First experimental results with tin limiter on FTU plasma.
Apruzzese G., Apicella M.L., Iafrati M., Mazzitelli G., FTU Team
In the framework of the liquid metal research it has been taken into account the use of liquid metals as plasma facing materials in fusion devices. Two different materials have been studied in the Frascati Tokamak Upgrade (FTU): lithium and tin. Since 2006, a liquid lithium limiter has been tested on FTU and the successful experiments and the promising results have pointed out the importance to explore other liquid metal materials for the limiter such as tin whose operating window is much larger than lithium. The possibility to increase the operation temperature allows increasing the steady-state heat load on the limiter surface up to very high values. The tin limiter has been tested on FTU in the last experimental campaign which started at the end of 2016. FTU is the first tokamak in the world operating with liquid tin limiter and one of the pioneers in liquid metal application. The preliminary analysis of the experimental data has been focalized to detect the presence of tin in the discharge: suitable monitors are the spectroscopic diagnostics in the visible range. The experimental observation of the tin spectral lines represents a new goal for extending the database of atomic nuclear data in the plasma tokamak research. In particular, 607.8 nm and 645.3 nm spectral lines of SnII have been observed. The results obtained during the first experiments with the tin limiter in FTU will be presented.