Numerical Simulation of an ICF Target Explosion in a Stratified Gas Atmosphere

Two-dimensional radiation hydrodynamic simulations of a light ion fusion target generated microfireball in a stratified gas atmosphere have been performed. The target location in a two region cavity was varied with the intent to reduce the overpressure on the diodes at the walls of a target chamber with a single cavity gas. Helium and nitrogen at 15 torr were used as the cavity gases; target explosions of 200 and 800 MJ were investigated. It was found that placing the target in a helium region surrounded by nitrogen could reduce the overpressure by a factor of 2 when compared with a single gas cavity of nitrogen. The surface heat flux was also reduced from a pure helium gas cavity.