First Operational Experience with the new Plasma Position and Current Control System of JET

The Pumped Divertor phase of JET involves the use of plasma configurations with complex control requirements. Therefore a new Plasma Position and Current Control system (PPCC) has been developed. It consists of two separate subsystems: Vertical Stabilisation (VS) and plasma Shape and Current Control (SC). SC performs a real time calculation of the plasma boundary using the Xloc algorithm [1]. It uses a full multivariable decoupling control algorithm which is applied to a combination of plasma wall-gaps and currents directly controlled [2]. SC and VS were brought into operation during the past months. The paper describes the operation of the system and reports on the performances achieved during the 1994 campaign.