Development of Candidate High Heat Flux Components for Steady State Operation of the EAST Device

J.L. Chen (Sp), J.G. Li, H. Li, Q.G. Guo, Chinese Academy of Sciences, Hefei (China); N. Noda, National Institute for Fusion Science, Toki-shi (Japan) 
EAST is a superconducting tokamak, now under construction in ASIPP as a National project in China, which will operate in high power and steady state, and impose severe requirements on plasma facing components (PFC). There are three aspects important: 1) PFM has high enough thermal conductivity, which can fulfill the criteria to exhaust the high power deposit on PFC and can meet the requirements of surface temperature constraints; 2) Erosion resistance is also very important, which directly related to the lifetime of plasma facing components and plasma recycling control. 3) Integration behavior of PFC under actively water-cooled conditions.
A series of multi-element doped graphite has been developed for the first wall, and a super carbon sheet has been chosen as compliant layer to improve the thermal contact and minimize the surface temperature; Contrary to CBM, SiC has much lower chemical and high-temperature sputtering, is capable of oxygen gettering and lower hydrogen recycling. The behavior of thick SiC gradient coatings on different CBM under steady state and pulsed high heat flux, and HT-7 limiter plasma irradiation was investigated.
Tungsten is now under development being considered as one of the promising candidate materials for the divertor plate of EAST device, several joining methods have been developed, 2mm thick tungsten tile brazed or direct by blast compound to copper alloy heat sink with functionally gradient layer, a modeling for residual stress analysis has been established and high heat flux experiments have also been finished, a small mock-up possess good performance, a large module is now under way. In the above experiments, the samples were examined with respect to the temperature distribution, changes of surface morphology, surface atomic composition and etc.

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