Modifying the Hohlraum Environment For Improved Drive in Inertial Confinement Fusion

This thesis contains simulation work carried out in order to understand the effect of modifying the hohlraum environment and the consequences of these modifications on the performance of an inertial confinement fusion capsule. Simulations were carried out using the radiation hydrodynamic codes HYADES and h2d. In addition, a view-factor code was developed in order to calculate the radiation symmetry for different hohlraum designs. Firstly, h2d was used to study the effect of lining the inside of a hohlraum with a mid-Z element, in this case copper, on the X-ray drive produced. A reduction in the hard X-ray component of the drive was found and attributed to the inclusion of the liner. The mechanism by which this reduction occurs was investigated and is outlined within this work. Secondly, the consequences of including a mid-Z liner were investigated by using HYADES to perform 1D implosions of capsules. A hohlraum with a reduced high energy X-ray content will be able to drive a capsule that contains lower levels of dopant. Implosions of capsules containing several different dopant concentrations were compared with regards to the ignition threshold energy in order to assess the benefit of using a lined hohlraum. Finally, a method for tailoring the X-ray drive symmetry in hohlraums via albedo-profiling of the hohlraum wall was investigated using a view-factor method. Symmetry control in geometries relevant to laser-driven and z-pinch driven hohlraums was obtained by using this method with the extent presented in the final results section of this thesis.