This invention relates to targets for fusion reactions, and in particular to targets for fusion-based power plants.
The National Ignition Facility (NIF) is laser-based inertial confinement fusion research machine at the Lawrence Livermore National Laboratory in Livermore, Calif. NIF uses lasers to heat and compress a capsule of deuterium and tritium fuel contained within a hohlraum to the temperatures and pressures to cause a nuclear fusion reaction. The laser beams do not strike the capsule directly; rather, they are focused onto the interior surface of the hohlraum, a technique known as indirect drive. A goal of NIF is to reach “ignition,” a condition that produces more energy than used to start the reaction.
The NIF hohlraum is a generally cylindrical cavity whose walls emit radiant energy towards the interior. In the indirect drive approach to inertial confinement fusion, the fusion fuel capsule is held inside a cylindrical hohlraum and the laser beams enter through laser entrance holes at the ends of the cylinder, striking the interior surface of the hohlraum. The hohlraum absorbs and re-radiates the energy as x-rays onto the capsule. The goal of this approach is to have the energy re-radiated in a more symmetric manner than would be possible in the direct drive approach in which the laser beams strike the fuel capsule directly, i.e., without an intervening hohlraum.
A typical prior art hohlraum and capsule, as used at NIF, is shown in FIG. 1.