The Impact of Refractory Material Properties on the Helium Cooled Divertor Design

Many divertor design studies for future fusion reactors rely on helium gas cooling. In these concepts, pressurized tubes or channels had to be operated at maximum temperatures between 1000 °C and 1300 °C while the lowest operating temperature is preset by the coolant inlet or by specific start-up and maintenance conditions. At such extreme temperature regimes, the only reduced activation material that would provide enough strength, paired with the necessary heat conductivity, is tungsten. Therefore, various tungsten materials and alloys are often publicized as candidate material for structural divertor applications.

However, there are also clear limitations. Therefore, an intensive study on the influence of microstructure and chemical composition on the fracture behavior of industrially produced tungsten materials has been perfomed. This paper reviews the results and some other relevant properties of tungsten materials with respect to possible applications for structural divertor parts. Drawbacks and possible alternatives are discussed.