Investigation of Optical Smoothing Techniques on Multiple Beams

ORAL

Abstract

Intense laser hotspots/speckles are a concern on high power laser facilities due to their role in seeding unwanted instabilities such as SBS (Stimulated Brillouin Scattering). Optical smoothing techniques such as SSD1,2 (Smoothing by Spectral Dispersion) are used to better homogenize the laser focal spot intensity pattern on the time scale of the instabilities. Here we report on a project that examines the combined laser electric fields of overlapping NIF beams including the effects of SSD, polarization rotation, and beat waves3. An overview of the simulation technique will be presented with updates on characterizing various optical smoothing techniques.

 1)François Walraet, Guy Bonnaud, and Gilles Riazuelo , "Velocities of speckles in a smoothed laser beam propagating in a plasma", Physics of Plasmas 8, 4717-4720 (2001) https://doi.org/10.1063/1.1405128

2)J. Garnier and L. Videau, "Statistical analysis of the sizes and velocities of laser hot spots of smoothed beams", Physics of Plasmas 8, 4914-4924 (2001) https://doi.org/10.1063/1.1405127

3)P. Michel, W. Rozmus, E. A. Williams, L. Divol, R. L. Berger, S. H. Glenzer, and D. A. Callahan , "Saturation of multi-laser beams laser-plasma instabilities from stochastic ion heating", Physics of Plasmas 20, 056308 (2013) https://doi.org/10.1063/1.4802828

*This document was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor Lawrence Livermore National Security, LLC, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or Lawrence Livermore National Security, LLC. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or Lawrence Livermore National Security, LLC, and shall not be used for advertising or product endor

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Presenters

  • Joshua Ludwig

    • Lawrence Livermore Natl Lab
    • Lawrence Livermore National Laboratory

Authors

  • Joshua Ludwig

    • Lawrence Livermore Natl Lab
    • Lawrence Livermore National Laboratory

  • Pierre A Michel

    • Lawrence Livermore Natl Lab
    • LLNL