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Title: Proton pinhole imaging on the National Ignition Facility

Abstract

Here, pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. When the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.

Authors:
ORCiD logo [1];  [2];  [2];  [3]; ORCiD logo [4]; ORCiD logo [2]; ORCiD logo [2];  [4]; ORCiD logo [4];  [2]; ORCiD logo [2]; ORCiD logo [2];  [2];  [4];  [2];  [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1341866
Report Number(s):
LA-UR-16-23558
Journal ID: ISSN 0034-6748; RSINAK; TRN: US1701753
Grant/Contract Number:
AC52-06NA25396; AC02-76SF00515
Resource Type:
Journal Article: 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:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Zylstra, Alex B., Park, H. -S., Ross, J. S., Fiuza, F., Frenje, J. A., Higginson, D. P., Huntington, C., Li, C. K., Petrasso, R. D., Pollock, B., Remington, B., Rinderknecht, H. G., Ryutov, D., Seguin, F. H., Turnbull, D., and Wilks, S. C.. Proton pinhole imaging on the National Ignition Facility. United States: N. p., 2016. Web. doi:10.1063/1.4959782.
Zylstra, Alex B., Park, H. -S., Ross, J. S., Fiuza, F., Frenje, J. A., Higginson, D. P., Huntington, C., Li, C. K., Petrasso, R. D., Pollock, B., Remington, B., Rinderknecht, H. G., Ryutov, D., Seguin, F. H., Turnbull, D., & Wilks, S. C.. Proton pinhole imaging on the National Ignition Facility. United States. doi:10.1063/1.4959782.
Zylstra, Alex B., Park, H. -S., Ross, J. S., Fiuza, F., Frenje, J. A., Higginson, D. P., Huntington, C., Li, C. K., Petrasso, R. D., Pollock, B., Remington, B., Rinderknecht, H. G., Ryutov, D., Seguin, F. H., Turnbull, D., and Wilks, S. C.. 2016. "Proton pinhole imaging on the National Ignition Facility". United States. doi:10.1063/1.4959782. https://www.osti.gov/servlets/purl/1341866.
@article{osti_1341866,
title = {Proton pinhole imaging on the National Ignition Facility},
author = {Zylstra, Alex B. and Park, H. -S. and Ross, J. S. and Fiuza, F. and Frenje, J. A. and Higginson, D. P. and Huntington, C. and Li, C. K. and Petrasso, R. D. and Pollock, B. and Remington, B. and Rinderknecht, H. G. and Ryutov, D. and Seguin, F. H. and Turnbull, D. and Wilks, S. C.},
abstractNote = {Here, pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. When the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.},
doi = {10.1063/1.4959782},
journal = {Review of Scientific Instruments},
number = 11,
volume = 87,
place = {United States},
year = 2016,
month = 7
}

Journal Article:
Free Publicly Available Full Text
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  • Pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4 ×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. Whenmore » the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.« less
  • 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-stationarymore » 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.« less
  • In pinhole-assisted point-projection backlighting, pinholes are placed a small distance (of order 1 mm) away from the backlighter source to produce images with large field of view. Pinholes placed close to high-power backlighter sources can vaporize and, if sufficiently small, close due to x-ray driven ablation, thereby potentially limiting the usefulness of this method. A study of streaked one-dimensional backlit imaging of 25 {mu}m W wires using the OMEGA laser at the University of Rochester is presented. The pinhole closure time scale for 10 {mu}m pinholes placed 0.45 and 1 mm distant from a 0.6 TW Ti backlighter is 1.3more » and 2.2 ns, respectively. Similar time scales for 5 {mu}m pinholes is also presented. Successful wire imaging prior to pinhole closure is clearly demonstrated.« less
  • We present results from a major experimental effort to understand the behavior of spatial filter pinholes and to identify and demonstrate a pinhole that will meet the requirements of the National Ignition Facility (NIF). We find that pinhole performance depends significantly on geometry and material. Cone pinholes are found to stay open longer and to cause less backreflection than pinholes of more conventional geometry. We show that a {+-}150-{mu}rad stainless-steel cone pinhole will pass a full-energy NIF ignition pulse with required margins for misalignment and for smoothing by spectral dispersion. On the basis of a model fitted to experimental results,more » a {+-}125-{mu}rad stainless-steel cone pinhole is also projected to meet these requirements. (c) 2000 Optical Society of America.« less