An analysis of induction brazed beryllium on copper alloy substrates [JET divertor]

Abstract

A long pulse JET divertor requires the production of beryllium clad copper alloy hypervapotron target plates. Vacuum brazing of beryllium poses a number of problems relating to the stable beryllium oxide and ready formation of brittle intermetallics. Induction brazing offers some advantages and a rig has been developed for producing vapotron test target plates for power load testing in the Neutral Beam Test Bed. The brazed components have survived over 1000 shots at 13 MW/m/sup 2/ with an ultimate power loading capability up to 17 MW/m/sup 2/. These results have been interpreted with respect to both localised stresses and thermal fatigue at the interface. This study analyses the power handling capability with respect to instantaneous heat flux failure, localised hot spots from target plate deflections and high cycle fatigue with a view to establishing an optimum unit size.