Accurate numerical description of laser ablation in structured high-Z foam targets remains challenging in radiation-hydrodynamic simulations. To address this issue, a hybrid ablation-expansion model for Ta₂O₅ foam targets is developed, extending the sub-grid framework of Hudec et al. and coupling to the radiation-hydrodynamics code FLASH. Its reliability is assessed through quantitative comparison with published experimental results, after which the validated model is used to investigate laser-Ta₂O₅ foam interaction. The simulations show that the foam microstructure enhances laser-foam coupling, leading to higher laser absorption, elevated electron temperature, and faster coronal-plasma expansion. As a result, the material density distribution becomes broader during ablation. The calculations further indicate that laser penetration is limited primarily by the persistence of unhomogenized microstructure, rather than solely by the formation of a critical-density surface. Parametric analysis is conducted to quantify the effects of foam density and laser intensity on laser absorption efficiency and X-ray conversion efficiency. Within the investigated density range, laser absorption efficiency increases with foam density and exhibits a non-monotonic dependence on laser intensity, first increasing and then decreasing, with a maximum of 99.6% at a foam density of  and a laser intensity of . Within the same density range, X-ray conversion efficiency increases with foam density and decreases with increasing laser intensity, although higher laser intensity produces a higher total X-ray energy output. An X-ray conversion efficiency of 17.3% is obtained at a foam density of  and a laser intensity of . These results indicate that the present model provides a physically consistent and quantitatively reliable description of laser interaction with Ta₂O₅ foam targets, and offers a useful numerical tool for simulations of high-Z foam ablation in inertial confinement fusion research.
 

inertial confinement fusion,Ta2O5 foam,hybrid ablation-expansion model,X-ray conversion efficiency,laser absorption efficiency,sub-grid model