Fatigue life of the plasma-facing components in PULSAR

The PULSAR project is a multi-institutional effort to determine the advantages that can be gained by building a tokamak with an entirely inductive current drive. This machine, which would operate in a pulsed mode, would feature reduced capital and operating costs compared with steady-state devices requiring complex current drive systems. However, a pulsed reactor would need an energy storage system and face greater structural demands from cyclic fatigue. This paper presents the results of the fatigue analyses for the plasma-facing components of PULSAR. PULSAR features two major engineering designs: a liquid lithium-cooled vanadium alloy design and a helium-cooled silicon carbide composite design. Results are given for each. It is shown that the superior thermal and strength properties of the vanadium alloy allow a much wider spectrum of design options. The SiC composite properties cause significantly more difficulty for the designer and, in particular, no credible design is found for a divertor fabricated solely from the SiC composite. This conclusion is based on current (limited) data for the thermophysical properties and fatigue strength of SiC fiber composites. The developments in these composites needed to create a viable SiC composite diverter are discussed.