The digital control system for the TCV Tokamak

Abstract

A new digital feedback control system has been developed, integrated and used successfully to control the TCV plasma. The system is designed to be modular, distributed, and easily expandable, accommodating hundreds of diagnostic inputs and actuator outputs. It offers the possibility to design advanced control algorithms using more information on the plasma state, as well as the ability to control all TCV actuators, including PF coils, gas valves, the gyrotron powers and launcher angles of the ECRH/ECCD system, as well as diagnostic triggering signals. The system consists of multiple PC nodes connected to a sharing memory network. The control algorithms are programmed as block diagrams in Simulink. Using Embedded Coder, the C code is generated automatically from the Simulink model, then compiled into a Linux shared library (“.so” file) and copied to target nodes. When the TCV discharge is progressing, an application on each node is executed and dynamically loads the shared library at runtime. During the real time process, to dedicate the whole CPU performance for the algorithms, all interrupts to the CPU on each node are suspended. Since its inception, the new digital control system has enabled a multitude of plasma control applications, ranging from basic experiments of coil current and density control to advanced experiments of MHD and plasma profile control, as well as real-time plasma transport simulations. This paper presents the architecture of the new control system and its integration into the TCV plant.