Shell mass effect on the hot-spot pressure in inertial confinement fusion implosion

Abstract

The effect of the shell mass on the hot spot pressure is investigated numerically for the Inertial Confinement Fusion (ICF) implosion. By using a simplified one-dimensional spherical model, it is found that there exists a critical shell mass that determines whether the hot spot can reach the maximum pressure. When the shell mass is larger than the critical mass, the hot spot pressure reaches the maximum value determined by the conventional scaling law Phsmax∝Mach3.2 (Mach is the Mach number of the imploding shell) and is independent of the shell mass. When the shell mass is smaller than the critical mass, the hot spot pressure decreases with decreasing shell mass. The dependence of the hot spot pressure on the shell mass can be uniformly described by an analytic formula. A similar effect of the shell mass on the hot spot pressure is also found in realistic ICF implosion for both direct drive and indirect drive. The conventional ICF implosions belong to the situation that the shell mass is smaller than the critical mass. The analytic formula can also be used to quantify the shell mass effect on the hot spot pressure for realistic ICF implosion when the effective shell mass is correctly taken into account.