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

Title: Simulations investigating the effect of a deuterium-tritium-ice coating on the motion of the gold cone surface in a re-entrant cone-guided fast ignition inertial confinement fusion capsule

Abstract

One- and two-dimensional multigroup radiation hydrodynamics simulations have been performed to investigate the motion of the gold plasma generated at the surface of the embedded gold cone in a re-entrant cone-guided inertial confinement fusion capsule. The effect of deuterium-tritium (DT) ice layers, and other possible tampers, of varying thickness, upon the motion of the gold cone plasma has been investigated. The effect of the x-ray drive spectrum incident upon the ice layer is also explored. Ice is shown to tamp the expansion of the gold cone, and whilst denser materials are shown to be more effective in this role, ice does not pollute the ignition region with intermediate-Z ions, which, though preferable to gold contamination, also tend to inhibit the attainment of high fuel-ion temperatures.

Authors:
;  [1];  [2]
  1. University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20975017
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 5; Other Information: DOI: 10.1063/1.2734584; (c) 2007 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; CAPSULES; CONES; DEUTERIUM; GOLD; HYDRODYNAMICS; ICE; INERTIAL CONFINEMENT; ION TEMPERATURE; IONS; LASERS; LAYERS; PLASMA; PLASMA SIMULATION; SURFACES; THERMONUCLEAR IGNITION; TRITIUM; X RADIATION; X-RAY SOURCES

Citation Formats

Pasley, J., Stephens, R., and General Atomics, 3550 General Atomics Court, San Diego, California 92121-1122. Simulations investigating the effect of a deuterium-tritium-ice coating on the motion of the gold cone surface in a re-entrant cone-guided fast ignition inertial confinement fusion capsule. United States: N. p., 2007. Web. doi:10.1063/1.2734584.
Pasley, J., Stephens, R., & General Atomics, 3550 General Atomics Court, San Diego, California 92121-1122. Simulations investigating the effect of a deuterium-tritium-ice coating on the motion of the gold cone surface in a re-entrant cone-guided fast ignition inertial confinement fusion capsule. United States. doi:10.1063/1.2734584.
Pasley, J., Stephens, R., and General Atomics, 3550 General Atomics Court, San Diego, California 92121-1122. Tue . "Simulations investigating the effect of a deuterium-tritium-ice coating on the motion of the gold cone surface in a re-entrant cone-guided fast ignition inertial confinement fusion capsule". United States. doi:10.1063/1.2734584.
@article{osti_20975017,
title = {Simulations investigating the effect of a deuterium-tritium-ice coating on the motion of the gold cone surface in a re-entrant cone-guided fast ignition inertial confinement fusion capsule},
author = {Pasley, J. and Stephens, R. and General Atomics, 3550 General Atomics Court, San Diego, California 92121-1122},
abstractNote = {One- and two-dimensional multigroup radiation hydrodynamics simulations have been performed to investigate the motion of the gold plasma generated at the surface of the embedded gold cone in a re-entrant cone-guided inertial confinement fusion capsule. The effect of deuterium-tritium (DT) ice layers, and other possible tampers, of varying thickness, upon the motion of the gold cone plasma has been investigated. The effect of the x-ray drive spectrum incident upon the ice layer is also explored. Ice is shown to tamp the expansion of the gold cone, and whilst denser materials are shown to be more effective in this role, ice does not pollute the ignition region with intermediate-Z ions, which, though preferable to gold contamination, also tend to inhibit the attainment of high fuel-ion temperatures.},
doi = {10.1063/1.2734584},
journal = {Physics of Plasmas},
number = 5,
volume = 14,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • The viability of fast-ignition (FI) inertial confinement fusion hinges on the efficient transfer of laser energy to the compressed fuel via multi-MeV electrons. Preformed plasma due to the laser prepulse strongly influences ultraintense laser plasma interactions and hot electron generation in the hollow cone of an FI target. We induced a prepulse and consequent preplasma in copper cone targets and measured the energy deposition zone of the main pulse by imaging the emitted K{sub {alpha}} radiation. Simulation of the radiation hydrodynamics of the preplasma and particle in cell modeling of the main pulse interaction agree well with the measured depositionmore » zones and provide an insight into the energy deposition mechanism and electron distribution. It was demonstrated that a under these conditions a 100 mJ prepulse eliminates the forward going component of {approx}2-4 MeV electrons.« less
  • A hemispherical conically guided indirectly driven inertial confinement fusion capsule has been considered. The fast ignition of the precompressed capsule driven by one or two laser-accelerated proton beams has been numerically investigated. The energy distribution of the protons is Gaussian with a mean energy of 12 MeV and a full width at half maximum of 1 MeV. A new scheme that uses two laser-accelerated proton beams is proposed. It is found that the energy deposition of 1 kJ provided by a first proton beam generates a low-density cylindrical channel and launches a forward shock. A second proton beam, delayed bymore » a few tens of ps and driving the energy of 6 kJ, crosses the low-density channel and heats the dense shocked region where the ignition of the deuterium-tritium nuclear fuel is achieved. For the considered capsule, this new two-beam configuration reduces the ignition energy threshold to 7 kJ.« less
  • We identify vapor-etched grain boundary grooves on the solid-vapor interface as the main source of surface roughness in the Deuterium-Tritium (D-T) fuel layers which are solidified and then cooled. Current inertial confinement fusion target designs impose stringent limits to the cross sectional area and total volume of these grooves. Formation of these grain boundaries occurs over timescales of hours as the dislocation network anneals, and is inevitable in a plastically deformed material. Therefore, either cooling on a much shorter time scale or a technique that requires no cooling after solidification should be used to minimize the fuel layer surface roughness.
  • Solid deuterium-tritium (D-T) fuel layers for inertial confinement fusion experiments were formed inside of a 2 mm diameter beryllium shell and were characterized using phase-contrast enhanced x-ray imaging. The solid D-T surface roughness is found to be 0.4 {micro}m for modes 7-128 at 1.5 K below the melting temperature. The layer roughness is found to increase with decreasing temperature, in agreement with previous visible light characterization studies. However, phase-contrast enhanced x-ray imaging provides a more robust surface roughness measurement than visible light methods. The new x-ray imaging results demonstrate clearly that the surface roughness decreases with time for solid D-Tmore » layers held at 1.5 K below the melting temperature.« less
  • A high-resolution optical imaging system and custom-designed image analysis software are used to make surface roughness measurements for deuterium-tritium (D-T) solid layers, equilibrated inside a 2-mm-inside-diameter re-entrant copper cylinder. Several experiments are performed that yield D-T layer thicknesses of between 75 and 139 {mu}m, with equilibration temperatures between 17.4 and 18.8 K. A 1024- x 1024-pixel charge-coupled-device imaging camera, coupled with a Maksutov-Cassegrain long-range microscope, produces a 2.5-{mu}m (single-pixel) image resolution. The error function fitting of the image analysis data produces submicron resolution of the layer interior surface finish. The length scale for the cylinder inner bore is just overmore » 6 mm, and the final layer surface roughness for this length ranges from 3- to 1.7-{mu}m root-mean-square. The feasibility is being explored of using these highly uniform and smooth D-T solid layers inside future targets for inertial confinement fusion reactors to produce surface finishes that will meet target design requirements for the National Ignition Facility. Techniques for improving the D-T solid layer surface finish are examined, limitations of the current D-T cell configuration and fuel mix are discussed, and cell configurations for future experiments are described. 10 refs., 8 figs.« less