Increasing the coupling efficiency in a heavy ion, inertial confinement fusion target

Abstract

A close coupled, distributed radiator heavy ion target is presented.Close coupled refers to a decrease in the distance between the hohlraum wall and the inertial confinement fusion capsule.In two dimensional, integrated, LASNEX calculations, this target produced 436 MJ of yield from 3.27 MJ of ion beam energy for a gain of 133.To achieve these results, the hohlraum dimensions were reduced by 27% from the previous distributed radiator, heavy ion target while driving the same capsule.This reduced the beam energy required from 5.9 to 3.27 MJ.Calculations of single mode Rayleigh-Taylor growth for this capsule show that this capsule is more stable than at least one of the NIF target designs (the PT design which uses a CH ablator doped with oxygen and bromine).This means that issues regarding the Rayleigh-Taylor instability for the heavy ion driven capsule can be settled on NIF.This close coupled target can also be scaled down in size for an Engineering Test Facility; LASNEX calculations predict that a gain of 94 can be achieved from 1.75 MJ of beam energy.In addition, gain curves for distributed radiator targets with the 'conventional' case to capsule ratio and the close coupled case to capsule ratio are presented.