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Title: Resolving Hot Spot Microstructure using X-ray Penumbral Imaging (invited)a)

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1389991
Report Number(s):
LLNL-PROC-695098
Journal ID: ISSN 0034--6748
DOE Contract Number:
AC52-07NA27344
Resource Type:
Conference
Resource Relation:
Journal Volume: 87; Journal Issue: 11; Conference: Presented at: High-Temperature Plasma Diagnostics, Madison, WI, United States, Jun 05 - Jun 09, 2016
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 99 GENERAL AND MISCELLANEOUS

Citation Formats

Bachmann, B, Hilsabeck, T, Field, J, Masters, N, Reed, C, Pardini, T, Alexander, N, Benedetti, L, Doeppner, T, Forsman, A, Izumi, N, LePape, S, Ma, T, MacPhee, A, Nagel, S, Patel, P, Rygg, J R, Spears, B, and Landen, O. Resolving Hot Spot Microstructure using X-ray Penumbral Imaging (invited)a). United States: N. p., 2016. Web. doi:10.1063/1.4959161.
Bachmann, B, Hilsabeck, T, Field, J, Masters, N, Reed, C, Pardini, T, Alexander, N, Benedetti, L, Doeppner, T, Forsman, A, Izumi, N, LePape, S, Ma, T, MacPhee, A, Nagel, S, Patel, P, Rygg, J R, Spears, B, & Landen, O. Resolving Hot Spot Microstructure using X-ray Penumbral Imaging (invited)a). United States. doi:10.1063/1.4959161.
Bachmann, B, Hilsabeck, T, Field, J, Masters, N, Reed, C, Pardini, T, Alexander, N, Benedetti, L, Doeppner, T, Forsman, A, Izumi, N, LePape, S, Ma, T, MacPhee, A, Nagel, S, Patel, P, Rygg, J R, Spears, B, and Landen, O. 2016. "Resolving Hot Spot Microstructure using X-ray Penumbral Imaging (invited)a)". United States. doi:10.1063/1.4959161. https://www.osti.gov/servlets/purl/1389991.
@article{osti_1389991,
title = {Resolving Hot Spot Microstructure using X-ray Penumbral Imaging (invited)a)},
author = {Bachmann, B and Hilsabeck, T and Field, J and Masters, N and Reed, C and Pardini, T and Alexander, N and Benedetti, L and Doeppner, T and Forsman, A and Izumi, N and LePape, S and Ma, T and MacPhee, A and Nagel, S and Patel, P and Rygg, J R and Spears, B and Landen, O},
abstractNote = {},
doi = {10.1063/1.4959161},
journal = {},
number = 11,
volume = 87,
place = {United States},
year = 2016,
month = 6
}

Conference:
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  • We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate themore » most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.« less
  • A general technique is presented for designing the thick apertures required to image penetrating radiation with high resolution. The new apertures are tapered in such a way that the radius of curvature varies inversely with distance from the source plane. The technique is used to design a high-resolution neutron penumbral-aperture microscope planned for the Nova laser. The design provides a resolution (determined by the sharpness of the aperture point-spread function) of {<=} 10 {mu}m over a field of view of 150 {mu}m. The point-spread function of these apertures is sufficiently isoplanatic and distortion-free to allow linear reconstruction of complex sourcemore » distributions. The design is generally appropriate for similar imaging techniques, such as high-resolution neutron or gamma-ray pinhole imaging.« less
  • Compact sources of 14-MeV neutrons have been imaged with a penumbral-coded aperture at a two-point resolution of 80{mu}m. We desire to improve the penumbral-aperture microscope to obtain resolutions as fine as 10{mu}m. In penumbral-coded-aperture imaging, the resolution is ultimately limited by the sharpness of the aperture point-spread function. I present a design for a thick penumbral aperture that provides the desired sharpness over a field of view of 150{mu}m. The point-spread function of these apertures is sufficiently isoplanatic and distortion-free to allow linear reconstruction of complex source distributions. The designs is generally appropriate for similar imaging techniques, such as fine-resolutionmore » neutron or gamma-ray pinhole imaging. 5 refs., 5 figs.« less
  • Penumbral imaging is a technique for imaging of neutrons or other penetrating radiations. The technique uses the facts that spatial information can be recovered from the shadow or penumbra that an unknown source casts through a simple large circular aperture. The limitation is that the straightforward image reconstruction will introduce some significant distortion for a large field of view because of non-isoplanaticity of the aperture point spread function. A genetic algorithm (GA) is proposed for reconstruction of penumbral images, and the technique allows distortion-free reconstruction over a large field of view. Furthermore, because in GA the complicated a priori constraintsmore » can be easily incorporated by the appropriate modification of the cost function, the algorithm is also tolerant of the noise.« less