Centralised Coordinated Control to Protect the JET ITER-like Wall
The JET ITER-Like Wall project (ILW) replaces the first wall carbon fibre composite tiles with beryllium and tungsten tiles which should have improved fuel retention characteristics but are less thermally robust. An enhanced protection system using new control and diagnostic systems has been designed which can modify the pre-planned experimental control to protect the new wall. Key design challenges were to extend the Level-1 supervisory control system to allow configurable responses to thermal problems to be defined without introducing excessive complexity, and to integrate the new functionality with existing control and protection systems efficiently and reliably. Alarms are generated by the Vessel Thermal Map (VTM) system if infra-red camera measurements of tile temperatures are too high and by the plasma wall load system (WALLS) if component power limits are exceeded. The design introduces two new concepts: local protection, which inhibits individual heating components but allows the discharge to proceed, and stop responses, which allow highly configurable early termination of the pulse in the safest way for the plasma conditions and type of alarm. These are implemented via the new Real-Time Protection System (RTPS), a centralised controller which responds to the VTM and WALLS alarms by providing override commands to the plasma shape, current, density and heating controllers. This paper describes the design and implementation of the RTPS system which is built with the Multithreaded Application Real-Time executor (MARTe) and will present results from initial operations.