National Ignition Campaign Milestone Achieved
2006:
Scientists at LLE and Lawrence Livermore National Laboratory completed a National Ignition Campaign milestone on 17 August 2006 dealing with hohlraum energetics experiments with elliptical phase plates. A set of 43 elliptical phase plates (E-IDI300) were designed and manufactured for these OMEGA experiments. Seven scale-1, thin-walled, gold hohlraums were irradiated with 40 beams smoothed with E-IDI-300 phase plates. Several gas fills were investigated. High-Zdopants were introduced into the gas fills to reduce hard x-ray production and laser scattering levels. The hohlraum energetics were measured for a 13.5-kJ-shaped laser pulse (PS26) with the following diagnostics: Dante, full-aperture backscatter, near-backscatter imaging, gated hard x-ray imaging, gated soft x-ray imaging, and the hard x-ray detector. The peak radiation temperature Tr inferred from the measured levels of the x-ray flux increased by 17 eV when the laser beams were smoothed with phase plates. The improved coupling was a consequence of reduced laser-scattering losses.
