This schematic diagram of the experimental layout at the Omega Laser Facility shows the glass sample as a vertical dashed line segment in front of the spherical mirror on the right. The diameter gold sphere is irradiated by 54 beams and emits nearly isotropic x rays. The probe beam passes through the sample twice. The transmitted beam and a reference picked off from B30 are relayed to a streak camera via optical fibers.
Panels (a) and (c) show the time-resolved incident (dashed) and (two-pass) transmitted (solid) powers, in relative units. Panels (b) and (d) show the two-pass transmission of the sample (black), and the x-ray fluence at the sample. The top panels (a) and (b) are for the shot, while the bottom panels are for the shot.
Panel (a) shows the recombination time-collisional rate parameter space for the absorption model, as constrained by the Omega data. The curve labeled “low-10%” gives the values that produce 10% absorption for the low-energy shot. All values below and to the left of this curve are consistent with the low-energy data. The “high-15%” and “high-25%” curves correspond to the minimum and maximum absorption values consistent with the high-energy shot data. The filled region shows the range of values of and allowed by the Omega data. Panel (b) shows the predicted absorption values of x-ray shields for , 192 beam NIF hohlraum shots, using the parameter constraints shown in panel (a). The lines and shading are the same as for panel (a). The range of predicted absorption values is 2%–11%.
Omega experimental parameters and data summary.
NIF Hohlraum parameters and predicted absorptivities.
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