Radiation-driven inertial fusion targets for implosion experiments: Theoretical analysis and numerical simulations

Abstract

This paper presents numerical simulations of compression, ignition, and burn of a radiation-driven inertial fusion capsule suitable for use in a heavy-ion-beam-driven laboratory microfusion facility to achieve breakeven (thermonuclear energy output=input radiation energy). These simulations have been carried out using a one-dimensional, three-temperature, Lagrangian computer code medusa-kat [J. Appl. Phys. 60, 898 (1986)]. The basic capsule design is simple and consists of a thin gold microballoon coated with a beryllium ablator. A high-pressure gaseous deuterium–tritium (DT) fuel is filled in the capsule. The capsule is driven by a shaped radiation pulse having a prepulse corresponding to a radiation temperature of 100 eV and a main pulse with a temperature of 300 eV. A parameter study of the capsule gain, G versus input radiation energy over a range 52–76 kJ, has been carried out. The fuel mass has also been varied over a range 0.3–0.8 μg. It has been found that G∼1 can be achieved with an absorbed radiation energy of 70 kJ provided that the fuel mass lies between 0.5 and 0.7 μg. These simulations have also been repeated over the same parameter range but using an unshaped pulse with a constant radiation temperature of 300 eV. An overall reduction of 10%–30% has been observed in the gain curves in this case.