Effects of impurity mixing on α-heating in two-temperature hot dense deuterium-tritium plasmas

The mixing of impurities with deuterium-tritium (DT) fuel affects the energy deposition of α particles in inertial confinement fusion (ICF). This study investigates how impurity mixing influences energy partition during α-heating when the ion temperature (T_i) exceeds the electron temperature (T_e). Two kinds of impurity ions, beryllium (Be) and gold (Au), are considered. We conduct calculations at mixture densities of 4.15 and 415.0 g/cm³, with T_e ranging from 0.1 to 100.0 keV. The average ionization degree and partial density of each ion species are obtained through the average atom model. Results show that when the number ratio of impurity ions to DT ions (R) reaches 0.05, the mixing of Be significantly reduces the energy partition fraction of DT ions (η_DT). In the case of Au mixing, it occurs at R = 0.01. At fixed T_e and R, the reduction in η_DT grows slowly with T_i, while the energy partition to electrons remains independent of T_i. Meanwhile, the heating of both impurity ions is easier than that of DT ions, with Au ions being heated faster than Be ions. The different effects caused by the two impurities primarily originate from their distinct charge states and masses. Our work quantitatively analyzes the influence of realistic two-temperature plasma conditions on impurity mixing effects. The findings provide references for impurity tolerance and shell material selection in ICF target design.