Inertial confinement fusion target insertion via augmented mass free fall

A critical concern in the fabrication of targets for inertial confinement fusion (ICF) is ensuring that the hydrogenic (D₂ or DT) fuel layer maintains spherical symmetry. Solid layered targets have structural integrity, but lack the needed surface smoothness. Liquid targets are inherently smooth, but suffer from gravitationally induced sagging. One method to reduce the effective gravitational field environment is freefall insertion into the target chamber. Calculations of London-Van der Waals forces between liquid deuterium and plastic indicate that the maximum thickness of the equilibrium liquid layer in reduced gravitational environments is dependent on the net gravitational acceleration. Deceleration from gas drag limits the effective gravitational acceleration to >10^-6 g thus restricting the symmetric fuel layer thickness to 3 μm. We show that augmented mass methods (mounting the target to a high density mass) can further reduce the net acceleration, increasing the permissible thickness of the symmetric liquid layer