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Title: The effects of convergence ratio on the implosion behavior of DT layered inertial confinement fusion capsules

Abstract

The wetted foam capsule design for inertial confinement fusion capsules, which includes a foam layer wetted with deuterium-tritium liquid, enables layered capsule implosions with a wide range of hot-spot convergence ratios (CR) on the National Ignition Facility. In this paper, we present a full-scale wetted foam capsule design that demonstrates high gain in one-dimensional simulations. In these simulations, increasing the convergence ratio leads to an improved capsule yield due to higher hot-spot temperatures and increased fuel areal density. High-resolution two-dimensional simulations of this design are presented with detailed and well resolved models for the capsule fill tube, support tent, surface roughness, and predicted asymmetries in the x-ray drive. Our modeling of these asymmetries is validated by comparisons with available experimental data. In 2D simulations of the full-scale wetted foam capsule design, jetting caused by the fill tube is prevented by the expansion of the tungsten-doped shell layer due to preheat. While the impacts of surface roughness and predicted asymmetries in the x-ray drive are enhanced by convergence effects, likely underpredicted in 2D at high CR, simulations predict that the capsule is robust to these features. Nevertheless, the design is highly susceptible to the effects of the capsule support tent, whichmore » negates all of the one-dimensional benefits of increasing the convergence ratio. Indeed, when the support tent is included in simulations, the yield decreases as the convergence ratio is increased for CR > 20. Finally and nevertheless, the results suggest that the full-scale wetted foam design has the potential to outperform ice layer capsules given currently achievable levels of asymmetries when fielded at low convergence ratios (CR < 20).« less

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
Contributing Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
1374335
Alternate Identifier(s):
OSTI ID: 1368606
Report Number(s):
LA-UR-17-23609
Journal ID: ISSN 1070-664X
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; 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 TECHNOLOGY; Plasma confinement; Computer simulation; Tectonophysics; Optical metrology; Metalloids

Citation Formats

Haines, Brian M., Yi, S. A., Olson, R. E., Khan, S. F., Kyrala, G. A., Zylstra, A. B., Bradley, P. A., Peterson, R. R., Kline, J. L., Leeper, R. J., and Shah, R. C. The effects of convergence ratio on the implosion behavior of DT layered inertial confinement fusion capsules. United States: N. p., 2017. Web. doi:10.1063/1.4993065.
Haines, Brian M., Yi, S. A., Olson, R. E., Khan, S. F., Kyrala, G. A., Zylstra, A. B., Bradley, P. A., Peterson, R. R., Kline, J. L., Leeper, R. J., & Shah, R. C. The effects of convergence ratio on the implosion behavior of DT layered inertial confinement fusion capsules. United States. doi:10.1063/1.4993065.
Haines, Brian M., Yi, S. A., Olson, R. E., Khan, S. F., Kyrala, G. A., Zylstra, A. B., Bradley, P. A., Peterson, R. R., Kline, J. L., Leeper, R. J., and Shah, R. C. Mon . "The effects of convergence ratio on the implosion behavior of DT layered inertial confinement fusion capsules". United States. doi:10.1063/1.4993065.
@article{osti_1374335,
title = {The effects of convergence ratio on the implosion behavior of DT layered inertial confinement fusion capsules},
author = {Haines, Brian M. and Yi, S. A. and Olson, R. E. and Khan, S. F. and Kyrala, G. A. and Zylstra, A. B. and Bradley, P. A. and Peterson, R. R. and Kline, J. L. and Leeper, R. J. and Shah, R. C.},
abstractNote = {The wetted foam capsule design for inertial confinement fusion capsules, which includes a foam layer wetted with deuterium-tritium liquid, enables layered capsule implosions with a wide range of hot-spot convergence ratios (CR) on the National Ignition Facility. In this paper, we present a full-scale wetted foam capsule design that demonstrates high gain in one-dimensional simulations. In these simulations, increasing the convergence ratio leads to an improved capsule yield due to higher hot-spot temperatures and increased fuel areal density. High-resolution two-dimensional simulations of this design are presented with detailed and well resolved models for the capsule fill tube, support tent, surface roughness, and predicted asymmetries in the x-ray drive. Our modeling of these asymmetries is validated by comparisons with available experimental data. In 2D simulations of the full-scale wetted foam capsule design, jetting caused by the fill tube is prevented by the expansion of the tungsten-doped shell layer due to preheat. While the impacts of surface roughness and predicted asymmetries in the x-ray drive are enhanced by convergence effects, likely underpredicted in 2D at high CR, simulations predict that the capsule is robust to these features. Nevertheless, the design is highly susceptible to the effects of the capsule support tent, which negates all of the one-dimensional benefits of increasing the convergence ratio. Indeed, when the support tent is included in simulations, the yield decreases as the convergence ratio is increased for CR > 20. Finally and nevertheless, the results suggest that the full-scale wetted foam design has the potential to outperform ice layer capsules given currently achievable levels of asymmetries when fielded at low convergence ratios (CR < 20).},
doi = {10.1063/1.4993065},
journal = {Physics of Plasmas},
number = 7,
volume = 24,
place = {United States},
year = {Mon Jul 10 00:00:00 EDT 2017},
month = {Mon Jul 10 00:00:00 EDT 2017}
}

