Novel Approaches to Indirect Drive Inertial Confinement Fusion

This thesis describes work that developed new techniques towards indirect drive inertial
confinement fusion. The work predominantly used the 1-dimensional (1D) and 2-dimensional
(2D) versions of the radiation hydrodynamics code HYADES.
The scaling of ablation pressures produced by the irradiation of a material with soft
X-rays was investigated. Materials with average atomic numbers between 3.5 and 22 were
irradiated by X-ray sources with radiation temperatures ranging from 100 eV to 400 eV. For
each material, pressure scaling laws were determined as a function of temperature and time.
Additionally, the maximum drive temperature for subsonic ablation was found for all the
materials. Materials with high atomic number tend to have weaker pressure scaling but
higher maximum subsonic drive temperatures.
The next study found the laser drive parameters required to produce shock-ignition-like
pressures through indirect drive. First, 1D simulations found an X-ray drive profile that
is capable of producing shock-ignition-like pressures in a beryllium target. From there, 2D
simulations were carried out to simulate the laser to X-ray conversion in a hohlraum. A laser
drive profile was found that was capable of producing the required X-ray intensity profile.
The final piece of work developed a new technique for controlling the X-ray flux in-
side hohlraums using burn-through barriers. Hohlraum designs that use multiple chambers
separated by burn-through barriers were proposed. The burn-through barriers are used to
modulate the spatial and temporal properties of the X-rays as they flow between the cham-
bers. It is shown how a number of different barrier designs can be used to manipulate the
properties of the X-rays in both time and space.