IMPLICATIONS OF STEADY-STATE OPERATION ON DIVERTOR DESIGN

As fusion experiments progress towards long pulse or steady state oper ation, plasma facing components are undergoing a significant change in their design. This change represents the transition from inertially c ooled pulsed systems to steady state designs of significant power hand ling capacity. A limited number of Plasma Facing Component (PFC) syste ms are in operation or planning to address this steady state challenge at low heat flux. However in most divertor designs components are req uired to operate at heat fluxes of 5 MW/m(2) or above. The need for da ta in this area has resulted in a significant amount of thermal/hydrau lic and thermal fatigue testing being done on prototypical elements. S hort pulse design solutions are not adequate for longer pulse experime nts and the areas of thermal design, structural design, material selec tion, maintainability, and lifetime prediction are undergoing signific ant changes. A prudent engineering approach will guide us through the transitional phase of divertor design to steady-state power plant comp onents. This paper reviews the design implications in this transition to steady state machines and the status of the community efforts to me et evolving design requirements.