ENERGY GAIN AND PERFORMANCE OF ABLATIVELY DRIVEN SHELL TARGETS

A model for the energy gain of inertial confinement fusion (ICF) targe ts is derived from realistic ignition profiles. The model considers th e ablative implosion of a spherical shell driven by a rather general p ower pulse and takes into account the main physical limitations constr aining the target performance. As a result, the model gives an interpr etation of the gain curves obtained by numerical simulations and recen tly reported in the lite The resulting scaling laws for the ignition e nergy and for the limiting gain are in good agreement with these simul ations. Besides, several physical features associated with the target gain and observed in the simulations are well described. In particular , it is found that, along the limiting gain, the ICF parameter of the fuel is almost constant and, for applications to indirect drive fusion , the implosion velocity is proportional to the radiation temperature. The explicit scaling laws provided by the model allow a parametric st udy of the target gain as a function of the constraints on symmetry, s tability and other physical quantities.