Comparing neutron and X-ray images from NIF implosions

¹ Los Alamos National Laboratory, Los Alamos, New Mexico, US
² Lawrence Livermore National Laboratory, Livermore, California, USA
³ Laboratory for Laser Energetics, U. of Rochester, Rochester, New York, USA
⁴ National Security Technologies, Livermore Operations, Livermore, CA, USA
⁵ National Security Technologies, Los Alamos Operations, Los Alamos, NM, USA

Published online: 15 November 2013

Abstract

Directly laser driven and X-radiation driven DT filled capsules differ in the relationship between neutron and X-ray images. Shot N110217, a directly driven DT-filled glass micro-balloon provided the first neutron images at the National Ignition Facility. As seen in implosions on the Omega laser, the neutron image can be enclosed inside time integrated X-ray images. HYDRA simulations show the X-ray image is dominated by emission from the hot glass shell while the neutron image arises from the DT fuel it encloses. In the absence of mix or jetting, X-ray images of a cryogenically layered THD fuel capsule should be dominated by emission from the hydrogen rather than the cooler plastic shell that is separated from the hot core by cold DT fuel. This cool, dense DT, invisible in X-ray emission, shows itself by scattering hot core neutrons. Germanium X-ray emission spectra and Ross pair filtered X-ray energy resolved images suggest that germanium doped plastic emits in the torus shaped hot spot, probably reducing the neutron yield.