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

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4959117· OSTI ID:22599966
; ; ; ; ; ; ; ; ; ;  [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)

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.

OSTI ID:
22599966
Journal Information:
Physics of Plasmas, Vol. 23, Issue 7; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
Country of Publication:
United States
Language:
English

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Plasma transport in an Eulerian AMR code journal April 2017
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Bulk hydrodynamic stability and turbulent saturation in compressing hot spots journal April 2018
Diffusion-driven fluid dynamics in ideal gases and plasmas journal June 2018
Using a 2-shock 1D platform at NIF to measure the effect of convergence on mix and symmetry journal October 2018
Impact of imposed mode 2 laser drive asymmetry on inertial confinement fusion implosions journal January 2019
Robustness to hydrodynamic instabilities in indirectly driven layered capsule implosions journal January 2019
Modeling of direct-drive cylindrical implosion experiments with an Eulerian radiation-hydrodynamics code journal April 2019
The modeling of delayed-onset Rayleigh-Taylor and transition to mixing in laser-driven HED experiments journal May 2019
Shock-driven hydrodynamic instability of a sinusoidally perturbed, high-Atwood number, oblique interface journal June 2019
Understanding turbulence in compressing plasma as a quasi-EOS journal June 2019
Fuel-shell interface instability growth effects on the performance of room temperature direct-drive implosions journal August 2019
Viscous dissipation in two-dimensional compression of turbulence journal August 2019
Computational study of instability and fill tube mitigation strategies for double shell implosions journal October 2019
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