LLE Review 162

Highlights

This volume of LLE Review 162, covering the period January–March 2020, is sectioned among research areas at LLE and external users of the Omega Laser Facility. Articles appearing in this volume are the principal summarized results of long-form research articles. Readers seeking a more-detailed account of research activities are invited to seek out the primary materials appearing in print, detailed in the publications and presentations section at the end of this volume.

Highlights of research presented in this volume include the following:

V. N. Goncharov et al. propose a new class of ignition designs for inertial confinement fusion. Hydrodynamic simulations demonstrate the feasibility of the new designs and the advantages and disadvantages of the concept compared with more-traditional ICF designs are discussed (p. 47).
S. P. Regan et al. describe quantitatively measuring the amount of hot-spot mix mass in laser-direct-drive inertial confinement fusion implosions of a plastic spherical shell surrounding a layer of cryogenic deuterium–tritium for the first time (p. 50).
D. Turnbull et al. use the laser-plasma simulation environment code to determine a scaling of absorption versus two-plasmon–decay threshold parameter (p. 53). This scaling will help rectify discrepancies that appear at increased intensities.
J. R. Rygg et al. report details of an experimental platform implemented at the National Ignition Facility to obtain in-situ powder diffraction data from solids dynamically compressed to extreme pressures (p. 56).
A. K. Schwemmlein et al. induce the target normal sheath acceleration mechanism in deuterated metal foils at intensities close to 1019 W/cm2 using the Multi-Terawatt Laser System (p. 59). It is reported that the total yield depends critically on the surface loading, while the shape of the spectrum is independent of it.
J. Hinz et al. find the insulator-to-metal transition of warm dense fluid hydrogen over a pressure range from 50 to 300 GPa by calculating optical and structural properties from quantum-molecular-dynamics simulations (p. 62).
D. I. Mihaylov, V. V. Karasiev, and S. X. Hu present theoretical grounds of thermal hybrid exchange-correlation functionals within the generalized Mermin–Kohn–Sham scheme for an improved description of warm dense matter (p. 64).
D. H. Barnak et al. demonstrate a cubic-spline interpolation that provides an alternative analytical way of solving for the temporally and spectrally resolved x-ray flux with no free parameters, assumptions about the geometry, or material of the emitting plasma (p. 67).
K. A. Bauer et al. present the results of early measurements taken with the full-beam-in-tank diagnostic (p. 71). The diagnostic gives new insight into the ability of the OMEGA Laser System to provide uniform fluence profiles that are consistent across all 60 beams in the laser.
J. B. Oliver et al. develop an optical component with a wavelength-scale, stepped-surface relief (p. 74). The methods used and metrology results are shown.iv
B. N. Hoffman et al. investigate the modifications of multilayer dielectric gratings arising from laser-induced damage using 0.6‑ps and 10-ps laser pulses at 1053 nm to better understand the damage-initiation mechanisms (p. 77).
J. U. Wallace et al. describe high laser-induced–damage threshold glassy liquid crystal materials for large-aperture polarization control/beam-smoothing optics that could replace current low-molar-mass liquid crystal devices on the OMEGA Laser System (p. 81).
K. R. P. Kafka et al. investigate the interactions of microparticles of different materials located on the surface of a multilayer dielectric mirror with intense 1053-nm laser pulses of varying fluence and duration (10 ps and 0.6 ps) (p. 84).
T. Z. Kosc et al. present a novel experimental design that enabled the determination of measurement artifacts, including polarization rotation of the pump and/or scattered light propagating through the sample and the contribution of additional overlapping phonon modes (p. 87).
A. A. Kozlov et al. report the results of a damage-testing campaign that monitored representative pulse compression grating samples that were positioned inside the OMEGA EP grating compressor vacuum chamber during normal operation (p. 91).
J. Puth et al. summarize operations of the Omega Laser Facility during the second quarter of FY20 (p. 95).