Nuclear fusion power is the promise of clean energy generation to meet the demands of the new century. The International Tokamak Experimental Reactor (ITER) is the first proof-of-concept reactor under construction. However, confining a plasma with a core temperature ten times hotter than that of our sun in no easy task. ITER’s confinement vessel must be constructed from resilient materials that can withstand both the heat and the bombardment of the plasma species to minimize the interruption of the reactor’s operation. As such, ITER has chosen tungsten (W) as the plasma-facing material for both its first-wall and divertor components.

The implantation of helium (He), a product of the deuterium-tritium reaction, into W is known to form nanoscale bubbles that would degrade its mechanical and thermal properties. A variety of techniques such as thermal desorption spectroscopy, time-of-flight elastic recoil detection, electron microscopy and grazing-incidence small-angle X-ray scattering have been used to characterize the temperature-dependent annealing behaviours and thermodynamics of He bubbles that have formed in W. A phenomenological “Ostwald-ripening-like” mechanism is proposed as the model explaining the difference in the annealing behaviours of He bubbles that is dependent on the sample temperature during He plasma exposure.

One issue regarding the use of W is its poor mechanical properties, such as its brittleness. W-based binary alloys involving tantalum (Ta) and chromium (Cr) have been tested in the literature to develop advanced materials that enhance the resilience of W to plasma exposure by either making it more ductile or more resistant to oxidation. The responses of W-based binary and ternary alloys involving Ta and Cr to He plasma have been characterized using the aforementioned techniques. This provides a means of comparison between the alloys under consistent plasma conditions. This also expands the knowledge base of the performance of these alloys to plasma exposure that would help better assess the viability of these alloys for use as plasma-facing materials in future fusion reactors.