Tungsten (W) is the leading plasma-facing candidate material for the International Thermonuclear Experimental Reactor and next-generation fusion reactors. The impact of synergistic helium ( \(\text {He}\) ), irradiation-induced microstructural changes, and the corresponding thermal-mechanical property degradation of W are critically important but are not well understood yet. Predicting the performance of W in fusion environments requires understanding the fundamentals of \(\text {He}\) -defect interactions and the resultant \(\text {He}\) bubble nucleation and growth in W. In this study, \(\text {He}\) retention in helium-ion-implanted W was assessed using neutron depth profiling (NDP), laser ablation mass spectrometry (LAMS), and thermal desorption spectroscopy (TDS) following 10 keV room-temperature \(\text {He}\) implantation at various fluences. These three experimental techniques enabled the determination of the \(\text {He}\) depth profile and retention in \(\text {He}\) -implanted W. A cluster dynamics model based on the diffusion–reaction rate theory was applied to interpret the experimental data. The model successfully predicted the He spatial depth-dependent profile in \(\text {He}\) -implanted W, which was in good agreement with the LAMS measurements. The model also successfully captured the major features of the \(\text {He}\) desorption spectra observed in the THDS measurements. The NDP quantified total \(\text {He}\) concentration values for the samples; they were similar to those estimated by LAMS. However, the depth profiles from NDP and LAMS were not comparable due to several factors. The combination of modeling and experimentation enabled the identification of possible trapping sites for \(\text {He}\) in W and the evolution of \(\text {He}\) -defect clusters during the TDS thermal annealing process.
