An analytical treatment of propagation of laser-induced divergent and convergent shock waves in a gas is presented. The temporal evolution of the plasma and the formation of diverging/converging shock waves are also studied. The interaction of imploding shock waves with the central fireball leads to the enhancement of plasma density and, in particular, of temperatures up to values obtainable in an inertial confinement fusion scheme. Its implications to spherical pinch are also discussed. Subsequently, the scaling laws of neutron production from deuterium gas are derived in a self-consistent manner for the cases when the converging shock wave interacts directly with the expanding plasma or with the explosive shock wave detached from the central fireball.