Drive to generate digital current for control vertical field in a small Tokamak

The horizontal position of a small Tokamak plasma has been controlled by a circuit to generate the control vertical field. The circuit must respond quickly to the position signal from a feedback circuit and feed a large current in a short time. We have assembled the circuit to generate a digital current called a drive. The drive includes several units, and each unit is made up of a capacitor, a transistor, a protective resistor and a comparator. We have installed the drive on a small Tokamak, the Hamana-T and obtained satisfactory results. The performance of the drive is described.