Materials requirements for high heat flux components

In-vessel components in all types of fusion devices are exposed to both high heat and high particle fluxes. Increased pulse lengths and high levels of auxiliary heating power in machines now coming on line and in various states of planning pose new demands on materials. The requirements of heat removal combined with constraints posed by plasma-materials interactions lead to problems of materials selection, development, characterization, fabrication and testing. Specifications for components in current and future machines are summarized, and heat removal technology in regimes applicable to fusion components is reviewed. Possible solutions to materials problems encountered in the design of high heat flux components are shown in a review of some recent pump-limiter design studies. Finally, development needs and some of the test facilities being developed to help address them are discussed.