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Opacity measurements are being carried out at the Z-facility at Sandia National Laboratories and at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. The current soft x-ray Opacity Spectrometer (OpSpec) used on the NIF uses two elliptically bent crystals in time-integrated mode on either an image plate or a film. Plans are under way to expand these opacity measurements into a mode of time-resolved detection, called OpSpecTR. Previously, considerations for the available hCMOS detector size and photometrics led to a crystal geometry redesign and the use of a grazing angle x-ray mirror. The mirror acts as a low-pass x-ray energy filter, reducing the contribution of higher energy x rays. The first tests of the mirror and the crystal for OpSpecTR are presented here. The size of the mirror reflection and the reflectivity is tested using a Manson x-ray source. The mirror coupled with the new elliptical crystal shape demonstrates OpSpecTR's spectral coverage. The results from the x-ray optics performance testing are shown along with the intended design. [ABSTRACT FROM AUTHOR]

X-ray polarization-splitting crystals separate incident x rays into two components with perpendicular polarization by Bragg reflections at 45° from paired sets of internal planes. Here, the polarization-splitting properties of a germanium crystal are verified using incompletely polarized synchrotron radiation. Cleaner data would have come from a beam with a higher degree of polarization, which is achievable with small changes in the experimental geometry. [ABSTRACT FROM AUTHOR]

The single-crystal spectropolarimeter envisioned by Baronova and Stepanenko splits an incident x-ray beam into two beams with mutually orthogonal linear polarizations by using simultaneous reflections at the perfectly polarizing 45° Bragg angle on certain pairs of internal planes in hexagonal or cubic crystals. These planes intersect along a threefold symmetry axis, making a 120° angle with each other, and are typically symmetric with respect to the crystal surface. In practice, the wavelength of the diagnostic x-ray lines does not exactly satisfy Bragg's law for the crystal in the ideal polarizing orientation, so the extinction of reflections is incomplete. Accepting this limitation, this paper shows that for cubic crystals, other pairs of internal planes exist that satisfy the polarization requirements approximately. Typically, they are accessible from the perfect polarization-splitting geometry by small rotations of the crystal. This paper includes examples of such planes for cubic crystals with {110} and {211} surface cuts. [ABSTRACT FROM AUTHOR]

X-ray films remain a key asset for high-resolution x-ray spectral imaging in high-energy-density experiments conducted at the National Ignition Facility (NIF). The soft x-ray Opacity Spectrometer (OpSpec) fielded at the NIF has an elliptically shaped crystal design that measures x rays in the 900–2100 eV range and currently uses an image plate as the detecting medium. However, Agfa D4 and D3sc x-ray films' higher spatial resolution provides increased spectral resolution to the data over the IP-TR image plates, driving the desire for regular use of x-ray film as a detecting medium. The calibration of Agfa D4 x-ray film for use in the OpSpec is communicated here. These calibration efforts are vital to the accuracy of the NIF opacity measurements and are conducted in a previously un-studied x-ray energy range under a new film development protocol required by NIF. The absolute response of Agfa D4 x-ray film from 705 to 4620 eV has been measured using the Nevada National Security Site Manson x-ray source. A broader range of energies was selected to compare results with previously published data. The measurements were taken using selected anodes, filters, and applied voltages to produce well-defined energy lines. [ABSTRACT FROM AUTHOR]

Hexagonal and cubic crystals contain paired sets of internal planes that reflect the linearly polarized components of certain x rays into two separate, perpendicular directions. For the cubic crystals, two distinct crystal orientations provide the same polarization-splitting geometry. One of the orientations may have advantages for plasma spectroscopy by suppressing unwanted reflections. This paper demonstrates the two orientations with a germanium crystal and K characteristic lines from copper and zirconium. [ABSTRACT FROM AUTHOR]