HIGH-Z PLASMA-FACING AND RELATED MATERIALS

The status of technical assessments on the suitability and issues of candidate high-Z materials is reviewed. The W-based alloys are considered attractive despite a few technical concerns. Use of Mo-based alloys is rather limited due to their relative sensitivity to irradiation embrittlement and high erosion rate. Cu-based alloys can meet the imposed requirements as a heat sink material provided that more investigation on radiation resistance and properties of brazed Cu/high-Z material zone are made in detail. The R&D activity plans provide for completion of the 1st stage of the conceptual design in 1990 including the choice of the divertor material, the radiation tests, and mock-up test as well. It is expected that efficient divertor structures on the basis of high-Z materials can be created using data and experimental opportunities available in 1991-1995.