Review of secondary and tertiary reactions, and neutron scattering as diagnostic techniques for inertial confinement fusion targets

Fuel areal density, 〈ρ R 〉, is a fundamental quantity for ICF implosions. For current and future targets, areal densities are large enough that a variety of neutron based diagnostic techniques can be used to determine fuel 〈ρ R 〉. These include measurements based on the secondary production of DT neutrons from initially pure deuterium fuel and, for higher 〈ρ R 〉 values, techniques utilizing high energy tertiary neutrons or lower energy scattered neutrons. This paper describes these techniques and gives an overview of the current experimental status.