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-11 M 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) similar to (1-5) x 10(19) m(-3) and electron temperature, Te(0) similar to 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, similar to 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-11 M 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 degreesC and He desorption was 50100 degreesC. (C) 2003 Published by Elsevier Science B.V.