LLE Review 114

Review 114


This volume of the LLE Review, covering January–March 2008, features a report on the status of layering cryogenic DT and D2 targets at LLE for inertial confinement fusion (ICF) targets. This critical effort achieves the important milestone of routinely providing cryogenic DT targets that meet the 1.0-µm (rms) OMEGA ice-quality-surface specification. The best D2-ice layers produced so far (rms roughness of 1.1 µm) are approaching the quality typically achieved in DT targets. Efforts to improve the consistency of this process are reported along with investigations supporting the National Ignition Campaign (NIC) studying issues relevant to indirect-drive and direct-drive cryogenic targets.

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

  • Simulations that show an improved laser speckle smoothing scheme that augments the current National Ignition Facility (NIF) 1-D SSD system by using multiple-FM modulators is sufficient for direct-drive-ignition targets and pulse shapes analyzed thus far, and may even allow reducing the bandwidth enough to eliminate the need for dual-tripler frequency conversion on the NIF.
  • Results of time-gated, monoenergetic proton radiography that provides unique measurements of implosion dynamics of spherical targets in direct-drive ICF.
  • Performance of a single-shot cross-correlator based on a pulse replicator with a demonstrated dynamic range higher than 60 dB over a temporal range larger than 200 ps.
  • A novel focal-spot diagnostic developed for OMEGA EP that will be used to characterize on-shot focal spots to support high-quality laser–matter interaction experiments.
  • A systematic study to improve the laser-damage resistance of multilayer high-reflector coatings for use at 351 nm on the OMEGA EP Laser System that lead to exceptional improvement over previous damage thresholds measured at this wavelength.

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