Abstract
A plasma horizontal position feedback control system (PHPFCS) and a digital current dirve (DCD) for control vertical magnetic field are made on an experimental base and the horizontal position of a plasma in a small tokamak (HAMANA-T) is controlled by PID operations from the initial phase of plasma generation. DCD consists of constant-current discharge units for plural condensers and drives a digital current analogous as a whole to the control signal of PHPFCS in the range of ± A. The maximum value of the digital current increases in proportion to the number of units. This PHPFCS elongates plasma duraton from 1.3 ms to 2.1 ms, makes smooth the wave form of plasma current and reduces plasma loop voltage from 25 V to 20 V. Furthermore, PHPFCS reduces the range of variation in plasma horizontal displacement from 3.5cm to within 0.5cm and makes it possible to set accurately the horizontal position from the initial phase in inner region of a vacuum chamber.
