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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. Here, 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 locationmore » 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.« less

Authors:
 [1];  [2];  [2];  [2];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1494399
Report Number(s):
LLNL-JRNL-732945
Journal ID: ISSN 0034-6748; RSINAK; 884521
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Fatherley, V. E., Barker, D. A., Fittinghoff, D. N., Hibbard, R. L., Martinez, J. I., Merrill, F. E., Oertel, J. A., Schmidt, D. W., Volegov, P. L., and Wilde, C. H. 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., Barker, D. A., Fittinghoff, D. N., Hibbard, R. L., Martinez, J. I., Merrill, F. E., Oertel, J. A., Schmidt, D. W., Volegov, P. L., & Wilde, C. H. Design of the polar neutron-imaging aperture for use at the National Ignition Facility. United States. doi:10.1063/1.4960314.
Fatherley, V. E., Barker, D. A., Fittinghoff, D. N., Hibbard, R. L., Martinez, J. I., Merrill, F. E., Oertel, J. A., Schmidt, D. W., Volegov, P. L., and Wilde, C. H. Mon . "Design of the polar neutron-imaging aperture for use at the National Ignition Facility". United States. doi:10.1063/1.4960314. https://www.osti.gov/servlets/purl/1494399.
@article{osti_1494399,
title = {Design of the polar neutron-imaging aperture for use at the National Ignition Facility},
author = {Fatherley, V. E. and Barker, D. A. and Fittinghoff, D. N. and Hibbard, R. L. and Martinez, J. I. and Merrill, F. E. and Oertel, J. A. and Schmidt, D. W. and Volegov, P. L. and Wilde, C. H.},
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. Here, 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},
journal = {Review of Scientific Instruments},
number = 11,
volume = 87,
place = {United States},
year = {2016},
month = {8}
}

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