Speaker
Description
The transport and retention of hydrogen isotopes is of vital importance for the realization of future commercial fusion reactors because it is closely related to plasma operation, fuel recycling, and radiation safety. Tungsten (W) is a leading plasma-facing material, and its performance can be significantly enhanced by the incorporation of small amounts of ultrafine oxide particles (such as La2O3, Y2O3, and ZrO2) or carbide particles (such as ZrC and TiC) , which suppress dislocation motion and grain boundary migration. However, systematic studies on hydrogen isotope permeation and retention in such dispersion-strengthened W materials remain limited. Furthermore, the plasma-material interactions present another critical operational challenge for fusion devices. Under irradiation by low-energy, high-flux helium (He) plasma, the W surface forms a nanostructured tendril-like layer known as fuzz, which can significantly modify near-surface transport pathways and thus influence hydrogen isotope permeation behavior. To date, the fuzz growth behavior on dispersion-strengthened W and its subsequent impact on deuterium (D) permeation have not yet been thoroughly explored.
This study systematically investigates the hydrogen isotope permeation and retention behavior of pure W, one carbide dispersion-strengthened W (W-ZrC), and three oxide dispersion-strengthened W materials (W-La2O3, W-Y2O3, and W-ZrO2) by means of D2 gas-driven permeation experiments and thermal desorption spectroscopy following static gas-phase D2 charging. Subsequently, the surface fuzz growth behavior of these materials under low-energy, high-flux He plasma irradiation was examined using the linear plasma device CLIPS. He plasma irradiation experiments were conducted over a fluence range from 6 × 1024 m-2 to 2 × 1026 m-2 at a He flux of 2.8 × 1022 m-2s-1, a sample temperature of 1193 K, and an incident He ion energy of 90 eV. The fuzz morphology and its fluence-dependent evolution were characterized by scanning electron microscopy (SEM) and focused ion beam (FIB) cross-sectioning. Transmission electron microscopy (TEM) was further employed to investigate the internal structure of the nanofibrous tendrils and the role of dispersed particles in fuzz growth. In addition, the influence of fuzz structures formed at different irradiation fluence on D permeation behavior was also examined.