Thermal Response of Bonded CFC/OFHC Divertor Mock-Ups for Fusion Experimental Reactors under Large Numbers of Cyclic High Heat Loads

Abstract

Plasma facing components for fusion experimental reactors such as the ITER/FER will be exposed to severe heat loads under high heat flux and large number of thermal cycles. From the engineering point of view, divertor mock-ups with different armor tile materials have been prepared in order to investigate their overall performances, in particular an adhesive property between the armor tile and the heat sink metal. Thermal cycling tests of the divertor mock-ups have been carried out under ITER/FER relevant heat flux conditions in a particle beam engineering facility at JAERI. As results of the tests, it has been confirmed that boned carbon-fiber-composite/copper (CFC/OFHC) divertor mock-ups have resisted to 10.0 MW/m2 for 1,000 cycles without cracks. At this experimental condition, the integrity and the durability of the bonds have also been confirmed. Furthermore, some bonded CFC/OFHC samples have resisted to 12.5 MW/m2 for 1,000 cycles without increase of the surface temperature, although a small crack was observed at a corner of the bonded layer. Residual stress from brazing has also been analyzed for three-dimensional models. The analytical results were not different in the results of manufactured test samples that no cracks or detachments in many samples were observed.