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Title: Argon X-ray line imaging - A compression diagnostic for inertial confinement fusion targets

Abstract

The paper describes argon X-ray line imaging which measures the compressed fuel volume directly by forming one-dimensional images of X-rays from argon gas seeded into the D-T fuel. The photon energies of the X-rays are recorded on the film of a diffraction-crystal spectrograph. Neutron activation, which detects activated nuclei produced by the interaction of 14-MeV neutrons with the selected materials of the target, allows to calculate the final compressed fuel density using a hydrodynamics simulation code and the knowledge of the total number of activated nuclei and the neutron yield. Argon X-ray appears to be a valid fuel-compression diagnostic for final fuel densities in the range of 10 to 50 times liquid D-T density.

Authors:
Publication Date:
Research Org.:
California, University, Livermore, Calif.
OSTI Identifier:
5258824
Resource Type:
Journal Article
Resource Relation:
Journal Name: Energy Technol. Rev.; (United States)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; PLASMA DIAGNOSTICS; ACTIVATION ANALYSIS; ARGON; COMPRESSION; DEUTERIUM; HYDROGEN FUELS; ION TEMPERATURE; LASER TARGETS; NEUTRON REACTIONS; PLASMA DENSITY; PULSES; SHIVA FACILITY; THERMONUCLEAR REACTORS; X RADIATION; BARYON REACTIONS; CHEMICAL ANALYSIS; ELECTROMAGNETIC RADIATION; ELEMENTS; FLUIDS; FUELS; GASES; HADRON REACTIONS; HYDROGEN ISOTOPES; IONIZING RADIATIONS; ISOTOPES; LIGHT NUCLEI; NONMETALS; NUCLEAR REACTIONS; NUCLEI; NUCLEON REACTIONS; ODD-ODD NUCLEI; RADIATIONS; RARE GASES; STABLE ISOTOPES; SYNTHETIC FUELS; TARGETS 700102* -- Fusion Energy-- Plasma Research-- Diagnostics

Citation Formats

Koppel, L.N.. Argon X-ray line imaging - A compression diagnostic for inertial confinement fusion targets. United States: N. p., 1980. Web.
Koppel, L.N.. Argon X-ray line imaging - A compression diagnostic for inertial confinement fusion targets. United States.
Koppel, L.N.. 1980. "Argon X-ray line imaging - A compression diagnostic for inertial confinement fusion targets". United States. doi:.
@article{osti_5258824,
title = {Argon X-ray line imaging - A compression diagnostic for inertial confinement fusion targets},
author = {Koppel, L.N.},
abstractNote = {The paper describes argon X-ray line imaging which measures the compressed fuel volume directly by forming one-dimensional images of X-rays from argon gas seeded into the D-T fuel. The photon energies of the X-rays are recorded on the film of a diffraction-crystal spectrograph. Neutron activation, which detects activated nuclei produced by the interaction of 14-MeV neutrons with the selected materials of the target, allows to calculate the final compressed fuel density using a hydrodynamics simulation code and the knowledge of the total number of activated nuclei and the neutron yield. Argon X-ray appears to be a valid fuel-compression diagnostic for final fuel densities in the range of 10 to 50 times liquid D-T density.},
doi = {},
journal = {Energy Technol. Rev.; (United States)},
number = ,
volume = ,
place = {United States},
year = 1980,
month = 1
}
  • A new technique for diagnosing compression in multiple regions of inertial confinement fusion targets is discussed. This diagnostic uses knock-on deuterons and protons that have been elastically scattered by 14.1 MeV deuterium-tritium (DT) fusion neutrons. The target is composed of three different materials: DT gas contained in a plastic shell overcoated by deuterated plastic. The effect on the knock-on deuteron spectrum of mixing of these layers from hydrodynamic instabilities is also discussed. (c) 2000 American Institute of Physics.
  • We present scaled demonstrations of backlighter sources, emitting bremsstrahlung x rays with photon energies above 75 keV, that we will use to record x-ray Compton radiographic snapshots of cold dense DT fuel in inertial confinement fusion implosions at the National Ignition Facility (NIF). In experiments performed at the Titan laser facility at Lawrence Livermore National Laboratory, we measured the source size and the bremsstrahlung spectrum as a function of laser intensity and pulse length from solid targets irradiated at 2x10{sup 17}-5x10{sup 18} W/cm{sup 2} using 2-40 ps pulses. Using Au planar foils we achieved source sizes down to 5.5 {mu}mmore » and conversion efficiencies of about 1x10{sup -13} J/J into x-ray photons with energies in the 75-100 keV spectral range. We can now use these results to design NIF backlighter targets and shielding and to predict Compton radiography performance as a function of the NIF implosion yield and associated background.« less
  • The use of measured spectra of secondary fusion protons for studying physical characteristics of D{sub 2}-filled inertial confinement fusion capsules is described theoretically and demonstrated with data from implosions in the OMEGA 60-beam laser facility. Spectra were acquired with a magnet-based charged-particle spectrometer and with a range-filter-based spectrometer utilizing filters and CR39 nuclear track detectors. Measurement of mean proton energy makes possible the study of a capsule's total areal density ({rho}R), since that is what affects the energy loss suffered by protons as they pass through fuel and shell while leaving the capsule. Details of specific shots will be presented.more » It is also shown that similar techniques should prove useful for diagnosis of future experiments with cryogenic D{sub 2}-filled capsules.« less
  • A gated x-ray detector is under development for use at the National Ignition Facility that is intended to provide plasma emission images in the presence of neutron yields up to 10{sup 15} expected during inertial confinement fusion experiments with layered cryogenic targets. These images are expected to provide valuable time-resolved measurements of core and fuel symmetries. Additional capabilities of this instrument will include the ability to make spatially resolved electron temperature measurements. A description of this instrument and its operation is given with emphasis on features that differentiate it from previous designs.
  • Pinhole imaging of the neutron production in laser-driven inertial confinement fusion experiments can provide important information about the performance of various capsule designs. This requires the development of systems capable of spatial resolutions on the order of 5 {mu}m or less for source strengths of 10{sup 15} and greater. We have initiated a program which will lead to the achievement of such a system to be employed at the National Ignition Facility (NIF) facility. Calculated neutron output distributions for various capsule designs will be presented to illustrate the information which can be gained from neutron imaging and to demonstrate themore » requirements for a useful system. We will describe the lines-of-sight available at NIF for neutron imaging and explain how these can be utilized to reach the required parameters for neutron imaging. We will describe initial development work to be carried out at the Omega facility and the path which will lead to systems to be implemented at NIF. Beginning this year, preliminary experiments will be aimed at achieving resolutions of 30--60 {mu}m for direct-drive capsules with neutron outputs of about 10{sup 14}. The main thrust of these experiments will be to understand issues related to the fabrication and alignment of small diameter pinhole systems as well as the problems associated with signal-to-background ratios at the image plane. Subsequent experiments at Omega will be described. These efforts will be aimed at achieving resolutions of about 10 {mu}m. Proposed developments for new imaging systems as well as further refinement of pinhole techniques will be presented.« less