Improvement, commissioning and operation of the JET Pellet Centrifuge

The target design parameters of the JET Pellet Centrifuge are pellet repetition frequencies up to 10 Hz with a velocity range 100-500 ms^-1. Prior to the 1997 the performance was not reliable, the 4 mm cubic pellets of deuterium ice were often undersize and the efficiency of delivery low. A number of mechanical design changes and improvements to control systems have subsequently been made, culminating in successful exploitation of the centrifuge in the 1998-9 JET programme. The system and its recent improvements will be discussed. Finally, an in-vessel track for high-field side pellet launch, installed in the 1999 shutdown, will be described. Operational experience and performance for inboard and outboard pellet injection into JET plasmas will also be presented