Near to backscattered light imaging diagnostic on the National Ignition Facility

Abstract

The National Ignition Facility (NIF) is being built at Lawrence Livermore National Laboratory for the U.S. Department of Energy Stockpile Stewardship Program. It will perform experiments for inertial confinement fusion ignition, high energy density science, and basic science. A target diagnostic is being developed for the NIF that will image nearly all the light scattered near the laser axis, (i.e., just outside the laser focusing lens). The diagnostic is called the near backscatter imager (NBI) and is presently required to measure stimulated Brillouin (SBS) and stimulated Raman (SRS) scattering so that the backscatter fraction will be determined with a goal of 30% uncertainty, and SBS and SRS temporal response with ∼200 ps resolution. The NBI will also provide an option to measure temporally resolved spectrum with 50 ps and ∼1 nm resolution. The diagnostic will obtain SBS and SRS scatter plate images with a retro-viewing optical digital camera placed inside the target chamber. Time integrated optical dio...