Heat transfer characteristics of the first wall with graphite sheet interlayer

Aiming at a design study of the first wall structure for next fusion devices and cost-down, the heat transfer characteristics of the first wall structure with CFC tiles bolted to a heat sink were investigated with a variety of graphite sheets and fixing-bolt torque conditions. The heat load tests of the mock-up were performed with the heat fluxes of 1 and 3 MW/m2 on JAEA electron beam irradiation system. The experimental results showed that the first wall structure with 0.1-mm thickness × 3 PGSs (Pyrolytic Graphite Sheet; Panasonic Co., Ltd.) had the highest heat transfer performance. Furthermore, the first wall structure with the PGSs withstood the heat fluxes of 1 MW/m2 × 100 s and 3 MW/m2 × 20 s. The maximum surface temperatures of the CFC tile were 500 °C, 800 °C, respectively. These results indicated that the bolted tile structure with the graphite sheets can be utilized as the first wall at the long pulse operation with the heat flux of several MW/m2.