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Title: Multispectral X-ray Imagaing for Core Temperature and Density Maps Retrieval in Direct Drive Implosions

Abstract

We report on the experiments aimed at obtaining core temperature and density maps in direct drive implosions at the OMEGA Laser Facility using multi-monochromatic X-ray imagers. These instruments use an array of pinholes and a flat multilayer mirror to provide unique multi-spectral images distributed over a wide spectral range. Using Argon as a dopant in the DD-filled plastic shells produces emission images in the Ar He-b and Ly-b spectral regions. These images allow the retrieval of temperature and density maps of the plasma. We deployed three identical multi-monochromatic X-ray imagers in a quasi-orthogonal line-of-sight configuration to allow tomographic reconstruction of the structure of the imploding core.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
889439
Report Number(s):
UCRL-CONF-221179
TRN: US200619%%562
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: High Temperature Plasma Diagnostics, Williamsburg, VA, United States, May 07 - May 11, 2006
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; ARGON; CONFIGURATION; IMPLOSIONS; LASERS; MIRRORS; PLASMA; PLASMA DIAGNOSTICS; PLASTICS

Citation Formats

Tommasini, R, Koch, J A, Izumi, N, Welser, L A, Mancini, R C, Delettrez, J, Regan, S, and Smalyuk, V. Multispectral X-ray Imagaing for Core Temperature and Density Maps Retrieval in Direct Drive Implosions. United States: N. p., 2006. Web.
Tommasini, R, Koch, J A, Izumi, N, Welser, L A, Mancini, R C, Delettrez, J, Regan, S, & Smalyuk, V. Multispectral X-ray Imagaing for Core Temperature and Density Maps Retrieval in Direct Drive Implosions. United States.
Tommasini, R, Koch, J A, Izumi, N, Welser, L A, Mancini, R C, Delettrez, J, Regan, S, and Smalyuk, V. Wed . "Multispectral X-ray Imagaing for Core Temperature and Density Maps Retrieval in Direct Drive Implosions". United States. doi:. https://www.osti.gov/servlets/purl/889439.
@article{osti_889439,
title = {Multispectral X-ray Imagaing for Core Temperature and Density Maps Retrieval in Direct Drive Implosions},
author = {Tommasini, R and Koch, J A and Izumi, N and Welser, L A and Mancini, R C and Delettrez, J and Regan, S and Smalyuk, V},
abstractNote = {We report on the experiments aimed at obtaining core temperature and density maps in direct drive implosions at the OMEGA Laser Facility using multi-monochromatic X-ray imagers. These instruments use an array of pinholes and a flat multilayer mirror to provide unique multi-spectral images distributed over a wide spectral range. Using Argon as a dopant in the DD-filled plastic shells produces emission images in the Ar He-b and Ly-b spectral regions. These images allow the retrieval of temperature and density maps of the plasma. We deployed three identical multi-monochromatic X-ray imagers in a quasi-orthogonal line-of-sight configuration to allow tomographic reconstruction of the structure of the imploding core.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Apr 26 00:00:00 EDT 2006},
month = {Wed Apr 26 00:00:00 EDT 2006}
}

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  • We report on the experiments aimed at obtaining core temperature and density maps in direct drive implosions at the Omega laser facility using multimonochromatic x-ray imagers. These instruments use an array of pinholes and a flat multilayer mirror to provide unique multispectral images distributed over a wide spectral range. Using argon as a dopant in the direct-drive filled plastic shells produces emission images in the Ar He-{beta} and Ly-{beta} spectral regions. These images allow the retrieval of temperature and density maps of the plasma. We deployed three identical multimonochromatic x-ray imagers in a quasiorthogonal line-of-sight configuration to allow tomographic reconstructionmore » of the structure of the imploding core.« less
  • We have performed an experiment using controlled drive asymmetry in order to explore the relationship between asymmetry and mix. It is seen that X rays image the shell material of an ICF implosion; knowledge of the burning core requires high-resolution neutron images. It is only recently that this has become a practical reality. We present results of asymmetric implosions (spherical, prolate, and oblate), using a pinhole neutron imaging system. A reconstruction technique is demonstrated that increases resolution by mathematical means.2 Simulations are used to show reliability of the technique. The results are compared to three-dimensional information from multiple X-ray cameramore » views, and to experimentally achieved beam symmetry.« less
  • In warm target direct-drive inertial confinement fusion implosion experiments performed at the OMEGA laser facility, plastic micro-balloons doped with a titanium tracer layer in the shell and filled with deuterium gas were imploded using a low-adiabat shaped laser pulse. Continuum radiation emitted in the core is transmitted through the tracer layer and the resulting spectrum recorded with a gated multi-monochromatic x-ray imager (MMI). Titanium K-shell line absorption spectra observed in the data are due to transitions in L-shell titanium ions driven by the backlighting continuum. The MMI data consist of an array of spectrally resolved images of the implosion. Thesemore » 2-D space-resolved titanium spectral features constrain the plasma conditions and areal density of the titanium doped region of the shell. The MMI data were processed to obtain narrow-band images and space resolved spectra of titanium spectral features. Shell areal density maps, ρL(x,y), extracted using a new method using both narrow-band images and space resolved spectra are confirmed to be consistent within uncertainties. We report plasma conditions in the titanium-doped region of electron temperature (Te) = 400 ± 28 eV, electron number density (N e) = 8.5 × 10 24 ± 2.5 × 10 24 cm –3, and average areal density = 86 ± 7 mg/cm 2. Fourier analysis of areal density maps reveals shell modulations caused by hydrodynamic instability growth near the fuel-shell interface in the deceleration phase. We observe significant structure in modes l = 2–9, dominated by l = 2. We extract a target breakup fraction of 7.1 ± 1.5% from our Fourier analysis. Furthermore, a new method for estimating mix width is evaluated against existing literature and our target breakup fraction. We estimate a mix width of 10.5 ±1 μm.« less
  • In warm target direct-drive inertial confinement fusion implosion experiments performed at the OMEGA laser facility, plastic micro-balloons doped with a titanium tracer layer in the shell and filled with deuterium gas were imploded using a low-adiabat shaped laser pulse. Continuum radiation emitted in the core is transmitted through the tracer layer and the resulting spectrum recorded with a gated multi-monochromatic x-ray imager (MMI). Titanium K-shell line absorption spectra observed in the data are due to transitions in L-shell titanium ions driven by the backlighting continuum. The MMI data consist of an array of spectrally resolved images of the implosion. Thesemore » 2-D space-resolved titanium spectral features constrain the plasma conditions and areal density of the titanium doped region of the shell. The MMI data were processed to obtain narrow-band images and space resolved spectra of titanium spectral features. Shell areal density maps, ρL(x,y), extracted using a new method using both narrow-band images and space resolved spectra are confirmed to be consistent within uncertainties. We report plasma conditions in the titanium-doped region of electron temperature (Te) = 400 ± 28 eV, electron number density (N e) = 8.5 × 10 24 ± 2.5 × 10 24 cm –3, and average areal density = 86 ± 7 mg/cm 2. Fourier analysis of areal density maps reveals shell modulations caused by hydrodynamic instability growth near the fuel-shell interface in the deceleration phase. We observe significant structure in modes l = 2–9, dominated by l = 2. We extract a target breakup fraction of 7.1 ± 1.5% from our Fourier analysis. Furthermore, a new method for estimating mix width is evaluated against existing literature and our target breakup fraction. We estimate a mix width of 10.5 ±1 μm.« less