The plasma facing components (PFCs) in energy producing fusion devices will experience 5-15 MW/m2 surface heat flux under normal operation (steady-state) and off-normal energy deposition up to 1 MJ/m2 within 0.1 to 1.0 ms. Refractory solid surfaces represent one type of PFC option. These PFCs are envisioned to have a refractory metal heat sink, cooled by helium gas, and a plasma facing surface, consisting of an engineered refractory metal surface or a thin coating of refractory material that minimizes thermal stresses. The materials being considered include tungsten alloys. Grant applications are sought to develop: (1) innovative tungsten alloys having good thermal conductivity , resistance to recrystallization and grain growth, good mechanical properties (e.g., strength and ductility), and resistance to thermal fatigue; (2) coatings or bulk specialized low-Z materials for improved plasma performance; (3) innovative refractory-metal heat sink designs for enhanced helium gas cooling; (4) efficient fabrication methods for engineered surfaces that mitigate the stresses due to high heat flux; and (5) joining methods, for attaching the plasma facing material to the heat sink, that are reliable, efficient to manufacture, and capable of high heat transfer – these new joining techniques may be applicable to either advanced, helium cooled, refractory heat sinks or present-day, water-cooled, copper-alloy heat sinks.

Another PFC option is to use a flowing liquid metal surface as a plasma facing component, an approach which will require the production and control of thin, fast flowing, renewable films of liquid lithium, gallium, or tin for particle control at diverters. Grant applications are sought to develop: (1) techniques for the production, control, and removal of flowing (velocity 0.01 to 10 m/s) liquid metal films (0.5-5 mm thick) over a temperature controlled substrate; (2) advances in materials that are wetted by liquid metals at temperatures near the respective metal melting point and that are conducive to the production of uniform well-adhered films; (3) techniques for active control of liquid metal flow and stabilization in the presence of plasma instabilities (time and space varying magnetic field).

Questions – Contact: Daniel Clark, daniel.clark@science.doe.gov

 

Reference

1. 1. U.S. Department of Energy Office of Fusion Energy Sciences. (2009). Research Needs for Magnetic Fusion Energy Sciences. Report of the Research Needs Workshop (ReNeW). Bethesda, Maryland. June 8-12, 2009. http://science.energy.gov/~/media/fes/pdf/workshop- reports/Res_needs_mag_fusion_report_june_2009.pdf

2. U.S. Department of Energy Office of Science: Fusion Energy Sciences Advisory Committee. (2012). Opportunities for Fusion Materials Science and Technology Research now and During the ITER Era. . http://science.energy.gov/~/media/fes/pdf/workshop-reports/20120309/FESAC-Materials-Science-final-report.pdf