Li3: first step studies of a liquid lithium limiter

Carbon (graphite) is the most popular material in use for todayʹs Tokamak first wall components. However, there are real concerns as to its ability to sustain reactor grade conditions, and alternative concepts are envisaged for future fusion reactors. One is the use of a liquid metal surface, which offers several attractive advantages: direct removal of the heat, high pumping capability, insensibility to neutron irradiation, self repairing in case of over-heating, etc. A preliminary study of a liquid lithium limiter has been carried out for Tore Supra, the only Tokamak that has been equipped from its first day of operation with actively cooled first wall elements (with carbon and CFC surfaces). This study is for a relatively small limiter module, with the aim of characterising the interaction of a high performance plasma with a liquid surface in fusion relevant conditions. Up to 5 l/s of liquid lithium flows over a 0.5 m2 surface, during 20–100 s. The heat removal capability of such a module could reach 1 MW steady state, with a maximum heat flux of 6 MW/m.