Expanded higher energy channel for the National Ignition Facility’s soft x-ray opacity spectrometer (OpSpec)

The National Ignition Facility's soft x-ray opacity spectrometer (OpSpec) currently records time-integrated spectra from ∼550 to 2000 eV. To accomplish this, two elliptical acid-phthalate crystals with different shapes are used together. They are called the low energy and standard energy OpSpec channels and they span roughly 550-1000 and 1000-2000 eV, respectively. Replacing the crystal in the low-energy mount with a PET crystal gives a new higher-energy channel. Slight modifications to the shape of the ellipse give the new channel an energy range of 1750-3000 eV. The new geometry, testing results, and data from the NIF opacity campaign are discussed in this article.