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

Abstract

Current indirect drive implosion experiments on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] 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:
; ; ; ; ; ;  [1]
  1. Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)
Publication Date:
OSTI Identifier:
22600000
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 7; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ASYMMETRY; CAPSULES; COMPUTERIZED SIMULATION; DESIGN; DISTURBANCES; HYDRODYNAMIC MODEL; HYDRODYNAMICS; IMPLOSIONS; NEUTRONS; PERTURBATION THEORY; PLASMA; THERMONUCLEAR IGNITION; TIME DEPENDENCE; TWO-DIMENSIONAL CALCULATIONS; US NATIONAL IGNITION FACILITY; WAVELENGTHS; X RADIATION

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.
@article{osti_22600000,
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 = {Current indirect drive implosion experiments on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] 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},
issn = {1070-664X},
number = 7,
volume = 23,
place = {United States},
year = {2016},
month = {7}
}