Shell stability and conditions analyzed using a new method of extracting shell areal density maps from spectrally resolved images of direct-drive inertial confinement fusion implosions
- Univ. of Nevada, Reno, NV (United States). Physics Department; Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Univ. of Nevada, Reno, NV (United States). Physics Department
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Rochester, NY (United States). Lab. for Laser Energetics
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. These 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 (Ne) = 8.5 × 1024 ± 2.5 × 1024 cm–3, and average areal density <ρR> = 86 ± 7 mg/cm2. 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.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Lawrence Livermore National Lab., Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- NA0000859; NA0002267; AC52-06NA25396; AC52-07NA27344
- OSTI ID:
- 1240381
- Alternate ID(s):
- OSTI ID: 1235975; OSTI ID: 1281660
- Report Number(s):
- LA-UR-14-29462; LLNL-JRNL-696064; PHPAEN
- Journal Information:
- Physics of Plasmas, Vol. 23, Issue 1; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Impact of 3D effects on the characteristics of a multi-monochromatic x-ray imager
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journal | January 2019 |
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Related Subjects
direct-drive ICF
mix width
hydrodynamic instability
shell areal density modulations
x-ray absorption spectroscopy
shell breakup
shell stability
70 PLASMA PHYSICS AND FUSION
42 ENGINEERING
direct-drive
OMEGA
shell-fuel mix width
shell pL modulations
Ti-doped shells
shell breakup and stability