratom-Cea
Balance
- Injected : 5.95 Bar.l- Pumped :4.14 Bar.l- Wall : 1.78 Bar.l
Retention at the end of the pulse : 30%
Integral particle balance reference pulse # 61751
Outgasing after the end of the pulse…
T Loarer – TFE meeting – 20 February 2004 10
TORE SUPRA
AssociationEuratom-Cea
Recovery after the reference pulse…
Ref pulse Series
Pvessel61751 < Pvessel62925
Less particles recovered…after the pulse with the highest retention!
T Loarer – TFE meeting – 20 February 2004 11
TORE SUPRA
AssociationEuratom-Cea
Figure to be revisited…1.0
0.8
0.6
0.4
0.2
0.0
Ret
enti
on
1086420
puff (1022
s-1
)
H mode (6 MW) H mode (17 MW) H mode Reversed B L mode Long (4 MW)
but not a « simple » drop of the values !
T Loarer – TFE meeting – 20 February 2004 12
TORE SUPRA
AssociationEuratom-Cea
Conclusions In the light of these results
- Speak to the experts on gas injection (going on)- Geometry of the plasma to be considered (DOC-L, U…)- Revisit the previous results on the retention
- cryopump regeneration and pressure gauge calibrations - Consistency with the 40% of tritium retention during the first phase
of the DTE1 ?
- Scryo to be adjusted with regards to the plasma geometry in the divertor ? -Repeat (?) under different conditions - Long discharges in JET : increase plasma duration = increasing of the outgasing flux between pulses ? (~ No effect in Tore Supra) - Geometry on the particle retention
- Strong fueling (7-8 1022s-1) H-mode...
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