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Title: Detailed high-resolution three-dimensional simulations of OMEGA separated reactants inertial confinement fusion experiments

Abstract

We present results from the comparison of high-resolution three-dimensional (3D) simulations with data from the implosions of inertial confinement fusion capsules with separated reactants performed on the OMEGA laser facility. Each capsule, referred to as a “CD Mixcap,” is filled with tritium and has a polystyrene (CH) shell with a deuterated polystyrene (CD) layer whose burial depth is varied. In these implosions, fusion reactions between deuterium and tritium ions can occur only in the presence of atomic mix between the gas fill and shell material. The simulations feature accurate models for all known experimental asymmetries and do not employ any adjustable parameters to improve agreement with experimental data. Simulations are performed with the RAGE radiation-hydrodynamics code using an Implicit Large Eddy Simulation (ILES) strategy for the hydrodynamics. We obtain good agreement with the experimental data, including the DT/TT neutron yield ratios used to diagnose mix, for all burial depths of the deuterated shell layer. Additionally, simulations demonstrate good agreement with converged simulations employing explicit models for plasma diffusion and viscosity, suggesting that the implicit sub-grid model used in ILES is sufficient to model these processes in these experiments. In our simulations, mixing is driven by short-wavelength asymmetries and longer-wavelength featuresmore » are responsible for developing flows that transport mixed material towards the center of the hot spot. Mix material transported by this process is responsible for most of the mix (DT) yield even for the capsule with a CD layer adjacent to the tritium fuel. Consistent with our previous results, mix does not play a significant role in TT neutron yield degradation; instead, this is dominated by the displacement of fuel from the center of the implosion due to the development of turbulent instabilities seeded by long-wavelength asymmetries. Through these processes, the long-wavelength asymmetries degrade TT yield more than the DT yield and thus bring DT/TT neutron yield ratios into agreement with experiment. Finally, we present a detailed comparison of the flows in 2D and 3D simulations.« less

Authors:
; ; ; ; ; ; ; ; ; ; ;  [1];  [2]; ; ;  [3]
  1. Los Alamos National Laboratory, MS T087, Los Alamos, New Mexico 87545 (United States)
  2. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
  3. Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)
Publication Date:
OSTI Identifier:
22599966
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 7; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CAPSULES; DEUTERIUM; HEAVY ION FUSION REACTIONS; HYDRODYNAMIC MODEL; HYDRODYNAMICS; IMPLOSIONS; INERTIAL CONFINEMENT; LARGE-EDDY SIMULATION; LASERS; LAYERS; NEUTRONS; PLASMA; POLYSTYRENE; THERMONUCLEAR REACTIONS; THREE-DIMENSIONAL CALCULATIONS; TRITIUM; TRITIUM IONS; VISCOSITY

Citation Formats

Haines, Brian M., E-mail: bmhaines@lanl.gov, Fincke, James R., Shah, Rahul C., Boswell, Melissa, Fowler, Malcolm M., Gore, Robert A., Hayes-Sterbenz, Anna C., Jungman, Gerard, Klein, Andreas, Rundberg, Robert S., Steinkamp, Michael J., Wilhelmy, Jerry B., Grim, Gary P., Forrest, Chad J., Silverstein, Kevin, and Marshall, Frederic J.. Detailed high-resolution three-dimensional simulations of OMEGA separated reactants inertial confinement fusion experiments. United States: N. p., 2016. Web. doi:10.1063/1.4959117.
Haines, Brian M., E-mail: bmhaines@lanl.gov, Fincke, James R., Shah, Rahul C., Boswell, Melissa, Fowler, Malcolm M., Gore, Robert A., Hayes-Sterbenz, Anna C., Jungman, Gerard, Klein, Andreas, Rundberg, Robert S., Steinkamp, Michael J., Wilhelmy, Jerry B., Grim, Gary P., Forrest, Chad J., Silverstein, Kevin, & Marshall, Frederic J.. Detailed high-resolution three-dimensional simulations of OMEGA separated reactants inertial confinement fusion experiments. United States. doi:10.1063/1.4959117.
Haines, Brian M., E-mail: bmhaines@lanl.gov, Fincke, James R., Shah, Rahul C., Boswell, Melissa, Fowler, Malcolm M., Gore, Robert A., Hayes-Sterbenz, Anna C., Jungman, Gerard, Klein, Andreas, Rundberg, Robert S., Steinkamp, Michael J., Wilhelmy, Jerry B., Grim, Gary P., Forrest, Chad J., Silverstein, Kevin, and Marshall, Frederic J.. Fri . "Detailed high-resolution three-dimensional simulations of OMEGA separated reactants inertial confinement fusion experiments". United States. doi:10.1063/1.4959117.
@article{osti_22599966,
title = {Detailed high-resolution three-dimensional simulations of OMEGA separated reactants inertial confinement fusion experiments},
author = {Haines, Brian M., E-mail: bmhaines@lanl.gov and Fincke, James R. and Shah, Rahul C. and Boswell, Melissa and Fowler, Malcolm M. and Gore, Robert A. and Hayes-Sterbenz, Anna C. and Jungman, Gerard and Klein, Andreas and Rundberg, Robert S. and Steinkamp, Michael J. and Wilhelmy, Jerry B. and Grim, Gary P. and Forrest, Chad J. and Silverstein, Kevin and Marshall, Frederic J.},
abstractNote = {We present results from the comparison of high-resolution three-dimensional (3D) simulations with data from the implosions of inertial confinement fusion capsules with separated reactants performed on the OMEGA laser facility. Each capsule, referred to as a “CD Mixcap,” is filled with tritium and has a polystyrene (CH) shell with a deuterated polystyrene (CD) layer whose burial depth is varied. In these implosions, fusion reactions between deuterium and tritium ions can occur only in the presence of atomic mix between the gas fill and shell material. The simulations feature accurate models for all known experimental asymmetries and do not employ any adjustable parameters to improve agreement with experimental data. Simulations are performed with the RAGE radiation-hydrodynamics code using an Implicit Large Eddy Simulation (ILES) strategy for the hydrodynamics. We obtain good agreement with the experimental data, including the DT/TT neutron yield ratios used to diagnose mix, for all burial depths of the deuterated shell layer. Additionally, simulations demonstrate good agreement with converged simulations employing explicit models for plasma diffusion and viscosity, suggesting that the implicit sub-grid model used in ILES is sufficient to model these processes in these experiments. In our simulations, mixing is driven by short-wavelength asymmetries and longer-wavelength features are responsible for developing flows that transport mixed material towards the center of the hot spot. Mix material transported by this process is responsible for most of the mix (DT) yield even for the capsule with a CD layer adjacent to the tritium fuel. Consistent with our previous results, mix does not play a significant role in TT neutron yield degradation; instead, this is dominated by the displacement of fuel from the center of the implosion due to the development of turbulent instabilities seeded by long-wavelength asymmetries. Through these processes, the long-wavelength asymmetries degrade TT yield more than the DT yield and thus bring DT/TT neutron yield ratios into agreement with experiment. Finally, we present a detailed comparison of the flows in 2D and 3D simulations.},
doi = {10.1063/1.4959117},
journal = {Physics of Plasmas},
number = 7,
volume = 23,
place = {United States},
year = {Fri Jul 15 00:00:00 EDT 2016},
month = {Fri Jul 15 00:00:00 EDT 2016}
}