LLE Review 152

Review 152


This volume of the LLE Review, covering July–September 2017, features "First Observation of Cross-Beam Energy Transfer Mitigation for Direct-Drive Inertial Confinement Fusion Implosions Using Wavelength Detuning at the National Ignition Facility," which reports on the results of experiments conducted at LLE and Lawrence Livermore National Laboratory using detuned laser-source wavelengths of interaction beams over the equatorial region of the target. Wavelength detuning was demonstrated to increase the equatorial region velocity by 16% and to alter the in-flight shell morphology. The experimental observation is consistent with the design prediction of radiation–hydrodynamics simulations that indicate a 10% increase in the average ablation pressure.

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

  • An accompanying article describes two novel target designs: a moderate-adiabat alpha-burning design and a lower-adiabat ignition design for using direct laser ablation (direct drive) at the National Ignition Facility. These target designs are the first to include the physical effects of cross-beam energy transfer with polar direct drive and a wavelength-detuning strategy to reduce scattered-light losses, allowing for ignition-relevant implosion velocities.
  • A process for extracting more dynamic range is described using the linearity of the photostimulated luminescence process to make repeated image-plate scanning a viable technique. A new model for the readout fading of the image plate is introduced, which relates the depth distribution of activated photostimulated luminescence centers within the image plate to the recorded signal. Model parameters are estimated from image-plate scan series for the hard x-ray image-plate diagnostic.
  • Experimental results recorded at The Institute of Optics and LLE for the construction of a time-to-frequency converter that demonstrated using an electro-optic phase modulator as a time lens, allowing the pulse shape in time to be transferred to the frequency domain are discussed. Numerical simulations were used to establish that a time-lens–based system can accurately measure the shape of infrared pulses between 3 ps and 12 ps. A numerical model is also used to determine how such a system can be modified to measure pulses whose width lies in the range of 1 to 30 ps, a range of interest for the OMEGA EP laser.
  • R. Mancini reports on the Ninth Omega Laser Facility Users Group Workshop.
  • This volume concludes with a summary of LLE's Summer School Research Program, the FY17 Laser Facility Report, and the National Laser Users' Facility and External Users' Programs.

Table of Contents