Simulated neutron diagnostics of imploding ICF targets for the Neutron Imaging System at the national ignition facility

Abstract

Summary form only given. The neutron imaging system (NIS), currently under development at Los Alamos National Laboratory, will be a phase 2 diagnostic for the National Ignition Facility at Lawrence Livermore National Laboratory. It is designed to provide neutron fluence images of imploded ICF capsule targets with neutron yields above 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Lambda</sup> 12, with a spatial resolution of 15-20 microns. These images are time-integrated through the period of TN burn. The DiME (defect iMplosion experiment) project seeks to design high-yield, direct-drive Omega capsule targets that will produce appreciable spatial "structure" in the resultant neutron images, for the purpose of testing the NIS instrument prior to fielding at NIF. Furthermore, we seek to quantify the expected performance of the NIS instrument, and to document how the data it provides will complement data from other NIF diagnostics (including, but not limited to, the gated microscope X-ray imager). Consequently, the design phase of the DiME project relies upon simulated capsule dynamics and simulated diagnostic output. We have performed both Lagrangian and Eulerian radiation-hydrodynamic calculations for a wide variety of DiME designs, and post-processed the results to produce both neutron and X-ray images. In general, we find the results to be complementary to one another. This talk will describe the DiME project in greater detail, including a description of the target design process, and will showcase our computational approach as well as our results to date. It will also compare our simulated diagnostic images to experimental shot data, pending availability of the latter; DiME targets are currently scheduled for Omega shots in spring of 2009.