The National Ignition Facility (NIF) Opacity Spectrometer (OpSpec) is a modular spectrometer designed initially for opacity experiments on NIF. The design of the OpSpec is presented in light of the requirements and constraints. Potential dispersing elements and detector configurations are presented, and the advantages and disadvantages of each configuration are discussed. The full OpSpec design covers the energy range from approximately 550 eV to 2 keV. The energy resolution of the OpSpec is E/ΔE > 500. Applications of the OpSpec are discussed, including relevant astrophysical applications for NIF experiments, and will compliment recently published work on the Z machine. (Bailey, et al., Nature 517, 56-59 (2015).) This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy.
For over fifteen years astronomers at the University of Maryland and theorists and experimentalists at LLNL have investigated the origin and dynamics of the famous Pillars of the Eagle Nebula, and similar parsec-scale structures at the boundaries of HII regions in molecular hydrogen clouds. Eagle Nebula was selected as one of the National Ignition Facility (NIF) Science programs, and has been awarded four NIF shots to study the cometary model of pillar formation. These experiments require a long-duration drive, 30 ns or longer, to drive deeply nonlinear ablative hydrodynamics. The NIF shots will feature a new long-duration x-ray source prototyped at the Omega EP laser, in which multiple hohlraums are driven with UV light in series for 10 ns each and reradiate the energy as an extended x-ray pulse. The new source will be used to illuminate a science package with directional radiation mimicking a cluster of stars. The scaled Omega EP shots tested whether a multi-hohlraum concept is viable — whether earlier time hohlraums would degrade later time hohlraums by preheat or by ejecting ablated plumes that would deflect the later beams. The Omega EP shots illuminated three 2.8 mm long by 1.4 mm diameter Cu hohlraums for 10 ns each with 4.3 kJ per hohlraum. At NIF each hohlraum will be 4 mm long by 3 mm in diameter and will be driven with 80 kJ per hohlraum.
X-ray imaging is integral to the measurement of the properties of hot plasmas. To this end, a suite of gated x-ray imagers
have been developed for use in a wide range of experiments at the National Ignition Facility (NIF). These instruments
are sensitive to x-rays over the range of 0.7-90keV and can acquire images at 20ps intervals for source intensities
ranging over several orders of magnitude. We review the design, technology, and construction of these instruments and
present recent results obtained from NIF experiments in which gated x-ray imagers have played a key role.
The radiation environment associated with Inertial Confinement Fusion (ICF) experiments presents unique challenges
for x-ray imaging. We report on the performance of gated imagers that have been optimized for this harsh environment
and describe diagnostics to be deployed in the near future that will provide x-ray images of imploding ICF capsules in
the presence of backgrounds associated with neutron yields above 1016. Such images will provide crucial data that will
enable even higher neutron yields and successful ignition.