Li-CPS limiter in tokamak T-11M

This paper is a review of the experimental investigations of Li-behavior as limiter material in real tokamak. All experiments were performed in tokamak T-11M with main parameters: plasma current, Ip=100 kA; duration of the discharge 0.1 s, toroidal magnetic field, B=1 T; major radius, R=0.7 m; minor radius, a=0.19–0.23 m; average electron density, ne∼(1–5)×1019 m−3 and electron temperature, Te(0)∼0.3–0.5 keV. Two moving limiters with similar geometry were installed for comparison in chamber—the conventional graphite-boron limiter and Li-limiter on the basis of capillary pore system (CPS). The Li-influx to plasma was measured by visible, UV and SX plasma emission. The main experimental results were: (a) no dramatic bursts of lithium injection at heat load close to the tokamak-reactor level, ∼10 MW/m2, were observed, (b) the total lithium erosion from limiter can be explained by deuterium plus lithium ions sputtering (self-sputtering), (c) high lithium radiation during disruptions prevent Li-limiter from high power load, and (d) the solid basis of CPS limiter had no damages after more than 200 shots with disruptions. The main effect of lithium use in T-11M was the rise of the first wall getter properties, i.e. recycling reduction for not only H2 and D2 but for He too. The temperature of hydrogen isotopes desorption was 350–400 °C and He desorption was 50–100 °C.