Pellet injection on START and MAST

Cryogenic pellet injection has been used in START and it is under commissioning for MAST for fuelling and diagnostics. In START NBI, heated plasmas fuelled with deuterium pellets, high normalized density (Greenwald number NG<=1.1) with good energy confinement time (?_E/_?Eelmf^ITER97<=1.3) both at high beta (?_T<=25%, ?_N<=4.9) have been obtained for time scales close to the energy confinement time (~?E). In addition, high fuelling efficiency (~100%) have also been simultaneously observed. A complete pellet injection programme is currently under development in MAST, including the commissioning of a eight pellet injector, technical aspects of launching pellets through guide tubes, dedicated diagnostics, and modelling.