Ignition criteria for x-ray fast ignition inertial confinement fusion

The derivation of the ignition energy for fast ignition inertial confinement fusion is reviewed and one-dimensional simulations are used to produce a revised formula for the ignition energy of an isochoric central hot-spot, which accounts for variation in the radius of the hot-spot r_h as well as the density rho. The required energy may be as low as 1 kJ when rho*r_h ~ 0:36 g cm^-2; T ~ 20 keV, and rho greater or equal to 700 g cm^-2. Although there are many physical challenges to creating these conditions, a possible route to producing such a hot-spot is via a bright source of nonthermal soft x-rays. Further one-dimensional simulations are used to study the non-thermal soft x-ray heating of dense DT and it is found to offer the potential to significantly reduce hydrodynamic losses as compared to particle driven fast ignition due to the hotspot being heated supersonically in a layer-by-layer fashion. A sufficiently powerful soft x-ray source would be difficult to produce, but line emission from laser-produced-plasma is the most promising option.