Narrowband radiography of ICF implosions on the NIF using the Crystal Backlighter Imager*

The Crystal Backlighter Imager (CBI) is a quasi-monochromatic, near-normal incidence, spherically-bent crystal imager at the NIF. Being narrowband (a few eV), this diagnostic mitigates self-emission from the capsule hotspot, allowing ICF capsule implosions to be radiographed significantly closer to stagnation than the previous broadband pinhole-based area-backlighter platform. CBI can now utilize the Single Line of Sight (SLOS1) camera, which couples pulse-dilation technology to a hybrid-CMOS detector to allow capturing of up to 4 rapidly gated (~50ps) frames. Using only a single crystal, CBI with SLOS is now capable of obtaining 4 high temporal and spatial resolution radiographs on a single NIF shot. Recently, CBI with SLOS produced 4 radiographs during the final ~300ps of an indirect-drive ICF implosion in which a high-density-carbon capsule with a tritium-hydrogen-deuterium ice layer was driven by a 1MJ laser pulse. Results from this experiment will be presented, together with efforts to increase the backlighter efficiency of the current 11.6keV CBI system and develop lower-energy CBI configurations. Release# LLNL-ABS-753490.