185 research outputs found
An accelerator based fusion-product source for development of Inertial Confinement Fusion nuclear diagnostics
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The KL Mix Model Applied to Directly Driven Capsules on the Omega Laser
The coefficients of the KL mix model were set by Dimonte to match RT and RM instabilities as measured on the Linear Electric Motor (LEM). The KL mix model has been applied to directly-driven capsule implosions with a variety of laser energies, ablator materials, ablator thicknesses and convergence ratios. The KL calculations nearly match the observed Y{sub DD}, Y{sub DT}, Y{sub P}, T{sub ion} and implosion times for many (but not all) capsules
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An apparatus for the characterization of warm, dense deuterium with inelastic x-ray scattering
Multi-Messenger Measurements of the Static Structure of Shock-Compressed Liquid Silicon at 100 GPa
Ionic structure of high pressure, high temperature fluids is a challenging
theoretical problem with applications to planetary interiors and fusion
capsules. Here we report a multi-messenger platform using velocimetry and
\textit{in situ} angularly and spectrally resolved X-ray scattering to measure
the thermodynamic conditions and ion structure factor of materials at extreme
pressures. We document the pressure, density, and temperature of shocked
silicon near 100 GPa with uncertainties of 6%, 2%, and 20%, respectively. The
measurements are sufficient to distinguish between and rule out some ion
screening models.Comment: Main Paper: 5 pages, 4 figures. Supplementary Material: 9 pages, 8
figure
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Laser-induced Ramp Compression of Tantalum and Iron to Over 300 GPa: EOS and X-ray Diffraction
Terawatt, Joule-Class Pulsed THz Sources from Microchannel Targets
Production of terawatt, joule class THz radiation sources from microchannel
targets driven with 100s of joule, picosecond lasers is reported. THz sources
of this magnitude are useful for non-linear pumping of matter and for charged
particle acceleration and manipulation. Microchannel targets demonstrate
increased conversion efficiency compared to planar foil targets, with laser
energy to THz energy conversion up to 0.9 percent.Comment: 9 pages, 2 figure
Ionization disequilibrium in K- and L-shell ions
Producción CientíficaTime-gated Sc K-shell and Ge L-shell spectra are presented from a range of characterized thermodynamic states spanning ion densities of 1e19-1e20cm-3 and plasma temperatures around 2000eV. For the higher densities studied and temperatures from 1000 to 3000 eV, the Sc and Ge x-ray emission spectra are consistent with steady-state calculations from the modern atomic kinetics model SCRAM. At the lower ion densities achieved through plasma expansion, however, the model calculations require a higher plasma temperature to reproduce the observed Ge spectrum. We attribute this to ionization disequilibrium of the Sc because the ionization time scales exceed the hydrodynamic timescale when the inferred temperatures diverge.This work has been supported by the Research Grant No. PID2019-108764RB-I00 from the Spanish Ministry of Science and Innovation
Experimental observation of open structures in elemental magnesium at terapascal pressures
Investigating how solid matter behaves at enormous pressures, such as those found in the deep interiors of giant planets, is a great experimental challenge. Over the past decade, computational predictions have revealed that compression to terapascal pressures may bring about counter-intuitive changes in the structure and bonding of solids as quantum mechanical forces grow in influence1,2,3,4,5,6. Although this behaviour has been observed at modest pressures in the highly compressible light alkali metals7,8, it has not been established whether it is commonplace among high-pressure solids more broadly. We used shaped laser pulses at the National Ignition Facility to compress elemental Mg up to 1.3 TPa, which is approximately four times the pressure at the Earth’s core. By directly probing the crystal structure using nanosecond-duration X-ray diffraction, we found that Mg changes its crystal structure several times with non-close-packed phases emerging at the highest pressures. Our results demonstrate that phase transformations of extremely condensed matter, previously only accessible through theoretical calculations, can now be experimentally explored
An imaging proton spectrometer for short-pulse laser plasma experiments
Ultra intense short pulse laser pulses incident on solid targets can generate energetic protons. In additions to their potentially important applications such as in cancer treatments and proton fast ignition, these protons are essential to understand the complex physics of intense laser plasma interaction. To better characterize these laser-produced protons, we designed and constructed a novel, spatially imaging proton spectrometer that will not only measure proton energy distribution with high resolution, but also provide its angular characteristics. The information obtained from this spectrometer compliments those from commonly used diagnostics including radiochromic film packs, CR39 nuclear track detectors, and non-imaging magnetic spectrometers. The basic characterizations and sample data from this instrument are presented
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