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Title: Neutron source reconstruction from pinhole imaging at National Ignition Facility

The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the ignition stage of inertial confinement fusion (ICF) implosions at NIF. Since the neutron source is small (∼100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, single-sided tapers in gold. These apertures, which have triangular cross sections, produce distortions in the image, and the extended nature of the pinhole results in a non-stationary or spatially varying point spread function across the pinhole field of view. In this work, we have used iterative Maximum Likelihood techniques to remove the non-stationary distortions introduced by the aperture to reconstruct the underlying neutron source distributions. We present the detailed algorithms used for these reconstructions, the stopping criteria used and reconstructed sources from data collected at NIF with a discussion of the neutron imaging performance in light of other diagnostics.
Authors:
; ; ; ; ; ;  [1] ; ; ; ;  [2]
  1. Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)
  2. Livermore National Laboratory, Livermore, California 94550 (United States)
Publication Date:
OSTI Identifier:
22253523
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
07 ISOTOPES AND RADIATION SOURCES; 74 ATOMIC AND MOLECULAR PHYSICS; ALGORITHMS; CROSS SECTIONS; DEUTERIUM; IGNITION; IMAGES; IMPLOSIONS; INERTIAL CONFINEMENT; ITERATIVE METHODS; NEUTRON SOURCES; NEUTRONS; TRITIUM; US NATIONAL IGNITION FACILITY; VISIBLE RADIATION