Analysis of fuel retention on MAST by global gas balance

Analysis of fuel retention on MAST by global gas balance

Analysis of fuel retention on MAST by global gas balance 150 150 Mathew

Analysis of fuel retention on MAST by global gas balance

The retention of deuterium fuel during MAST discharges has been studied using the method of global gas balance. The results show that with inter-shot 4 He- GDC, the total number of particles retained for a discharge increases with total number of injected particles, and the total retention fraction stays very high, mostly around 80%, and can be almost 100%. However, it is observed that disruptions can reduce the wall inventory. With inter-shot 4 He-GDC to recondition surfaces on MAST, the retention for all shots analyzed has not been observed to saturate, while if there is no 4 He-GDC before a shot, the following plasma density can become uncontrollable owing to lower wall pumping capacity. This indicates a majority of injected particles is retained in the walls/divertors during each discharge and most of them can be recovered with 4 He-GDC, suggesting that on the short time-scale of MAST pulses, the particle balance is dominated by dynamic retention, which is mostly attributed to direct implantation of ions and neutral particles in a shallow surface layer.

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01/01/2010