Influence of Tungsten Substrate on the Dynamic Hydrogenic Retention in Lithiated Porous Tungsten *

Liquid low-Z, porous high-Z hybrid plasma-facing components (PFCs) potentially offer continuously replenishable low-Z plasma-liquid interfaces while tolerating both high steady-state and transient heat fluxes. Lithium (Li) PFCs have been seen to improve plasma performance by enabling flat electron temperature profiles and increasing confinement time. Enhanced plasma performance is attributed to lower particle recycling in the boundary plasma. For these benefits in addition to tritium safety limits in a fusion reactor, it is vital to understand and quantify hydrogenic retention in candidate hybrid Li PFCs.  

Retention and diffusion of deuterium (D) in hybrid liquid Li- porous tungsten (W) substrates are studied with the DIONISOS experiment at MIT, investigating the effects of porosity on the dynamic retention of D in lithiated porous W. Spark plasma sintering with 5 mm, and 20 mm W powders results in samples with pores sizes of ~1.5 mm, and ~ 10 mm, respectively, and densities of 70% to 80%. Fully dense hot rolled W is used for reference. Lithiated and non-lithiated samples are exposed to D plasma fluence of ~10²⁴ D/m² at room temperature and 300°C. In-situ, in-operando Nuclear Reaction Analysis with ³He is used to obtain D depth profiles in the samples during and immediately after plasma exposure. The results are discussed in the context of how D retention and diffusion under these conditions are affected by the porous morphology of the samples.  

 

Work supported by DOE Awards DE-SC0021119 and DE-SC0021178