Li-CPS limiter in tokamak T-11M

摘要

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, I_p = 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, n_e ～ (1―5) x 10~(19) m~(-3) and electron temperature, T_e(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/m~2 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 H_2 and D_2 but for He too. The temperature of hydrogen isotopes desorption was 350―400℃ and He desorption was 50―100℃.