High heat flux testing of tungsten plasma facing materials

Both tungsten with a microstructure of ultra-fine grain size (sub-micron grain size) and functionally graded W/Cu materials have been fabricated by a newly developed technology named resistance sintering under ultra-high pressure. It is found that when decreasing the grain size of tungsten (from 7 μm to 0.5 μm), the micro-hardness and bend strength of tungsten will increase significantly. Thermal shock resistance by water quenching shows that the concept of functionally graded materials is effective at reducing the thermal stress between tungsten and copper. High heat flux testing using a laser beam shows that tungsten with sub-micron grain size can endure a higher heat load than that of tungsten with a grain size of larger than 1 μm, and functionally graded W/Cu materials can endure a higher heat load than that of pure tungsten.