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Title: Design of the polar neutron-imaging aperture for use at the National Ignition Facility

Abstract

The installation of a neutron imaging diagnostic with a polar view at the National Ignition Facility (NIF) required design of a new aperture, an extended pinhole array (PHA). This PHA is different from the pinhole array for the existing equatorial system due to significant changes in the alignment and recording systems. The complex set of component requirements, as well as significant space constraints in its intended location, makes the design of this aperture challenging. In addition, lessons learned from development of prior apertures mandate careful aperture metrology prior to first use. This paper discusses the PHA requirements, constraints, and the final design. The PHA design is complex due to size constraints, machining precision, assembly tolerances, and design requirements. When fully assembled, the aperture is a 15 mm × 15 mm × 200 mm tungsten and gold assembly. The PHA body is made from 2 layers of tungsten and 11 layers of gold. The gold layers include 4 layers containing penumbral openings, 4 layers containing pinholes and 3 spacer layers. In total, there are 64 individual, triangular pinholes with a field of view (FOV) of 200 μm and 6 penumbral apertures. Each pinhole is pointed to a slightly different location inmore » the target plane, making the effective FOV of this PHA a 700 μm square in the target plane. The large FOV of the PHA reduces the alignment requirements both for the PHA and the target, allowing for alignment with a laser tracking system at NIF.« less

Authors:
; ; ; ; ;  [1]; ; ;  [2]
  1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
  2. Lawrence Livermore National Laboratory, Livermore, California 94551-0808 (United States)
Publication Date:
OSTI Identifier:
22596492
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ACCURACY; ALIGNMENT; APERTURES; DESIGN; DIAGNOSTIC TECHNIQUES; GOLD; IGNITION; IMAGES; LASERS; LAYERS; LIMITING VALUES; NEUTRONS; RECORDING SYSTEMS; SPACERS; TUNGSTEN

Citation Formats

Fatherley, V. E., E-mail: vef@lanl.gov, Martinez, J. I., Merrill, F. E., Oertel, J. A., Schmidt, D. W., Volegov, P. L., Wilde, C. H., Barker, D. A., Fittinghoff, D. N., and Hibbard, R. L. Design of the polar neutron-imaging aperture for use at the National Ignition Facility. United States: N. p., 2016. Web. doi:10.1063/1.4960314.
Fatherley, V. E., E-mail: vef@lanl.gov, Martinez, J. I., Merrill, F. E., Oertel, J. A., Schmidt, D. W., Volegov, P. L., Wilde, C. H., Barker, D. A., Fittinghoff, D. N., & Hibbard, R. L. Design of the polar neutron-imaging aperture for use at the National Ignition Facility. United States. https://doi.org/10.1063/1.4960314
Fatherley, V. E., E-mail: vef@lanl.gov, Martinez, J. I., Merrill, F. E., Oertel, J. A., Schmidt, D. W., Volegov, P. L., Wilde, C. H., Barker, D. A., Fittinghoff, D. N., and Hibbard, R. L. 2016. "Design of the polar neutron-imaging aperture for use at the National Ignition Facility". United States. https://doi.org/10.1063/1.4960314.
@article{osti_22596492,
title = {Design of the polar neutron-imaging aperture for use at the National Ignition Facility},
author = {Fatherley, V. E., E-mail: vef@lanl.gov and Martinez, J. I. and Merrill, F. E. and Oertel, J. A. and Schmidt, D. W. and Volegov, P. L. and Wilde, C. H. and Barker, D. A. and Fittinghoff, D. N. and Hibbard, R. L.},
abstractNote = {The installation of a neutron imaging diagnostic with a polar view at the National Ignition Facility (NIF) required design of a new aperture, an extended pinhole array (PHA). This PHA is different from the pinhole array for the existing equatorial system due to significant changes in the alignment and recording systems. The complex set of component requirements, as well as significant space constraints in its intended location, makes the design of this aperture challenging. In addition, lessons learned from development of prior apertures mandate careful aperture metrology prior to first use. This paper discusses the PHA requirements, constraints, and the final design. The PHA design is complex due to size constraints, machining precision, assembly tolerances, and design requirements. When fully assembled, the aperture is a 15 mm × 15 mm × 200 mm tungsten and gold assembly. The PHA body is made from 2 layers of tungsten and 11 layers of gold. The gold layers include 4 layers containing penumbral openings, 4 layers containing pinholes and 3 spacer layers. In total, there are 64 individual, triangular pinholes with a field of view (FOV) of 200 μm and 6 penumbral apertures. Each pinhole is pointed to a slightly different location in the target plane, making the effective FOV of this PHA a 700 μm square in the target plane. The large FOV of the PHA reduces the alignment requirements both for the PHA and the target, allowing for alignment with a laser tracking system at NIF.},
doi = {10.1063/1.4960314},
url = {https://www.osti.gov/biblio/22596492}, journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 11,
volume = 87,
place = {United States},
year = {2016},
month = {11}
}

Works referenced in this record:

The neutron imaging diagnostic at NIF (invited)
journal, October 2012


Simultaneous usage of pinhole and penumbral apertures for imaging small scale neutron sources from inertial confinement fusion experiments
journal, October 2012


Review of the National Ignition Campaign 2009-2012
journal, February 2014


Neutron source reconstruction from pinhole imaging at National Ignition Facility
journal, February 2014


Works referencing / citing this record:

Aperture design for the third neutron and first gamma-ray imaging systems for the National Ignition Facility
journal, October 2018


Fabrication, Assembly, and Metrology of the Neutron Imaging Pinhole
journal, January 2018