Designing the Plasma Vertical Position Control System in the KTM Tokamak

Abstract

The Tokamak KTM plant with the aspect ratio of A = 2 and a plasma current of around 750 kA, which is being put into operation in Kurchatov (Kazakhstan), will be able to produce heat loads on the tested samples of materials that are characteristic of the ITER plant, and owing to additional HF heating the plasma pulse duration will reach about 4 s. One of the stages of this work involves studies aimed at obtaining an efficient plasma vertical position control system. The system includes special fast control windings located between the toroidal winding and the inner chamber, and also a fast-acting power supply with feedback. Currently, the tokamak inner chamber with all main systems and windings has been assembled, and a plasma discharge with duration of about 100 ms has been obtained in the limiter configuration. To support operation of the plasma vertical position control system, an own power supply has been designed and assembled, which consists of a thyristor rectifier connected in series with a controlled voltage inverter on IGBT transistors, which has a significant margin in power and response speed. Preliminary computation experiments were carried out in the MATLAB environment, which have confirmed the adequacy of the selected power supply and the system for discharging the energy stored in the windings to the water-cooled ballast resistance. With the remaining tokamak systems having sequentially been put into operation and the first experimental data on plasma motion characteristics in the divertor configuration having become available, it is planned to carry out a series of program experiments aimed at developing and optimizing the feedback system controller algorithm in the power supply of the KTM tokamak fast control windings.