The liquid lithium limiter control system on FTU

In the second half of 2005, a liquid lithium limiter (LLL) with capillary porous system (CPS) configuration was installed to test on Tokamak FTU. The liquid lithium flows through capillaries from a reservoir to the side faced to the plasma to form a thin lithium film as wall coating. The system includes three stainless steel cases, which contain two thermocouples each one. A heating system brings the Li temperature about 200 °C to allow the liquid to flow. This temperature, monitored by thermocouples, needs to be controlled.To carry out this experimental procedure, some new features have been introduced in the existent control system based on Opto22™ modules and a CORBA/PHP/MySQL software architecture. The historical data storage to keep the lithium temperature evolution has been added. Two graphical tools – developed in MATLAB™ and Java environments, respectively, to monitor the lithium temperature coming from thermocouples – have been also implemented. The LLL control system allows to regulate the heater temperature in each unit to reach operational conditions, where the temperature adjustment can be performed either automatically through a specific control law or manually by the operator. During the plasma shot the system switches off the limiter power supply to prevent instruments damage. Moreover, in the same experimental context, a first approach to automatically obtain executable code – starting from control laws designed by Simulink™ tool – has been realized.