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  • Cited by 1
  • A set of laser implosion experiments were conducted at the OMEGA laser at the Univ. of Rochester, Laboratory for Laser Energetics (LLE) to study the effect of He concentration in DT-filled target shells on fusion yield in ICF implosions.. Eleven laser fusion shells consisting of 1100-{mu}m diameter, hollow, fused silica spheres with 4.6 to 4.7-{mu}m-thick walls were loaded with 520 kPa of deuterium-tritium (DT) and then with {sup 3}He (101.3 or 520 kPa). The {sup 3}He permeabilities of the shells were determined by measuring the pressure rate of rise into a system with known volume. A mathematical method was developedmore » that relied on the experimental fill pressure and time, and the rate of rise data to solve differential equations using MathCAD to simultaneously calculate {sup 3}He permeability and initial {sup 3}He partial pressure inside the shell. Because of the high permeation rate for {sup 3}He out of the shells compared to that for DT gas, shells had to be recharged with {sup 3}He immediately before being laser imploded or 'shot' at LLE. The {sup 3}He partial pressure in each individual shell at shot time was calculated from the measured {sup 3}He permeability. Two different partial pressures of {sup 3}He inside the shell were shown to reduce neutron and gamma yields during implosion. (authors)« less
  • In this study, we present the results of high-resolution simulations of the implosion of high-convergence layered indirect-drive inertial confinement fusion capsules of the type fielded on the National Ignition Facility using the xRAGE radiation-hydrodynamics code. In order to evaluate the suitability of xRAGE to model such experiments, we benchmark simulation results against available experimental data, including shock-timing, shock-velocity, and shell trajectory data, as well as hydrodynamic instability growth rates. We discuss the code improvements that were necessary in order to achieve favorable comparisons with these data. Due to its use of adaptive mesh refinement and Eulerian hydrodynamics, xRAGE is particularlymore » well suited for high-resolution study of multi-scale engineering features such as the capsule support tent and fill tube, which are known to impact the performance of high-convergence capsule implosions. High-resolution two-dimensional (2D) simulations including accurate and well-resolved models for the capsule fill tube, support tent, drive asymmetry, and capsule surface roughness are presented. These asymmetry seeds are isolated in order to study their relative importance and the resolution of the simulations enables the observation of details that have not been previously reported. We analyze simulation results to determine how the different asymmetries affect hotspot reactivity, confinement, and confinement time and how these combine to degrade yield. Yield degradation associated with the tent occurs largely through decreased reactivity due to the escape of hot fuel mass from the hotspot. Drive asymmetries and the fill tube, however, degrade yield primarily via burn truncation, as associated instability growth accelerates the disassembly of the hotspot. Finally, modeling all of these asymmetries together in 2D leads to improved agreement with experiment but falls short of explaining the experimentally observed yield degradation, consistent with previous 2D simulations of such capsules.« less
  • Cited by 1
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