JT-60U Plasma Control System

Abstract

A review on the plasma position and current control system for the JT-60 upgrade is presented. In the control system, advanced digital technologies such as the versa module Europe bus, the computer automated measurement and control technology, and Ethernet are applied to fast equilibrium control of the vertically elongated divertor plasmas. The delay of the overall feedback loop with a sampling period of 0.25 ms is <1.3 ms, including the delay of the power supply for the horizontal field coil. Multivariable control with matrix gain has been adopted in the system for decoupling control of the equilibrium parameters such as the plasma current and the horizontal position. The idea of an “algorithm number preprogram” was newly introduced into the control system for more flexible control. This made it possible to dynamically switch the control algorithms at any time of plasma pulse discharge. Several experiences in plasma control are presented. The development of a real-time plasma shape visualization system for advanced monitoring and control is also described.