Ra 1 AMELIORATION OF PLASMA-MATERIAL INTERACTIONS AND IMPROVEMENT OF PLASMA PERFORMANCE WITH A FLOWING LIQUID LI LIMITER AND LI CONDITIONING ON EAST

The use of lithium conditioning with multiple techniques, i.e. flowing liquid lithium limiters and lithium injection, has contributed to the achievement of H-mode discharges with greater than 100 s pulse length; new results are described from several of these techniques. First new results from two designs of a midplane flowing liquid lithium limiter and associated experiments in EAST are presented, comparing against the first generation results. Generation 2 used the same stainless steel-coated copper heat sink as used in Generation 1, with a thicker stainless steel protective layer, while Gen. 3 was fabricated from solid TZM, a molybdenum alloy. Gen. 2 and 3 were exposed to higher current plasmas and substantially higher auxiliary heating power than Generation 1, and plasma performance was generally improved. In addition ELM elimination was achieved with the use of real-time lithium injection in discharges that used the upper tungsten divertor, extending previous results with the lower carbon divertor. A marked reduction in the W sputtering source was also observed with Li powder injection. Finally the ability of lithium granules to trigger and pace ELMs is documented, along with the observation of a critical granule size threshold for ELM triggering as conceptually predicted by theory.