Influence of alpha-particle energy slowing-down and mass deposition effects on ICF hotspot burning

Based on our previous work on the double-temperature hotspot model, an alpha-particle quasi-steady-state slowing-down hotspot model is further developed in this paper to study the influence of alpha-particle energy slowing down and mass deposition effects on hotspot burning. In the quasi-slowing-down model, alpha particles are divided into escaped alpha particles, non-deposited high-energy alpha particles, and deposited thermalized alpha particles. Under the typical inertial confinement fusion parameter settings, the burning process of the quasi-slowing-down model, compared with the double-temperature model, shows a decrease in the peak value of the ion temperature, an increase in the expansion velocity of the hotspot, and a reduction in both the final burn fraction and the degree of electron-ion temperature nonequilibrium. Further investigation shows that the main reason for the decrease in the burn fraction and electron-ion nonequilibrium degree in the quasi-slowing-down model is the energy slowing down effect of high-energy alpha particles, that is, the internal energy of high-energy alpha particles increases (decreases) as the electron temperature increases (falls), thereby reducing (increasing) the deposition power of alpha particles. The mass deposition of thermalized alpha particles slightly increases the expansion velocity of the hotspot, but it generally has little impact on the burn fraction and electron-ion temperature nonequilibrium. In addition, the differences in the burn fraction and electron-ion temperature nonequilibrium between the quasi-slowing-down model and the double-temperature model are more sensitive to changes in initial parameters in the region dominated by the mechanical work loss mechanism, while they are less sensitive in the region dominated by the electron heat conduction loss mechanism.