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Title: Mitigating the impact of hohlraum asymmetries in National Ignition Facility implosions using capsule shims

Abstract

Here, current indirect drive implosion experiments on the National Ignition Facility (NIF) are believed to be strongly impacted by long wavelength perturbations driven by asymmetries in the hohlraum x-ray flux. To address this perturbation source, active efforts are underway to develop modified hohlraum designs with reduced asymmetry imprint. An alternative strategy, however, is to modify the capsule design to be more resilient to a given amount of hohlraum asymmetry. In particular, the capsule may be deliberately misshaped, or “shimmed,” so as to counteract the expected asymmetries from the hohlraum. Here, the efficacy of capsule shimming to correct the asymmetries in two recent NIF implosion experiments is assessed using two-dimensional radiation hydrodynamics simulations. Despite the highly time-dependent character of the asymmetries and the high convergence ratios of these implosions, simulations suggest that shims could be highly effective at counteracting current asymmetries and result in factors of a few enhancements in neutron yields. For higher compression designs, the yield improvement could be even greater.

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. 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
OSTI Identifier:
1438727
Alternate Identifier(s):
OSTI ID: 1268442
Report Number(s):
LLNL-JRNL-691112
Journal ID: ISSN 1070-664X; PHPAEN
Grant/Contract Number:
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 7; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION

Citation Formats

Clark, D. S., Weber, C. R., Smalyuk, V. A., Robey, H. F., Kritcher, A. L., Milovich, J. L., and Salmonson, J. D.. Mitigating the impact of hohlraum asymmetries in National Ignition Facility implosions using capsule shims. United States: N. p., 2016. Web. doi:10.1063/1.4958812.
Clark, D. S., Weber, C. R., Smalyuk, V. A., Robey, H. F., Kritcher, A. L., Milovich, J. L., & Salmonson, J. D.. Mitigating the impact of hohlraum asymmetries in National Ignition Facility implosions using capsule shims. United States. doi:10.1063/1.4958812.
Clark, D. S., Weber, C. R., Smalyuk, V. A., Robey, H. F., Kritcher, A. L., Milovich, J. L., and Salmonson, J. D.. Fri . "Mitigating the impact of hohlraum asymmetries in National Ignition Facility implosions using capsule shims". United States. doi:10.1063/1.4958812. https://www.osti.gov/servlets/purl/1438727.
@article{osti_1438727,
title = {Mitigating the impact of hohlraum asymmetries in National Ignition Facility implosions using capsule shims},
author = {Clark, D. S. and Weber, C. R. and Smalyuk, V. A. and Robey, H. F. and Kritcher, A. L. and Milovich, J. L. and Salmonson, J. D.},
abstractNote = {Here, current indirect drive implosion experiments on the National Ignition Facility (NIF) are believed to be strongly impacted by long wavelength perturbations driven by asymmetries in the hohlraum x-ray flux. To address this perturbation source, active efforts are underway to develop modified hohlraum designs with reduced asymmetry imprint. An alternative strategy, however, is to modify the capsule design to be more resilient to a given amount of hohlraum asymmetry. In particular, the capsule may be deliberately misshaped, or “shimmed,” so as to counteract the expected asymmetries from the hohlraum. Here, the efficacy of capsule shimming to correct the asymmetries in two recent NIF implosion experiments is assessed using two-dimensional radiation hydrodynamics simulations. Despite the highly time-dependent character of the asymmetries and the high convergence ratios of these implosions, simulations suggest that shims could be highly effective at counteracting current asymmetries and result in factors of a few enhancements in neutron yields. For higher compression designs, the yield improvement could be even greater.},
doi = {10.1063/1.4958812},
journal = {Physics of Plasmas},
number = 7,
volume = 23,
place = {United States},
year = {Fri Jul 22 00:00:00 EDT 2016},
month = {Fri Jul 22 00:00:00 EDT 2016}
}

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