Materials for Fusion Reactors
The demanding radiation environment within fusion plasma chamber places a set of challenges to plasma facing materials. Reactor maintenance cycle length depend on accumulation of radiation induced defects and absorbed tritium levels. An intensive research is on going for radiation hard materials development and testing. Development of high entropy metal compound an materials are presenting new versatile possibilities suited for fusion and other harsh radiation environments. Tritium removal from reactor walls is turned out to be problematic. Outgassing of tritium by heat treatment requires high temperatures and heating of large masses without compromising cooling system. Methodologies enabling lower thermal treatments are studied in conjunction of optimal material selection/development.
In accelerator laboratory plasma effects on reactor wall materials are modeled by ion beams. Information about light element diffusion and defect creation in materials is acquired by ion beam analysis, positron annihilation spectroscopy, X-ray photoelectron spectroscopy and thermal desorption spectrometry.
Situated along the bottom of the vacuum vessel, the function of the divertor is to extract heat, helium ash, and other impurities from the plasma. The 54 divertor cassettes are composed of a supporting structure made primarily of stainless steel, and three plasma-facing components: the inner vertical target, the outer vertical targets, and the dome. Image: US ITER