Li Experiments on T-11M and T-10 in Support of Steady State Tokamak Concept with Li Closed Loop Circulation

Full text: The concept of a steady state tokamak with the first wall and plasma facing components (PFC) on the basis of the closed loop of liquid Lithium circulation demands the decision of three tasks: Lithium injection to the plasma, Lithium ions collection before their deposition on the vacuum vessel and Li returning from collector to the zone of injection. For practical solution of these problems in T-11M and T-10 tokamak experiments have been applied Li and graphite rail limiters. In this report the general attention has been paid to the investigation of the Lithium collection by different limiters and the studying of Lithium ions behavior close tokamak boundary. The behaviour of Lithium in the SOL area and efficiency of its collection by limiters in T-11M and T-10 tokamaks were investigated by sample-witness analysis and also (T-11M) by use of the mobile graphite probe (limiter) as a recombination target in relation to the stream of Lithium ions. It was measured, that characteristic depth of Lithium penetration in the SOL area of T-11M is about 2 cm and 4 cm in SOL of T-10. That is equal proportional of their major radius R. The calculations by code SOL-DINA, allow to assume, that a collector of Lithium in the form of a ring limiter with width of 5cm could collect in T-11M tokamak (the small radius a = 20 cm) up to 90% of the Lithium injected by a rail limiter-emitter. The quantitative analysis of the sample-witnesses located on local rail limiters T-11M showed, that nearby 60 ± 20% of the Lithium injected during plasma operating of T-11M had been collected by lateral surfaces of T-11M limiters. It confirms a potential opportunity of collection of the main part of the injected Lithium by the limiters-collectors located in the SOL area of steady state tokamak and by that a realization of the closed loop of Lithium circulation near the tokamak first wall and solution by this way the PFC problem of steady state tokamak-reactor. (author)