One-dimensional planar hydrodynamic theory of shock ignition

A one-dimensional planar compressible-piston-like model is used to investigate the basic physics behind shock-ignition inertial confinement fusion implosions. We discuss the theoretical limit set by rarefaction waves on the maximum hot-spot pressure achievable through conventional compression. Three ignitor shock techniques are presented to mitigate the effects of rarefaction waves, enhance the stagnation hot-spot pressure, and improve the ignition conditions. Elimination of rarefaction waves can lead to an ∼80% increase in peak implosion pressures, while implosions augmented with ignitor shocks are shown to increase the peak pressures by a factor of ∼4. These techniques are then discussed and the optimal energy ratio between the initial shell kinetic energy and the ignitor pulse energy is given.