Control and data acquisition system for multi-barrel pellet injector

A control and data acquisition system has been developed for the Mega-Amp Spherical Tokamak (MAST) multi-barrel pellet injector to allow reliable operation with multiple pellet sizes. The system operates with one PC running Windows NT with four embedded PCI cards. All measurements and control functions are implemented on a PC. The system software consists of two programs. The first program provides pellet firing and registration of up to four fast signals associated with each pellet–pellet speed, mass, and other signals. The second program controls pellet preparation and all the pellet injector equipment. This program is realised as state machine—allowing a sequence of any number of states, it includes independent digital PID control of the temperature of each barrel. Both programs run conjointly using message exchange. The system is integrated and synchronised with the MAST control and data acquisition systems.