skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules

Abstract

In the context of the French Laser-Megajoule fusion-research program, the hydrodynamic stability of the baseline direct-drive target is investigated at the hot spot surface during the deceleration phase by means of modeling and simulations. Using the convergence of the flow towards a self-similar solution, a closed system of ordinary differential equations is derived for the main hydrodynamic variables. An exact linear stability analysis is performed to compute the Rayleigh-Taylor growths. All theoretical predictions are compared to one-dimensional and two-dimensional single-mode detailed numerical results.

Authors:
; ; ; ; ;  [1];  [2];  [2];  [3]
  1. ETSI Aeronauticos, Universidad Politecnica de Madrid, 28040 Madrid (Spain)
  2. (France)
  3. (Spain)
Publication Date:
OSTI Identifier:
20782351
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 12; Journal Issue: 11; Other Information: DOI: 10.1063/1.2130315; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 36 MATERIALS SCIENCE; CAPSULES; DIFFERENTIAL EQUATIONS; HOT SPOTS; ICF DEVICES; INERTIAL CONFINEMENT; LASER TARGETS; LASER-PRODUCED PLASMA; LASERS; PLASMA SIMULATION; RAYLEIGH-TAYLOR INSTABILITY; RESEARCH PROGRAMS; STABILITY

Citation Formats

Sanz, J., Garnier, J., Cherfils, C., Canaud, B., Masse, L., Temporal, M., Laboratoire de Probabilites et Modeles Aleatoires and Laboratoire Jacques-Louis Lions, Universite Paris VII, 2 Place Jussieu, 75251 Paris Cedex 5, Commissariat a l'Energie Atomique, Direction des Applications Militaires, Boite Postale 12, 91680 Bruyeres-le-Chatel, and ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real. Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules. United States: N. p., 2005. Web. doi:10.1063/1.2130315.
Sanz, J., Garnier, J., Cherfils, C., Canaud, B., Masse, L., Temporal, M., Laboratoire de Probabilites et Modeles Aleatoires and Laboratoire Jacques-Louis Lions, Universite Paris VII, 2 Place Jussieu, 75251 Paris Cedex 5, Commissariat a l'Energie Atomique, Direction des Applications Militaires, Boite Postale 12, 91680 Bruyeres-le-Chatel, & ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real. Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules. United States. doi:10.1063/1.2130315.
Sanz, J., Garnier, J., Cherfils, C., Canaud, B., Masse, L., Temporal, M., Laboratoire de Probabilites et Modeles Aleatoires and Laboratoire Jacques-Louis Lions, Universite Paris VII, 2 Place Jussieu, 75251 Paris Cedex 5, Commissariat a l'Energie Atomique, Direction des Applications Militaires, Boite Postale 12, 91680 Bruyeres-le-Chatel, and ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real. Tue . "Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules". United States. doi:10.1063/1.2130315.
@article{osti_20782351,
title = {Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules},
author = {Sanz, J. and Garnier, J. and Cherfils, C. and Canaud, B. and Masse, L. and Temporal, M. and Laboratoire de Probabilites et Modeles Aleatoires and Laboratoire Jacques-Louis Lions, Universite Paris VII, 2 Place Jussieu, 75251 Paris Cedex 5 and Commissariat a l'Energie Atomique, Direction des Applications Militaires, Boite Postale 12, 91680 Bruyeres-le-Chatel and ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real},
abstractNote = {In the context of the French Laser-Megajoule fusion-research program, the hydrodynamic stability of the baseline direct-drive target is investigated at the hot spot surface during the deceleration phase by means of modeling and simulations. Using the convergence of the flow towards a self-similar solution, a closed system of ordinary differential equations is derived for the main hydrodynamic variables. An exact linear stability analysis is performed to compute the Rayleigh-Taylor growths. All theoretical predictions are compared to one-dimensional and two-dimensional single-mode detailed numerical results.},
doi = {10.1063/1.2130315},
journal = {Physics of Plasmas},
number = 11,
volume = 12,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
  • The baseline DT ice layer inertial confinement fusion (ICF) ignition capsule design requires a hot spot convergence ratio of ~34 with a hot spot that is formed from DT mass originally residing in a very thin layer at the inner DT ice surface. In the present paper, we propose alternative ICF capsule designs in which the hot spot is formed mostly or entirely from mass originating within a spherical volume of DT vapor. Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts—the DT wetted hydrocarbon (CH) foam concept and the “fast formed liquid”more » (FFL) concept—are described and compared to simulations of standard DT ice layer capsules. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low vapor pressure (DT ice) and high vapor pressure (DT liquid) capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules are less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density, with a potentially improved robustness to low-mode x-ray flux asymmetry.« less
  • The baseline DT ice layer inertial confinement fusion (ICF) ignition capsule design requires a hot spot convergence ratio of ∼34 with a hot spot that is formed from DT mass originally residing in a very thin layer at the inner DT ice surface. In the present paper, we propose alternative ICF capsule designs in which the hot spot is formed mostly or entirely from mass originating within a spherical volume of DT vapor. Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts—the DT wetted hydrocarbon (CH) foam concept and the “fast formed liquid”more » (FFL) concept—are described and compared to simulations of standard DT ice layer capsules. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low vapor pressure (DT ice) and high vapor pressure (DT liquid) capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules are less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density, with a potentially improved robustness to low-mode x-ray flux asymmetry.« less
  • We suggest that a potentially dominant but previously neglected source of pusher-fuel and hot-spot “mix” may have been the main degradation mechanism for fusion energy yields of modern inertial confinement fusion (ICF) capsules designed and fielded to achieve high yields — not hydrodynamic instabilities. This potentially dominant mix source is the spallation of small chunks or “grains” of pusher material into the fuel regions whenever (1) the solid material adjacent to the fuel changes its phase by nucleation, and (2) this solid material spalls under shock loading and sudden decompression. Finally, we describe this mix mechanism, support it with simulationsmore » and experimental evidence, and explain how to eliminate it and thereby allow higher yields for ICF capsules and possibly ignition at the National Ignition Facility.« less
  • The linear stability analysis of accelerated ablation fronts is carried out self-consistently by retaining the effect of finite thermal conductivity. Its temperature dependence along with the density gradient scale length are adjusted to fit the density profiles obtained in the one-dimensional simulations. The effects of diffusive radiation transport are included through the nonlinear thermal conductivity ({kappa}{approximately}{ital T}{sup {nu}}). The growth rate is derived by using a boundary layer analysis for Fr{gt}1 (Fr is the Froude number) and a WKB approximation for Fr{lt}1. The self-consistent Atwood number depends on the mode wavelength and the power law index for thermal conduction. Themore » analytic growth rate and cutoff wave number are in good agreement with the numerical solutions for arbitrary {nu}{approx_gt}1. {copyright} {ital 1996 American Institute of Physics.}« less