LLE Review 156

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Highlights

This volume of the LLE review covering July–September 2018 features “Resonance Absorption of a Broadband Laser Pulse,” which reports on the reduction of resonance absorption of an incoherent infrared broadband pulse compared with a monochromatic pulse. In the linear regime where the ponderomotive response of ions is neglected, bandwidth has little effect on resonance absorption; in the nonlinear regime, however, bandwidth suppresses enhanced absorption resulting from the electromagnetic decay instability. These simulations show that, regardless of bandwidth, an inertial confinement fusion implosion will confront at least linear levels of resonance absorption.

Additional highlights of research presented in this issue include the following:

• A high-spatial-resolution imaging system based on pump–probe and photon-counting techniques for detecting nanoparticles in a thin-film coating made of HfO₂ and SiO₂ layers is presented. The system confirmed submicrometer spatial resolution in both absorption and luminescence imaging modes.
• A nuclear experiment platform developed on the OMEGA EP short-pulse laser system is introduced. Energetic ions generated in the “converter” target via the target normal sheath acceleration process are sent through a secondary “physics” target in which nuclear reactions occur to produce neutrons and other charged particles. First experiments to validate the performance of this setup studied the d(d,n)3He and 9Be(d,n)10B reactions. This experimental platform is especially suitable for survey-type studies of nuclear reactions and for reactions involving rare or radioactive ions like tritium.
• The measurement of rapid evolution of electron density and temperature in a laser-produced underdense plasmas using collective Thomson scattering is reported. A pulse-front–tilt compensated streaked spectrometer enables picosecond time-resolution measurement of plasma-wave dynamics. The Thomson-scattering spectra were compared with theoretical calculations of the fluctuation spectrum.
• M. Koepke reports on the Tenth Omega Laser Facility Users Group Workshop.
• This volume concludes with a summary of LLE’s Summer School Research Program, the FY18 Laser Facility Report, and the National Laser Users’ Facility and External Users’ Programs.