Preventing vaporization and destructive shock waves in ICF target-chamber first walls

The authors describe a sacrificial frozen-nitrogen x-ray and debris shield that is placed around fusion fuel pellets. The inner and outer radii of this shield are 100 and 165 mm, respectively. The shield absorbs nearly half of the fuel pellet energy and converts it into kinetic energy, spreading the energy deposition time at the target-chamber first wall by 4 orders of magnitude from --10 ns to > 100 ..mu..s. The authors also include the design of a 1400 1400-MJ-yield, 3-m-inner-radius aluminum target chamber with a no-vaporization first wall. With this shield, shock waves are reduced in magnitude so that no spall is predicted. The shield also adds thermal inertia, which allows 15 minutes between the removal of the cryostat (used to keep the fuel pellet and shield at liquid hydrogen temperatures before a shot) and the illumination of the fuel pellet by driver beams.