Optical Thomson Scattering and the Motivation for a 5ω Beamline at the NIF*

The National Ignition Facility has an extensive suite of almost 120 diagnostics [1], designed to study many aspects of the capsule implosion and the exotic states of matter created in the hohlraum. However, measurements of the plasma created at the laser entrance hole (LEH) and within the hohlraum gas cannot be made. Knowledge of parameters such as the electron and ion temperatures, mean ionization state and flow velocity would allow for the benchmarking of rad-hydro codes. These can all be provided by Optical Thomson Scattering (OTS) operating in the correct regime. Developing predictive capabilities in hohlraum design will be particularly important as the NIF aims to increase laser energy and obtain ever higher yields, requiring larger capsules and new hohlraums.  This poster reviews the basic theory of OTS, the fitting process to extract key plasma parameters, and the challenges involved.