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Impact of asymmetries on fuel performance in inertial confinement fusion
摘要： Low-mode asymmetries prevent effective compression, con?nement, and heating of the fuel in inertial con?nement fusion (ICF) implosions, and their control is essential to achieving ignition. Ion temperatures (Tion) in ICF experiments are inferred from the broadening of primary neutron spectra. Directional motion (?ow) of the fuel at burn also impacts broadening and will lead to arti?cially in?ated “Tion” values. Flow due to low-mode asymmetries is expected to give rise to line-of-sight variations in measured Tion. We report on intentionally asymmetrically driven experiments at the OMEGA laser facility designed to test the ability to accurately predict and measure line-of-sight differences in apparent Tion due to low-mode asymmetry-seeded ?ows. Contrasted to CHIMERA and xRAGE simulations, the measurements demonstrate how all asymmetry seeds have to be considered to fully capture the ?ow ?eld in an implosion. In particular, ?ow induced by the stalk that holds the target is found to interfere with the seeded asymmetry. A substantial stalk-seeded asymmetry in the areal density of the implosion is also observed.
关键词： CHIMERA,xRAGE simulations,OMEGA laser facility,inertial con?nement fusion,ion temperatures,low-mode asymmetries
更新于2025-09-23 15:21:21
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Optimized x-ray sources for x-ray diffraction measurements at the Omega Laser Facility
摘要： The use of x-ray diffraction (XRD) measurements in laser-driven dynamic compression experiments at high-power laser facilities is becoming increasingly common. Diffraction allows one to probe in situ the transformations occurring at the atomic level at extreme conditions of pressure, temperature, and time scale. In these measurements, the x-ray source is generated by irradiation of a solid foil. Under certain laser drive conditions, quasimonochromatic He-α radiation is generated. Careful analysis of the x-ray source plasma spectra reveals that this radiation is not a single line emission and that monochromaticity is highly dependent on the laser irradiance. In this work, we analyze how the spectra emitted by laser-irradiated copper, germanium, and iron foils at the Omega Laser vary depending on different laser drive conditions and discuss the implications for XRD experiments.
关键词： laser irradiance,x-ray diffraction,Omega Laser Facility,quasimonochromatic He-α radiation,laser-driven dynamic compression
更新于2025-09-12 10:27:22