Laue transmission x-ray spectrograph for inertial confinement fusion (ICF) diagnostics

An absolutely calibrated, focusing Laue transmission crystal spectrograph has been developed for inertial confinement fusion (ICF) diagnostics of high-energy x-ray continuum at NOVA. A single flat EddT 020 crystal, 500-μm thick, provides continuous energy coverage over the 5.5–25 keV energy range. The spectrograph is designed with low dispersion and low resolving power E/ΔE of between 10 and 50 for high sensitivity to continuum. Greater resolving power with lower continuum sensitivity is possible by increasing dispersion. The focusing design achieves very low background and provides a compact flat field for coupling to various position sensitive detectors including streak cameras. In addition to EddT, PET 020 has high efficiency in transmission in this energy range and used in the Cauchois geometry achieves high to moderate resolving power that is independent of ICF source size. Initial experiments with gold targets at NOVA with the EddT spectrograph show high sensitivity for single shot recording of continuum and gold L lines on Kodak DEF film. Factors affecting instrument design, resolving power, and sensitivity will be discussed.