Fusion Science and Technology / Volume 48 / Number 1 / July 2005 / Pages 306-309
Technical Paper / Tritium Science and Technology - Tritium Handling Facilities
A series of 39 consecutive and repetitive discharges (Ip = 2MA, BT = 2.4T, <ne> = 3.8 × 1019m-3, gas rate ~1.5 × 1022 Ds-1 and with 2.8 MW of ICRH over a duration of 11s) has been performed in JET for a full day in order to study the particle retention behaviour as a function of the wall inventory and the global balance for a significant number of discharges associated to a high gas injection. Since the active pumping was achieved using the divertor cryopump only, its regeneration has allowed a direct calibration of the value of the pumped particle flux to be used in the particle balance analysis during the plasma operations for the "DOC-L" configuration. Taking into account the outgased flux between the discharges, the resulting wall inventory over the full day of operation is zero. During, the 11 sec of the ICRH power, about 8 % of the particles injected are retained in the machine equilibrated by a particle recovery between of 8% of the quantity injected. This shows that the gas released between pulses has been overestimated in previous JET gas balance analysis and that the particles trapped in the machine are localised in areas which are outgasing between the discharges.