In Fiscal Year 2020 (FY20), Lawrence Livermore National Laboratory’s (LLNL’s) High-Energy-Density Physics (HED) and Indirect Drive Inertial Confinement Fusion (ICF-ID) programs conducted numerous campaigns on the OMEGA and OMEGA-EP (EP) laser systems. This was the 22ndyear of National Lab collaborative experiments at OMEGA since the Nova Laser at LLNL shut down in 1999, building upon prior collaborations. In FY20overall,these LLNL programs led 375target shots, with 166shots using just the OMEGA laser system and209 shots using just the EP laser system. Approximately 34% of the total number of shots (35OMEGA shots and 93EP shots) supported the Indirect Drive Inertial Confinement Fusion Campaign. The remaining 66% (131OMEGA-only shots and 116EP-only shots) were dedicated to experiments for High-Energy-Density Physics.Highlights of the various HED and ICF-ID campaigns are summarized in the following reports.

We introduce a setup to measure high-resolution inelastic x-ray scattering at the High Energy Density scientific instrument at the European X-Ray Free-Electron Laser (XFEL). The setup uses the Si (533) reflection in a channel-cut monochromator and three spherical diced analyzer crystals in near-backscattering geometry to reach a high spectral resolution. An energy resolution of 44 meV is demonstrated for the experimental setup, close to the theoretically achievable minimum resolution. The analyzer crystals and detector are mounted on a curved-rail system, allowing quick and reliable changes in scattering angle without breaking vacuum. The entire setup is designed for operation at 10 Hz, the same repetition rate as the high-power lasers available at the instrument and the fundamental repetition rate of the European XFEL. Among other measurements, it is envisioned that this setup will allow studies of the dynamics of highly transient laser generated states of matter.

Author(s): Kritcher, Andrea L; Swift, Damian C; D¨oppner, Tilo; Bachman, Benjamin; Benedict, Lorin X; Collins, Gilbert W; DuBois, Jonathan L; Elsner, Fred; Fontaine, Gilles; Gaffney, Jim A; Hamel, Sebastien; Jenei, Amy; Johnson, Walter R; Kostinski, Natalie; Kraus, Dominik; MacDonald, Mike; Maddox, Brian; Martin, Madison E; Neumayer, Paul; Nikroo, Abbas; Nilsen, Joseph; Remington, Bruce A; Saumon, Didier; Sterne, Phillip A; Sweet, Wendi; Correa Tedesco, Alfredo A; Whitley, Heather D; Falcone, Roger W; Glenzer, Siegfried H

THE FIRST OBSERVATION OF THE BCC PHASE IN COMPRESSED ALUMINUM1 DANAE POLSIN, T. BOEHLY, G. COLLINS, J. RYGG, S. BURNS, J. DELETTREZ, M. GREGOR, B. HENDERSON, University of Rochester Laboratory for Laser Energetics, D. FRATANDUONO, R. SMITH, R. KRAUS, J. EGGERT, A. JENEI, D. SWIFT, F. COPPARI, P. CELLIERS, Lawrence Livermore National Laboratory, C. MCCOY, Sandia National Laboratory — Ramp compression is used to near isentropically compress Aluminum samples to pressures up to 600 GPa and at temperatures below the melt. Nanosecond in situ X-ray diffraction is performed at University of Rochester’s Laboratory for Laser Energetics and the National Ignition Facility to directly measure the crystal structure at pressures where fcc-hcp and hcp-bcc phase transformations of Al exist. Velocimetry provided the pressure in the Al. The fcc-hcp and hpc-bcc transformations are confirmed experimentally at 240 GPa and 450 GPa, respectively. This is the first experimental evidence of the bcc phase of Al and a confirmation of the fcc-hcp transition previously observed under static compression at 217 GPa. The existence of these solid-solid phase transformations confirms that these transitions occur on the order of tens of nanoseconds time scales.

X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH2 targets on the OMEGA laser facility at the Laboratory for Laser Energetics in Rochester, NY. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Knowledge gained in this experiment shows a promising future for further XRTS measurements on indirectly driven OMEGA targets.

In FY14, LLNL’s High-Energy-Density Physics (HED) and Indirect Drive Inertial Confinement Fusion (ICF-ID) programs conducted several campaigns on the OMEGA laser system and on the EP laser system, as well as campaigns that used the OMEGA and EP beams jointly. Overall these LLNL programs led 324 target shots in FY14, with 246 shots using just the OMEGA laser system, 62 shots using just the EP laser system, and 16 Joint shots using Omega and EP together. Approximately 31% of the total number of shots (62 OMEGA shots, 42 EP shots) shots supported the Indirect Drive Inertial Confinement Fusion Campaign (ICF-ID). The remaining 69% (200 OMEGA shots and 36 EP shots, including the 16 Joint shots) were dedicated to experiments for High- Energy-Density Physics (HED). Highlights of the various HED and ICF campaigns are summarized in the following reports.