The physics issues that determine inertial confinement fusion target gain and driver requirements: A tutorial

This paper presents a simplified, tutorial approach to determining the gain s of inertial confinement fusion (ICF) targets, via a basic, zero-dimension al ("0-D''), energy "bookkeeping'' of input (parametrized by ICF drivers' c oupling efficiencies to the target, and subsequent hydrodynamic efficiencie s of implosion) versus output (thermonuclear burn efficiency and target fue l mass). Physics issues/constraints such as hydrodynamic instabilities, sym metry and implosion velocity requirements will be discussed for both the di rect drive (driver impinging directly on the target) and indirect drive (x- ray implosion within a driver heated hohlraum) approaches to ICF. Supplemen ting the 0-D model with simple models for hohlraum wall energy loss (to pre dict coupling efficiencies! and a simple one-dimensional (1-D) model of the implosion as a spherical rocket (to predict hydrodynamic implosion efficie ncies) allows gains to be predicted that compare well with the results of c omplex two-dimensional (2-D) radiation hydrodynamic simulations. (C) 1999 A merican Institute of Physics. [S1070-664X(99)92205-X].