X-ray powder diffraction in reflection geometry on multi-beam kJ-type laser facilities

Time-resolved X-ray diffraction diagnostic development for the National Ignition Facility

We present the development of an experimental platform that can collect four frames of x-ray diffraction data along a single line of sight during laser-driven, dynamic-compression experiments at the National Ignition Facility. The platform is comprised of a diagnostic imager built around ultrafast sensors with a 2-ns integration time, a custom target assembly that serves also to shield the imager, and a 10-ns duration, quasi-monochromatic x-ray source produced by laser-generated plasma. We demonstrate the performance with diffraction data for Pb ramp compressed to 150 GPa and illuminated by a Ge x-ray source that produces ∼7 × 1011, 10.25-keV photons/ns at the 400 μm diameter sample.

Time-resolved near backscatter imaging system on Laser MegaJoule

The newly operating near-backscattering imaging (NBI) system on the Laser MegaJoule (LMJ) is briefly described with emphasis on the temporally resolved measurements and their synchronization with the LMJ laser pulse through target shots taken as part of the diagnostic commissioning campaign. The NBI measures the stimulated Brillouin and Raman scattered light around two quadruplets (one inner and one outer) of the upper LMJ hemisphere. The temporal resolution is achieved with a unique system: a specifically designed wide-open optical lens images 40 points of a diffuser onto an array of optical fibers with the scattered light recorded on a multiplexed photodiode array.