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Title: Fabrication, Assembly, and Metrology of the Neutron Imaging Pinhole

Abstract

The neutron imaging pinhole is a complex aperture that is designed to have its image plane at the center of a laser fusion capsule implosion. The aperture’s high-Z materials of tungsten and gold block the neutrons so that only the neutrons passing through the machined apertures make it to the image plane and detector. The pinhole assembly consists of 11 layers of gold in between two layers of tungsten and gold. These 64 triangular pinholes and six penumbra apertures provide a matrix image that can be reconstructed to image complex deuterium-tritium neutron burn details in laser fusion capsules. The gold layers were diamond turned flat before the profiles were cut into their faces. Four of the layers were profiled with penumbral profile arrays that tapered from a radius of 250 to 150 µm. Three gold layers were just diamond turned to wedges to set the tilt of the whole aperture. Three gold layers were profiled on both sides with triangle groove arrays that consist of eight equilateral triangles with the depth of 200 to 15 µm over the 200-mm length, with a tolerance of 2 µm. Custom software programming routines were written using Labview to move the diamond-turning profiler throughmore » the required X-Y-Z movements to cut the penumbral and grooved profiles of the pinhole into the varying tilted arrays of features. The software is optimized to push the profile of the whole part into the face while eliminating any unneeded passes that do not cut any material. Each layer was thoroughly inspected on both sides using an optical coordinate measuring machine and white-light interferometer to validate each of the profiles. The pinhole assembly was inspected on a rotary stage so that both ends of the assembly can be inspected and presented in a single point cloud. The process of machining, programming, assembly, and inspection of the neutron imaging pinhole is covered.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
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  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1485402
Report Number(s):
LA-UR-17-24885
Journal ID: ISSN 1536-1055
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Accepted Manuscript
Journal Name:
Fusion Science and Technology
Additional Journal Information:
Journal Volume: 73; Journal Issue: 3; Journal ID: ISSN 1536-1055
Publisher:
American Nuclear Society
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; target fabrication; neutron imaging pinhole; assembly

Citation Formats

Martinez, John I., Schmidt, Derek W., Day, Thomas H., Wilson, Christopher, and Fatherley, Valerie E. Fabrication, Assembly, and Metrology of the Neutron Imaging Pinhole. United States: N. p., 2018. Web. doi:10.1080/15361055.2017.1406238.
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Martinez, John I., Schmidt, Derek W., Day, Thomas H., Wilson, Christopher, & Fatherley, Valerie E. Fabrication, Assembly, and Metrology of the Neutron Imaging Pinhole. United States. https://doi.org/10.1080/15361055.2017.1406238
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Martinez, John I., Schmidt, Derek W., Day, Thomas H., Wilson, Christopher, and Fatherley, Valerie E. Thu . "Fabrication, Assembly, and Metrology of the Neutron Imaging Pinhole". United States. https://doi.org/10.1080/15361055.2017.1406238. https://www.osti.gov/servlets/purl/1485402.
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@article{osti_1485402,
title = {Fabrication, Assembly, and Metrology of the Neutron Imaging Pinhole},
author = {Martinez, John I. and Schmidt, Derek W. and Day, Thomas H. and Wilson, Christopher and Fatherley, Valerie E.},
abstractNote = {The neutron imaging pinhole is a complex aperture that is designed to have its image plane at the center of a laser fusion capsule implosion. The aperture’s high-Z materials of tungsten and gold block the neutrons so that only the neutrons passing through the machined apertures make it to the image plane and detector. The pinhole assembly consists of 11 layers of gold in between two layers of tungsten and gold. These 64 triangular pinholes and six penumbra apertures provide a matrix image that can be reconstructed to image complex deuterium-tritium neutron burn details in laser fusion capsules. The gold layers were diamond turned flat before the profiles were cut into their faces. Four of the layers were profiled with penumbral profile arrays that tapered from a radius of 250 to 150 µm. Three gold layers were just diamond turned to wedges to set the tilt of the whole aperture. Three gold layers were profiled on both sides with triangle groove arrays that consist of eight equilateral triangles with the depth of 200 to 15 µm over the 200-mm length, with a tolerance of 2 µm. Custom software programming routines were written using Labview to move the diamond-turning profiler through the required X-Y-Z movements to cut the penumbral and grooved profiles of the pinhole into the varying tilted arrays of features. The software is optimized to push the profile of the whole part into the face while eliminating any unneeded passes that do not cut any material. Each layer was thoroughly inspected on both sides using an optical coordinate measuring machine and white-light interferometer to validate each of the profiles. The pinhole assembly was inspected on a rotary stage so that both ends of the assembly can be inspected and presented in a single point cloud. The process of machining, programming, assembly, and inspection of the neutron imaging pinhole is covered.},
doi = {10.1080/15361055.2017.1406238},
journal = {Fusion Science and Technology},
number = 3,
volume = 73,
place = {United States},
year = {2018},
month = {2}
}
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Journal Article:
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Publisher's Version of Record
https://doi.org/10.1080/15361055.2017.1406238
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Figures / Tables:

Figure 1 Figure 1: Assembly of Pinhole gray bars are tungsten and the colored layers are gold.
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Works referenced in this record:

Design of the polar neutron-imaging aperture for use at the National Ignition Facility
journal, August 2016

  • Fatherley, V. E.; Barker, D. A.; Fittinghoff, D. N.
  • Review of Scientific Instruments, Vol. 87, Issue 11
  • DOI: 10.1063/1.4960314

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

  • Merrill, F. E.; Bower, D.; Buckles, R.
  • Review of Scientific Instruments, Vol. 83, Issue 10
  • DOI: 10.1063/1.4739242

Combined neutron and x-ray imaging at the National Ignition Facility (invited)
journal, October 2016

  • Danly, C. R.; Christensen, K.; Fatherley, V. E.
  • Review of Scientific Instruments, Vol. 87, Issue 11
  • DOI: 10.1063/1.4962194

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

  • Lindl, John; Landen, Otto; Edwards, John
  • Physics of Plasmas, Vol. 21, Issue 2
  • DOI: 10.1063/1.4865400

Fabrication of a 3X3 Neutron Pinhole Array
journal, May 2007

  • Day, Robert D.; Brooks, Paul M.; Edwards, Randall L.
  • Fusion Science and Technology, Vol. 51, Issue 4
  • DOI: 10.13182/FST07-A1478
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