A real-time current driving control system for the TJ-II coils

摘要

Since the start of plasma operation in the TJ-II stellarator, the required values of DC currents that are fed to its different coil sets have been controlled to high precision along the complete discharge flat-top. As a result each current configuration produced a highly stable magnetic-field configuration.rnRecently, the configurational flexibility of the TJ-II has been broadened by the commissioning of a new mode of operation that allows magnetic configurations to be varied dynamically during the discharge flattop. In order to achieve this, new hardware and software features have been added to the TJ-II Control System. These new features may also provide new strategies for feedback control in accordance with parameters measured in one or more diagnostics. In this new set-up, coil current profiles are generated and controlled to millisecond timescales by a system based on VMEbus and OS9 real-time operating system. A new communication middleware architecture called XML-based Messages Distribution Service (X-MDS) has been designed to exchange XML-based data with calling clients. Furthermore, with this software, a fully functional Java application for supervision and for current profiles settings has been developed.rnThis paper provides a detailed description of the complete TJ-II real-time current-profile control system and results obtained during its operation.