Optimizing laser focal spot size using self-focusing in a cone-guided fast-ignition ICF target

This paper presents a scheme for strong self-focusing of laser beam interacting with cone-guided fast-ignition inertial confinement fusion target using cone pre-plasma filling as an optical medium reducing the waist. The objective is to reduce focal spot size at interior tip re-entrant that required efficient coupling dense imploded fuel core. challenging achieve in large system standard components chirped-pulse-amplified (CPA) laser-beam chain where sizes produced are often significantly larger than would be desirable fast ignition. approach described also makes use presence cone. Such difficult avoid entirely when illuminating high-energy CPA due challenges pre-pulse below threshold plasma production. For deriving differential equation which governs progress beam-width propagation distance, paraxial theory WKB approximation has been used. A simulation performed assuming accordance parameters and density profile chosen.